黄粉虫（Tenebrio molitor）肠道中聚乳酸塑料降解菌的筛选及其降解特性

聚乳酸（polylactic acid,PLA）材料是一种环境友好型的可降解塑料,在堆肥或高温条件下可以快速生物降解,但在自然条件下降解缓慢,产生大量的微塑料。本研究拟从黄粉虫肠道中筛选具有降解聚乳酸能力的微生物,鉴定降解菌的种类及测定降解菌的降解特性。采用PLA粉末为唯一食物喂养黄粉虫60 d,将其肠道提取液接种在以PLA为唯一碳源的固体培养基上进行富集、筛选及纯化降解菌。结合菌种形态观察、扫描电镜分析的方法和ITS序列序列信息构建系统进化树确定降解菌的分类;将筛选菌接入添加不同营养条件下的PLA液体发酵培养基,测定其降解效能。结果筛选出11株具有降解PLA塑料潜力的菌株,其中一株鉴定为真菌毛栓孔菌（Trametes hirsuta）FJ001菌株,接种在含有1.0%葡萄糖的PLA薄膜无机盐液体培养基中连续培养30 d,降解率可达20.1%。研究表明,黄粉虫肠道存在对PLA塑料有一定降解性的真菌,为降解聚乳酸材料微生物资源的开发提供了理论依据。

Isolation and identification of polylactic acid degrading microorganisms from mealworm（Tenebrio molitor）gut

Polylactic acid (PLA) is biodegraded rapidly under composting or thermophilic temperature but slowly under natural conditions with substantial microplastics generated. In this study, microorganisms with the ability to degrade PLA were screened from the gut of mealworm, and the degrading bacteria were identified and the degradation characteristics were determined. Mealworms was fed with PLA powder as the only food for 60 days, and the gut extract of mealworms was inoculated on the solid medium with PLA as the sole carbon source to enrich, screen and isolate PLA-degrading microorganisms. Isolated strains were identified through morphological, physiological and biochemical properties as well as ITS gene sequences analysis, the phylogenic tree was constructed to identify the taxonomic status of the strains. The screened bacteria were added to the PLA liquid fermentation medium under different nutrient conditions to determine their degradation efficiency. The results showed that 11 strains with PLA degradation potential were screened from the mealworms gut. A PLA-degrading strain (FJ001) was initially identified as the fungus Trametes hirsuta. After inoculating FJ001 in PLA thin film inorganic salt liquid medium containing 1.0% glucose for 30 days, the PLA degradation rate could reach 20.1%. In conclusion, Trametes hirsuta FJ001 was isolated from mealworms with capable of degrading PLA plastics effectively. The results suggested that strains which can degrade PLA plastics could be isolated from mealworms gut. The result showed that there were fungi that can degrade PLA in the gut of mealworm, which provided a theoretical basis for the development of microbial resources for degrading polylactic acid materials.