| what are micro organisms | very small organisms
archaea, bacteira and some species of eukaryotes |
| what do micro organisms use for metabolism | a wide variety of substrates and produce a range of products from their metabolic pathways |
| why are micro organisms used in industry | because of their adaptability, ease of cultivation and speed of growth |
| what is biosynthesis | the production of complex molecules within living organisms or cells |
| what do micro organisms require for biosynthesis | raw materials
such as amino acids, vitamins and fatty acids |
| where are the raw materials required for biosynthesis supplied from | many micro organisms produce all the complex molecules required for bio synthesis
other micro organisms require these to be supplied in the growth media |
| what are the two forms of basic growth media | broth
agar |
| where is an energy derived from for biosynthesis | an energy source is derived either from chemical substrates or from light in photosynthetic micro organisms such as cyanobacteria and algae |
| what must cells in culture be supplied with in order to grow | must be supplied with the correct nutrient medium but also correct culture conditions |
| how is temperature controlled | using an incubator |
| how is pH controlled | using buffers or the addition of an acid or an alkali |
| how is sterility controlled | by methods such as heat sterilisation or disinfection |
| why is controlling oxygen levels in growth medium important | in a gaseous environment some microorganisms are anaerobic and will not grow in the presence of oxygen, others will require good oxygen levels |
| why is controlling light in growth medium important | if it is a photosynthetic organism |
| what is the effect of having sterile conditions in fermenters | sterile conditions in fermenters reduce competition with desired micro organisms for nutrients and reduce the risk of spoilage of the product |
| what are the four phases to the growth curve | the lag phase
the log/exponential phase
the stationary phase
the death phase |
| describe the lag phase | where enzymes are induced to metabolise substrates |
| what is the log/exponential phase | contains the most rapid growth of micro organisms due to plentiful nutrients |
| what is the stationary phase | occurs due to the nutrients in the culture media becoming depleted and hte production of toxic metabolites
secondary metabolites are also produced such as antibiotics. In the wild these metabolites confer an ecological advantage by allowing the micro organisms which produce them to outcompete other micro organisms |
| describe the death phase | occurs due to the toxic accumulation of metabolites or the lack of nutrients in the culture |
| what is a viable cell count | involves counting only the living micro organisms |
| what is a total cell count | involves counting viable and dead cells |
| what type of cell count can show a death phase | viable cell count only
if you took a total cell count, cell number in the culture would remain constant regardless of if cells were dead or not |
