The gut wastes of Sardinella longiceps were used as substrate for protease production. The gut waste has 61.6% proteins, 21.8% lipids, 8.5% carbohydrates on dry weight basis and trace elements. The signifcant factors of protease fermentation were screened by Plackett-Burman design. A protease activity of 68.56 U/ml was predicted at 46.31°C, incubation time 71.11h, inoculum 4.86% (v/v) and substrate concentration 2.66% (w/v), using response surface methodology. However, the validation experiment showed 73.52 U/ml activity. The artifcial neural network was found as a better tool to predict the experimental results. The partially purifed protease showed higher activity at pH 9 and 10 and retained 90% activity after 120h at pH 9. It showed maximum activity at 50°C and retained 88% residual activity until 90min at 50°C. Zn++ enhanced the protease activity by 40%. The protease retained an activity of 93, 103, 90 and 98% against urea, β-mercaptoethanol, SDS and tween 80 respectively. The alkaline protease was compatible with all the commercial detergents tested with the residual activity above 90%. The alkaline protease exhibited 22% higher activity on the tryptone soya substrate. The gut waste of S. longiceps is a worthy low cost substrate for the production of industrially important alkaline protease.

The gut wastes of Sardinella longiceps were used as substrate for protease production. The gut waste has 61.6% proteins, 21.8% lipids, 8.5% carbohydrates on dry weight basis and trace elements. The signifcant factors of protease fermentation were screened by Plackett-Burman design. A protease activi...