Abstract
The growth medium of the citrus peel was fermented by Trichoderma harzianum in solid state fermentation
(SSF) at pH 5.5 and 28°C for 72 hours. It was observed that addition of yeast extract, and tween-80 into the
growth medium enhanced pectin lyase production by Trichoderma harzianum whereas peptone showed
negative effect on microbial growth. The maximum activity of pectin lyase (16.2 U/mllmin) was recorded in the
culture filterates harvested after 72 hours of SSF of basal growth medium of citrus peel with 70% moisture at
pH 5.5 in the presence of 0.4% yeast extract, 2.5 ml (25%) Inoculum and 0.2% tween-80. The comparison of
solid state fermentation (SSF) and liquid state fermentation (LSF) showed that SSF was better than LSF as it
gave higher yield of pectin lyase (15.55 Ulmllmin) as compared to LSF (10.57 U/mllmin). The enzyme showed
maximum activity, at pH 7 and 40°C temperature, but it showed considerable stability upto 60°C. Pectin lyase
produced in SSF was partially purified by ammonium sulfate precipitation and residue showed more enzyme
activity (41.745 U/mllmin) than supernatant (31.59 U/mllmin) after precipitation with 20% ammonium sulfate.
Key words: Citrus peel, Solid state fermentation, Pectin lyase, Optimization, Trichoderma harzianum
