Question

In batch fermentation:
A.Substrates are added to the system all at once and runs until product is harvested
B.Nutrients are continuously fed into the reactor and the product is siphoned off during the run
C.New batches of microorganisms are screened for increase yield
D.Small-scale production is used to synthesise product

Answer 1

Hint: Batch fermentation is a type of fermentation process in which a large volume of nutrient medium and substrate is inoculated in the vessel until the maximum yields of the end product concentration are achieved. The vessel used is a bioreactor which is sterilised before starting with a new batch every time. The batch fermentation process requires the usage of fermentors. The process is completed when all the nutrients are consumed.

Complete answer:
Option A- Substrates are added to the system all at once and run until the product is harvested
As the growth of microorganisms takes place in the medium, the product accumulates in the reactor in two forms i.e. Biomass and metabolites.
Option B- Nutrients are continuously fed into the reactor and the product is siphoned off during the run
Nutrients are fed once into the reactor and the product is taken after the run.
Option C- New batches of microorganisms are screened for increase yield
Microbes show a pattern of growth with distinct phases that are log, transient, exponential, deceleration, stationary and death phase. Microorganisms are incorporated once until the product is formed in the particular batch.
Option D- Small-scale production is used to synthesise product
Large scale production is done by batch fermentation in separate batches.

Hence the correct answer is OPTION(A)

Note: The disadvantage of this process is that it requires cleaning, sterilisation and fermentors which causes loss in productivity. It is only possible when the initial investment for the batch is higher which then results in the same amount of productivity. Another disadvantage is that the growth medium uses a limited amount of carbon from the source, this causes limitations in the production of lysine in the process. Still lysine production is used in small fermentation plants.