Aim: Development and optimization of an efficient and inexpensive medium for succinic acid production by Escherichia coli under anaerobic conditions.
Methods and Results: Initially, 0·8 gl−1 of succinic acid was produced in 60 h in 300‐ml medium. On optimization, glucose and peptone were replaced by cane molasses and corn steep liquor. Three hundred ml of this medium was inoculated with 4% (v/v) of seed inoculum, incubated at 39°C for 72 h, resulted in 7·1 gl−1 of succinic acid in 36 h. Scale up in a 10‐l fermentor under conditions of controlled pH and continuous CO2 supply in this medium resulted in 17 gl−1 of succinic acid in 30 h.
Conclusions: A ninefold increase in succinic acid production was obtained in 500‐ml anaerobic bottles with optimized medium having cane molasses and corn steep liquor as against initial medium containing glucose and peptone. However, a subsequent scale up in a 10‐l fermentor resulted in a 2·5‐fold increase in succinic acid production as against optimized medium used in 500‐ml anaerobic bottles.
Significance and Impact of the Study: Succinic acid production was enhanced in medium consisting of inexpensive carbon and nitrogen sources in a shorter span of time.
Statistically based experimental design was employed for the optimization of fermentation conditions for maximum production of enzyme tannase from Aspergillus niger. Central composite rotatable design (CCRD) falling under response surface methodology (RSM) was used. Based on the results of 'one-at-a-time' approach in submerged fermentation, the most infl uencing factors for fl tannase production from A. niger were concentrations of r tannic acid and sodium nitrate, agitation rate and incubation period. Hence, to achieve the maximum yield of tannase, interaction of these factors was studied at optimum production pH of 5.0 by RSM. The optimum values of parameters obtained through RSM were 5% tannic acid, 0.8% sodium nitrate, 5.0 pH, 5 x I0 7 spores/50mL inoculum density, 150 rpm agitation and incubation period of 48 h which resulted in production of 19.7 UmL -1 of the enzyme. This activity was almost double as compared to the amount obtained by 'one-at-a-time' approach (9.8 UmL -1 ).
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