[Screening, Identification, and Performance of Microplastic-degrading Functional Bacteria in Saline-alkali Soil Environment].

The combined effects of salinization and microplastic pollution will have a detrimental impact on soil fertility and the ecological integrity of soil ecosystems. Three strains of salt-resistant microplastic-degrading functional bacteria were obtained from the soil of the Hetao irrigation area, which served as a source of inoculum. The strains were identified using metagenomics and were found to belong to the genera Agrobacterium, Aspergillus fumigatus, and Streptomyces. The strains were designated Agrobacterium_salinitolerans strain （A）, Aspergillus fumigatus strain （F）, and Streptomyces sudanensis strain （S）, respectively. The degradation of polyethylene （PE） and polyethylene terephthalate （PET） by single and mixed bacteria was compared using the weight loss rate of microplastics as a constraint. The findings revealed that the weight loss rates of PE and PET under the combined conditions of the three strains of functional bacteria were 21.900% and 23.800% at 60 d, which was significantly better than that of single bacteria and the mixture of two strains. Based on the growth process of functional bacteria, the characteristics of key enzyme genes, and the changes of surface morphology and functional groups during the degradation of PE and PET, the mechanism of PE and PET being degraded after long-chain depolymerization, β oxidation cycle, and tricarboxylic acid cycle under the action of mixed functional bacteria was revealed. These findings provide a theoretical basis and technical support for the control of microplastic pollution in salinized soil.