Bacteria Lec 33333333333333333rd sem.pptx

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1. Bacteria

2. Bacteria FOOD SAEFTY AND MOCROBIOLOGY

3. Objective At the end of this presentation, the student will be able to : Understand the bacteria Know about the characteristics of bacteria Know about the classification of bacteria Know about the structure of bacteria Know about the disease cause by bacteria physiological characteristics of bacteria , cultural characteristics of bacteria

4. Bacteria The word bacteria is derived from a Latin and a Greek word Bakteria meaning “ cane ”. (Rod) Bacteria is a micro organism with few micro meter in length and have wide range of shapes (round, oval, rod and spiral shapes). First discover by Antony Van Leeun Hook in 1676, initially called “ Animalcules ” Study about bacteria is know as “ Bacteriology ”, while study about the harmful effect of bacteria on human body is known as “ Medical bacteriology ”.

5. Bacteria Bacteria are found everywhere on earth i.e. in soil, water, air, deep earth crust, radio active waste and acidic hot spring A single gram of soil contain 40 million bacteria while a million bacteria found in an ml of fresh water. However only few of these are harm full to human body causes disease They produce more Oxygen than plants

6. Bacteria Bacteria are earlier form of life form on earth. Their fossils are found 2.5 billions years ago

7. Characteristics of Bacteria Size of bacteria rang between 0.5 to 5 micrometer They are prokaryotic microbes (have no membrane bounded Nucleus and mitochondria) Have a single chromosome as Genetic material Enclosed in a rigid cell wall made up of peptidoglycane Some bacteria, along with plasma membrane, contain an additional membrane called Capsule Some bacteria are aerobic, meaning that they require oxygen in order to survive. Other bacteria are anaerobes, meaning that they do not require oxygen to survive

8. Characteristics of Bacteria….. Reproduce by Amitosis (asexual form of reproduction) Many bacteria form Spores Some bacteria are Auto tropes while some are hetro tropes Most grow best at pH of 6.5 to 7.0 Many act as decomposers recycling nutrients

9. Nutrition Source for bacteria Saprobes – feed on dead organic matter Parasites feed on a host cell Photoautotroph use sunlight to make food Chemoautotroph oxidize inorganic matter such as iron or sulfur to make food

10. Classification of bacteria Bacteria are classified according to following properties According to Morphology According to Needs for Oxygen According to Staining they retain According to Heat Tolerance According to Pathoginicity

11. According to Morphology According to morphology (shape), Bacteria are classified into Cocci Those who appear in Round or oval shape Bacilli Those who appear in Rod shape Spirillia Those who appear in spring spiral or shape

12. According to Morphology…

13. Arrangement of Bacteria Diplococci Arrange in pairs Stephylo cocci Arrange in cluster Strepto cocci Chain like arrangement

14. According to Needs for Oxygen According to their need for oxygen, Bacteria are classified into Aerobic Those who required Oxygen to live Anaerobic Those who don’t required Oxygen to live Facultative Aerobic Those who can adjust in either presence or absence of Oxygen

15. According to Staining they retain According to stain (color) they retain or appear during the procedure of gram staining, Bacteria are classified into Gram Positive Those who appear blue , purple or violate in color Gram Negative Those who appear red or pink in color

16. Gram + Gram -

17. According to Heat Tolerance According to temperature on which Bacteria can be best live, they are classified into Psychrophilic bacteria Can survive on extreme cold temperature Mesophilic bacteria Can survive on moderate temperature Thermophilc bacteria Can survive on extreme hot temperature

18. According to Pathoginicity According to disease causing ability of bacteria, they are of two types Pathogenic bacteria Those who cause disease in human Non-Pathogenic bacteria Those who cannot cause disease in humans

19. Structure of Bacteria

20. Structure of Bacteria Capsule Cell wall Ribosomes Nucleoid Flagella Pilli Cytoplasm

21. Capsule Capsule : tight protective covering Around the cell in many bacterial species. keeps the cell from drying out and helps it stick to food or other cells. Composed of polysaccharides and proteins.

22. Cell Wall Thick outer covering that maintains the overall shape of the bacterial cell. Thin, delicate, flexible, selectively Permeable. Similar chemical composition to eukaryotic cell membranes. Regulates material transport in and out of the cell. Houses enzymes for energy production. Resembles mitochondria membrane in eukaryotic cells

23. Ribosomes cell part where proteins are made Ribosomes give the cytoplasm of bacteria a granular appearance in electron micrographs

24. Chromosome A ring made up of DNA Bacteria contain a single chromosome

25. Cytoplasm The cell materials bounded by cytoplasmic membrane may be divided into i) the fluid portion with dissolved substances ii ) the cytoplasmic area granular in appearance and rich in macromolucular RNA- protien bodies(ribosome) which synthesis protien iii ) the chromatinic area,rich in DNA

26. Microbiology – Chapter 4, Bacteria Bacterial appendages: Pilli (fimbriae) and Flagella Pilli are short, hair-like, protein: function “adherence” – stick to each other, stick to surfaces, harder to wash away Specialized “sex” pilus – conjugation Pilli( pilus ) provide a port for entry of genetic Materials during bacteria mating.

27. Flagella A whip-like tail that some bacteria have for locomotion A = monotrichous B = amphitrichous C = lophotrichous D = peritrichous A:Monotrichous bacterium possesses a single Flagellum B:Amphitrichous bacterium is characterized by groups of flagella inserted at both ends of bacteria C:A lophotrichous organism has a group of 2 or more flagellum. peritrichous bacterium flagella are dispersed on the entire surface of bacteria. .some bacteria have no flygella called atricous .

28. Bacteria Reproduction Under optimum conditions bacteria can reproduce every 20 minutes. (double every 10 to 20 minutes. Bacteria reproduction is controlled by various factors including : temperature and food availability. Their reproduction can be by: Asexual: Binary fission Sexual: conjugation

29. Binary Fission It involves the copying of the DNA and the splitting into two new cells.

30. Conjugation Sexual reproduction One bacteria is able to transfer its DNA into another bacteria by means of a pilus ( pili )

31. Gram stains: Important in medicine because provides information for treatment of bacterial disease. Bacteria stain either gram positive (purple) or gram negative (pink). Gram positive tend to respond to penicillin and like antibiotics. Gram negative respond to types of antibiotics unrelated to penicillin.

32. Crystal violet dye Iodine Alcohol Safranin Gram Stain Process: Purple Decolorizes Pink Counterstain

33. A Gram Stain is usually performed on a smear preparation that has been heat fixed. One function of fixation is to secure (fix) the cells to the slide.

34. Gram positive = purple because of large amount of peptidoglycan in cell wall. Polymer consisting of sugars and amino acids that forms a mesh-like layer outside the plasma membrane of eubacteria.

35. Gram negative = pink because ¨ lipopolysaccharide membrane is removed by alcohol and thin peptidoglycan layer allows dye to escape. ( LPS ) is a large molecule consisting of a lipid and a polysaccharide (carbohydrate) joined by a covalent bond.

36. physiological characteristics of Bacteria Chemical Reactions Induced by Bacterial Growth and Activity Hydrolysis of Complex Carbohydrates Reaction : Complex carbohydrates (like starches and cellulose) are broken down into simpler sugars ( monosaccharides and disaccharides) by bacterial enzymes. Enzymes Involved : Amylases and cellulases . Examples : Breakdown of starch in bread by amylase-producing bacteria.

37. Hydrolysis of Proteins Hydrolysis of Proteins Reaction : Proteins are hydrolyzed into polypeptides, which are further broken down into amino acids, and then to ammonia or amines. Enzymes Involved : Proteases and peptidases. Examples : Degradation of meat proteins by spoilage bacteria leading to the production of foul-smelling amines . Pseudomonas : This genus of bacteria is commonly found on meat and is known for its proteolytic activity. Pseudomonas species can break down proteins and produce foul-smelling amines as byproducts. Clostridium : Some species in this genus are anaerobic bacteria that can also degrade proteins in meat, leading to the production of putrescine and cadaverine .

38. Hydrolysis of Fats Reaction : Fats (triglycerides) are broken down into glycerol and fatty acids. Enzymes Involved : Lipases. Examples : Rancidity in dairy products due to the action of lipase-producing bacteria.

39. Oxidation-Reduction Reactions Oxidation-Reduction Reactions Purpose : Bacteria utilize these reactions to obtain energy from various food components. Substrates : Carbohydrates, other carbon compounds, and simple nitrogen-carbon compounds. Products : Organic acids (e.g., lactic acid), alcohols (e.g., ethanol), aldehydes, ketones, and gases (e.g., carbon dioxide, hydrogen). Examples : Fermentation of sugars by lactic acid bacteria to produce lactic acid in yogurt; production of ethanol and carbon dioxide by yeast in bread and alcoholic beverages.

40. Lactic acid bacteria (LAB ) such as Lactobacillus , Streptococcus , and Leuconostoc ferment sugars (e.g., lactose in milk) to produce lactic acid . Bread Making : Yeast ferments the sugars present in the dough, producing ethanol and carbon dioxide. The carbon dioxide gets trapped in the dough, causing it to rise, while the ethanol evaporates during baking. Alcoholic Beverages : Yeast ferments sugars in fruit juice or grain mash to produce ethanol, which is the primary alcohol in beverages like wine, beer, and spirits . Flavor Compounds : In cheese and fermented dairy products, certain bacteria produce aldehydes (e.g., acetaldehyde) and ketones (e.g., diacetyl ) that contribute to the complex flavors of these products. Gases (e.g., Carbon Dioxide, Hydrogen) During fermentation, many microorganisms produce gases as byproducts. Bread Making : The carbon dioxide produced by yeast fermentation causes the dough to rise, creating a light and airy texture in the baked bread.

41. Classification Based on Nutrition bacteria are classified as : Autotrophs – can synthesise all their organic compounds by utilising atmospheric CO 2 & N 2. No medical importance. Heterotrophs – unable to synthesise their own metabolites & depend on preformed organic compounds. All pathogens

42. Growth Factors Some bacteria require certain organic compounds in minute quantities – Growth Factors OR Bacterial Vitamins. It can be : Essential – when growth does not occur in their absence. Accessory – when they enhance growth, without being absolutely necessary for it

43. Bacterial Nutrition Water constitutes 80% of the total weight of bacterial cells. Proteins, polysaccharides, lipids, nucleic acids, mucopeptides & low molecular weight compounds make up the remaining 20%. For growth & multiplication, the minimum nutritional requirements are water, a source of carbon, a source of nitrogen & some inorganic salts

44. OTHER GROWTH FACTORS Identical with mammalian nutrition Vitamin B complex – thiamine riboflavine nicotinic acid pyridoxine folic acid & Vit.B 12

45. GROWTH It is an increase in all the cell components, which ends in multiplication of cell leading to an increase in population. It involves - an increase in the size of the cell & an increase in the number of individual cells. Bacteria divide by binary fission.

46. OTHER FACTORS AFFECTING BACTERIAL GROWTH Temperature Atmosphere – O 2 & CO 2 H-ion concentration Moisture & drying Osmotic effects Radiation Mechanical & sonic stress

47. Temperature Vary in their temperature requirements. Temperature range – growth does not occur above the maximum or below the minimum . Optimum Temperature – growth occurs best, 37 º C for most pathogenic bacteria .

48. CLASSIFICATION BASED ON TEMP Mesophilic – grows best between 25 º C and 40 º C. e.g. most bacterial pathogens Psychrophilic (cold loving) – grows best below 20 º C e.g. Flavobacterium spps Thermophilic – grows best at high temp, 55- 80 º C e.g. Bacillus sterothermophilus Thermal Death Point:Lowest Temp that kills a bacterium under standard conditions in a given time. Mesophilic bacteria having thermal death point 50c-65C. Spores having thermal death point b/w 100 to 120

49. OXYGEN Depending on the O 2 requirement, bacteria are divided into : Strict (Obligate) Aerobes – require O 2 for growth e.g. Pseudomonas aeruginosa Strict (Obligate) Anaerobes – grow in the absence of O 2 & may even die on exposure to O 2 e.g. Bacteroides fragilis Microaerophilic – grow best in the presence of low oxygen levels e.g. Campylobacter spp, Helicobacter spp 7

50. Atmosphere 4.Facultative anaerobe – aerobic but can also grow in the absence of O 2 e.g. Staphylococcus spps 5.Aerotolerant anaerobe – anaerobic, but tolerates exposure to O 2 e.g. Clostridium perfringens 6. Capnophilic organism – requires high CO 2 levels eg Neisseria spps

51. The Effect of Oxygen (O2) on Growth Needs oxygen Grows best in oxygen, but can grow without Only grows without oxygen Grows in low concentrations of oxygen Grows with or without oxygen

52. H-ion Concentration pH range, optimum pH Neutral or slightly alkaline pH (7.2 – 7.6) – majority of pathogenic bacteria grow best. Lactobacilli – acidic pH Vibrio cholerae – alkaline pH

53. Moisture and drying Water – essential ingredient of bacterial protoplasm. Hence drying is lethal to cells. Effect of drying varies : T.pallidum – highly sensitive Staphylococcus spp– stand for months Spores – resistant to dessication , may survive for several decades

54. Cultural Characteristics of Bacterial Growth : Bacterial growth in or on food can render it unattractive or objectionable to consume. Pigmented bacteria can cause discolorations on food surfaces, form films on liquid surfaces, make surfaces slimy, or lead to extensive growth causing cloudiness or sedimentation in liquids.

55. Cultural Characteristics of Bacterial Growth: Bacterial growth in or on food can render it unattractive or objectionable to consume. Pigmented bacteria can cause discolorations on food surfaces, form films on liquid surfaces, make surfaces slimy, or lead to extensive growth causing cloudiness or sedimentation in liquids. Culture Medium: Definition: The substances required for growing microorganisms outside the body (in vitro) are called culture medium. Uses: Identifying the cause of infection from clinical samples for appropriate treatment. Studying characteristics or properties of microorganisms. Preparing biological products such as vaccines, toxoids, and antigens .

56. Types of Culture Media : Classification based on physical state: a) Solid medium b) Semi-solid medium c) Liquid medium Solid Medium: A culture medium where solidifying agents, such as agar, are added to make the medium solid. This provides a surface for microbial growth and allows for the isolation and observation of individual colonies . Semi-Solid Medium: A culture medium with a moderate consistency, between solid and liquid. It is often used for motility tests to observe the movement of microorganisms. Liquid Medium: A culture medium that remains in a liquid state without solidifying agents. It provides a homogeneous environment for microbial growth and is often used for studying microbial physiology and growth characteristics.

57. Bacteria Culture Test: Purpose: Confirms bacterial infections and identifies the specific type of bacteria for treatment decisions. Sample sources: Blood, stool, urine, skin, mucus, or spinal fluid. Indications for the test: Symptoms of bacterial infections such as bronchitis, food poisoning, kidney infection, pneumonia, sepsis, infections of the oral pharynx and tonsils, urinary tract infections, and wound infections. Fungal Culture Test: Purpose: Diagnosing fungal infections caused by exposure to fungi like yeasts and molds. Fungi presence: Fungi exist ubiquitously in the environment.

58. Beneficence of Bacteria Makes cheese, yogurt, buttermilk and pickles Produces vitamins in your intestine Helps in digestion of insoluble fibers In industry, bacteria are important in sewage treatment and the breakdown of oil spills, the recovery of gold, copper and other metals in the mining sector,

59. Beneficence of Bacteria Bacteria are also helpful in biotechnology, and the manufacture of antibiotics and other chemicals. Many act as decomposers recycling nutrients Actinomycetes, produce antibiotics such as streptomycin and nocardicin. Saprobes help to break down dead organic matter.

60. Harmful effect of Bacteria Cause disease in body including: TB Pertusis Diphtheria Tetanus Dysentery Typhoid Meningitis, Encephalitis Gonorrhea Pneumonia Syphilis

61. Endospores Some bacteria are capable to produce spore that are highly resistant to extreme environmental condition. In favorable condition, bacteria re grow again to a bacteria

62. Toxins Some bacteria release poisons known as toxins which cause food poisoning. Some toxins, known as exotoxins multiply in food. These toxins are not easily destroyed by cooking and may remain in food once they have developed. Other bacteria produce toxins inside the human body only after the food has been eaten. These are called endotoxins

63. Thank you