Screening And Identification Of Polythene Degrading Bacteria From The Larval Gut Of Galleria Mellonella L.

Insects have the ecological function of decomposers in the forest ecosystem.Tenebrio molitor,Plodia interpunctella and Galleria mellonella are widespread in forest ecosystem,and they are important decomposers in forest ecosystem.Insect gut microbes play an important role in insect digestion of food substances and resistance to biological and abiotic stress.Insect gut microbes play an important role in the digestion of food,resistance to biotic and abiotic stresses.In recent years,the research on the degradation of plastics by intestinal microorganisms of the larva of the G.mellonella provides a new way for the biological treatment of agricultural wastes which are difficult to degrade.This study mainly carried out the research work from the following aspects:1.The optimal egg density for mass rearing and harvesting of Carposina sasakii was studied by the age-stage,two-sex life table.An analysis method of age-stage,twosex life table of insect mass rearing and harvesting system including uncertain factors was designed to guide the artificial feeding of the G.mellonella.Inoculate 20 eggs in445cm3 feed.According to the analysis of the life table data,the development cycle of the G.mellonella was obviously shortened,and the fecundity(F=1868.4)was relatively high.Therefore,the mass rearing system based on the density gradient experiment of the Carposina sasakii could guide the mass rearing of the G.mellonella.2.Polyethylene(PE)was used as the sole carbon source to screen the intestinal microorganisms of the healthy larvae of the G.mellonella,and a mixed group of bacteria which can degrade polyethylene was screened.The surface of PE film was observed by scanning electron microscopy(SEM)and atomic force microscopy(AFM).It was found that the surface of PE film formed a bacterial film,which became rough and concave at the same time,indicating that the mixed bacterial group had degradation effect on PE material.The results of 16 Sr DNA identification and microbial diversity identification of polythene degradation bacteria showed that Acinetobacter sp.,Thermus sp.,Cupriavidus sp.and Escherichia-Shigella were the dominant species in the mixed bacteria.3.The plastic degrading enzyme PETase was mutated in combination and expressed in Pichia pastoris,the mutant PETase-sl(S238F/L88F)had the best degradation effect on bis(2-hydroxyethyl)terephthalate(BHET).