Optimisation of process parameters for chitinase production by soil isolates of Penicillium chrysogenum under solid substrate fermentation

Fifteen isolates of Aspergillus flavus, six isolates of Aspergillus niger and two isolates of Penicillium chrysogenum showing chitinolytic activity were isolated from chitin-rich soils of shrimp drying fields. Major process parameters affecting the production of chitinases by two isolates of P. chrysogenum, PPCS 1 and PPCS 2 have been optimised under solid substrate conditions. Maximum chitinase was recovered from mouldy bran with 1% sodium chloride solution, which showed temperature and pH optima at 40 °C and 4.0, respectively. MS–HCl as a moistening medium and 24 °C growth temperature were most suitable for chitinase production by both isolates. Isolate PPCS 1 yielded maximum chitinase (3809 units g−1 (U g−1) initial dry substrate) at pH 5.0; inoculum size 1 × 106 spore ml−1 and 80% initial moisture content, whereas isolate PPCS 2 yielded maximum chitinase (2516 U g−1 initial dry substrate) at pH 4.0; inoculum size 1 × 1010 spore ml−1 and 120% initial moisture content.