Fishmeal Wastewater as A Low-Cost Nitrogen Source for -Polyglutamic Acid Production Using Bacillus subtilis

Fishmeal wastewater, a fishmeal processing waste, was used as culture medium to study the effect of Bacillus subtilis A3 on the production of -polyglutamic acid (-PGA). The results showed that the optimum concentration of chemical oxygen demand (CODCr) for fishmeal wastewater was 15g/L. Moreover, addition of 30g/L glucose and 25g/L glutamic acid in the medium was beneficial to cell growth and production of -PGA. The study also showed that the high salinity of wastewater had little effect on cell growth and production of -PGA after dilution. Thus, the optimal medium consisted of COD 15, 30g/L glucose, 25g/L glutamic acid, in which the average yield of -PGA (25.07 +/- 0.34g/L) was obtained. The study suggested that fishmeal wastewater can be a replacement for nitrogen source for -PGA production, and hence it can be the cost-effective alternative in -PGA production. Meanwhile, the process can offset the disposal costs of the wastes.