Pretreatment Of Corn Stalks With Compound Bacteria And The Potential Of Anaerobic Fermentation For Gas Production

The spatial structure of corn stalks is stable and difficult to be used by anaerobic digestion.In order to improve the utilization rate of agricultural waste and break through the bottleneck of low utilization rate of straw,the independent screening of lignocellulosic decomposing composite bacteria strains on the decomposition effect and gas production potential of different lignocellulosic materials was discussed,and the composite bacterial strains were identified.The fermentation cycle is 15 days.The degradation effect of corn stalks is evaluated by p H,corn stalk weight loss,enzyme activity,lignocellulose content,SCOD content,organic acid content,methane production and other indicators,and high-throughput sequencing technology is used.Microbial diversity.This experiment integrates physical and chemical biological pretreatment methods and compares different pretreatment methods.The results show that the self-selected composite bacterial system has a significant degradation effect on simple structure cellulose materials such as filter paper and corn stalks.When the simple fiber material and straw are degraded,the p H will first decrease,then rise,and finally stabilize gradually.The filter paper begins to lyse after 3 days of pretreatment with composite bacteria,and it is completely broken in 6 days,with a weight loss rate of 76%.The weight loss rate of absorbent cotton pretreatment for 7 days is 85%.The pretreatment of 20 mesh corn stalk powder with composite bacteria has the best methanogenesis effect.The degradation rate of hemicellulose is 35.2%,the degradation rate of cellulose is 23.7%,the degradation rate of lignin is 37.1%.Endonuclease and exonuclease activity reached the highest 0.033 IU/m L and 0.035 IU/m L on the 5th day,β-glucosidase gradually increased and reached the peak 0.032IU/m L on the 7th day,and then began to decrease.Xylanase began to degrade to All showed an upward trend at the end,reaching a peak of 0.045 IU/m L on the9 th day.Manganese peroxidase and lignin peroxidase gradually increased,the highest activity reached 11.47 IU/m L and 7.25 IU/m L on the 5th day,and the laccase showed an upward trend and reached the peak value of 12.52 IU/m L on the 9th day.The methane output of 20 mesh corn stover meal pretreated by the composite bacterial system reached 262.5 m L/g VS,which was 60.6% higher than the unpretreated 20 mesh corn stover meal,and the daily methane production peak was 2 days earlier.Compared with the recognized best gas production size of 40 mesh corn stalk powder,the gas production increased by 49.8%,and the daily methane production peak was 2 days earlier.Compared with the granular corn stover pretreated by Phanerochaete chrysosporium,the methanogenesis increased by 48.4%.Compared with Na OH pretreatment,methane production increased by 96.6%.Microbial flora analysis: by restrictive cultivation conditions and continuous transgenerational and filtering to obtain a set of effective decomposition of corn stalk compound bacteria system,using high-throughput sequencing technology of compound bacteria degrade system samples the bacteria were analyzed,and found that the deformation bacteria Proteobacteria and thick wall bacteria door Firmicutes is a compound bacteria levels on predominant groups of bacteria.At the subordinate level,Pseudomonas and Sphingomonas were the dominant species.Sphingomonas is a new microbial resource that can be used for the biodegradation of aromatic compounds including cellulose materials.All the phyla and genera detected by the compound bacterial lines can secrete cellulase and have the ability of lignocellulosic degradation.