Classification of bacteria

CLASSIFICATION OF BACTERIA

1. CLASSIFICATION OF BACTERIA & IT’S STRUCTURE P RESENTED BY MISS TASMIA ZEB

2. T opics Classification of bacteria Baterial cell structure Difference between prokaryotes and eukaryotes,fungus,bacteria,virus Obligate intracellular organisms.

3. Classification On the basis of Staining : Gram staining : Gram positive Gram negetive. Acid-fast staining. Albert’s staining.

4. Example of Gram positive : Gram positive Cocci Baci l l i S t r ep t ococcas S t aphy l ococcus Bacillus Clostridium Corynebac t er i um Listeria Actinomyces coagulase + S. aureus coagulase - S. epidermitis, S . sap r ophy t i cus Peptostreptococci P. magnus Alpha hemolytic S. pneumoniae Viridens streptococci Beta hemolytic - group A : S. pyogens - group B : S. agalactiae - group D : E. faecalis, S. bovis.

5. Example of Gram negetive : Gram negetive Cocci B a c i l l i Neisseria meningitidis Neisseria gonorrhoeae Enteric Non-enteric Respiratory Animal source Escherichia, Klebsiella, Haemophilus, Brucella Salmonella, Proteus, Bordetella, Francisella Shigella , Pseudomonas, Legionella Pasturella Vibrio, Bacteroides Yersinia Campylobactor

6. Example of Acid-fast bacilli : Mycobacterium tuberculosis Mycobacterium leprae Nocardia Actinomytes Example of Albert’s stain : Corynebacterium diptheriae.

7. On the basis of Shape : Cocci : oval or spherical; may be arranged in pairs(pneumococci, meningococci, gonococci), tetrads (micrococci), chains (Streptococci), clusters ( Staphylococci ). Bacilli : rod shaped; may show arrangements like – a)coccobacilli, in which length and width are approx. same (e.g- Brucella ), streptobacilli, which are arranged in chains (e.g- Streptobacillus ), comma shaped (e.g- Vibrio ), spirella ( Spirillum ).

8. 3. Spirochetes : slender,flexious,spiral ( Treponema ). 4. Actinomytes : branching filamentous.

9. On the basis of Growth and nutrition : A. Oxygen requirements : Aerobic : Obligate aerobe : P. aeruginous. Facultative aerobe : E.coli. Microaerophilic : Campylobactor jejuni. Anaerobic : Obligate anaerobe : Clostridium tetani , Bacteroids. Aerotolerant anaerobe : indifferent to O2.

10. B. Carbon dioxide requirement : 1. Capnophilic bacteria : Which require higher amount of CO2 for their growth (5-10% CO2 and 15% O2). Ex – H. influenzae, Brucella abortius. C. Temperature : Psychrophiles : microbes that grow within 0-20°C. Mesophiles : microbes that grow within 25-40°C. Thermophiles : microbes that grow within 55-80°C. Ex- B. stearothermophilus.

11. D. pH : Acidophile : which grow at acidic pH (below4.0). Ex- Lactobacilli. Alkaliphile : which grow at alkaline pH (8.2-8.9). Ex.- V. cholerae. Neutrophile : which grow at neutral pH (7.2-7.6). Most pathogenic bacterias are neutrophiles. E. Light : Phototrophs : bacteria deriving energy from sunlight. Chemotrophs : bacteria deriving energy from chemical sources.

12. F. Osmotic pressure : Halophiles : which can survive at high salt concentration. Osmophiles : which can survive at high sugar concentration. G. Carbon source : Autotrophs : which reduce inorganic carbon into organic compounds, such as through photosynthesis Heterotrophs : bacteria that grow by using the carbon that has been reduced by the autotrophs.

13. H. Method of obtaining nutrition : Heterotropic bacteria- Obtain their food from other living organisms, as they cannot synthesize it on their own. Symbiotic Bacteria - Obtain nutrition from host organism by offering something in return. Establish a mutual give-and-take relationship with host. Pathogenic Bacteria - Obtain food from host but are harmful to the host, generally causing diseases. Saprophytic Bacteria - Obtain Nutrition from dead and decaying matter.

14. On the basis of presence of Flagella : A. With flagella : Monotrichous (single polar flagellum) : Vibrio cholerae. Lophotrichous (multiple polar flagella) : Spirilla. Peritrichous (flagella distributed over the entire cell) : Salmonella, E. coli etc. Amphitrichous (single flagellum at both ends) : Spirillum minus. B. Without flagella : These are called Atrichous bacteria.

15. On the basis of Motility : Motile : Salmonella Vibrio cholerae - Pseudomonas etc. Non motile : Staphylococcas, - Shigella.

16. Cell Structure Essential components Nonessential components Cell wall : Peptidoglycan Outer membrane (in Gram –ve bacteria) Surface fibers (in Gram +ve bacteria). 1. Capsule. 2. C ytoplasmic membrane 2. Glycocalyx 3. Ribosome 3. Pilus/Fimbria 4. Nucleoid 4. Flagellum 5. Mesosome 5. Plasmid 6. Periplasmic space (Gram –ve bacteria) 6. Granules 7. Spore

17. Cell wall : fairly rigid and chemically complexed outermost component, common to all bacteria except Mycoplasma species. multilayerd,located external to the cytoplasmic membrane. composed of : 1. Peptidoglycan Outer membrane Surface fibers.

18. Illustration of cell wall of Gram +ve and Gram –ve Bacteria

19. Gram +ve Cell Wall : thick (15-80 nm) consists of : 1. peptidoglycan. teichoic acid. teichuronic acid.

20. Peptidoglycan : synonym : murein and mucopeptide. thick; 40 sheets which comprises 50% of cell wall. complexed polymer consisting a backbone, composed of alternating two sugar derivatives N-acetyleglucosamine and N- acetylemuramic acid connected by β-1→4 linkage. a tetrapeptide side chain, consisting of D- and L- amino acid with L-lysine. a pentaglycine bridge, which connects the tetrapeptide side chains.

21. Importance : provides rigid support for the cell maintain its characteristic shape and allows it to withstand media of low osmotic pressure. good target for antimicrobial which inhibit transpeptidase thus inhibit synthesis peptidoglycan. lysozyme, a natural resistance of host, cleaves disaccharide backbone by breaking glycosyle bond (β-1→4 linkage).

22. Teichoic acid : polymer of polyribitol phosphate or polyglycerol phosphate which are connected by phosphodiester linkage. two types : a) wall teichoic acid (WTA) b) membrane teichoic acid or lipoteichoic acid (LTA). most teichoic acids contain large amount of D- alanine .

23. Importance : togather with peptidoglycan it provides elasticity, porosity, tensile strength, electrostatic properties of the envelop. used as antigen for serological classification. binds Mg and supply this ion to the cell. induce inflammation and septic shock. mediate the attachment of staph. to mucosal cell.

24. Teichoronic acid : consists of repeat units of sugar acids (such as N-acetylemannuronic acid or D-glucosuronic acid). they are synthesized when phosphate is limiting. Polysaccharides : -also contains neutral sugars; such as, mannose, arabinose, rhamnose, glucosamine and acidic sugars; such as glucoronic and mannuronic acid.

25. Gram –ve cell wall : more complexed than Gram +ve bacteria. consists of : 1. peptidoglycan lipopolysaccharides outer membrane lipoprotein layer.

26. Peptidoglycan : thin (2-8 nm); 1-2 sheets which comprises 5- 10% of the cell wall. complexed polymer consisting a backbone, composed of alternating two sugar derivatives N-acetyleglucosamine and N- acetylemuramic acid connected by β-1→4 linkage. a tetrapeptide side chain, consisting of D- and L- amino acid with mesodiaminopimelic acid. pentaglycine bridge is absent.

27. Lipopolysaccharide : is synthesized on the cytoplasmic membrane and transported to its final exterior position. consists of three main component : Lipid A core oligosaccharide O polysaccharide or O antigen

28. Lipid A : consists of phosphorylated glucosamine disaccharide to which a number of long chain fatty acids are attached. also consists of hydroxymyristic acid, a unique fatty acid. Core oligosaccharide : includes two characteristic sugars : ketodeoxyoctulonate acid heptose both joined togather by lipid A.

29. c) O antigen : - an outer polysaccharide consisting of up to 25 repeating units of 3-5 sugars. Importance : LPS is the endotoxin which causes fever, shock, DIC by activating macrophage, complement and coagulation system. LOS is an important virulent factor. O antigen is used to identify certain organism in the clinical lab.

30. Outer membrane : bilayered structure; outer membrane contains LPS and inner one resembles cell membrane. porins : make special channels of outer membrane. outer membrane protiens : includes Omp C,D,F and PhoE and LamB, Tsx, Omp A. minor protiens: enzymes,phospholipases,protease.

31. Importance : large antibiotics penetrate it slowly which makes high antibiotic resistance of gram-ve bacteria. permit passive diffusion of hydrophilic compounds, such as, sugar, amino acid and certain ions. Some special molecules are also transported, such as vitamin B12. exclude hydrophobic molecules, such as bile salt. serve to protect the cell.

32. 4. Lipoprotein layer : - contains : a) 57 amino acids, representing 15 amino acid sequence. b) diglyceride thioether linked to a terminal cysteine. Impotance : stabilize the outer membrane and anchor it to the peptidoglycan layer.

33. Periplasmic space : space between the inner and outer membrane. contains peptidoglycan layer and 20-40% of cell volume. Importance : has binding protein for specific substance. has hydrolytic enzymes that break down nontransportable substance to transportable one. has detoxifying enzymes that inactivate certain antibiotic.

34. The acid fast cell wall : contains large amount of waxes,named Mycolic acid. composed of peptidoglycan and asymmetric lipid bilayer. inner lipid bilayer contains mycolic acid linked to arabinoglycan and outer layer contains extractable lipids. Importance : protect the acid fast bacilli from harsh chemicals and detergents .

35. Cell wall deficient bacteria : Protoplast : produced from gram +ve bacteria on treatment with lysozyme,in hypertonic media. Spheroplast : derived from gram-ve bacteria treated with lysozyme in presence of EDTA . L-form : produced more easily with penicillin than with lysozyme. They are able to grow and devide. Mycoplasma : wall lacking bacteria measuring 50-300nm.

36. Cytoplasmic membrane : thin (5-10nm) semipermiable membrane. composed of a phospholipid bilayer and 200 different kinds of protein.

37. Importance : acts as osmotic barrier and regulate the tranportation of metabolites to and from protoplasm. electron transport and oxidative phosphorylation. excretion of hydrolytic exoenzyme and pathogenicity protein. Biosynthetic function. Chemotactic systems.

38. Cytoplasm : matrix is largely formed with 70% water. lack endoplasmic reticulam, mitocondria. consists : 1. Ribosome mesosome Intracytoplasmic inclusion bodies .

39. Ribosome : look like small featureless particle. two subunits of 30S and 50S, giving a net 70S. Importance : serve as a site for protein synthesis . site of action of antibiotic such as aminoglycosides, macrolids and tetracycline.

40. Mesosome : vesicular and multilaminated structure formed as invagination of plasma membrane into the cytoplasm. two types : 1. septal 2. lateral. Importance : septal mesosome coordinate nuclear and cytoplasmic divisions during binary fission. principal sites of respiratory enzymes in bacteria.

41. Intracytoplasmic inclusion bodies : two types : organic : contains glycogen or polyhydroxybutyrate. inorganic : polyphosphate granules or sulfer granules. Importance: used for storage; they are the source of carbon, inorganic substance and energy. some func to reduce osmotic pressure.

42. Nucleoid : absence of nuclear membrane and mitotic apparatus. consists of a single circular molecule of loosely organised DNA (.58-10million base pairs). exception : V. cholerae and Brucella melitensis have two dissimilar chromosome . - bacterial DNA has no introns.

43. Capsule : - a condensed,well defined layer closely surrounds the cell, which excludes particle like india ink. -composed of polysaccharide, collectively reffered as exopolysaccharide, which are sometimes homopolysaccharide or negetively charged (except in Bacillus anthracis, in which capsule comprises of polypeptide, such as D-glutamic acid.)

44. Importance : It is a determinant of virulence of many bacteria for its antiphagocytic property. Specific identification of an organism can be made by ‘Quellung reaction’. Used as vaccines due to their capability of eliciting protective antibodies. May play a role in the adherence of bacteria to human tissue.

45. Glycocalyx : - is defined as polysaccharide-containing material lying outside the cell. -if it is loosely associated with the cell and does not exclude particles, it is refered to as Slime layer. Importance : helps in adherence with foreign body to host cell. facilitates Streptococcas mutens to adhere tightly with tooth enamel and the acid excreted by this bacteria causes dental carries.

46. Flagella : thread like appendages intricately embedded in cell envelop. 3-20μm in length and .01-.03μm in diameter. consists of : filament, made up of protein flagellin. hook, acts as propeller. basal body, a set of rings; one pair in gram +ve and two pairs in gram –ve bacteria.

47. Function : primarily responsible for motility of bacteriam by chemotaxis. may play a role in bacterial survival pathogenesis. highly antigenic, possess H antigens, which are different in different bacterias. Important in serological diagnosis.

48. Pili/Fimbria : hair-like filaments that extend from cell surface and exclusively present in gram –ve bacteria. composed of structural protein subunit pilin arranged in helical structure.. .5μm long, 10nm thick. antigenic in nature. Importance : 1. adherence of symbiotic and pathogenic bacteria to host cells.

49. Transfer of bacterial DNA takes place through sex pili during the process of conjugation. Antigenic variation of pili of Neisseria gonorrhoeae makes it to survive even after the presence of antibody against the original type of pili. Inhibit phagocytic ability of leukocyte. Helps in identification by haemagglitination.

50. Difference between Flagella and Pili : Characteristics Flagella pili 1. Definition Long, whip like, helical appendages, made up of flagellin, that protrude through the cell membrane. Short, straight, hair like, filamentous appendages, made up of pilin, that protrude from the surface of cell. 2. Length, width 3-20μm long .5μm long 3. Thickness 0.01-0.03μm 10nm thick 5. Number Can also be one in number numerous 6.Occurance Polar, lateral or peritrichous Thouthout the surface 7. Found in Both Gram +ve and Gram –ve bac. Exclusively on Gram –ve bac. 10. Required for conjugation No Yes 12. Function Motility Attachment, transfer of DNA. 13. Motion Wave like, undulating. Twitching motility.

51. Plasmid : extrachromosomal, double-standed, circular DNA molecules. capable of replicating independently of the bacterial chromosome. occurs both in gram +ve and gram -ve bacteria. types : transmissible non-transmissible.

52. Importance : they carry genes for – resistance to antibiotic, heavy metal, ultraviolet light. synthesis of pili. enzymes and toxins- exotoxin, enterotoxin.

53. Spore : highly resistance, metabolically inart structure. contains bacterial DNA, a small amount of cytoplasm, cell membrane, peptidoglycan, very little water and a thick keratin coat. composed of : 1. core. spore wall cortex protein coat (keratin) resistance of spore is due to dipicolinic acid, a calcium chelator. spores may be central, subterminal or terminal and oval or spherical, bulging or non bulging.

54. Difference Between Prokaryotes & Eukaryotes

55. Structure Prokaryotes Eukaryotes Nucleus 1. Nuclear membrane Absent Present 2. Nucleolus Absent Present 3. Chromosome One, circular More than one,linear 4.Location Free in cytoplasm, Attached to mesosome. Contained in membrane bound structure 6. Replication Binary fission Mitotic division 6. Extrachromosomal DNA Plasmid Inside the mitochondria Cytoplasm 1. Cytoplasmic organalle Absent Present 2.Cytoplasmic streaming Absent Present 3. Lysosomes Absent Present 4. Ribosome 70S(50S+30S),free in cytoplasm or bound to cell membrane 80S(60S+40S),attached to rough ER Chemical composition 1. Cell wall Present Absent,except for fungi 2. Sterols Absent Present 3. Muramic acid Present Absent 4. Energy production site Electron transport chain located in the cell membrane. Within membrane bound mitochondria

56. Characteristics Viruses Bacteria Fungi Protozoa and Helminths 1. Cell No yes Yes Yes 2. Approximate diameter (μm) .02-.2 1-5 3-10 15-25 3. Nucleic acid Either DNA or RNA Both DNA and RNA Both DNA and RNA Both DNA and RNA 4. Type of nucleus None Prokaryotic Eukaryotic Eukaryotic 5. Ribosomes Absent 70S 80S 80S 6. Mitochondria Absent Absent Present Present 7. Nature of outer surface Protein capsid and lipoprotein envelop Rigid wall containing pe p tid og l y can Rigid wall containing chitin Flexible membrane 8.Motility None Some None Most 9. Method of replication Not binary fission Binary fission Budding or mitosis Mitosis

57. Obligate Intracellular Organism : organisms that can not reproduce outside the cell. includes : viruses bacteria: Chlamydia, Rickettsia, Coxiella, Mycobacterium leprae. protozoa: Plasmodium spp., Toxoplasma gondi, leishmania spp., trypanosoma cruzi. fungi: Pneumocystis jirovecii - people with T-cell deficiencies are particularly susceptible to intracellular pathogen.

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