Research Of Lignin Degrading Ability And The Enzyme Production By Bacteria In Agriculture And Forestry Waste Composting

economic development. The waste treatment technology of composting entered a new stage of science development as a technology of agricultural and forestry waste utilization. In order to improve the disadvantage of composting, increase the compost efficiency, and make it can be used in large scale, many researchers at home and abroad carried out a lot of researches. The biodegradation of limits speed organic compound is considered as the key of composting. In agricultural and forestry composting, the lignocellulose is the major organic compound that limiting composting speed. This organic compound has hard structure, and is separated difficultly. Especially the lignin, it is considered the key of fast compost, its degradation is essential for the operation of composting.In the paper, lignocelluloses biodegradation and its microbial characteristics during composting of agricultural wastes were expounded. Through the traditional method, we sieve the bacterias that have good ability of lignocelluloses degradation. We studied the characteristic and the mechanism of lignocelluloses degradation by bacterias in solid fermentation.A strain of microorganism was isolated from the agricultural waste composting, and was identified as Bacillus subtilis. This strain was found to be capable of utilizing several lignin model compounds, indicating that B. subtilis had the ability to decompose the hycroxybenzene and nonhydroxybenzene lignin compounds of low molecular weight. B. subtilis could also degrade natural rice-straw lignin with the rate of 9.47%.after 30 days solid-state fermentation. At the same time,the cellulose and hemicelluloses were degraded greatly, with the degradation rates of the cellulose and hemicelluloses being 38.8% and 41.84% respectively after 30 days'incubation. The analyses of enzyme production further proved that B. subtilis had ligninolytic ability. Five kinds of enzymes, lignin peroxidase, manganses peroxidase, laccase, cellulase and hemicellulase were believed to be the most important catalyzes in biodegrading process, and they always worked synergistically. In addition, the structure of the untreated straw and treated straw were analyzed through infrared spectroscopy. The results indicated that the structure of straw was greatly altered by B. subtilis and the effect of B. subtilis on different functional groups of lignin was dissimilar.