UTS End of Chapter Questions Flashcards
Diff of microbial growth in submerged and solid state
Submerged fermentation involves the submersion of microorganisms in an aqueous medium with all the nutrients required for growth, meanwhile solid state fermentation involves the growing of microbes on the surface of a solid substrate. The microbes typically used in submerged state are those that require high aw for growth, while for solid media, it involves those that require low aw.
Benefits of sumberged over solid
Higher purity obtained, distribution of microbes throughout the media is more even, easier to control parameters,
Product assc growth
Phenomena of microbial growth in which the pH optimum for growth is also the pH optimum for product formation
considerations for large scale fermentation
maintenance of homogeneity of growth conditions, including pH, temperature, oxygen concentration, substrate; changes in medium due to sterilization time, mutation potentially occuring
which reactor used for high viscosity liquids
STR because dispersion of gas and mixing of culture is most efficient and can be regulated with stirrer speed
airlift vs str
simpler construction, no moving parts, mixing and aeration are not decoupled
aeration in ssf
availability of inlet and exhaust nozzles, such as those in rotary drum fermentor; or forced aeration from the bed of substrate such as in static bed fermentor and tunnel fermentor
continuous ssf
tunnel fermentor; highly automoated through continuous feeding, mixing, inoculation and harvest of substrate
microbial isolation vs screening
ISOLATION
obtaining of single colony separated from the bulk microbial population in a sample (to obtain a certain type of microbe or identification). can be done using pour plate or spread plate methods, then isolate visually similar colonies by observing appearance.
SCREENING
selection of potential microbe based on their ability to produce certain products, grow in certain products, etc (proteolytic activity, amylolytic activity). can be done physically or biochemically theough primary and secondary screening.
factors of microbial isolation and screening
- microbial source
- methods of cultivation (physical/biochemical)
- screening methods (primary/secondary)
principles of culture preservation
- slow down growth rate by providing less nutrients or providing sub-optimal growth conditions
- slow down metabolic activities by reducing temperature
- maintain viability by cryoprotective agents
how do microbes regulate metabolism
regulation of synthesis of inducible enzymes at transcriptional level
regulatory vs structural genes
regulatory are set of genes that control the expression of structural genes. structural genes are those that encode for functional proteins, present adjacent to each other and their transcription is controlled by promoter and operator
cumulative vs sequential feedback control
cumulative: end products inhibit first enzyme by a certain percentage independent of other inhibitory products
sequential: products inhibit enzymic step of its own branch respectively
how do microbes sense high MW substrate
bacteria detect their presence due to constitutive enzymes present, and the degradation products will act as the inducer.
