General characters of bacteria and clasification

bacteria

1. “General characters and classification of Bacteria”

2. Content General characters Size of bacteria Shape of bacteria Classification of Bacteria.

3. General characters Vary in sizes, measure approximately 0.1 to 10.0 μm Widely distributed. It can be found in soil, air, water, and living bodies. Some bacteria can cause diseases for human, animals and plants. Some bacteria are harmless.

4. Size of Bacteria Unit of measurement in bacteriology is the micron (micrometer, µm). Bacteria of medical importance (0.2 – 1.5 µm) in diameter (3 – 5 µm) in length.

5. Shape of Bacteria Coccus Bacillus Coccobacillus Vibrio (curved) Spirillum Spirochete Square Star

6. Coccus Shaped Bacteria

7. Bacillus Shaped Bacteria

8. Spirillum Shaped Bacteria

9. Coccobacillus Shaped Bacteria

10. Vibrio Shaped Bacteria

11. Spirochete Shaped Bacteria

12. Square Shaped Bacteria

13. Star Shaped Bacteria

14. Classification of Bacteria On the basis of shape On the basis of staining On the basis of action On the basis of oxygen requirement On the basis of pH On the basis of temperature On the basis of osmotic pressure.

15. On the basis of shape :- Cocci : (a) Dipplococci : any of several spherical bacteria occurring in pairs . (b)Streptococci :any of several spherical or oval bacteria of the genus  Streptococcus, occurring in pairs or chains, certain species of which are  pathogenicfor humans, causing scarlet fever, tonsillitis, etc. (c) Sarcina :any of several spherical, saprophytic bacteria of the genus  Sarcina, having  a  cuboidal  cell arrangement. (d)Tetrad :a group of four  chromatids  formed by  synapsis  at thebeginning Of meiosis. (e)Staphylococci :any of several spherical bacteria of the genus  Staphylococcus, occurring in pairs, tetrads, and irregular clusters, certain species ofwhich , as  S.  aureus ,  can be pathogenic for humans.

16. Baccilli : (a) dipplobacilli :a double  bacillus ;  two  bacilli  linked end to end. (b) coccobacilli :A short, thick bacterial rod having the shape of an oval. Vibrio : (a) Sprial (b)Spirochete :any of various spiral-shaped motile bacteria of the Family Spirochaetaceae ,  certain species, as  Treponema ,  Leptospira ,  and Borrelia ,  being pathogenic   to humans and other animals, and  otherspecies  being free-living,  saprophytic, or parasitic.

17. On the basis of staining :- Gram positive Gram negative

18. On the basis of oxygen requirement :- Obligate aerobes : An  obligate aerobe  is an organism that needs at least 20% oxygen in its surroundings to grow. The term obligate, as in 'obligatory' or 'required,' suggests that oxygen is absolutely essential for the survival and multiplication of obligate aerobes. Facultative anaerobes : An organism that lives and grows in  the absence of molecular oxygen.

19. Aerotolerant anaerobes : anaerobes  are damaged by the presence of oxygen.   Aerotolerant  organisms cannot use oxygen for growth but are tolerate its presence. And facultative  anaerobes  can grow without oxygen but use oxygen if it is present. Obligate anaerobes : Obligate anaerobes  are poisoned by oxygen, so they gather at the bottom of the tube where the oxygen concentration is lowest. Microaerophiles : Microaerophiles  need oxygen because they cannot ferment or respire anaerobically . However, they are poisoned by high concentrations of oxygen. 

20. On the basis of pH :- Acidophiles : Acidophiles  or  acidophilic  organisms are those that thrive under highly acidic conditions (usually at pH 2.0 or below).  Neutrophiles : Neutrophils  (also known as  neutrocytes ) are the most abundant type of  granulocytes  and the most Abundant (40% to 75%) type of  white blood cells in most  mammals . Alkalophiles : Alkaliphiles  are a class of extremophilic microbes capable of survival in alkaline (pH roughly 8.5–11) environments, growing optimally around a pH of 10.

21. On the basis of temperature:- Psychrophiles : Psychrophiles  or cryophiles (adj. cryophilic) are extremophilic organisms that are capable of growth and reproduction in cold temperatures, ranging from −20 °C to +10 °C.  Psychrotrophs : Psychrotrophic bacteria are bacteria that are capable of surviving or even thriving in extremely cold environment.

22. Mesophiles : A mesophile is an organism that grows best in moderate temperature, neither too hot nor too cold, typically between 20 and 45 °C (68 and 113 °F).  Thermophiles : A  thermophile  is an organism a type of extremophile that thrives at relatively high temperatures, between 41 and 122 °C (106 and 252 °F). Hyperthermophiles : A  hyperthermophile  is an organism that thrives in extremely hot environments—from 60 °C (140 °F) upwards. An optimal temperature for the existence of  hyperthermophiles  is above 80 °C (176 °F).

23. On the basis of osmotic pressure :- Osmotolerant : Osmotolerant  bacteria are those bacteria that can tolerate high osmolarity . Osmolarity is established when there are solutions of different concentrations on either sides of a semipermeable membrane. Halophiles : Halophiles  are organisms that thrive in high salt concentrations. They are a type of extremophile organisms.

24. Reference book : BACTERIA in Biology , Biotechnology and Medicine . by Paul Singleton.

25. Thank you…….