Study On Screening Of Dominant Strains Of Cellulose Degrading Bacteria From Sugarcane Field Soil

The over-application and partial application of chemical fertilizers in crop production in China are serious.Sugarcane is the largest field crop with the highest bio-amount per unit area.It has a long growth period and requires a large amount of fertilizer.The sugarcane growing fields in Guangxi,Yunnan,Guangdong,and Hainan comprise hilly red soils,which are influnenced by drastic climatic circumstances.The bastion of sugarcane is shallow and easy to lose;the soil is infertile,and acidification is widespread;the soil pellet structure is scarce and easy to compact.Continuous improvement and improvement of sugarcane production as soil productivity is one of the key technologies for reducing fertilizer input,reducing production costs,and achieving green industrial development.While the raw cane stalks are being harvested into the plant,about 20%of the sugarcane field biomass,including unstemmed sugarcane plants,cane shoots,sugarcane leaf,and leaf sheaths,is discarded in the field.These straws contain large amounts of carbon,nitrogen and phosphorus.Potassium and other trace elements have a high cellulose content and a C/N ratio of about 60,which has great potential for transformation and utilization of nutrients but slower degradation.The traditional methods for treating sugar cane straw are mostly incineration,which not only pollutes the environment but also causes a waste of nutrients.In recent years,the efficient utilization of crop straw returning and cellulose resources has received extensive attention at home and abroad.In particular,biotechnology approaches that use soil microorganisms to efficiently degrade and convert cellulose have become a hot topic in the industry.In order to increase knowledge about this interest,we have isolated and screened out cellulose degrading bacteria from sugarcane field soil.Moreover,highly efficient cellulose-degrading bacteria were also investigated for cellulase production at the different condition for efficient use in biotechnology.Cellulose was used as the sole carbon source to screen out cellulose-degrading bacteria.Additionally,morphological,physiological,biochemical,and molecular methods were employed for identifications and confirmation of the bacterial species.Three aspects such as time,initial pH value,and temperature were studied to optimize conditions to establish cellulose-degrading bacteria.In this study,two bacterial strains,G-3-3 and 41-3,and one fungal strain,M51,which were effective to degrade cellulose were selected through strain screening and rescreening.The results revealed that G-3-3,41-3,and M51 belong to the genus Pseudomonas sp.,Bacillus sp.and Parascedosporium and phylogenetic trees of the above strains were built.The selected strains G-3-3,41-3 and M51 were optimized at the different condition to produce cellulase.The results showed that:G-3-3 had the highest activity at 6 pH value,culture temperature of 30?,and culture time of 4 days.41-3 In the medium initial pH value of 7,the culture temperature of 35?,the culture time of 5 days,the CMC enzyme activity is highest;M51 had the highest activity of CMC enzyme under the conditions of initial pH value of 7 in a culture medium,25? culture temperature,and 5 days culture time.