Solid state fermentation of maize (Zea mays) cob by Pleurotus ostreatus strain EM-1: Biopolymer profiles and cellulose degradability

The low digestibility and low protein content of maize cob are major limitations to its use as animal feed in Ghana. The possibility of enhancing the feed potential of maize cob through solid state fermentation byPleurotus ostreatus strain EM-1 was investigated. At the end of spawn run, lignin, cellulose and hemicellulose content had decreased by 42.3, 5.6% and 41.0% respectively. No further reduction in lignin content occurredthereafter. In contrast, after 28 days, cellulose and hemicellulose had been degraded by 36.0% and 58.5% respectively. A biphasic protein profile, characterized by a 6-fold increase by day 14, followed by a dramatic decline was observed. The rate of release of reducing sugars from spent maize cobs during incubation with exogenous cellulase was 400% greater than that of untreated maize cobs. The present findings indicate that the positive effects of P. ostreatus strain EM-1 on the nutritive value of maize cob appear to be optimal after complete colonization by mycelia. At this stage, maximum biodegradation of lignin had occurred, protein content was markedly elevated and the reduction in cellulose content was negligible. Thus, solid state fermentation by Pleurotus ostreatus strain EM-1 may be an efficient means of transforming maize cob into nutritive animal feed. Keywords: Oyster mushroom, delignification, animal feed, biodegradation, cellulose, hemicellulose