Screening And Interaction Of Functional Strains For Straw Degradation

As agricultural country,our country is rich in crop straw and high yield.Crop straw,as an important renewable biomass resources,can be decomposed into nutrients to improve soil fertility and nutrient availability,reduce agricultural waste pollution,save the use of chemical fertilizer,improve the ecological environment,and play a positive role in promoting the sustainable development of agriculture.The complex composition and structure of crop straw lead to the slow decomposition speed and poor use effect,which has become the bottleneck restricting the extensive application of straw resource returning to the field.The effective degradation of straw requires the synergistic effect of a variety of microorganisms,but it is not clear how the strains cooperate and degrade straw together.Therefore,in this study,through the greenhouse straw incubation experiment,the succession process of straw degrading microbial community structure with time was analyzed.Combined with the pure culture technology,several strains with straw cellulose degrading ability were screened out.The growth status of the strain combinations under different nutritional conditions was studied,and the interaction between the straw cellulose-degrading strains was revealed.The effects of combined inoculation strains on straw decomposition and soil physicochemistry were investigated.The main results are as follows:Community analysis showed that the addition of straw could significantly increase the relative abundance of Firmicutes compared with the control treatment,and further analysis showed that Bacillus was the dominant genus.Forty-six cellulose-degrading bacteria were isolated from the soil,45 of which belonged to Bacillus,suggesting that this strain might play an important role in straw decomposition.Through the strain co-culture test,it was found that under the condition of high nutrition,the six strains tested tended to have more negative interactions among each other,and had higher cellulase activity.Under poor nutrient conditions,bacteria tend to more positive interactions due to the lack of nutrients,but the cellulase activity is lower.These results indicated that the internal interaction and overall function of the microflora were regulated by the nutritional environment.Although the competitive relationship may have adverse effects on individuals,it may be beneficial from the perspective of population structure and function.The further test of the combination strains showed that the straw decomposition degree and the effect on soil nutrients under the interaction of strains were significantly higher than that of single strains.It is indicated that the multi-bacterial combination mode is helpful to improve the decomposition speed of straw returning to the field,and has a certain application potential.This study revealed the interaction mode of functional bacterial strains in the straw returning decomposition process,clarified the influence of bacterial interaction on the community function,and confirmed that the use of combined bacterial strains is helpful to improve the efficiency of straw decomposition,which provides a certain resource and theoretical basis for the development and use of straw decomposition combined bacterial agents.