Screening For High-temperature Cellulose-degrading Strains And Effect Of The Compositive Microbial Inoculants On Crop Straw Degradation

In order to promote the decomposition of crop straw then return it into soil rapidly and solve the problems such as the waste of straw resources, high-temperature straw lignocelluloses-degradation microbe was screened and their effect on straw degradation were studied, with the aim of accelerating the decomposition of straw and returning into soil to provide microbial resources and technical support. In this study, two high efficient cellulose degrading actinomycetes, named Fl and F2, were isolated through the high temperature enrichment, CMC-Na Congo-red medium and domestication subculture. According to morphology, culture characteristics,physiological and biochemical characteristics, both of these strains were confirmed belonging to Streptomyces sp.By comparing the effect of filter paper decomposing, cellulose enzyme activity and simulation compost test among each single bacteria and the mixed strains, results showed that each strain had certain capability of decomposing cellulose, but mixed strains behaved the best and these two strains bacteria had obviously synergistic effect. Within12hours, they started to decompose filter paper, and could completely decompose the filter paper in35hours, the effect was better than those of each single strain. Cellulose enzyme activity of mixed culture was increased compared with single culture, the maximum enzyme activity was22.96U/mL, higher than those of F1and F2(11.64U/mL and14.77U/mL)(P<0.05). It was also showed that strains had synergistic effects. In the simulated composting trials, the effect of degradation rice straw of these two strains were good, the rate of decomposing rice straw was over20%within10days at50℃, two bacterial mixed culture on rice straw degradability is up to31.27%.Through the high-temperature acclimation, liquid culture and expansion of solid fermentation, a quick decomposition inoculant was developed. Laboratory pot degradation and outdoor amplification test were taken in order to evaluate the effectiveness of such bacteria. In the laboratory pot experiment, the bacteria demonstrated efficient degradation of straw cellulose and the rice straw was decomposed within25days. In amplicated rice straw degradation experiment, the experiment was divided into two parts:no inoculants (CK) and inoculantion of complex microbial agent, then studied the decomposition of straw composting process. Four indicators were tracked by straw color, pile temperature, shear tension and seed germination index (GI). The results showed that adding microbe can reach high temperature fastly, make the fermentation temperature stable at60℃and speed up the process of straw decomposition. Two days later, the compost pile of adding microbial agents reached thermophilic temperature phase (>50℃), high temperature phase was lasting more than three weeks, highest peak temperature of microbial decomposition bacteria was60.3℃, while the none inoculated agents was only40℃. The agents can therefore be used in high-temperature composite straw, accelerating the decomposition rate of rice straw, increasing soil organic matter such as nitrogen, potassium nutrient content, improving soil fertility, It can also overcome crop obstacles and reduce the risk of pests and diseases. Meanwhile obtained compositive agents in straw decomposition have a good effect and broad application prospects. Using straw decomposition agent has laid a solid foundation for the development of agricultural production.