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Classification of Bacteria- Alka Kumari, Assistant Professor
- 1. Classification of Micro-organism By ALKA KUMARI ASSISTANT PROFESSOR DEPARTMENT OF FOOD TECHNOLOGY VFSTRU- GUNTUR
- 2. Bacteria SYLLABUS Morphological characteristics important in Food Bacteriology Cultural and Physiological characteristics important in Food Bacteriology Genera of bacteria important in Food Bacteriology groups
- 5. Prokaryotes Vs Eukaryotes Character Prokaryotes Eukaryotes Nucleus Nuclear membrane Absent Present Nucleolus Absent Present Chromosome One circular One or more paired and linear Cell division Binary fission Mitosis Cytoplasmic membrane Structure and Composition fluid phospholipid bilayer, lacks sterols fluid phospholipid bilayer containing sterols Function Incapable of endocytosis (phagocytosis and pinocytosis) and exocytosis Capable of endocytosis and exocytosis
- 6. Nucleolus • It is the largest structure in the nucleus of eukaryotic cell, where it primarily serves as the site of ribosome synthesis
- 7. Endocytosis It is a form of active transport in which a cell transports molecules (such as proteins) into the cell (endo- + cytosis) by engulfing them in
- 8. Endoplasmic Reticulum • The endoplasmic reticulum is an organelle in the eukaryotic cells that forms an interconnected network of tube-like structures known as cisternae • Two types • rough ER: is studded with ribosomes that are the sites of protein synthesis • Smooth ER: lacks ribosomes and functions in lipid manufacture and metabolism, the production of steroid hormones, and detoxification
- 9. Golgi apparatus • The Golgi apparatus is a major collection and dispatch station of protein products received from the ER
- 10. A) Pinocytosis: the ingestion of liquid into a cell by the budding of small vesicles from the cell membrane. B) Phagocytosis: the ingestion of solid into a cell by the budding of small vesicles from the cell membrane
- 11. Sterols They occur naturally in plants, animals, and fungi, with the most familiar type of animal sterol being cholesterol
- 12. Morphological Classification Morphological Classification of Bacteria is based on- 1. Shape 2. Structure 3. Aggregation 4. Staining
- 13. • Prokaryote • Single celled microorganism • size: 0.5–5.0 µ Morphological Characteristics
- 14. Morphology: Shape of Bacteria 1. Coccus (Cocci): bacterium that has a spherical, ovoid, or generally round shape
- 15. Bacteria- Cocci B) Diplococci • pairs of cocci • Example: Streptococcus pneumoniae C) Streptococci • chains of cocci • e.g. Streptococcus pyogenes
- 16. D) Staphylococci • Irregular (grape-like) clusters of cocci • e.g. Staphylococcus aureus E) Tetrads • Clusters of four cocci arranged within the same plane • e.g. Micrococcus Bacteria- Cocci
- 17. F) Sarcina • cuboidal arrangements of eight cocci Bacteria- Cocci
- 18. Shape- Bacilus • Rod-shaped bacteria • On the basis of arrangement of organisms, they can be described as A) Bacillus: The rod-shaped bacteria cells, are present as single individuals.
- 19. B) Diplobacilli: • Two bacilli arranged side by side with each other C) Streptobacilli: • Bacilli arranged in chains Shape- Bacilus
- 20. D) Vibrios: • They are comma-shaped bacteria • e.g. Vibrio cholarae E) Spiral: • Spiral shape • Eg. Spirillus Shape- Bacilus
- 21. Pleomorphic Bacteria • These bacteria lack in rigid cell wall • Highly pleomorphic and of indefinite shape • They occur in round or oval bodies and in interlacing filaments • Eg. Mycoplasmas
- 23. Basis-Presence of Flagella A. Monotrichous e.g Pseudomona auregenosa B. Amphitrichous C. Lophotrichous e.g Pseudomona flouresence D. Peritrichous e.g Salmonella typhi E. Atrichous e.g spirochas
- 24. Arrangement of Flagella A) Monotrichous • single flagellum at one pole • e.g Pseudomona auregenosa B) Amphitrichous • flagella at both poles • Eg. Alkaligens faecalis.
- 25. C) Lophotrichous • Tuft of flagella at one end • e.g Pseudomona flouresence D) Peritrichous – • flagella all over • e.g Salmonella typhi Arrangement of Flagella
- 26. E) Amphilophotrichous: • tuft of flagella at both ends Arrangement of Flagella
- 27. On the basis of Staining • Gram positive • Gram Negative
- 28. Gram Staining • Gram staining is a method of staining used to differentiate bacterial species into two large groups • Differential Technique • Technique by Danish bacteriologist- Hans Christian Gram Gram-positive Gram-positive
- 29. Cell wall of Gram (+) and Gram (-) Bacteria
- 30. Gram Staining
- 31. Cell wall of G (+) and G (-) bacteria
- 33. 1. Crystal Violet: 2. Gram’s Iodine • First of all microbial smear is treated with crystal violet dye • It stains all microorganism purple • Mordant Gram’s Iodine is added • It acts as a stabilizer that causes the dye to form large complexes in the peptidoglycan layer of the cell wall • The thicker Gram positive cell wall peptidoglycan is able to trap more firmly the large complex than those of Gram negative cell Gram Staining
- 34. 3. Alcohol: 4. Safranin: Addition of alcohol dissolve the lipid in the outer layer and removes the dye from peptidoglycan layer- only in case of G (-) bacteria After alcohol treatment, Gram negative bacteria are colourless, counterstain safranin stains them pink Gram Staining
- 35. Encapsulation Capsule: It is a polysaccharide layer that lies outside the cell wall sticky capsule helps the bacterium to adhere to the cell surfaces inside the host tissues. Capsules also contain water which protects the bacteria against desiccation It enhances the ability of bacteria to cause disease
- 36. Capsule • Gram Positive - immediately exterior to the murein peptidoglycan layer • Gram Negative- outer membrane (Lipopolysaccharide layer ) • A
- 37. Some Killers Have Pretty Nice Capsule • Streptococcus pneumoniae • Klebsiella pneumoniae • Haemophilus influenzae • Pseudomonas aeruginosa • Neisseria meningitidis • Cryptococcus neoformans
- 39. Endospores • An endospore is a dormant, tough, and non-reproductive structure produced by certain bacteria • Endospores are formed at an intracellular site, are very refractile, and are resistant to • heat • ultraviolet light • desiccation
- 41. Cultural Characteristic of Bacteria • When grown on a variety of media, microorganisms will exhibit visible physical differences in appearance in their isolated colonies and their growth • These differences are called cultural characteristics or morphology • Significance: may be used as an aid in identifying and classifying some organisms
- 43. Cultural characteristics • Cultural characteristics or morphology are determined by culturing microorganisms in nutrient broth and on nutrient agar plates and slants. • After incubation, the characteristics are observed.
- 48. • After incubation, in a nutrient broth, bacteria may exhibit a particular form of growth • Turbidity: In a liquid media, some bacteria grow diffusely causing a uniform clouding of the media • Pellicle: Layering of growth or accumulation of cells at the top • Sediment: accumulation of cells at the bottom of the broth tells something about the microorganism’s oxygen requirements • Flocculent: Bacterial aggregations are formed and the bacterial growth appears as small puff balls floating in the broth • Observation of such factors also helps in recognizing types of bacteria. Cultural Characteristics in Broth media
- 49. Cultural Characteristics in Broth media
- 50. The basic categories of bacterial colony appearance, forms and characteristics on solid media include: A)Colony form (shape): Colony shape may be described as • Circular • Irregular • punctiform (tiny) B) margin (edge):The margin may be • entire (smooth with no irregularities) • undulate (wavy) • lobate (lobed) • Filamentous • rhizoid (branched like roots) Cultural Characteristics on Solid media
- 51. Cultural Characteristics • C) Elevation: Colony elevations include • Flat • Raised • Convex • pulvinate (very convex), and • umbonate (raised in the centre)
- 52. Cultural Characteristics D) pigmentation (colour) • Pigment production may be influenced by environmental factors such as temperature and nutrient supply • Colony color may be combined with optical properties such as opaque, translucent, shiny, or dull E) Texture: Colony texture may be • Moist • Mucoid • dry
- 53. Pigmented Bacteria Pigments Microorganism Violet Chromobacterium violacein Yellow Xanthomonas campestris Orange Sarcina Red Serratia marcescens Brown Rhizobium Golden Staphylococcus aureus White Staphylococcus epidermis Pink Micrococcus roseus
- 54. Protein 1 Polypeptide Peptide Amino Acid 1- Proteinase 2- Peptidase 3. Peptidase 2 3 Physiological characteristic of Bacteria
- 55. Physiological characteristic of Bacteria . E coli
- 56. Carbohydrate- aerobic condition C6H12O6 CO2 H2O
- 57. Microorganism Products (anaerobic condition) Streptococcus and Lactobacillus lactic acid Propionibacterium Propionic acid + acetic acid + carbon dioxide Escherichia coli acetic acid, lactic acid, succinic acid, ethyl alcohol, carbon dioxide, and hydrogen Enterobacter formic acid, ethyl alcohol, 2,3-butanediol, lactic acid, carbon dioxide, and hydrogen Clostridium butyric acid, butyl alcohol, acetone, isopropyl alcohol, carbon dioxide, and hydrogen Physiological characteristic of Bacteria
- 58. Genera of Bacteria important in Food Bacteriology
- 59. Genus Acetobacter • Acetic acid bacteria are characterized by the ability to convert ethanol to acetic acid in the presence of oxygen • Acetobacter • rod-shaped • motile • Source: fruits, vegetables, souring fruits, and alcoholic beverages. • Causes spoilage in alcoholic beverages
- 60. Genus Alcaligenes Alkaline reaction is produced in the medium of growth A. viscolactis. causes ropiness in milk, and A. metalcaligenes gives a slimy growth on cottage cheese. Source Manure Feeds soil Water
- 61. The endospores are aerobic to facultative may be • mesophilic (B. subtilis) • thermophilic (B. stearothermophilus) • actively proteolytic ( sweet-curdle milk; B. cereus ) • moderately proteolytic, or non proteolytic • gas-forming or not • lipolytic or not Genus Bacillus (Gram Positive) Source: Soil
- 62. Genus Clostridium (Gram Positive) • Endospores: anaerobic to microaerophilic • swell the end or middle of the rods • mesophilic(C perfringens - "stormy fermentation" of milk, Clostridium butyricum) • thermophilic (Clostridium thermosaccharolyticum)
- 63. • actively proteolytic (C. Botulinum-group I) • non proteolytic (C. Botulinum-group II) • gas-forming (Clostridium thermosaccharolyticum) Genus Clostridium (Gram Positive)
- 64. Genus E coli (Gram Negative) • Gram-negative • non-spore forming, • facultative anaerobic • rod-shaped • Source: • Water • Intestinal tract of warm blooded organism • Sewage
- 65. Genus Lactobacillus (Gram positive) Heterofermentative • They ferment sugar to lactic acid, alcohol, other acid • Hetero-fermentative species growing at higher temperatures L. delbrueckii. L. fermentum lower temperatures are L. brevis L. buchneri L. pastorianus Homofermentative • They ferment sugar chiefly to lactic acid • optimal temperatures of 37 C or above include L. bulgaricus L. lactis L. acidophilus L.thermophilus. • lower optimal temperatures include L. casei L. plantarum L. leichmannii
- 66. • Heterofermentative • Convert sugar to lactic acid plus acetic acid, ethyl alcohol, and carbon dioxide • generally slime-forming • catalase-negative ??? Genus Leuconostoc (Gram positive) Citric acid Diacetyl L. dextranicum and L. cremoris
- 67. Genus Leuconostoc (Gram positive) • ovoid cocci • form chains • Habitat - surface of plants
- 68. Genus Streptococcus (Gram positive) • pairs, chains • all Homofermentative • catalase-negative • Groups: 1. pyogenic 2. viridans 3. lactic 4. enterococcus groups
- 69. The pyogenic • pus-producing group pathogenic streptococci • S. agalactiae- mastitis in cows (fatal mammary gland infection) • S. pyogenes-human septic sore throat, scarlet fever, and • The pyogenic streptococci cannot grow at 10 or 450C
- 70. The viridans • It includes S. thermophilus S. bovis • it is thermoduric • these species can grow at 450C but not at 100C
- 71. The lactic • group contains the important dairy bacteria, S. lactis and S. cremoris* • grow at 100C but not at 450C • These bacteria are used as starters for cheese, cultured buttermilk, butter, along with Leuconostoc spp., and • S. lactis often is concerned in the souring of raw milk.
- 72. The enterococci • consists of S. faecalis and S. faecium • S.faecalis is usually the more heat-resistant and comes more from human sources • whereas S. faecium come from plant source • Bacteria of this group can grow at both 10 0C and 45 0C.
- 73. Group of Bacteria important in Food Bacteriology
- 74. Saccharolytic bacteria • Disaccharides /polysaccharides sugars. • Amylolytic bacteria possess amylase to bring about the hydrolysis of starch outside the cell. • Amylolytic bacteria Bacillus subtilis Clostridium butyricum
- 75. Lactic acid bacteria or lactics • These bacteria ferment sugars to lactic acid. • desirable in making products such as sauerkraut and cheese. • undesirable in terms of spoilage of wines because they usually form acid rapidly. • Example: Leuconostoc Lacto bacillus Streptococcus Pediococcus.