Characterization of novel hydrocarbon-degrading <i>Gordonia paraffinivorans</i> and <i>Gordonia sihwensis</i> strains isolated from composting

Hydrocarbons are important environmental pollutants, and the isolation and characterization of new microorganisms with the ability to degrade these compounds are important for effective biodegradation. In this work we isolated and characterized several bacterial isolates from compost, a substrate rich in microbial diversity. The isolates were obtained from selective culture medium containing n-hexadecane, aiming to recover alkane-degraders. Six isolates identified as Gordonia by MALDI-TOF and 16S rRNA sequencing had the ability to degrade n-hexadecane in three days. Two isolates were selected for genomic and functional characterization, Gordonia paraffinivorans (MTZ052) and Gordonia sihwensis (MTZ096). The CG-MS results showed distinct n-hexadecane degradation rates for MTZ052 and MTZ096 (86% and 100% respectively). The genome sequence showed that MTZ052 encodes only one alkane degrading gene cluster, the CYP153 system, while MTZ096 harbors both the Alkane Hydroxylase (AH) and the CYP153 systems. qPCR showed that both gene clusters are induced by the presence of n-hexadecane in the growth medium, suggesting that G. paraffinivorans and G. sihwensis use these systems for degradation. Altogether, our results indicate that these Gordonia isolates have a good potential for biotransformation of hydrocarbons.烃类是重要的环境污染物，分离并鉴定具备降解这类化合物能力的新型微生物，对于实现高效生物降解具有关键意义。本研究从微生物多样性丰富的堆肥基质中分离并鉴定了多株细菌菌株。本次分离所用的选择性培养基以正十六烷为唯一碳源，旨在筛选烷烃降解菌。经基质辅助激光解吸电离飞行时间质谱（MALDI-TOF）及16S核糖体RNA（16S rRNA）测序鉴定，其中6株属于戈登氏菌属（Gordonia），且可在3天内降解正十六烷。本研究选取其中两株进行基因组与功能表征，分别为嗜石蜡戈登氏菌（Gordonia paraffinivorans，MTZ052）及锡霍特戈登氏菌（Gordonia sihwensis，MTZ096）。气相色谱-质谱联用（CG-MS）检测结果显示，MTZ052与MTZ096的正十六烷降解率存在显著差异，分别为86%与100%。基因组测序结果表明，MTZ052仅携带1个烷烃降解基因簇——CYP153系统；而MTZ096则同时拥有烷烃羟化酶（Alkane Hydroxylase，AH）与CYP153两套系统。实时定量聚合酶链反应（qPCR）结果显示，两套基因簇的表达均受培养基中正十六烷的诱导，表明嗜石蜡戈登氏菌与锡霍特戈登氏菌正是通过这些系统实现烷烃降解。综上，本研究结果表明，这些戈登氏菌属菌株具备良好的烃类生物转化应用潜力。