Construction of actinomycetes complex flora in degrading corn straw and an evaluation of their degradative effects

Abstract

As a type of agricultural waste, there is a large amount of lignocellulose in corn (Zea mays) straw, but it is difficult to utilize efficiently owing to its recalcitrance to enzymatic degradation. Three strains of actinomycetes that degrade cellulose were constructed as complex flora, and the conditions of cellulose degradation conditions and their degradative activity were optimized and evaluated. When the complex flora were inoculated into the fermentation medium at pH 7 and 3% (v/v), the rate of degradation of corn straw reached 38.24% after 5 d of fermentation at 28ºC and 180rpm. Cellulose, hemicellulose, and lignin in the corn straw were degraded by 33.97%, 34.08%, and 21.52%, respectively. The results from scanning electron microscopy showed that the waxy layer on the surface of corn straw became thin and gradually disappeared following fermentation by the complex flora. Fourier-transform infrared spectroscopy showed that the complex flora could change the internal functional groups of corn straw at different fermentation periods. The compounds detected in the fermentation system indicated that the corn straw was efficiently degraded. These results indicated that the constructed complex flora was more effective at degrading corn straw than the individual strains and provides research concepts for the development and utilization of biomass resources.