ERT 107 Microbiology for Bioprocess Engineering MICROBIAL NUTRITION

Element of life macroelements (macronutrients) ◦ C, O, H, N, S, P found in organic molecules such as proteins, lipids, carbohydrates, and nucleic acids ◦ K, Ca, Mg, and Fe cations and serve in variety of roles including enzymes, biosynthesis ◦ required in relatively large amounts

micronutrients (trace elements) ◦ Mn, Zn, Co, Mo, Ni, and Cu ◦ required in trace amounts ◦ Part of certain enzyme ◦ often supplied in media components Microbes need balanced mixture of nutrients. If an essential nutrients is in short supply, microbial growth will be limited

Requirements for Carbon, Hydrogen, and Oxygen All organisms need C, H, O & electron C – used to synthesize organic mol H & O – important element in organic mol Electron – electron transport & oxidation reduction Requirement for C, H, O often satisfied together ◦ carbon source often provides H, O, and electrons

heterotrophs ◦ use organic molecules as carbon sources – also obtain H, O & e- from same mol. (which often also serve as energy source) ◦ can use a variety of carbon sources autotrophs ◦ use carbon dioxide as their sole or principal carbon source ◦ Cannot b used as source of H, O & e◦ must obtain energy from other sources

Nutritional Types of Organisms Biologist use specific term to define how the requirements are fullfilled based on energy source ◦ phototrophs use light ◦ chemotrophs obtain energy from oxidation of chemical compounds (organic/inorganic) based on electron source ◦ lithotrophs use reduced inorganic substances ◦ organotrophs obtain electrons from organic compounds

Classes of Major Nutritional Types Based on primary sources of carbon, energy and electron majority of microorganisms known ◦ photolithoautotrophs (photoautotrophs) - Light energy, e- fro, reduced inorganic mol, carbon sources is CO 2 ◦ chemoorganoheterotrophs (chemoheterotrophs) - energy from oxiation of organic/in compound, e- from organic mol, C sources from organic mol.

Requirements for Nitrogen, Phosphorus, and Sulfur needed for synthesis of important molecules (e. g. , amino acids, nucleic acids) phosphorus usually supplied as inorganic phosphate sulfur usually supplied as sulfate via assimilatory sulfate reduction

Sources of Nitrogen organic molecules ammonia nitrate via assimilatory nitrate reduction nitrogen gas via nitrogen fixation

Sources of Phosphorus and Sulfur phosphorus ◦ most organisms use inorganic phosphorus which is directly incorporated into their cells sulfur ◦ most organisms use sulfate and reduce it by assimilatory sulfate reduction

Growth Factors Some microbes require specific growth factor to support growth organic compounds essential cell components (or their precursors) that the cell cannot synthesize must be supplied by environment if cell is to survive and reproduce

Classes of Growth Factors amino acids ◦ needed for protein synthesis purines and pyrimidines ◦ needed for nucleic acid synthesis vitamins ◦ function as enzyme cofactors Some microbes can synthesize many growth factors eg vit Vit C (Gluconobacter) Vit D (Saccharomyces)

Culture Media culture media is solid or liquid preparation need to grow, transport, and store microorganisms in the laboratory must contain all the nutrients required by the organism for growth Specialized media – isolation & identification, antibiotic testing, water& food analysis Majority need C, N, P, S, growth factor Some need precise composition

classification ◦ chemical constituents from which they are made ◦ physical nature ◦ function

Chemical and Physical Types of Culture Media Defined or synthetic Complex

Defined or Synthetic Media All chemical components are known liquid (broth)/ solid Use to culture photolitoautotrophs, grown on medium contain CO 2 (sodium carbonate/bicarbonate) Chemoorganoheterotrophs- glucose as C souces Used widely to know what the microorganism is metabolizing

Complex Media contain some ingredients of unknown composition and/or concentration Single complex media may be sufficient to meet all the nutrients requirement of many microbes. Used to culture unknown nutritional requirement of particular microbes, thus defined medium cannot be constructed

Some complex Media Components peptones ◦ protein hydrolysates prepared by partial digestion of various protein sources extracts ◦ aqueous extracts, usually of beef or yeast ◦ Beef extract contain a. acid, peptides, nucleotides, organic acid, vit, mineral ◦ Yeast extract source of vit B, N and C

agar ◦ sulfated polysaccharide used to solidify liquid media ◦ Extracted from red algae ◦ Microbes grow on agar can be incubated at wide range of temp. ◦ Melt at 90°C ◦ most microorganisms cannot degrade it

Functional type of media

Functional Types of Media supportive or general purpose media ◦ support the growth of many microorganisms ◦ e. g. , tryptic soy agar/broth enriched media ◦ general purpose media supplemented by blood or other special nutrients ◦ e. g. , blood agar (encourage growth of fastidious microbes)

Selective media favor the growth of some microorganisms and inhibit growth of others Bile salts/basic fuschin/crystal violet suppress gram +ve , no effect on gram -ve e. g. , Mac. Conkey agar (bile salt), endo agar ◦ selects for gram-negative bacteria (E. coli) Bacteria may also be selected by incubation with nutrient they

Differential media distinguish between different groups of microorganisms based on their biological characteristics e. g. , blood agar (protein, carbo, iron, vit) ◦ hemolytic (streptococci) versus nonhemolytic bacteria ◦ Produce clear zone- blood cell destruction e. g. , Mac. Conkey agar (lactose, red dye) ◦ lactose fermenters versus nonfermenters ◦ Colony appear pink

Assignment Find a journal about isolation and characterization of microbes Explain: 1) reason for isolation done? 2)the technique used for isolation and obtain a pure culture 3) growth media used for isolation and selection of the microbes of interest; how do they select microbes of interest 4) Method used for identification of