Morphology of bacteria

Shape and Arrangements of Bacteria

1. Morphology of Bacteria By:Assist.Prof Chaitali kalamkar.S Arihant COP , Ahmadnagar

2. Morphological classification of bacteria Definition of morphology Size Shape and Arrangements

3. Morphology : M orphology is the study of the shapes and arrangement of parts of organisms, in order to determine their function, their development, and how they may have been shaped by evolution. The microorganisms being of very small size are usually expressed in microm- m eters ( μ m ) .

4. Size The unit of measurement used in bacteriology is the micron (micrometer) The limit of resolution with the unaided eye is about 200 microns. Bacteria ar smaller which can be visualized only under magnification. Bacteria of medic al importancee generally measure 0.2 – 1.5 μ m in diameter and about 3-5 μ m in length.

5. Shape and arrangements True bacteria Cocci (Singular: coccus) Bacilli (rods) (Singular: rod, bacillus) Vibrios (Singular: vibrio) Spirilla (Singular: spirillum) 2.Actinomycetes 3.Spirochaetes 4.Mycoplasmas 5.Rickettsiae 6.Chlamydiae

6. Shape .... 1.True bacteria i.Cocci These are round or oval bacteria measuring about 0.5–1.0 um in diameter.  When multiplying, cocci may form pairs, chains, or irregular groups.

7. Arrangements cocci in pairs are called diplococci, e.g. meningococci and gonococci. cocci in chains are called streptococci , e.g.  Streptococcus pyogenes . cocci in irregular groups are called staphylococci , e.g.  Staphylococcus aureus .

8. Shape.. ii.Rods (bacilli) These are stick-like bacteria with rounded, tapered (fusiform), square, or swollen ends. They measure 1–10 um in length by 0.3–1.0 um in width. The short rods with rounded ends are often called coccobacilli.

9. Arrangements When multiplying, bacterial rods do not usually remain attached to one another, but separate. Occasionally, however, they may: From chains , e.g. Streptobacillus species. form branching chains, e.g. lactobacilli. mass together, e.g.  Mycobacterium leprae . remain attached at various angles resembling Chinese letters, e.g.  Corynebacterium diphtheriae

10. Shape and Arrangements iii.Vibrios These are small slightly curved rods measuring 3–4 um in length by 0.5 um in width. Most vibrios are motile with a single flagellum at one end. They show rapid darting motility, e.g. Vibrio cholerae

11. Shape and Arrangements iv.Spirilla These are small, regularly coiled, rigid organisms measuring about 3–4 um in length. Each coil measures about 1 um. Spirilla are motile with groups of flagella at both ends. An example of a spirillum is  Spirillum minus .

12. Shape and Arrangements 2.Actinomycetes They are rigid organism but look like fungi. They exhibit branching and tend to form filaments. T hey are Gram positive They are widely distributed in soil, compost etc. They are heterotrophic, aerobic, an mesophilic c organisms. Some organisms are thermophilic growing at more than 55°C lik thermoactinomycetes s, streptomyces etc

13. Shape and Arrangements Actinomycetes

14. Shape .. 3.Spirochaetes These are flexible, coiled, motile organisms. They progress by rapid body movements. Most are not easily stained by the Gram method. Spirochaetes are divided into three main groups:

15. Arrangements .Spirochaetes Tr eponemes , which are thin delicate spirochaetes with regular tight coils, measuring from 6–15 um by 0.2 um in width. Examples include  Treponema pallidum  and  Treponema pertenue . Bo rreliae , which are large spirochaetes with irregular open coils, measuring 10–20 um in length by about 0.5 um in width. Examples include  Borrelia duttoni  and  Borrelia vincenti . Le ptospires , which are thin spirochaetes with many tightly packed coils that are difficult to distinguish. They measure 6–20 um in length by 0.1 um in width and have hooked ends. The leptospire of medical importance is  Leptospira interrogans  (contains many serovars).

16. Shape and Arrangements 4. Mycoplasmas These are naturally occurring stable bacteria that lack a rigid cell wall. They are among the smallest living microorganisms capable of independent existence, ranging in size from 0.1–2 um. Species of medical importance include  Mycoplasma pneumoniae  and  Ureaplasma urealyticum.

17. Shape and Arrangements 5. Rickettsia They are non-motile, Gram negative, non-spore forming, small intracellula and d pleomorphic bacteria. They are also present as cocci (0.1 µm in diameter), rods (1-4 µm long), or thread-like (10 µm long) forms. Rickettsia species are the pathogens responsible for typhus, rickettsial pox, Boutonneuse fever and are susceptible to antibiotics of the tetracycline group. Examples: Rickettsia conorii, Rickettsia typhi etc .

18. Shape and Arrangements 6.Chlamydiae They are ovoid in shape and Gram negative bacteria. Their cell wall is consisting of peptidoglycan and other proteins. They are very small, obligate intracellular parasites. They multiply in the cytoplasm of their host cell by a distinctive developmental cycle. They commonly infect humans are eye disease, pneumonia, psittacosis etc. Examples: Chlamydia trachomatis (causes trachoma eye disease), Chlamydophila pneumonia (causes pneumonia), Chlamydophila psittaci (causes psittacosis)

19. Chlamydiae

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