Jatropha curcas seed cake as substrate for production of xylanase and cellulase by Aspergillus niger FGSCA733 in solid-state fermentation

Jatropha curcas seed-cake was evaluated for use as a solid state fermentation substrate for production of cellulolytic and xylanolytic enzymes by Aspergillus niger. Supplementation of the seedcake with 10% thatch grass (Hyperrhaenia sp.) resulted in a fivefold increase in xylanase production. Ammonium chloride supplementation increased production of xylanase by 13%. Under the same conditions, cellulase production was not influenced by supplementation with grass or the nitrogen sources used. Maximum xylanase was produced at 25 °C whilst cellulase was maximally produced at 40 °C. Highest xylanase activity was obtained when the cultures had an initial pH of 3 whereas cellulase was maximally produced at an initial pH of 5. Under optimised conditions, 6087 U and 3974 U of xylanase and cellulase respectively were obtained per gram of substrate. Zymograms of crude enzyme extracts showed six active bands ranging from 20 kDa to 43 kDa for cellulase and a 31 kDa active band for xylanase.