Chair of Medical Biology, Microbiology, Virology, and Immunology THE PHYSIOLOGY OF MICROORGANISMS. Lecturer As. Prof. O. Pokryshko

Lecture schedule 1. Growth of bacteria. 2. Reproduction of bacteria. 3. Respiration of bacteria.

3 Carbon sources Carbon sources Heterotroph – must obtain carbon in an organic form made by other living organisms such as proteins, carbohydrates, lipids and nucleic acids Heterotroph – must obtain carbon in an organic form made by other living organisms such as proteins, carbohydrates, lipids and nucleic acids Autotroph - an organism that uses CO 2, an inorganic gas as its carbon source Autotroph - an organism that uses CO 2, an inorganic gas as its carbon source not nutritionally dependent on other living things not nutritionally dependent on other living things Nutritional Types

4 Nitrogen Sources Nitrogen Sources Main reservoir is nitrogen gas (N 2 ); 79% of earth’s atmosphere is N 2. Main reservoir is nitrogen gas (N 2 ); 79% of earth’s atmosphere is N 2. Nitrogen is part of the structure of proteins, DNA, RNA & ATP – these are the primary source of N for heterotrophs. Nitrogen is part of the structure of proteins, DNA, RNA & ATP – these are the primary source of N for heterotrophs.

5 Nitrogen Sources Nitrogen Sources Some bacteria & algae use inorganic N nutrients (NO 3 -, NO 2 -, or NH 3 ). Some bacteria & algae use inorganic N nutrients (NO 3 -, NO 2 -, or NH 3 ). Some bacteria can fix N 2. Some bacteria can fix N 2. Regardless of how N enters the cell, it must be converted to NH 3, the only form that can be combined with carbon to synthesis amino acids, etc. Regardless of how N enters the cell, it must be converted to NH 3, the only form that can be combined with carbon to synthesis amino acids, etc.

6 Energy source Energy source chemotroph – gain energy from chemical compounds chemotroph – gain energy from chemical compounds phototrophs – gain energy through photosynthesis phototrophs – gain energy through photosynthesis Nutritional Types

7 Transport: Movement of Chemicals Across the Cell Membrane Passive transport –does not require energy; substances exist in a gradient and move from areas of higher concentration towards areas of lower concentration Passive transport –does not require energy; substances exist in a gradient and move from areas of higher concentration towards areas of lower concentration diffusion diffusion osmosis – diffusion of water osmosis – diffusion of water facilitated diffusion – requires a carrier facilitated diffusion – requires a carrier

8 Transport: Movement of Chemicals Across the Cell Membrane Active transport – requires energy and carrier proteins; gradient independent Active transport – requires energy and carrier proteins; gradient independent active transport active transport group translocation – transported molecule chemically altered group translocation – transported molecule chemically altered

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11 Gas Requirements Oxygen As oxygen is utilized it is transformed into several toxic products: As oxygen is utilized it is transformed into several toxic products: singlet oxygen (O 2 ), superoxide ion (O 2 - ), peroxide (H 2 O 2 ), and hydroxyl radicals (OH - ) singlet oxygen (O 2 ), superoxide ion (O 2 - ), peroxide (H 2 O 2 ), and hydroxyl radicals (OH - ) Most cells have developed enzymes that neutralize these chemicals: Most cells have developed enzymes that neutralize these chemicals: superoxide dismutase, catalase superoxide dismutase, catalase If a microbe is not capable of dealing with toxic oxygen, it is forced to live in oxygen free habitats. If a microbe is not capable of dealing with toxic oxygen, it is forced to live in oxygen free habitats.

12 Categories of Oxygen Requirement Aerobe – utilizes oxygen and can detoxify it Aerobe – utilizes oxygen and can detoxify it obligate aerobe - cannot grow without oxygen obligate aerobe - cannot grow without oxygen facultative anaerobe – utilizes oxygen but can also grow in its absence facultative anaerobe – utilizes oxygen but can also grow in its absence microaerophylic – requires only a small amount of oxygen microaerophylic – requires only a small amount of oxygen

13 Categories of Oxygen Requirement Anaerobe – does not utilize oxygen Anaerobe – does not utilize oxygen obligate anaerobe - lacks the enzymes to detoxify oxygen so cannot survive in an oxygen environment obligate anaerobe - lacks the enzymes to detoxify oxygen so cannot survive in an oxygen environment aerotolerance anaerobes – do no utilize oxygen but can survive and grow in its presence aerotolerance anaerobes – do no utilize oxygen but can survive and grow in its presence

14 Carbon Dioxide Requirement All microbes require some carbon dioxide in their metabolism. capneic – grows best at higher CO 2 tensions than normally present in the atmosphere capneic – grows best at higher CO 2 tensions than normally present in the atmosphere

Oxygen requirements Aerobic cultureAnaerobic cultureMicroaerobic culture Obligate anaerobe 2. Facultative anaerobe 3. Microaerophile 4. Obligate aerobe

Growth requirements Temperature Temperature Pyschrophiles 4-20°C Pyschrophiles 4-20°C Mesophiles15-48°C Mesophiles15-48°C Thermophiles42-68°C Thermophiles42-68°C Extreme thermophiles>68°C Extreme thermophiles>68°C

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18 Effects of pH Majority of microorganisms grow at a pH between 6 and 8 Majority of microorganisms grow at a pH between 6 and 8 Obligate acidophiles – grow at extreme acid pH Obligate acidophiles – grow at extreme acid pH Alkalinophiles – grow at extreme alkaline pH Alkalinophiles – grow at extreme alkaline pH

The Population Growth Curve In laboratory studies, populations typically display a predictable pattern over time – growth curve. In laboratory studies, populations typically display a predictable pattern over time – growth curve.

20 The Population Growth Curve Stages in the normal growth curve: Stages in the normal growth curve: 1. ______phase – “flat” period of adjustment, enlargement; little growth 2. _____________________ phase – a period of maximum growth will continue as long as cells have adequate nutrients and a favorable environment

21 The Population Growth Curve Stages in the normal growth curve: Stages in the normal growth curve: 1. _________ phase – rate of cell growth equals rate of cell death caused by depleted nutrients and O 2, excretion of organic acids and pollutants 2. _________ phase – as limiting factors intensify, cells die exponentially in their own wastes

Nutrient media Ordinary (simple) media Ordinary (simple) media Special media (serum agar, serum broth, coagulated serum, pota­toes, blood agar, blood broth, etc.). Special media (serum agar, serum broth, coagulated serum, pota­toes, blood agar, blood broth, etc.). Elective media Elective media Enriched media Enriched media

Nutrient media Differential diagnostic media: (1) proteolytic action; Differential diagnostic media: (1) proteolytic action; (2) fermentation of carbohydrates (Hiss media); (2) fermentation of carbohydrates (Hiss media); (3) haemolytic activity (blood agar); (3) haemolytic activity (blood agar); (4) reductive activity of micro-organisms; (4) reductive activity of micro-organisms; (5) media containing substances assimilated only by certain microbes. (5) media containing substances assimilated only by certain microbes.

Biochemical properties

Colonies

Colonies

Colonies

Pure Cultures Isolation

Isolated colonies obtaining