Basics of Microbiology
· Exo microbiology – Exploration of life in outer space.
· Antony – van – Leewan hooke – animal cules (or) little animals.
· Microbes arise from non living material – spontaneous generation (or) abiogenesis.
· “Grancis Appert” developed a technique of preserving food by cooling the tins and boiling. This process is known as “Appertisation”.
Basics of Microbiology
· Louis Pasteur – father of microbiology – developed narrow goose necked flasks Fermentation Pasteurization.
· John tyndall – Heat resistant phase and heat labile phase Tyndalization, Dust free chamber.
· The process of discontinuous boiling is called “Tyndalisation”.
Basics of Microbiology
· Heating ferment half an hour at 62.80C gives good products. This process is known as “Pasteurisation”.
· Von plenciz: proposed that the germs are responsible for disease (Germ theory of disease).
· “Etiology” is the study dealing with disease.
· O. Brefeld – Isolated a single cell of fungus for pure culture voing a solid medium “Gelatin”.
· Edward Jenner: use cowpox vaccine to immunize people against small pox.
· The culture which is kept long for many days it is said to be attenuated culture. These attenuated cultures as “Vaccines”.
Basics of Microbiology
· Alexander fleming – Pencillin (1929).
· Pure culture structure – Culture of a Micro Organism without any contamination.
· DNA can be altered by introducing a piece of new DNA by a process called “Recombination”.
· “E.V. Haeckel” proposed a separate kingdom called “Protista”.
· “Mesosomes” are present in prokaryotes absent in Eukaryotes.
· In prokaryotes cell wall chains Peptidoglycan layer.
1. Streptococci – Attached in Chains.
2. Staphylo cocci – Cells divide in any plane and are grouped in bunches.
3. Sarcinae – Divided in 3 plains and have cuboidal structure.
Basics of Microbiology
· Some bacteria contain multinucleate filaments – mycelium.
· Half curved (or) comma shaped – Vibroid.
· Bacteria which have more than one turn – Helical.
· “Flagellum” useful for the movement of bacterium.
· Protein of filament is “flagellin”.
· Bacteria move according to external stimuli are called “Tactic movement”.
· F pilus (Sex pilus) helps in the movement of genetic material from one bacterium to another bacterium.
· More number of cells are embedded in that coat, that coat is called “Slime”.
· Bacteria which require extreme conditions are grouped in “archebacteria”.
· Cell wall of eubacteria is made up of poly saccharides and lipids.
· After staining Gram +Ve appear deep violet; Gram –Ve – red colour.
· Site for synthesis of ATP – “Plasmalemma (or) Cytoplasmic membrane”.
· Cytoplasmic membrane appears to be infolded more than one point these infolding are called “mesosomes” – involve in binary fission.
Basics of Microbiology
· The spores are enclosed in Sac called “Sporangiospores”. If they are not enclosed they are called “Conidiospores”.
· “Strain” indicates the group of individuals derived from the initial pure culture.
· Clones: are derived from a single cell.
· Type strain: Is a strain, in which characters are fully studied and becomes a permanent example for that Sps.
· In DNA homology expts: if the “Heteroduplexes” are formed they will be considered that they are similar at the Sps. level. If no heteroduplexes are formed they are not similar at the Sps. Level.
· Sidero capsaceae: Bacteria of this family are generally found in iron containing water.
· Typoid – Salmonella typhosa / typhi
· Kingdom of prokaryote.
1. Gracilicutes – thin cell wall gram –Ve type.
2. Fermicutes – thick cell wall gram +Ve type.
3. Tenericutes – that have no cell wall – Mycoplasma.
4. Mendosicutes – Archeobacteria.
· Constituent of Co-enzyme A – Sulphur.
· If the source of carbon is CO2 the microbe is called an “autotroph”.
· If the source of carbon is organic compound it is called “heterotroph”.
· If the organism can grow on a single carbon source without the requirement of growth factory additional organic compounds the organism is called “Phototroph”.
· If as organism requires additional organic compounds or growth factors for their growth the growth is called “auxotroph”.
· “Chemoautotrophs” – utilizes CO2 in the presence of reduced inorganic compounds such as NH3, H2, H2S.
· Chemoheterotrophs – This group of bacteria uses organic compound as carbon and energy sources.
· Optimum pH of bacteria – 6.7 to 7.0.
· Facultative anerobic bacteria – They can grow either in the presence (or) absence of O2.
· Micro aerophilic bacteria – They require low levels of O2 concentration.
· Certain yeasts and moulds require higher concentration of sugars these are called “Osmophiles”.
· Certain bacteria require high concentration of salts for their growth and these are called “Halophites”.
· Most common method of multiplication in bacteria “Transverse binary fission”.
1. Lag phase – There will not be any cell multiplication.
2. Log phase – Cell multiply in an exponential manner. Primary metabolites produced.
3. Stationary phase – Because of limiting nutrient concentration and other factors the cells cannot continuously multiply. Secondary Metabolites
4. Death phase – During this phase some of the cells will be die and some cells will be active but will not multiply.
· For studying various physiological and metabolic activites, cells present in log phase are to be taken into consideration.
· Maintaining the culture continuously in log phase is known as “Coninurs culture”.
· Maintaining culture so that all the cells will divide at only one time called “Synchronus culture”.
· When all metabolites are synthesized at the relatively equal rates the growth is called “Balanced growth”.
· If a strain is supplied with two organic compounds it will exhibit a growth called “Diauxic growth”. Diauxic growth will have ‘two lag phases’ by J. Monaod.
· Micro scopic method of counting cells is usually done by using patroff – Hauser counting chamber.
· Indirect method – Plate count methods.
· The principle in plate count method is that each viable cell will give rise to a single colony.
· Membrane filter counting method: useful in a large volume of water (or) air.
· In turbidometric method the number of cells can be determined using a “Calorimeter”.
· In aerobic organisms O2 is terminal electron acceptor where as in anaerobic organisms Nitrate, Sulphate (or) CO2 will be electron acceptor.
Basics of Microbiology
· Under anaerobic condition pyruvate reduced to “lactic acid”.
· Pentose phosphate pathway also known as “Shunt glycolysis”.
· In this process only reduced NADP molecules can be produced and there is not production of ATP.
· Entner – Doudoroff (or) off pathway present in both aerobic and anaerobic prokaryotes. This is absent in Eukaryotes.
· Fermentation is anaerobic oxidation of organic compounds by micro organisms. It does not involve O2 (or) electron transport chain.
· “Glyoxylate pathway” is under taken by organisms where “acetate” is the major source of the organic carbon (or) where acetyl COA is produced without formation of “pyruvic acid”.
· In this cycle “Isocitrate lyase” and malate synthase” are specific enzymes for this cycle.
· Hill and Bendall proposed “Z-Schme” in which the components of photo synthetic units are arranged as per the redox potential.
· Viruses cause disease during replication in host cell.
· Viruses multiply inside host cells and released by the process of “lysis” – Lytic phage.
· The fully structurally matured virus capable of infecting the host is called virion.
· Bacteriophages become the tool for the viral and genetic research.
1. Lytic phase: When lytic phase infect, bacteria will immediately respond.
2. Temperate phase: Bacteria response is not immediately shown.
· The Nucleic acid of the bacteriophase is covered with a protein coat called “Capsid”.
· Capsid is made up of number of sub units called “Capsomeres”.
· Types of Bacteriophages:
A – type – Hexagonal head, rigid tail with tail fibres.
B – type – Hexagonal head and a flexible tail.
C – type – Hexagonal head and a short tail.
D – type – Hexagonal head without tail. The capsomers are large in size.
E – type – Hexagonal head without tail. The capsomers are small in size.
F – type – They are filamentous (rod shaped).
Basics of Microbiology
· The phages A, B and C are unique to bacteriophages.
D, E – are unique for animals and few plants.
F – is mostly present in plants.
A,B, C – contain double stranded DNA.
D,F – Contain single stranded DNA.
E – Contain single stranded RNA.
· Stanley – crystallized virus particles.
· Iwanowski – virus as filterable agent.
· Beijerinck – named virus as TMV.
· Virioids – They are smallest and infectious agents of plants and cause number of diseases to plants.
· Adoptation: The phenotypic changes that result due to variation in environment condition is called “adaptation”.
· Type of mutations:
1. Point mutation
2. Frame shift mutation
· Point mutation : This mutation results due to substitution of one neucleotide for another if the purine is substituted for another purine (or) called “Transition type of mutation”.
· If purine is substituted by pyramidine (or) vice versa it is called “Transversion” pyramidone for pyramodine it is type of mutation.
· Frame shift mutation – The change in the sequence of nucleotides may result in the production of mRNA which results in the synthesis of non-functional protein.
· The addition (or) deletion of nucleotide sequence is called Insertion (or) deletion mutations.
· Types of chemical mutagens:
1. Which react with DNA – Eg: Nitrous acid
2. Base analogs – 2 – amino purine.
3. Intercalating agents – Nitrogen mustand, Bromouracil, Acridine orange.
· Three types of gene transfer.
1. Conjugation – Transfer of genes between the cells when they are in physical contact with each other.
2. Transduction – Transfer of genes between the cells due to bacteriophages.
3. Transformation – Transfer of naked DNA to the receptor cell.
Basics of Microbiology
· Plasmid is circular and gets integrated with bacterial chromosome and it is known as “Episome”.
· Prophage: The bacteriophage which is capable of integrating with the bacterial chromosome.
· Lysogeneic bacteria: The bacteria carrying the prophase.
· “Induction” is a process where the substrate is required for the synthesis of enzymes.
· Structural genes are responsible for the determination of aminoacid sequence of the enzymes.
· The regulatory genes control the rate of synthesis of enzymes.
· “Operon” consists of both the structural genes and the regulatory genes.
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Basics of Microbiology
