ABSTRACT

Cotton (Gossypium spp.) is a major agricultural crop grown in the world. Cottonseed meal (CSM) is the by-product of cotton obtained after seeds are crushed and which are rich in quality protein. However, its consumption is limited because of the presence of gossypol which is highly toxic to monogastric and ruminant animals which cause growth depression, abnormalities to intestine, reproductive organ and other internal organs. As they are rich source of protein and could be used as an alternate protein source for human and animal consumption, provided it is detoxified from gossypol and careful removal of fiber. Consumption of gossypol free glandless cotton seed flour promoted the growth, increased weight gain and a positive nitrogen balance. Therefore, the study was aimed to isolate gut bacteria from P. gossypiella and optimize the culture conditions and characterize the gossypol degrading enzyme and validate the biodegradation of gossypol in CSM by SSF. The culture conditions for the four gut bacterial isolates P1, P4, P12 and P13 were optimized and production of gossypol degrading enzyme was found maximum when 0.6g/L of gossypol was provided as sole source of carbon, inoculum level 2%, medium pH 8.0 and incubation temperature 30 oC. Optimum pH, temperature required for the gossypol degrading enzyme activity was pH at 9.0, 30 oC. Electrophoresis indicated that there were several protein bands obtained in the enzyme preparation with molecular weight from 29 to 124 kDa. The optimum fermentation conditions of CSM were found to be IMC 70%, pH 9.0, temperature 30oC and inoculum level 30%. The results indicated that the isolated bacteria were able to utilize gossypol as sole source of carbon in CSM and found to increase production of gossypol degrading enzyme and thus could be implicated in biodegradation of gossypol in CSM to enhance it’s utilization for consumption.