Bacteria play an important historical and ongoing role in food production and spoilage. The document outlines the early developments in food preservation dating back to the 18th century and key events related to food spoilage and foodborne illness. It then provides details on common foodborne bacteria including their morphological and cultural characteristics as well as their importance in foods like sauerkraut, pickles, olives, chocolate and more. Various lactic acid bacteria and other microorganisms are used in the fermentation processes of many traditional and commercial food products.

1. HISTORICAL
DEVELOPMENTS,
Microorganisms important
in food BACTERIA- general
characteristics,
classification and
importance
Presented by
Deepika Rana
1601
M.Sc. Microbiology (3rd Sem)

2. HISTORICAL
DEVELOPMENTS
• Although it is extremely difficult to pinpoint
the precise beginnings of human awareness of
the presence and role of microorganisms in
foods, the available evidence indicates that
this knowledge preceded the establishment of
bacteriology or microbiology as a science.
• Some of the more significant dates and events
in the history of food preservation, food
spoilage, food poisoning,are

3. Year Event
1782 Canning of vinegar was introduced by a Swedish chemist.
1813 Use of SO2 as a meat preservative is thought to have originated around this time
1839 Tin cans came into wide use in the United States.
1840 Fish and fruit were first canned.
1853 R. Chevallier-Appert obtained a patent for sterilization of food by autoclaving.
1854 Pasteur began wine investigations. Heating to remove undesirable organisms was
introduced commercially in 1867- 1868.
1855 Grim wade in England was the first to produce powdered milk.

4. 1865 The artificial freezing offish on a commercial scale was begun in the
United States. Eggs followed in 1889.
1880 The pasteurization of milk was begun in Germany.
1882 Krukowitsch was the first to note the destructive effects of ozone
on spoilage bacteria.
1890 Mechanical refrigeration for fruit storage was begun in Chicago.
1907 E. Metchnikoff and co-workers isolated and named one of the
yogurt bacteria, Lactobacillus bulgaricus.
1908 Sodium benzoate was given official sanction by the United States
as a preservative in certain foods.
1928 The first commercial use of controlled atmosphere storage of
apples was made in Europe (first used in New York in 1940)
1950 The D value concept came into general use.

5. Year Event
1680 Leeuwenhoek was the first to observe yeast cells.
1780 Scheele identified lactic acid as the principal acid in sour milk.
1857 Pasteur showed that the souring of milk was caused by the growth
of organisms in it.
1873 The first reported study on the microbial deterioration of eggs was
carried out by Gayon.
— Lister was first to isolate Lactococcus lactis in pure culture.
1888 Miquel was the first to study thermophilic bacteria.
1895 S.C. Prescott and W. Underwood traced the spoilage of canned
corn to improper heat processing for the first time.
1915 Bacillus coagulans was first isolated from coagulated milk by B. W.
Hammer.

6. Year Event
1857 Milk was incriminated as a transmitter of typhoid fever by W.
Taylor of Penrith, England.
1888 Gaertner first isolated Salmonella enteritidis from meat that had
caused 57 cases of food poisoning.
1896 Van Ermengem first discovered Clostridium botulinum.
1906 Bacillus cereus food poisoning was recognized
1937 Paralytic shellfish poisoning was recognized.
1955 Similarities between cholera and Escherichia coli gastroenteritis
in infants were noted by S. Thompson.
1960 The production of aflatoxins by Aspergillus flavus was first
reported.

8. BACTERIA
important in food general characteristics, classification and
importance
Morphological characteristics important in food bacteriology
1. Encapsulation
2. Formation of endospores
3. Formation of cell aggregates
Cultural characteristics important in food bacteriology
Bacterial growth in or on food often is extensive enough to make the food unattractive
in appearance or otherwise objectionable. Pigmented bacteria cause discolouration
on the surface of the food; films may cover the surface of liquid ; growth may make
surface slimy; or growth throughout the surface may result in undesirable cloudiness
or sediment.
Eight Sources of Bacteria to Foods
Soil and water, Plants/ products, Food utensils, Gastrointestinal tract, Food
handlers, Animal feeds, Animal hides, Air and dust

9. SYNOPSIS OF COMMON FOODBORNE BACTERIA
Acinetobacter (unable to move).
•Gram negative
•Rod shaped
•Oxidase negative
•Strict aerobes
•Do not reduce nitrates
•Although rod-shaped cells are formed in
young cultures, old cultures contain many
coccoid shaped cells.
•Widely distributed in soil and waters and
may be found on many foods,
•Especially refrigerated fresh products.
On chromagar

10. Aeromonas (ae • ro • mo'nas; gas producing).
•These are typically aquatic gram-negative rods
formerly in the family Vibrionaceae but now in
the family Aeromonadaceae.
•As the generic name suggests, they produce
copious quantities of gas from those sugars
fermented.
•They are normal inhabitants of the intestines
of fish, and some are fish pathogens.
•The mol% G + C content of DNA is 57-65.
Food market egg salads have been reported
contaminated with Aeromonas bacteria.

11. Alcaligenes (alkali producers).
•Although gram negative, these organisms
•sometimes stain gram positive.
•They are rods that do not, as the generic
name suggests, ferment sugars but instead
produce alkaline reactions, especially in litmus
milk.
•Nonpigmented, 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.
•Curdlan consists of β-(1,3)-linked glucose
residues and forms elastic gels upon heating in
aqueous suspension. The production of
curdlan by Alcaligenes faecalis is being
developed to be used in gel production as well.

12. Alteromonas (al • te • ro • mo'nas; another
monad). These are marine and coastal water
inhabitants
that are found in and on seafoods; all
species require seawater salinity for growth.
They are gram-negative motile rods that are
strict aerobes.
Citrobacter
slow lactose-fermenting,
gram-negative rods.
All members can use citrate as the sole
carbon source. C.freundii is the most prevalent
species in foods, and it and the other species
are not uncommon on vegetables and fresh
meats.

13. •Arcobacter (Ar'co • bac • ter; L. arcus, bow).
•They are gram-negative
•curved or S-shaped rods
•except they can grow at 15°C and are aero
tolerant.
•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.
Arcobacter Septicus Bacteria, SEM
Molluscs filter-feed, contaminated sea water
could result in the bioaccumulation of A. butzleri

14. Bacillus
•gram-positive
•sporeforming rods
•are aerobes
•most are mesophiles, psychrotrophs and
thermophiles
• Two pathogens: B. anthracis (cause of anthrax) and
B. cereus.
•Although most strains of the latter are nonpathogens,
some cause foodborne gastroenteritis.
•grow as low as about 35°C to 700C, and over the pH
range 2 to 6.
•B.cereus is a food borne pathogen
•Growth of B. cereus in pasteurised milk is considered
the main limiting factor determining the shelf life of
this food product. Too high levels of B. cereus in
pasteurized milk before the end of shelf life or
prolonged refrigerated storage cause common
structural defects known as sweet curdling and bitty
cream

15. Campylobacter
•gram-negative,
•spirally curved rods
•Formerly classified as vibrios.
•Microaerophilic to anaerobic.
•Campylobacter jejuni is the most common
cause of bacterial foodborne illness in the
United States.
Clostridium (spindle).
•Anaerobic sporeforming rods
•widely distributed in nature
•C. perfringens food poisoning and botulism
Mesotrophic, psychrotrophic, and thermophilic

16. Corynebacterium (club).
•True coryneform genera
•gram-positive, rod-shaped
•involved in the spoilage of vegetable and
meat products.
•Most are mesotrophs, although psychrotrophs
are known, and one, C. diphtheriae, causes
diphtheria in humans.
Erwinia
•Gram-negative
•enteric rods
•associated with plants, where they cause
bacterial soft rot

17. Flavobacterium
•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.
Leuconostoc
•gram-positive, catalase-negative cocci
•Heterofermentative
•produce lactic acid and diacetyl
•Leuconstoc mesenteroides used primarily in
sauerkraut production
•In fermented milk and meat products, diacetyl is
responsible for butter flavor.
•L.carnosum produces bacteriocins, and these are
used to inhibit Listeria monocytogenes in dairy and
meat products.

18. Lactobacillus
•gram-positive,
•catalase-negative rods that often occur in long
chains.
•They typically occur on most, if not all,
vegetables, along with some of the other lactic
acid bacteria.
•Their occurrence in dairy products is common.
•L. suebicus, was recovered from apple and
pear mashes; it grows at pH 2.8 in 12-16%
ethanol.
•Miso, tempeh, umeboshi, which is a type of
pickled plum, and pickles along with a number
of other fermented vegetables, can contain
active cultures of lactobacilli, but only if they're
not pasteurized or subjected to high heat.

19. Micrococcus
•Gram positive cocci
•Catalase positive,
•produce pink to orange-red to red pigments,
•whereas others are nonpigmented.
•Grow at high levels of NaCl,
•mesotrophs, psychrotrophic also known.
•M.luteus used in cheese production
Listeria
•Gram-positive,
•Nonsporing rods
•identical cell walls, fatty acid, and
cytochrome composition.

20. Proteus (pro'te • us).
•Enteric gram-negative rods
•aerobic pleomorphic,
•Motile
•Produce swarming growth on moist agar
plates
•Present in the intestinal tract of humans and
animals.
•Isolated from a variety of vegetable and meat
products, especially those that undergo
spoilage at temperatures in the mesophilic
range.

21. Pseudomonas (false monad).
•Gram-negative rods
•Largest genus of bacteria that exists in
fresh foods.
•Typical of soil and water bacteria
•Widely distributed among foods,
especially vegetables, meat, poultry, and
seafood products.
•Bring about the spoilage of refrigerated
fresh foods because many species and
strains are psychrotrophic.
•Some are notable by their production of
watersoluble, blue-green pigments,
whereas many other food spoilage types
are not.
P. aeruginosa growing on Skim Milk Agar.

22. Shigella
All members are human enteropathogens.
Staphylococcus (grapelike
coccus).
These gram-positive, catalase-positive
cocci include S. aureus, which causes several
disease syndromes in humans, including
foodborne gastroenteritis.
Serratia
•Gram-negative rods
•belong to Enterobacteriaceae
•aerobic and proteolytic,
•Produce red pigments on culture
media and in certain foods, although
nonpigmented strains are not
uncommon.
•S. liquefaciens most prevalent of the
foodborne species; it causes spoilage
of refrigerated vegetables and meat
products.

23. •Vibrio (vib'ri • o).
•These gram-negative straight or curved rods
are members of the family Vibrionaceae.
•Several species cause gastroenteritis and
other human illness;
•V. parahaemolyticus typically causes non-
bloody diarrhea.
•In persons with liver disease, cancer, or
another immune-compromising condition, V.
vulnificus typically infects the bloodstream,
causing a life-threatening illness.
•Half of the infections are fatal, and death can
occur within two days.
•Transmission by raw shellfish, enter the body
via a wound that is exposed to warm seawater.
Yersinia (yer • si'ni • a).
This genus includes the agent of human
plague, Y.pestis, and at least one
species that causes foodborne gastroenteritis,
Y. enterocolitica.
Yersinia pestis rod-shaped bacteria in the
bubonic form

24. Acidophilus milk is made with Lactobacillus acidophilus.
Butter is made from pasteurized cream, to which a lactic acid starter has been added. The
starter contains, for example, Streptococcus cremoris or S. lactis, but requires Lactobacillus
diacetylactis to give it its characteristic flavor and odor.
Cheese is often made with Streptococcus and Lactobacillus bacteria. Fermentation lowers
the pH, thus helping in the initial coagulation of the milk protein, as well as giving
characteristic flavors. Lactococcus lactis and Leuconostoc cremoris are used most often.
Propionibacterium shermanii is used in the preparation of swiss cheese.

25. Kefir includes many different microbes, including yeasts, lactobacilli, lactococci, and
leuconostocs. Depending on geographical locations, the precise types of microbes will
vary.
Yogurt usually requires the addition of Lactobacillus bulgaricus, Lactococcus
thermophilus, and/or Streptococcus thermophilus to the milk.

26. Glutamic acid requires Corynebacterium glutamicum for its formation. By growing C.
glutamicum on limited amounts of biotin(cofactor for lipid synthesis), it causes the
bacterial membrane to leak sufficient quantities of glutamic acid.
Lysine -- The bacterium, Brevibacterium flavum is used in the industrial biosynthesis of
lysine. Mutants no longer susceptible to feedback inhibition have been isolated to be
used industrially to increase the yield of amino acids.
Soy sauce is made from a mixture of soy beans and rice fermented by Lactobacillus
delbrueckii
•Meat products, like salami and bologna sausages, require some fermentation with
Pediuococcus cerevisiae, Lactobacillus plantarum and some members of the genus Bacillus.
Izushi (sushi), a Japanese delicacy made from a mixture of fish, rice, and other vegetables
is produced by fermentation with lactobacilli.

27. •Sauerkraut-making requires the bacteria Leuconostoc mesenteroides and
Lactobacillus brevis to ferment sugars that provide a variety of such organic products
as lactic acid, acetic acid, ethanol, and mannitol. Later a 'homofermentative' bacteria,
Lactobacillus plantarum takes over, producing only lactic acid. Later, Enterococcus
faecalis and Pediococcus cerevisiae assume the fermentation process if the salt brine
is not what it should be.
•Dill pickles are simply fermented cucumbers. Streptococci starts the process of
fermentation, but as the pH level falls, leuconostoc and pediococcus species, as well as
Lactobacillus plantarum continue the process.
•Olives are edible only after fermentation with Lactobacillus plantarum and Lactobacillus
mesenteroides.
•Coffee and chocolate require Erwinia dissolvens, leuconostoc, and lactobacillus species
plus the yeasts of the genus Saccharomyces to remove the tough outer coats. The
microbes confer the characteristic taste to cocoa and chocolate. It is thought that the
chocolate provides protection for the bacterium as it passes through the acidic
environment of the stomach. This was observed when higher incidents of illness were
reported in children.

28. Sauerkraut
Dill pickles
Fermented olives Chocolate and coffee

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https://www.foodsafety.gov/poisoning/causes/bacteriaviruses/
2. Bacteria in food production | effca
www.effca.org/content/bacteria-food-production
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https://en.wikipedia.org/.../List_of_microorganisms_used_in_food_and_beverage_pre...
4. Modern Food Microbiology, sixth edition, James M. Jay(2000)