Construction Of Microbial Degradation Conortium And Study On Degradation Characteristics Of Marine Polyethylene Plastics

We have now entered the plastic era,and plastic pollution poses a certain threat to marine ecosystems,but plastic waste disposal is another headache challenge.Biological methods can be applied as an environmentally friendly method for plastic waste removal and plastic waste recycling,but the current degradation efficiency of a single strain of bacteria is still too low.In this study,polyethylene plastic was selected as a representative,and an attempt was made to obtain microbial strains with high degradation activity that can be used to degrade plastic(microplastics)through targeted domestication,with the aim of providing technical support for the biological method to treat marine microplastic pollution.In addition,potentially efficient degradation bacteria were successfully isolated from the microbial line with high degradation activity.The degradation characteristics of the microbiota and the potentially efficient degrading bacteria were also investigated by using loss-in-weight method,scanning electron microscopy and Fourier transform infrared,and the main results of this study are as follows:(1)The differences in microbial community composition among the passaged cultures W1,W2 and W3 were not significant,and the top10 species at the phylum level,top10species at the order level and top20 species at the genus level were consistent,and the dominant species were similar,and the microbial community could reach the stability period in the medium with PE film as the only carbon source for 7 days,and a microbiota that could passaged stably for 7 days was obtained.(2)The rate of film degradation of the above microbiota was 2.0±0.15 g/d·m~3in 30 days,and the rate of degradation was above 1.9±0.15 g/d·m~3for each generation in 6 consecutive incubations,with obvious holes and bumps appearing on the surface of PE film,and Fourier infrared spectroscopy indicated that the unstable polar functional groups were introduced into the chemical structure of PE after the action of microbial colonies(C-O stretching,-C=C-,-OH).Based on the above results,the microbiota were screened to obtain a microbial consortium that can stably degrade PE film within 30 days after 7 days of stable transmission.(3)From the above-mentioned microbiota,36 single strains were isolated and screened to grow in the medium with polyethylene as the only carbon source.The 36 strains of degradation bacteria were measured by weight loss method,and four strains with good degradation effect were selected for characterization of degradation characteristics.Based on the above results,four strains of Roseibium aggregatum MY02,Marinobacter salinexigens MY04,Zhouia amylolytica MY12 and Alcanivorax dieselolei MY15 were obtained.(4)The degradation characteristics of the four highly efficient degradation strains MY02,MY04,MY12 and MY15 were studied.Within 30 days,the degradation efficiency of MY02 reached 1.3±0.12 g/d·m~3,MY04 reached 1.1±0.12 g/d·m~3,MY12 reached 0.98±0.09g/d·m~3,MY15 reached 1.1±0.08 g/d·m~3,folds,furrows and holes appeared on the surface of PE film,and FTIR The results indicated that unstable polar functional groups(COO-,C-O,C-O-C,C=O,-OH)were introduced into the chemical structure of polyethylene after the action of microbial flora.