Microorganisms important in livestock products

Microorganisms causing spoilage of meat
and meat products, eggs and poultry
Dr Ravi Kant Agrawal, MVSc, PhD
Senior Scientist (Veterinary Microbiology)
Food Microbiology Laboratory
Division of Livestock Products Technology
ICAR-Indian Veterinary Research Institute
Izatnagar 243122 (UP) India

Acinetobacter is a genus of
Gram-negative, rod shaped bacteria
belonging to the wider class of
Gammaproteobacteria.
Acinetobacter species are strict
aerobic, non – fermentative non-
motile and oxidase-negative, do not
reduce nitrates, and occur in pairs
under magnification.
Although, rod-shaped cells are
formed in young cultures, old
cultures contain many coccoid-
shaped/cocco-bacillary cells.
They show preponderantly a
coccobacillary morphology on non-
selective agar.
Rods predominate in fluid media,
especially during early growth
They are important soil organisms
Acinetobacter (akinetos: unable to move)Acinetobacter (akinetos: unable to move)

Acinetobacter species are a key source of infection in debilitated
patients in the hospital, in particular the species
Acinetobacter baumannii.
These Gram-negative rods show some affinity to the family
Neisseriaceae, and some that were formerly achromobacters and
moraxellae are placed here.
Also, some former acinetobacters are now in the Genus
Psychrobacter.
They differ from psychrobacter and moraxellae in being oxidase
negative.
They are widely distributed in soils and waters and may be found
on many foods, especially refrigerated fresh products.
The mol% G+C content of DNA for the genus is 39-47.
It has been proposed, based on DNA-rRNA hybridization data,
that the genera Acinetobacter, Moraxella, and Psychrobacter be
placed in a new family (Moracellaceae), but this proposal has not
been approved.
Acinetobacter (akinetos: unable to move)Acinetobacter (akinetos: unable to move)

Alcaligenes is a genus of Gram -ve, aerobic,
rod-shaped/ coccal rods or cocci, sized
about 0.5-1.0 x 0.5-2.6 μm.
The species are motile with one or more
peritrichous flagella and rarely non-motile.
It is a genus of non-fermenting bacteria.
Although Gram -ve, these organisms
sometimes stain Gram positive.
They are rods that Do not ferment sugars
but instead produce alkaline reactions,
especially in litmus milk.
Non-pigmented, they are widely
distributed in nature in decomposing
matter of all types.
Raw milk, poultry products, and fecal
matter are common sources.
The mol% G+C content of DNA is 58-70,
suggesting that the genus is
heterogeneous.
AlcaligenesAlcaligenes (alkali producers)(alkali producers)
Circular, smooth, entire,
opaque colonies of
Alcaligenes on a nutrient
agar plate

MoraxellaMoraxella
Moraxella is a genus of Gram-negative bacteria in the
Moraxellaceae family.
It is named after the Swiss ophthalmologist Victor Morax.
These short Gram-negative rods are sometimes classified as
Acinetobacter.
They differ from the latter in being sensitive to penicillin and
oxidase positive.
The organisms are short rods, coccobacilli or, as in the case of
Moraxella catarrhalis, diplococci in morphology, with a-
saccharolytic, oxidase-positive and catalase-positive properties.
Moraxella catarrhalis is the clinically most important species
under this genus.
Have a mol % G+C content of DNA of 40-46.
The newly erected genus Psychrobacter includes some that were
once placed in this genus.
Their metabolism is oxidative, and they do not form acid from
glucose.

This genus was created primarily to accommodate some of the
non-motile Gram-negative rods that were once classified in the
genera Acinetobacter and Moraxella.
They are plump Coccobacilli that Occur often In pairs.
Also, they are aerobic, non-motile, and catalase and oxidase
positive, and generally they do not ferment glucose.
Growth occurs in 6.5% NaCl and at 1°C, but generally not at 35°C
or 37°C.
They hydrolyze Tween-80, and most are egg-yolk positive
(lecithinase).
They are sensitive to penicillin and utilize 7-aminovalerate,
whereas the Acinetobacters do not.
They are distinguished from the Acinetobacters by being
oxidase positive and Amino-valerate users and from non-motile
Pseudomonads by their inability to utilize glycerol or fructose.
Because they closely resemble the moraxellae, they have been
placed in the family Neisseriaceae.
They are common on meats, poultry, and fish, and in waters.
PsychrobacterPsychrobacter

 These are typically aquatic, Gram-negative, facultative anaerobic, rod-
shaped bacterium formerly in the family Vibrionaceae but now in the
family Aeromonadaceae.
 Aeromonas morphologically resembles members of the family
Enterobacteriaceae.
 As the generic name suggests, they produce copious quantities of gas
from those sugars fermented.
 Most of the 14 described species have been associated with human
diseases.
 The most important pathogens are A. hydrophila, A. caviae, and
A. veronii biovar sobria.
 The organisms are ubiquitous in fresh and brackish water.
 They group with the gamma subclass of the Proteobacteria.
 They are normal inhabitants of the intestines of fish, and some are fish
pathogens.
 Two major diseases associated with Aeromonas are gastroenteritis and
wound infections, with or without bacteremia.
 Gastroenteritis typically occurs after the ingestion of contaminated
water or food, whereas wound infections result from exposure to
contaminated water.
 The mol% G+C content of DNA is 57-65.
AeromonasAeromonas (aeromonas: gas producing)(aeromonas: gas producing)

FlavobacteriumFlavobacterium
These Gram-negative rods are characterized by their production
of yellow to red pigments on agar and by their association with
plants.
Some are mesotrophs, and others are psychrotrophs, where
they participate in the spoilage of refrigerated meats and
vegetables.
This genus has undergone drastic redefinition, resulting in the
creation of several new genera Weeksella, Chryseobacterium,
Empedobacter, and Bergeyella), none of which appear to be
associated with foods.
Some of the new genera contain fish pathogens and some are
halophiles.

These Gram-positive, non-spore forming, rods are closely related
to the genera Lactobacillus and Listeria.
Although, they are not true coryneforms, they bear resemblance
to this group.
Typically, exponential-phase cells are rods, and older cells are
coccoids, a feature typical of coryneforms.
Their separate taxonomic status has been re-affirmed by rRNA
data, although only two species are recognized: B.
thermosphacta and B. campestris.
They are common On processed Meats and On fresh and
processed meats that are stored in gas-impermeable packages at
refrigerator temperatures.
In contrast to B. thermosphacta, B. campestris Is rhamnose and
hippurate positive.
The mol% G+C content of DNA is 36%.
They do not grow at 37°C.
They Share Some features with the genus Microbacterium.
Brochothrix (brochos, loop; thrix, thread)Brochothrix (brochos, loop; thrix, thread)

AlteromonasAlteromonas (another monad)(another monad)
They are Gram-negative, strict aerobes.
 Its cells are curved rods, motile with a single polar flagellum.
Alteromonas is a genus of Proteobacteria found in sea water,
either in the open ocean or in the coast
These are marine and coastal water inhabitants.
That are found in and on seafoods.
 All species require seawater salinity for growth.

These Gram-negative rods constitute the largest genus of
bacteria that exists in fresh foods.
The mol %G+C content of their DNA of 58-70 suggests that it is a
heterogeneous group, and this has been verified.
They are typical of soil and water bacteria and are widely
distributed among foods, especially vegetables, meat, poultry,
and seafood products.
They are, by far, the most important group of bacteria that bring
about the spoilage of refrigerated fresh foods because many
species and strains are psychrotrophic.
Some are notable by their production of water–soluble, blue-
green pigments, whereas many other food spoilage types are
not.
Some plant-associated species have been transferred to the
genus Burkholderia, including the species that causes bongkrek.
A new genus, Ralstonia, has been created to accommodate some
Burkholderia and Alcaligenes species, notably R. solanecearum,
which causes wilt of tomato.
Pseudomonas (false monad)Pseudomonas (false monad)

ShewanellaShewanella
The bacterium once Classified As Pseudomonas putrefaciens And
later As Alteromonas putrefaciens Has been Placed in this new
genus as S. putrefaciens.
They are Gram-negative, straight or curved rods, non-
pigmented, and motile by polar flagella.
They are oxidase positive and have a mol% G+C of 44-47.
The other three species in this genus are S. hanedai, S. benthica,
and S. colwelliana.
All are associated with aquatic or marine habitats, and the
growth of S. benthica is enhanced by hydrostatic pressure.

Staphylococcus (grape like coccus)Staphylococcus (grape like coccus)
These Gram-positive, catalase-positive cocci include S. aureus,
which causes several disease syndromes in humans, including
foodborne gastroenteritis.

MicrococcusMicrococcus
These cocci are Gram positive and catalase positive.
Some produce pink to orange-red to red pigments, whereas
others are non-pigmented.
Most can grow in the presence of high levels of NaCl, and most
are mesotrophs, although psychrotrophic species/ strains are
known.
This once very large genus has been reduced by the creation of
at least five new genera: Dermacoccus, Stomatococcus, Kocuria,
Kytococcus, and Nesterenkonia.
Micrococcus agilis has been transferred to the arthrobacters as
Arthrobacter agilis, and some former M. roseus strains have
been transferred to the genus Salinicoccus.
The type species is M. luteus, and the redefined genus has a mol
% G+C content of DNA of 69-76.
The organism once classed as M. freudendreichii is now in the
genus Pediococcus.

 These are Gram-positive, spore forming
rods that are aerobes, in contrast to the
clostridia, which are anaerobes.
 Although most are mesophiles,
psychrotrophs and thermophiles exist.
 The genus contains only two pathogens:
B. anthracis (cause of anthrax) and B.
cereus.
 Although most strains of the latter are
non-pathogens, some cause foodborne
gastroenteritis.
 B. cereus food poisoning is principally
associated with the storage of cooked
foods
 Found in raw materials and processed
foods which were not sterilized by heat
or irradiation.
 Polymixin pyruvate egg yolk mannitol
bromothymol blue agar (PEMBA) and
Mannitol egg yolk agar are selective
media
 B. licheniformis, B. pumilus and B. subtilis
were the most commonly isolated
Bacillus species in bakeries and milk
BacillusBacillus
BLOOD AGAR
large, spreading,
gray-white
colonies, with
irregular
margins
Bacillus cereus
SELECTIVE
MEDIA: MANNITOL
EGG YOLK AGAR

 The phylogenetic heterogeneity of this genus employing small-subunit
rRNA Sequence data allowed five groups to be formed.
 Group 1 includes B. cereus, B. subtilis, B. coagulans, and B. anthracis
among others, and it seems likely that this group will be retained as
Bacillus.
 The group 3 cluster has been given the generic name Paenibacillus; and
B. stearothermophilus clustered with group 5.
 The thermoacidophilic Bacillus species, B. acidocaldarius, B.
acidoterrestris, and B. cycloheptanicus, have been reclassified in the
new genus Alicyclobacillus.
 The latter have mol % G+C of 51.6-60.3, grow as low as about 35°C to
700
C, and over the pH range 2 to 6.
 The B. brevis cluster of 10 species has been reclassified into a new
genus, Brevibacillus based on 16SRNA gene sequences.
BacillusBacillus

 These are Gram Positive, anaerobic, spore forming rods are widely
distributed in nature, as are their aerobic counterparts, the bacilli.
 The genus contains many species, some of which cause disease in
humans (C. perfringens food poisoning and botulism).
 Mesotrophic, psychrotrophic, and thermophilic species/strains exist;
therefore important in the thermal canning of foods.
 A reorganization of the genus involves the creation of the five new
genera: Caloramater, Filifactor, Moorella, Oxobacter, and Oxalophagus.
 These five new Genera appear to be unimportant in foods.
 The clostridial species of known importance in foods remain in the
genus at this time.
Clostridium (Gr. closter, a spindle)Clostridium (Gr. closter, a spindle)
Gram Stain: They usually stain Gram-positive, at least in very early stages of growth.
Morphology Cells of most strains occur as straight or slightly curved rods.
Size: 0.3-2.0 micrometers by 1.5-20.0 micrometers in length.
Motility: Motility occurs by peritrichous flagella.
Capsules: None.
Spores: Clostridium spp. form oval or spherical endospores that usually distend the
cell.
Other: Most have round, tapering ends; long filaments are formed by some species.

Clostridia possess no one typical
colony morphology.
 They are generally a large
colony (>2mm) with irregular
edges or swarming growth.
 Some Clostridia form small,
convex, non-hemolytic colonies
with a smooth edge.
Cl. perfringens
Tryptose sulphate cycloserine agar,
Sulphate- polymixin-sulphadiazine agar,
Shahid Ferguson perfringens agar,
Neomycin blood agar.
Cl. botulinum Horse blood agar,
Anerobic egg yolk agar
Cl. botulinum on egg yolk agarSELECTIVE MEDIA

This newly established genus comprises organisms formerly in the
genera Bacillus and Clostridium, and it includes the species: P.
alvei, P. amylolyticus, P. azotofixans, P. circulans, P. durum, P.
larvae, P. macerans, P. macquariensis, P. pubuli, P. pulvifaciens,
and P. validus.
 Recently, two new species were added (P. lautus and P. peoriae).
Paenibacillus (almost a bacillus)Paenibacillus (almost a bacillus)

 This is clearly the most widely studied genus of all bacteria.
 The genus is named after Theodor Escherich, the discoverer of Escherichia coli
.
 Escherichia is a genus of Gram-negative, non-spore forming,
facultatively anaerobic, rod-shaped bacteria from the family
Enterobacteriaceae.
 1.1-1.5 um by 2.0-6.0 um.
 They occur singly or in pairs.
 Escherichia spp. are motile by peritrichous flagella or are non-motile.
 In addition to flagella, most strains have fimbriae (pili) that extend from the
bacterial surface into the surrounding medium. Some fimbriae have specific
functions as adhesive organs.
 Capsules or microcapsules occur in many strains.
 Are inhabitants of the gastrointestinal tracts of warm-blooded animals.
 Some strains cause foodborne gastroenteritis.
 E. coli act as an indicator of food safety.
EscherichiaEscherichia
For culture: Tryptic Soy Agar, Nutrient Agar, Blood Agar 5%.
For selective isolation: MacConkey Agar, EMB Agar, MacConkey with Sorbitol ( E. coli O157).
For maintenance: Tryptic Soy Agar, Nutrient Agar, Blood Agar 5%. For long-term
storage at - 70 degrees C., TSB with 15% Glycerol or Skim Milk Media
is recommended

E. coli O157: H7
Escherichia coli O157:H7 is an
enterohemorrhagic serotype of the
bacteria Escherichia coli and a cause of
illness, typically through consumption
of contaminated and raw food
including raw milk Children under five
years of age and the elderly, the
infection can cause
hemolytic uremic syndrome (HUS), in
which the red blood cells are
destroyed and the kidneys fail
MUG( 4-Methylumbelliferyl ß-D-
Glucuronide) sorbitol agar
Escherichia coli produce
small, dark colonies with a
green metallic sheen on EMB
agar

SalmonellaSalmonella
All members of this genus of Gram-negative enteric
bacteria are considered to be human pathogens
belong to the family Enterobacteriaceae .
 The Mol% G+C content of DNA is 50-53.

ShigellaShigella
All members of this genus are presumed to be human
enteropathogens.
Family Enterobacteriaceae.

These Gram-negative rods that belong to the family
Enterobacteriaceae are aerobic and proteolytic, and they
generally produce red pigments on culture media and in
certain foods, although non-pigmented strains are not
uncommon.
S. liquefaciens is the most prevalent of the foodborne species;
it causes spoilage of refrigerated Vegetables and meat
products.
The mol % G+C content of DNA is 53-59.
SerratiaSerratia

CitrobacterCitrobacter
Citrobacter is a genus of Gram-negative coliform bacteria in the
Enterobacteriaceae family.
All members Can Use Citrate As The Sole carbon source.
These Enteric Bacteria Are Slow lactose-fermenting.
C. freundii is the most prevalent species In foods, and it and the
other Species are not uncommon on vegetables and fresh
meats.
The mol% G+C content of DNA is 50-52.
Common species are C. amalonaticus, C. koseri, and C. freundii .
Citrobacter species are differentiated by their ability to convert
tryptophan to indole, ferment lactose, and use malonate.

Enterobacter is a genus of common Gram-negative,
facultatively anaerobic, rod-shaped, non-spore-forming bacteria
of the family Enterobacteriaceae.
These bacteria are typical of other Enterobacteriaceae relative to
growth requirements, although they are not Generally adapted
to the gastrointestinal tract.
The genus Enterobacter is a member of the coliform group of
bacteria.
Two clinically important species from this genus are E. aerogenes
and E. cloacae.
Several strains of these bacteria are pathogenic and cause
opportunistic infections in immunocompromised (usually
hospitalized) hosts.
The genus Enterobacter ferments lactose with gas production
during a 48-hour incubation at 35-37 °C in the presence of bile
salts and detergents.
It is oxidase-negative, indole-negative, and urease-variable.
E. agglomerans has been transferred to the genus Pantoea.
EnterobacterEnterobacter

ErwiniaErwinia
Erwinia is a genus of Enterobacteriaceae containing mostly
plant pathogenic species which was named for the famous
plant pathologist, Erwin Frink Smith.
These Gram-negative enteric rods are especially associated
with Plants, where they cause bacterial soft rot.
At least three species Have been transferred to the genus
Pantoea.
The mol% G+C content of DNA is 53.6-54.1.

This genus consists of Gram-negative, non-capsulated, non-
sporing straight rods, most of which are motile by peritrichous
flagella.
They are widely distributed and are found on plants and in seeds,
in soil, water, and human specimens.
Some are plant pathogens.
The four recognized species were once classified as
enterobacters or erwinias.
P. agglomerans includes the former Enterobacter agglomerans,
Erwinia herbicola, and E. milletiae; P. ananas includes the former
Erwinia ananas and E. uredovora; P. stewartii was once E.
stewartii; and P. dispersa is an original species.
The G+C content of DNA ranges from 49.7 to 60.6 mol%.
PantoeaPantoea

HafniaHafnia
Hafnia is the genus of the Enterobacteriaceae family which are
Gram-negative, facultatively anaerobic, rod-shaped bacterium.
These Gram-negative enteric rods are important in the spoilage
of refrigerated meat and vegetable products.
H. alvei is the only species at this time.
H. alvei is a commensal of the human gastrointestinal tract and
not normally pathogenic, but may cause disease in
immunocompromised patients.
It is often resistant to multiple antibiotics, including the
aminopenicillins.
It is motile and lysine and ornithine positive.
It has a mol% G+C content of DNA of 48-49.

These enteric Gram-negative rods are aerobes that often display
pleomorphism, hence the generic name.
All are motile and typically produce swarming growth on the
surface of moist agar plates.
They are typical of enteric bacteria in being present in the
intestinal tract of humans and animals.
They may be isolated from a variety of vegetable and meat
products, especially those that undergo spoilage at
temperatures in the mesophilic range.
ProteusProteus

 Gram-negative coccobacillus-shaped
bacterium, belonging to
family Enterobacteriaceae.
 Motile at 25°c/ non-motile at 37°c
 Non-spore-forming, catalase positive
oxidase negative facultatively anaerobic
 This genus includes the agent of human
plague, Y. pestis, and at least one species
that causes foodborne gastroenteritis, Y.
enterocolitica.
 The mol% G+C content of DNA is 45.8-46.8.
 The sorbose-positive biogroup 3A strains
have been elevated to species status as Y.
mollaretti and the sorbose-negative Strains
as Y. bercovieri.
 Selective Media:
 Cefsulodin-irgasan-novobiocin agar (CIN)
 Virulent Yersinia enterocolitica agar (VYE)
 Salmonella-Shigella-deoxycholate-calcium
chloride agar
 Mac Conkey agar.
YersiniaYersinia
CIN (Cefsulodin-Irgasan-
Novobiocin) agar
MLA

These Gram-negative, spirally curved rods
were formerly classified as vibrios.
Small, thin (0.2 - 0.5 um X 0.5 - 5.0 um), helical
(spiral or curved) cells with typical Gram-
negative cell wall; “Gull-winged” appearance
• Tendency to form coccoid & elongated forms
on prolonged culture or when exposed to O2
They are microaerophilic to anaerobic &
capnophilic 5%O2,10%CO2,85%N2
Oxidase-positive, non-fermentative bacteria.
Long sheathed polar flagellum at one (polar)
or both (bipolar) ends of the cell
Move via unipolar or bipolar flagella-
Distinctive rapid darting motility (Corkscrew
like motility)
• Motility slows quickly in wet mount
preparation
Most Campylobacter species are pathogenic
and can infect humans and other animals.
Campylobacter (campylo, curved)Campylobacter (campylo, curved)
Skirrows media

Selective media used :
i) Campy – BAP
ii) Campy – CVA
iii) Modified Skirrows media
iv) Charcoal based Selective medium agar (blood free)
v) Butzler’s media
Incubation – at 42o
C for 48 hrs at 5% O2.
Colonies - Grey, moist, flat or convex
At least a dozen species of Campylobacter have been implicated
in human disease, with C. jejuni and C. coli the most common.
C. jejuni is now recognized as one of the main causes of
bacterial foodborne disease in many developed countries.
The genus has been restructured since 1984.
The once C. nitrofigilis and C. cryaerophila have been transferred
to the New genus Arcobacter; the once C. cinnaedi and C. fenneliae
are now in the genus Helicobacter; and the once Wolinella carva
and W. recta Are Now C. curvus and C. rectus?
Campylobacter (campylo, curved)Campylobacter (campylo, curved)

This genus was created (in 1992) during revision of the genera
Campylobacter, Helicobacter, and Wolinella, and the three
species were once classified as Campylobacter.
 They are Gram-negative, curved or S-shaped rods, 1-3 µm x 0.2-
0.4µ m that are quite similar to the campylobacters except they
can grow at lower temperature (150
C) and in air (are
aerotolerant).
Single polar flagellum and typical corkscrew-like motility
Colonies :off-white, white or greyish color on blood agar plates.
After 48 h incubation: 2-4 mm in diameter and convex with
entire edges
This genus currently consists of five species: A. butzleri, A.
cryaerophilus, A. skirrowii, A. nitrofigilis, and A. sulfidicus. Three
of these five known species are pathogenic.
They are found in poultry, raw milk, shellfish, and water; and in
cattle and swine products.
These oxidative and catalase positive organisms cause abortion
and enteritis in some animals, and the latter in humans is
associated with A. butzleri.
ArcobacterArcobacter (arcus – bow)(arcus – bow)

Corynebacterium (Gr. coryne, club)Corynebacterium (Gr. coryne, club)
This is one of the true coryneform genera of Gram-positive, rod-
shaped bacteria that are sometimes involved in the spoilage of
vegetable and meat products.
They are catalase-positive, aerobic or facultatively anaerobic,
generally non-motile bacteria
2 - 6 μm in length and 0.5 μm in diameter
The bacteria group together in a characteristic way, which has
been described as the form of a "V", "palisades", or "Chinese
letters".
Corynebacteria grow slowly, even on enriched media. In terms
of nutritional requirements, all need biotin to grow
Sometimes involved in the spoilage of meat products
Most are mesotrophs, although psychrotrophs are known.
 C. diphtheriae, causes diphtheria in humans.
The genus has been reduced in species with the transfer of
some of the plant Pathogens to the genus Clavibacter and
others to the genus Curtobacterium.

Bacteria grow in Loeffler’s medium, blood
agar and Trypticase soya agar
Small, grayish colonies with a granular
appearance, mostly translucent, but with
opaque centers, convex, with continuous
borders.
Color tends to be yellowish-white in
Loeffler's medium.
 In TSA, they can form grey colonies with
black centers and dentated borders that
look similar to flowers

Kocuria is a genus of Gram positive bacteria in the phylum
Actinobacteria, including the sequenced species
Kocuria rhizophila.
 The three species (K. rosea, K. varians, and K. kristinae) are
oxidase negative and catalase positive.
 Mol% G+C content of DNA is 66-75.
Kocuria (after M. Kocur)Kocuria (after M. Kocur)

This genus of 15 species of Gram-positive, non-sporing,
facultative anaerobic, non spore forming rods
Closely related to Brochothrix.
Named after Joseph Lister.
Causes listeriosis in humans by foodborne route.
L. monocytogenes, L. innocua, L. ivanovii, L. grrayi, l.
welshimeri, L. seeligeri
ListeriaListeria

VibrioVibrio
These Gram-negative, straight or curved rods are members of
the family Vibrionaceae.
 Several former species have been transferred to the genus
Listonella.
 Several species cause gastroenteritis and other human illness.
 The Mol %G+C content of DNA is 38-51.

lactic acid bacteria (LAB)lactic acid bacteria (LAB)
 Lactic acid bacteria (LAB) are Gram-positive, acid-tolerant, generally
non-sporulating, either rod- or cocci-shaped bacteria.
 Usually found in decomposing plants/milk products, produce
lactic acid as the major end product of carbohydrate fermentation.
 This trait has, throughout history, linked LAB with food fermentations
, as acidification inhibits the growth of spoilage agents.
 Lactic acid and other metabolic products contribute to the
organoleptic and textural profile of a food item.
 Bacteriocins are produced by several LAB strains and provide an
additional hurdle for spoilage and pathogenic microorganisms.
 The industrial importance of the LAB is further evinced by their
generally recognized as safe (GRAS) status, due to their ubiquitous
appearance in food and their contribution to the healthy microflora
of human mucosal surfaces.
 The genera that comprise the LAB are at its core Lactobacillus,
Leuconostoc, Pediococcus, Lactococcus, and Streptococcus, as well as
the more peripheral Aerococcus, Carnobacterium, Enterococcus,
Oenococcus, Vagococcus, and Weisella also Sporolactobacillus and
Tetragenococcus.

Lactobacillus, also called Döderlein's bacillus, is a genus of
Gram-positive facultative anaerobic or microaerophilic rod-shaped
bacteria.
They are Gram-positive, catalase-negative rods that often occur in
long chains.
Although, those in foods are typically microaerophilic, many true
anaerobic strains exist, especially in human stools and the rumen.
They are a major part of the Lactic acid bacteria group, named as
such because most of its members convert lactose and other
sugars to lactic acid.
In humans they are present in the vagina and the
gastrointestinal tract, where they make up a small portion of the
gut flora.
Based on 16S rRNA sequence data, three phylogenetically distinct
clusters are revealed, with one cluster encompassing Weissella.
In all probability, this genus will undergo further reclassification.
It helps in preventing yeast infections, urinary tract infection, IBS,
traveler's diarrhea , diarrhea resulting from Clostridium difficile,
treating lactose intolerance, skin disorders (fever blisters, eczema,
acne) and prevention of respiratory infections .
LactobacillusLactobacillus

LactabacillusLactabacillus
 They typically occur on most, if not all,
vegetables, along with some of the other lactic
acid bacteria.
 There are more than 50 species of lactobacilli.
 Their occurrence in dairy products is common.
 Many fermented products are produced.
 Foods that are fermented, like yogurt, and
dietary supplements also contain these
bacteria.
 A recently described species, L. suebicus, was
recovered from apple and pear mashes; it
grows at pH 2.8 in 12-16% ethanol.
 Taxonomic techniques that came into wide use
during the 1980s have been applied to this
genus, resulting in some of those in the ninth
edition of Bergey's Manual being transferred
to other genera.

 Leuconostoc is a genus of Gram-positive bacteria, catalase-negative,
cocci placed within the family of Leuconostocaceae. They are
generally ovoid cocci, often forming chains.
 Along with the lactobacilli, this is another of the genera of lactic acid
bacteria.
 Leuconostoc spp. are intrinsically resistant to vancomycin and are
catalase-negative (which distinguishes them from staphylococci).
 All species within this genus are HETEROFERMENTATIVE and are able
to produce dextran from sucrose.
 They are generally slime-forming.
 These catalase-negative heterofermentative cocci and are typically
found in association with the lactobacilli.
 Blamed for causing the 'stink' when creating a sourdough starter,
some species are also capable of causing human infection.
 Leuconostoc is, along with other lactic acid bacteria such as
Pediococcus and Lactobacillus, responsible for the fermentation of
cabbage, making it sauerkraut.
 It is similarly part of the symbiotic colonies of microbes involved in the
fermentation of kefir, a fermented milk beverage.
 The former L. oenos has been transferred to a new genus, Oenococcus
as O. oeni, and the former L. paramesenteroides has been transferred
to the new genus as Weissella paramesenteroides.
Leuconostoc (colorless nostoc)Leuconostoc (colorless nostoc)

LeuconostocLeuconostoc
Members of Leuconstoc spp. are very often
used in production of fermented foods
because of their ability to produce lactic
acid and diacetyl.
Leuconostoc are used to inhibit Listeria
monocytogenes in dairy and meat products.

Weissella: (Weissella, after N. Weiss)Weissella: (Weissella, after N. Weiss)
This genus of lactic acid bacteria was established in 1993 in part
to accommodate The “leuconostoc branch” Of The lactobacilli.
The seven species are closely related to the leuconostocs, and
with the exception of W. paramesenteroides and W. hellenica
they produce DL-lactate from glucose.
All produce gas from carbohydrates.
W. hellenica is a new species associated with fermented Greek
sausages.
The former Leuconostoc paramesenteroides is now W.
paramesenteroides, and the following five species were formerly
classified as Lactobacillus spp.: W. confusa, W. halotolerans, W.
kandleri, W. minor, and W. viridescens.
The G+C content of DNA is 37-47mol%.

 Lactococcus is a genus of LACTIC ACID BACTERIA that were formerly
included in the genus Streptococcus Group N1.
 They are known as HOMOFERMENTORS meaning that they produce a
single product, lactic acid in this case, as the major or only product of
glucose fermentation-L-Lactic acid is the predominant end product.
 They are Gram-positive, non-motile, and catalase-negative spherical or
ovoid cells that occur singly, in pairs, or as chains.
 They grow at 100
C but not at 450
C, and most strains react with group N
antisera-The genus contains strains known to grow at or below 7˚C.
 These organisms are commonly used in the dairy industry in the
manufacture of fermented dairy products, such as cheeses.
 They can be used in single-strain starter cultures, or in mixed-strain
cultures with other lactic acid bacteria such as Lactobacillus and
Streptococcus.
 Special interest is placed on the study of L. lactis subsp. lactis and L.
lactis subsp. cremoris, as they are the strains used as starter cultures in
industrial dairy fermentations.
 Their main purpose in dairy production is the rapid acidification of
milk; this causes a drop in the pH of the fermented product, which
prevents the growth of spoilage bacteria.
 The bacteria also play a role in the flavor of the final product.
LactococcusLactococcus

This genus was created to accommodate the group N lactococci
based on 16S sequence data.
They are Gram positive and Catalase negative, and grow at 100
C
but not at 45°C.
They are motile by peritrichous flagella,
They grow in 4% NaCl but not 6.5%, and no growth occurs at pH
9.6.
The cell wall peptidoglycan is Lys-D-Asp, And the mol% G+C is
33.6.
At least one species produces H2S.
They are found on fish, in feces, and in water and may be
expected to occur on other foods.
Vagococcus (wandering coccus)Vagococcus (wandering coccus)

Enterococcus is a large genus of LACTIC ACID BACTERIA of the
phylum Firmicutes.
This is normally found in the intestinal tract of humans .
This genus was erected to accommodate some of the Lancefield
serologic group D cocci - were in the genus Streptococcus.
It has since been expanded to more than 16 species of Gram
positive, ovoid cells that occur singly, in pairs, or in short chains.
Some species do not react with group D antisera.
Enterococci are facultative anaerobic organisms, i.e., they are
capable of cellular respiration in both oxygen-rich and oxygen-poor
environments.
Though they are not capable of forming spores, enterococci are
tolerant of a wide range of environmental conditions: extreme
temperature (10-45°C), pH (4.5-10.0) and high sodium chloride
concentrations.
Two species are common commensal organisms in the intestines of
humans: E. faecalis (90-95%) and E. faecium (5-10%).
Rare clusters of infections occur with other species, including E.
casseliflavus, E. gallinarum, and E. raffinosus.
Enterococcus faecium SF68 is a specific probiotic strain that has
been used in the management of diarrhoeal illnesses.
EnterococcusEnterococcus

Enterococcus on
blood agar plate
smooth, cream or
white colonies
with entire edges
For culture:
TSA Agar,
Blood Agar 5%,
Chocolate Agar, Nutrient Agar
For selective
isolation:
Bile Esculin Azide (BEA) Media,
6.5% NaCl Broth
6.5% NaCl Agar
Columbia CNA
Mannitol Salt Agar
Mannitol Salt Broth
For
maintenance:
TSA Agar, Blood Agar 5%. Media
containing cryoprotectants such as
glycerol or serum may be used for
long-term storage at -70 degrees C.
(i.e. Brucella with Glycerol, TSB with
Glycerol).
Quadrant 1: Enterococcus faecalis, is resistant to the antibiotics colistin and naladixic acid.
Quadrant 2: Enterobacter aerogenes, is sensitive to the antibiotics and is Gram-negative.
Quadrant 3: Escherichia coli, is sensitive to the antibiotics and is Gram-negative.
Quadrant 4: Staphylococcus aureus, is resistant to the antibiotics and is Gram-positive.
Growth on Columbia CNA

These HOMO-FERMENTATIVE cocci are lactic acid bacteria that
exist in pairs and tetrads resulting from cell division in two
planes.
P. acidilactici, a common starter species,
Reported to cause septicemia in a 53-year-old male.
Their mol% G+C content of DNA is 34.4.
The once P. halophilus is now in the genus Tetragenococcus
as T. halophilus - It can grow in 18% NaCl.
PediococcusPediococcus

 Carnobacterium is a genus of Gram-positive bacteria within the family
Leuconostocaceae.
 This genus of Gram positive, catalase-negative rods was formed to
accommodate some organisms previously classified as lactobacilli.
 They are phylogenetically closer to the enterococci and vagococci than the
lactobacilli.
 They differ from the lactobacilli in being unable to grow on Acetate medium
and in their synthesis of oleic acid.
 They are HETERO-FERMENTATIVE, and most grow at 00
C and none at 450
C.
 Gas is produced from glucose By some species.
 C. divergens and C. maltaromaticum are dominating part of microflora of
chilled vacuum or modified atmosphere-packed meat as well as on fish and
poultry meats.
 They can grow anaerobically.
 These species are not known to be pathogenic in humans, but may cause
disease in fish.
 C. maltaromaticum strain CB1, has been evaluated under the
Canadian Environmental Protection Act, 1999, as a food additive for vacuum-
or modified atmosphere-packaged ready-to-eat meat and fresh comminuted,
processed meat-Based on the hazard and exposure considerations, the risk
assessment conducted by Health Canada concluded that C.
maltaromaticum strain CB1 is not considered to be toxic to the Canadian
environment or human health as described in Section 64 of CEPA 1999.
 The Mol% G+C for the genus is 33.0-37.2.
Carnobacterium (carnis, of flesh-meat bacteria)Carnobacterium (carnis, of flesh-meat bacteria)

Bifidobacteria
There are approx. 30 species of
bifidobacteria.
They are found in the intestinal tract
within days of birth, especially in
breastfed infants.
They help in the improvement of
abdominal pain, bloating, bowel
dysfunction, incomplete evacuation,
straining, and the passage of gas.

Streptococcus
This produces large quantities of the
enzyme lactase, making it effective.
It helps in the prevention of lactose
intolerance.

Saccharomyces
The only yeast probiotic.
It is effective in treating diarrhea
associated with the use of antibiotics and
traveler's diarrhea.
It has also been reported to prevent the
reoccurrence of Clostridium difficile, to
treat acne, and to reduce side effects of
treatment for Helicobacter pylori.

Foodborne Moulds
• Aspergillus
• Alternaria
• Aureobasidium (Pullularia)
• Botrytis
• Byssochlamys
• Chladosporium
• Collectotrichum
• Fusarium
• Geotrichum
• Monilinia
• Mucor
• Penicillium
• Rhizopus
• Thamnidium
• Trichothesium
• Other moulds
Miscellaneous genera that are found in some foods but are generally
not regarded as significant: Cephalosporium, Diplodia and Neurospora
Xerophiles: Aspergillus, Eurotium, Basipetospora, Chrysosporium,
Eremascus, Polypaecilum, Wallemia, and Xeromyces

Common Moulds in Food
Filamentous fungi that grow in the form of a tangled mass that
spreads rapidly and may cover several inches of area in 2 to 3
days.
The total of the mass or any large portion of it is referred to as
mycelium.
Mycelium is composed of branches or filaments referred to as
hyphae.
Those of greatest importance in foods multiply by
zygospores/oospores, ascospores, or conidia.

Morphology
 The morphology of moulds as judged by their macroscopic and
microscopic appearance is used for its identificationa nd
classification.
 The mould thallus consist of a mass of branching intertwined
filaments called hyphae.
 Whole mass of these hyphae is called mycelium.
 Hyphae may be submerged (growing in to food) or aerial (growing in
to air above food)
 Hyphae may be vegetative or growing and hence involved chiefly in
nutrition of mold or fertile, involved in production of reproductive
parts.
 In most moulds, fertile hyphae are aerial but in some may be
submerged.
 Hyphae may be septate or non-septate (coenocytic)
 The hyphae of most moulds are clear but in som it may be dark or
smoky.
 Septate hyphae increase in length by means of division of tip cell
(apical growth) or of cells within hypha (Intercalary growth)- the type
of growth being characteristic of type of mold
 Special mycelial structures or parts aid in the identification of moulds.
E.g. rhizoids/hodfasts in Rhizopus and Absidia; the foot cell in
Aspergillus and dichotomous or y-shaped, branching in Geotrichium.

Reproductive Parts or Structures
 Molds can grow from a transplanted part of mycelium.
Reproduction in molds mainly occurs by means of asexual
spores.
Some molds also form sexual spores. Such molds are termed as
“perfect” and include Zygomycetes or Oomycetes (non-septate)
or ascomycetes and basidiomycetes if septate. In contrast,
Imperfect moulds i.e. Fungi Imperfecti (typically septate)
multiply by only asexual spores.
Asexual Spores: Asexual spores of molds are produced in large
numbers and are small, light and resistant to drying. They are
readily spread through air. Three types of asexual spores are:
Conidia
Sporangiospore
Arthrospores/oidia
Chlamydospores

Asexual Spores
Conidia: Conidia are cut off or bud from special fertile hyphae
called conidiophores and usually are in open (not enclosed in
container).
Sponragiospores: Sponragiospores are produced in a
sac/container (called sporangium) at the tip of the fertile
hyphae called sporangiophores
Arthrospores: Arthrospores are formd by fragmentation of the
hypha so that the cells of the hypha become arthrospores.
Chlamydospores: Produced by many molds. Here cells in the
mycelium here and there stores up reserve food, swells and
forms a thicker wall than the surrounding cells. This is
chlamydospore or resting cell.

Asexual spores in Identification
 The morphology of the asexual spore is helpful in identification of
genus and speices of the mold.
 Sporangiospores differ in shape size and colour.
 Conidia also may be smooth or roughened and one, two or many
celled.
 Also helpful in identification of mold is the appearance of fertile
hyphae and arrangement of asexual spores on them.
 If sporangiospores are formed, sporangiophores may be simple or
branched; type of branching and sizem shape and color and location
of sporangia hint about the speices.
 The swollen tip of the sporangiophore is called columella, which
usually projects in to the sporangium, assumes shapes typical of
species of mold.
 Conidia may be borne singly on conidiophores or in spore heads of
differing arrangement and complexity. A look at the appearance of
spore head is sufficient for genus identification.
 Some molds have conidia in chains, squeezed off one by one from a
special cell, a sterigma, or phialide at the tip of the conidiophore.
 Other molds have irregular masses of conidia which cut off from
conidiophore with out evident sterigmata.

Sexual Spores
The non-septate molds (phycomycetes) reproduce by oospores
are termed oomycetes. These molds are mostly aquatic but also
include “downy mildews” which cause late blight of potato and
buckeye rot of tomatoes. The oospores are formed by union of
small male gamete and large female gamete.
The zygospores are formed by zygomycetes by the union of tip
of two hyphae from the same mycelium or different mycelium.
Both oospores and zygospores are covered by a tough wall and
can survive drying for prolong period.
The ascomycetes produce ascospores in a sac called ascus
Usually 08 ascospores are produced in an ascus. The asci may be
single or may be grouped within a covering called an ascocarp
formed by branchinga and intertwinning of the adjacent
hyphae.
The basidiomycetes, which include most mushrooms, plant
rusts and smuts produce basidiospores.

Aspergillus Aspergillus is defined as a group of conidial fungi
 The aspergilli appear yellow to green to black on
a large number of foods
 Found on country-cured hams and on bacon
 It is widely distributed and contains many species
important in food.
 Members have septate hyphae and produce
black-colored asexual spores or conidia.
 Many are xerophilic (able to grow in low Aw) and
can grow in grains, causing spoilage.
 They are also involved in spoilage of foods such
as jams, cured ham, nuts, and fruits and
vegetables (rot).
 Some species or strains produce mycotoxins (e.g.
Aspergillus flavus produces aflatoxin).
 Many species or strains are also used in food and
food additive processing e.g.
Asp. oryzae is used to hydrolyze starch by α-
amylase in the production of sake.
Asp. niger is used to process citric acid from
sucrose and to produce enzymes such as b-
galactosidase. Colony of A. flavus on SDA

Alternaria
Alternaria is a genus of ascomycete fungi.
Members are septate and form dark-colored spores or conidia.
Septate mycelia with conidiophores and large brown conidia
are produced
The conidia have both cross and longitudinal septa and are
variously shaped.
They cause rot in tomatoes and rancid flavor in dairy products.
Some species or strains produce mycotoxins.
Species: Alternaria tenuis
Sabouraud dextrose agar

Aureobasidium
Ubiquitous black, yeast-like fungus
Cultivated on potato dextrose agar, where it produces
smooth, faint pink, yeast-like colonies covered with a
slimy mass of spores
Colony on PDA

Cladosporium
Most abundant mold in air
A genus of fungi having dematiaceous or dark-
colored conidiophores with oval or round spores
Species produce olive-green to brown or black colonies, and have
dark-pigmented conidia that are formed in simple or branching
chains
C. herbarum can cause "black spot" spoilage of meat
C. herbarum on PDA

Penicillium
 Genus of ascomycetous fungi
Typical colors on foods are blue to blue-
green
It is widely distributed and contains many
species.
Members have septate hyphae and form
conidiophores on a blue-green, brushlike
conidia head (Figure 2.1).
Some species are used in food
production, such as Penicillium
roquefortii and Pen. camembertii in
cheese.
Many species cause fungal rot in fruits
and vegetables.
They also cause spoilage of grains,
breads, and meat.
Some strains produce mycotoxins (e.g.,
Ochratoxin A). Penicillium colony on PDA

Rhizopus
Common saprophytic fungi
Rhizopus species grow as
filamentous, branching hyphae that
generally lack cross-walls
Hyphae are aseptate and form
sporangiophores in sporangium.
Reproduce by forming asexual and
sexual spores
They cause spoilage of many fruits
and vegetables.
Rhizopus stolonifer is the common
black bread mold.
Colony on acidified PDA

Thamnidium
Genus (the type of the family Thamnidiaceae) of molds
Related to the typical bread molds
Characterized by branched sporangiophores and sporangia

Fusarium:
Many types are associated with rot in citrus fruits, potatoes, and
grains.
They form cottony growth and produce septate, sickle-shaped
conidia. Species: Fusarium solani.
Geotrichum:
Members are septate and form rectangular arthrospores.
They grow, forming a yeast like cottony, creamy colony.
They establish easily in equipment and often grow on dairy
products (dairy mold). Species: Geotrichum candidum.
Mucor:
It is widely distributed.
Members have non-septate hyphae and produce sporangiophores.
They produce cottony colonies.
Some species are used in food fermentation and as a source of
enzymes.
They cause spoilage of vegetables.
Species: Mucor rouxii.

Foodborne Yeasts
• Saccharomyces
• Schizosaccharomyces
• Zygosaccharomyces
• Candida
• Cryptococcus
• Rhdotorula
• Pichia
• Brettanomyces
• Debaryomyces
• Henseniaspora
• Issatchenkia
• Kluyveromyces (Fabospora)
•Torulaspora
• Trichosporon

Morphology
Yeast may be spherical to ovoid, lemon shaped, pear shaped,
cylindrical, triangular or even elongated in to a false or true
mycelium.
Most yeast reproduce asexually by multilateral or polar
budding.
Some yeast species reproduce by fission and one by
combination of budding and fission.

Saccharomyces
Cells are round, oval, or elongated. It is the most important
genus and contains heterogenous groups.
Saccharomyces cerevisiae variants are used in baking for
leavening bread and in alcoholic fermentation.
They also cause spoilage of food, producing alcohol and CO2.
Zygosaccharomyces:
Cause spoilage of high-acid foods, such as sauces, ketchups,
pickles, mustards, mayonnaise, salad dressings, especially those
with less acid and less salt and sugar (e.g., Zygosaccharomyces
bailii).

Dimorphic fungus that grows both as yeast and filamentous
cells
Most common yeasts in fresh ground beef and poultry
Many species spoil foods with high acid, salt, and sugar and
form pellicles on the surface of liquids. Some can cause
rancidity in butter and dairy products (e.g., Candida lipolyticum).
Candida on SDA
Candida

Cryptococcus
Sexual forms or teleomorphs of Cryptococcus species are
filamentous fungi in the genus Filobasidiella
Asporogenous, reproduce by multilateral budding, and are
nonfermenters of sugars
Colonies on a macroscopic level are cream-color to pale pink,
with the majority of colonies being smooth with a mucoid
appearance
INDIA INK STAINING COLONY ON SDA

Rhodotorula
They are pigment-forming yeasts and can cause discoloration of
foods such as meat, fish, and sauerkraut.
Unicellular pigmented yeasts, part of the division Basidiomycota
Distinctive orange/red colonies when grown on SDA
(Sabouraud's Dextrose Agar)
Species: Rhodotorula glutinis

Pichia
 Cells are oval to cylindrical and form pellicles in beer, wine, and
brine to cause spoilage.
 Some are also used in oriental food fermentation.
 Species: Pichia membranaefaciens

Trichosporon
Trichosporon is a genus of anamorphic fungi in
the family Trichosporonaceae
All species of Trichosporon are yeasts with no known
teleomorphs (sexual states)
Common flora in fresh meat
Common Species: T. pullulans
COLONY ON SDA

Yarrowia
Yarrowia is a fungal genus in the family Dipodascaceae
Can use unusual carbon sources, such as hydrocarbons
Commonly isolated from poultry meat

Viruses Viruses are important in food for three reasons.
 Some are able to cause enteric disease, and thus, if present in a food, can
cause foodborne diseases e.g. Hepatitis A and Norwalk-like viruses have
been implicated in foodborne outbreaks. Several other enteric viruses,
such as polio, echo, and Coxsackie virus, can cause foodborne diseases. In
some countries where the level of sanitation is not very high, they can
contaminate foods and cause disease.
 Some bacterial viruses (bacteriophages) are used to identify some
pathogens (Salmonella spp., Staphylococcus aureus strains) on the basis of
the sensitivity of the cells to a series of bacteriophages at appropriate
dilutions.
 Bacteriophages are used to transfer genetic traits in some bacterial
species or strains by a process called transduction (e.g., in Escherichia coli
or Lactococcus lactis).
 Finally, some bacteriophages can be very important because they can
cause fermentation failure. Many lactic acid bacteria, used as starter
cultures in food fermentation, are sensitive to different bacteriophages.
They can infect and destroy starter-culture bacteria, causing product
failure. Among the lactic acid bacteria, bacteriophages have been
isolated for many species in the genera Lactococcus, Streptococcus,
Leuconostoc, and Lactobacillus; no bacteriophage of Pediococcus is yet
known. Methods are being devised to genetically engineer lactic starter
cultures so that they become resistant to multiple bacteriophages.

Bacterial Groups in Foods
Among the microorganisms found in foods, bacteria constitute
major important groups.
This is not only because many different species but also because
of their rapid growth rate, ability to utilize food nutrients, and
ability to grow under a wide range of temperatures, aerobiosis,
pH, and water activity, as well as to better survive adverse
situations, such as survival of spores at high temperature.
For convenience, bacteria important in foods have been
arbitrarily divided into several groups on the basis of similarities
in certain characteristics.
This grouping does not have any taxonomic significance. Some
of these groups and their importance in foods are listed here.

A. Lactic Acid Bacteria
 They are bacteria that produce relatively large quantities of lactic acid from
carbohydrates. Species mainly from genera Lactococcus, Leuconostoc,
Pediococcus, Lactobacillus, and Streptococcus thermophilus are included in
this group.
B. Acetic Acid Bacteria
 They are bacteria that produce acetic acid, such as Acetobacter aceti.
C. Propionic Acid Bacteria
 They are bacteria that produce propionic acid and are used in dairy
fermentation. Species such as Propionibacterium freudenreichii are included
in this group.
D. Butyric Acid Bacteria
 They are bacteria that produce butyric acid in relatively large amounts. Some
 Clostridium spp. such as Clostridium butyricum are included in this group.
E. Proteolytic Bacteria
 They are bacteria that can hydrolyze proteins because they produce
extracellular proteinases.
 Species in genera Micrococcus, Staphylococcus, Bacillus, Clostridium,
Pseudomonas, Alteromonas, Flavobacterium, Alcaligenes, some in
Enterobacteriaceae, and Brevibacterium are included in this group.
Bacterial Groups in Foods……

F. Lipolytic Bacteria
They are bacteria that are able to hydrolyze triglycerides because
they produce extracellular lipases.
Species in genera Micrococcus, Staphylococcus, Pseudomonas,
Alteromonas, and Flavobacterium are included in this group.
G. Saccharolytic Bacteria
They are bacteria that are able to hydrolyze complex carbohydrates.
Species in genera Bacillus, Clostridium, Aeromonas, Pseudomonas, and
Enterobacter are included in this group.
H. Thermophilic Bacteria
They are bacteria that are able to grow at 500
C and above.
Species from genera Bacillus, Clostridium, Pediococcus, Streptococcus,
and Lactobacillus are included in this group.
I. Psychrotrophic Bacteria
They are bacteria that are able to grow at refrigerated temperature
(<5􀁲C).
Some species from Pseudomonas, Alteromonas, Alcaligenes,
Flavobacterium, Serratia, Bacillus, Clostridium, Lactobacillus,
Leuconostoc, Carnobacterium, Brochothrix, Listeria, Yersinia, and
Aeromonas are included in this group.

J. Thermoduric Bacteria
 They are bacteria that are able to survive pasteurization temperature
treatment.
 Some species from Micrococcus, Enterococcus, Lactobacillus, Pediococcus,
Bacillus (spores), and Clostridium (spores) are included in this group.
K. Halotolerant Bacteria
 They are bacteria that are able to survive high salt concentrations (>10%).
 Some species from Bacillus, Micrococcus, Staphylococcus, Pediococcus, Vibrio,
and Corynebacterium are included in this group.
L. Aciduric Bacteria
 They are bacteria that are able to survive at low pH (<4.0).
 Some species from Lactobacillus, Pediococcus, Lactococcus, Enterococcus, and
Streptococcus are included in this group.
M. Osmophilic Bacteria
 They are bacteria that can grow at a relatively higher osmotic environment
than that needed for other bacteria. Some species from genera
Staphylococcus, Leuconostoc, and Lactobacillus are included in this group.
 They are much less osmophilic than yeasts and molds.
N. Gas-Producing Bacteria
 They are bacteria that produce gas (CO2, H2, H2S) during metabolism of
nutrients.
 Species from Leuconostoc, Lactobacillus, Propionibacterium, Escherichia,
Enterobacter, Clostridium, and Desulfotomaculum are included in this group.

O. Slime Producers
 They are bacteria that produce slime because they synthesize
polysaccharides.
 Some species or strains from Xanthomonas, Leuconostoc, Alcaligenes,
Enterobacter, Lactococcus,and Lactobacillus are included in this group.
P. Spore Formers
 They are bacteria having the ability to produce spores. Species from Bacillus,
Clostridium, and Desulfotomaculum are included in this group.
 They are further
 divided into aerobic spore formers, anaerobic spore formers, flat sour spore
formers, thermophilic spore formers, and sulfide-producing spore formers.
Q. Aerobes
 They are bacteria that require oxygen for growth and multiplication. Species
from Pseudomonas, Bacillus, and Flavobacterium are included in this group.
R. Anaerobes
 They are bacteria that cannot grow in the presence of oxygen. Species from
Clostridium are included in this group.
S. Facultative Anaerobes
 They are bacteria that are able to grow in both the presence and absence of
oxygen. Lactobacillus, Pediococcus, Leuconostoc, enteric pathogens, and some
species of Bacillus, Serratia, and coliforms are included in this group.

T. Coliforms
 Species from Escherichia, Enterobacter, Citrobacter, and Klebsiella are
included in this group. They are used as an index of sanitation.
U. Fecal Coliforms
 Mainly Escherichia coli is included in this group. They are also used as an index
of sanitation.
V. Enteric Pathogens
 Pathogenic Salmonella, Shigella, Campylobacter, Yersinia, Escherichia, Vibrio,
Listeria, hepatitis A, and others that can cause gastrointestinal infection are
included in this group.

SUMMARY
Bacteria, yeast and moulds contribute majorly in food spoilage
Some bacteria can even survive pasteurization and vaccum
packaging
Spoilage leads to deterioration of product and render it
unpalatable
Bacteria and fungi can also be pathogen and may lead to
diseases and food poisoning
Proper hygenic measures in production, processing, packaging
and storage can render food free from spoilage and
pathogenic organisms

Thanks
Acknowledgement: All the material/presentations available online on the subject
are duly acknowledged.
Disclaimer: The author bear no responsibility with regard to the source and
authenticity of the content.
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