Abstract

A protease producing Bacillus sp. GA CAS10 was isolated from ascidian Phallusia arabica, Tuticorin, Southeast coast of India. Response surface methodology was employed for the optimization of different nutritional and physical factors for the production of protease. Plackett-Burman method was applied to identify important factors (anchovy waste, KH₂PO₄, NaCl and temperature) influencing protease production. Further optimization was done by response surface methodology using central composite design. Under the optimized conditions by central composite design, the protease experimental yield (842.102 U/ml) closely matched the predicted yield by the statistical model (830.307 U/ml) with R² = 99.94%. The time course of protease production was increased using the RSM optimized medium (856.29 U/ml) (anchovy waste 20.50 g/l, KH₂PO₄ 3.06 g/l, NaCl 42.91 g/l, temperature 43.36°C, 42 h and pH 9) compared with the un-optimized basal medium (267.33 U/ml). The improvement of protease production by microbial conversion of anchovy waste suggested its potential utilization to generate high value added products using cheap carbon and nitrogen substrates.  

Key words: Protease, anchovy waste, statistical optimization, ascidian associated bacteria.

Abbreviation

Abbreviations: RSM, Response surface methodology; CCD, central composite design; ANOVA, analysis of variance; PCR, polymerase chain reaction.