BATCH CULTURE IN MICROBIOLOGY

BATCH CULTURE IN MICROBIOLOGY

OVERVIEW:

Microbial culture processes that are used in industrial applications can be explained with three models of fermentation:

-batch

-continuous

-fed batch fermentations.

BATCH FERMENTATION:

A batch fermentation system is called as a “closed system”.

At time t=0, the sterilized nutrient solution in

the fermenter is inoculated with microorganisms and incubation is proceeded at a relevant temperature and gaseous environment for a relevant period of time. In aerobic fermentation only add oxygen used as an antifoam agent and acid or base to control pH.

The medium composition, biomass concentration and metabolite concentration change constantly because metabolism of the cells which are continuously taking place.

After inoculating sterile nutrient solution with microorganisms and cultivation , 6 phases of growth are observed…Growth occurred because of consumption of nutrients.

1) At initial lag phase, there is no apparent growth but metabolic turnover takes place which shows cells are adapting to the new environmental conditions growth will start.

2) In transient acceleration phase, growth of inoculum results.

3) In exponential phase, microbial growth occurred at maximum possible rate in and is at limited duration.

4) In deceleration phase, as nutrient conditions change and growth rate decreases.

5) In stationary phase overall growth will stop because of nutrient exhaustion.

6) The final phase is called as the death phase where growth rate has ceased. Most biotechnological batch processes are stopped before this death stage as decreasing metabolism will cause cell lysis.

ADVANTAGES OF BATCH CULTURE :

1) Reduced risk of infection or cell mutation because the growth period is short.

2) Lower capital funding when in comparison to continuous processes for the same bioreactor quantity.

3) More flexibility with varying product/organic structures.

4) Higher raw material conversion levels because of controlled growth rate.

DISADVANTAGES OF BATCH CULTURE:

1) Lower productivity stages due to time for filling, heating, sterilization, cooling, emptying

and cleaning the reactor.

2) Increased consciousness on instrumentation due to frequent sterilization.

3) More expense in preparing several subcultures for inoculation.

4) More investment for labour and process

5) More hygiene risks because of potential contact with pathogenic microorganisms or

pollution.

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