1. Microbiology, Virology, and Immunology Department
Lecturer Taras I. Pyatkovskyy

2. Chemical composition of bacteria
Cell metabolism
Types of microbial nutrition
Respiration of bacteria
Growth and reproduction of microbes
Bacterial transport systems
Bacterial enzymes
Nutrient media
Isolated colonies obtaining

3. Carbon source
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 CO2, an inorganic gas as its carbon source
not nutritionally dependent on other living things

4. Chemical composition of bacteria
Protein
55 %
Total RNA
20.5 %
DNA
3.1 %
Phospholipid
9.1 %
  Lipopolysaccharide 
3.4 %
Murein
2.5 %
Inorganic ions 
1.0 %

5. Bacterial cell consists of:
Water – % Dry weight – %
Proteins – 55 %, 2,35 million of molecules, 1850 different types of molecules
RNA – 20,5 %, molecules, 660 different types of molecules
DNA – 3,1 %, 2 molecules
Lipids – 9 %, 22 million of molecules
Lipopolysaccharides –3,4 %, 1,5 million of molecules
Peptidoglycan – 1 molecule

6. Microbial metabolism 1. Catabolism (Dissimilation)
- Pathways that breakdown organic substrates
(carbohydrates, lipids, & proteins) to yield metabolic energy
for growth and maintenance.
2. Anabolism (Assimilation)
- Assimilatory pathways for the formation of key
intermediates and then to end products (cellular
components).
4. Intermediary metabolism - Integrate two processes

7. Energy source chemotrophs – gain energy from chemical compounds
phototrophs – gain energy through photosynthesis

9. As oxygen is utilized it is transformed into several toxic products:
singlet oxygen (O2), superoxide ion (O2-), peroxide (H2O2), and hydroxyl radicals (OH-)
Most cells have developed enzymes that neutralize these chemicals:
superoxide dismutase, catalase
If a microbe is not capable of dealing with toxic oxygen, it is forced to live in oxygen free habitats.

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

11. Anaerobe – does not utilize oxygen
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

12. All microbes require some carbon dioxide in their metabolism.
Capnophiles – grows best at higher CO2 tensions than normally present in the atmosphere

14. Anaerobic conditions

15. Anaerobic conditions

16. Anaerobic conditions

17. Temperature Pyschrophiles 4-20 °C Mesophiles 15-48 °C
Thermophiles °C
Extreme thermophiles >68 °C

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

20. Reproduction results in growth
Microbial growth – an increase in a population of microbes rather than an increase in size of an individual
Result of microbial growth is discrete colony – an aggregation of cells arising from single parent cell
Reproduction results in growth 20

21. division exactly in half
most common means of bacterial reproduction
forming two equal size progeny
genetically identical offspring
cells divide in a geometric progression doubling cell number

22. In laboratory studies, populations typically display a predictable pattern over time – growth curve.

23. The Population Growth Curve
Stages in the normal growth curve:
lag phase – “flat” period of adjustment, enlargement; little growth
exponential or log phase – a period of maximum growth will continue as long as cells have adequate nutrients and a favorable environment

24. The Population Growth Curve
Stages in the normal growth curve:
stationary phase – rate of cell growth equals rate of cell death caused by depleted nutrients and O2, excretion of organic acids and pollutants
death phase – as limiting factors intensify, cells die exponentially in their own wastes

25. Passive transport –does not require energy; substances exist in a gradient and move from areas of higher concentration towards areas of lower concentration
diffusion
osmosis – diffusion of water
facilitated diffusion – requires a carrier

27. Osmosis
Osmotic pressure

28. Active transport – requires energy and carrier proteins; gradient independent
group translocation – transported molecule chemically altered

30. Enzymes are biological catalysts that increase the rate of a chemical reaction by lowering the energy of activation
The enzyme is not permanently altered in the reaction
Enzyme promotes a reaction by serving as a physical site for specific substrate molecules to position

31. Simple enzymes – consist of protein alone
Conjugated enzymes or holoenzymes – contain protein and nonprotein molecules
Apoenzyme – protein portion
Cofactors – nonprotein portion
Metallic cofactors: iron, copper, magnesium
Coenzymes, organic molecules: vitamins

33. Endoenzymes – retained intracellularly and function there
Exoenzymes – transported extracellularly, where they break down large food molecules or harmful chemicals
Cellulase, amylase, penicillinase
Endoenzymes – retained intracellularly and function there
Most enzymes are endoenzymes

35. Bacterial enzymes are subdivided into some groups:
1. Hydrolases which catalyse the breakdown of the link between the carbon and nitrogen atoms, between the oxygen and sulphur atoms, binding one molecule of water (esterases, glucosidases, proteases, amilases, nucleases, etc.).
2. Transferases perform catalysis by transferring certain radicals from one molecule to another (transglucosidases, transacylases. transaminases).
3. Oxidative enzymes (oxyreductases) which catalyse the oxidation-reduction processes (oxidases, dehydrogenases, peroxidases, catalases).
4. Isomerases (Rearrangement atoms of a molecule).
5. Lyases (remove chemical groups from molecules without adding water).
6. Lygases (join two molecules together and usually require energy from ATP).

36. Constitutive enzymes – always present, always produced in equal amounts or at equal rates, regardless of amount of substrate
Enzymes involved in glucose metabolism
Regulated enzymes – not constantly present; production is turned on (induced) or turned off (repressed) in response to changes in concentration of the substrate

38. Nutrient media Culture media may be found in one of three states:
liquid (called broth)
semi-solid
solid.
Media are solidified by the addition of solidifying agents such as agar.
Varying the concentration of agar will yield varying degrees of solidification.

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

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

42. Nutrient media

43. Nutrient media

44. Nutrient media

45. Nutrient media

46. Nutrient media

49. Isolated colonies obtaining

50. Isolated colonies obtaining

51. Isolated colonies obtaining