Zeng Qi, Jian Lili, Shi Songbiao, Guo Qiaoqiao, Quadri Syed Raziuddin, Long Lijuan, Tian Xinpeng
State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China.
Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China.
Appl Environ Microbiol. 2025 Aug 20;91(8):e0113625. doi: 10.1128/aem.01136-25. Epub 2025 Jul 24.
Mangrove ecosystems are critical for coastal protection and biodiversity but are increasingly threatened by plastic pollution, particularly polyethylene terephthalate (PET). In this study, a novel marine bacterium, strain SCSIO 80796, was isolated from PET debris collected from the mangrove in QiAo Island, Zhuhai, China. Using a polyphasic taxonomic approach, including 16S rRNA gene sequencing, genome-based comparisons (average nucleotide identity [ANI] 72.2%, digital DNA-DNA hybridization [dDDH] 19.0%, average amino acid identity [AAI] 70.6%), and phenotypic and chemotaxonomic analyses, the strain was classified as a novel species within the genus . It is proposed as sp. nov. (type strain SCSIO 80796ᵀ = MCCC 1K08369 = KCTC 92826). Genomic analysis revealed that strain SCSIO 80796ᵀ encodes a novel PET-degrading enzyme, Cut, which degrades PET and yields 105-120 µM of degradation products [terephthalic acid (TPA), mono(2-hydroxyethyl) terephthalate (MHET), bis(2-hydroxyethyl) terephthalate (BHET)] within 48 h at 60°C. Cut exhibits both structural and evolutionary novelty, featuring a unique PET-binding module (PBM) absent in known PETases. PBM is characterized by a long, positively charged α-helix enriched in aromatic residues, forming a distinct substrate-interacting surface with potential as a transferable domain to enhance the efficiency of other plastic-degrading enzymes. This study not only expands the known diversity within but also highlights the potential of marine-derived microbes in addressing plastic pollution through biotechnological applications.IMPORTANCEThe discovery of sp. nov. advances marine microbial ecology by revealing a novel species in the scarcely studied genus , which previously contained only one cultured representative. Isolated from plastic-polluted mangroves, this bacterium exemplifies microbial adaptation to anthropogenic habitats. Its functional uniqueness is underscored by a phylogenetically distinct polyethylene terephthalate (PET)-degrading enzyme (Cut), forming an evolutionary clade separate from all known plastic-degrading enzymes. By integrating taxonomic discovery with functional genomics, this study bridges the gap between microbial diversity and biotechnological potential. The dual novelty of -as a taxonomic addition and a source of evolutionarily unique enzymes-highlights the importance of exploring understudied environments to address global challenges like plastic pollution.
红树林生态系统对海岸保护和生物多样性至关重要，但正日益受到塑料污染的威胁，尤其是聚对苯二甲酸乙二酯（PET）。在本研究中，从中国珠海淇澳岛红树林收集的PET碎片中分离出一种新型海洋细菌，菌株SCSIO 80796。采用多相分类方法，包括16S rRNA基因测序、基于基因组的比较（平均核苷酸同一性[ANI]72.2%、数字DNA-DNA杂交[dDDH]19.0%、平均氨基酸同一性[AAI]70.6%）以及表型和化学分类分析，该菌株被归类为该属内的一个新物种。提议将其命名为 sp. nov.（模式菌株SCSIO 80796ᵀ = MCCC 1K08369 = KCTC 92826）。基因组分析表明，菌株SCSIO 80796ᵀ编码一种新型PET降解酶Cut，该酶在60°C下48小时内可降解PET并产生105 - 120 μM的降解产物[对苯二甲酸（TPA）、单（2 - 羟乙基）对苯二甲酸酯（MHET）、双（2 - 羟乙基）对苯二甲酸酯（BHET）]。Cut在结构和进化上均具有新颖性，具有一个已知PET酶中不存在的独特PET结合模块（PBM）。PBM的特征是富含芳香族残基的长正电荷α - 螺旋，形成一个独特的底物相互作用表面，有可能作为可转移结构域来提高其他塑料降解酶的效率。本研究不仅扩展了该属内已知的多样性，还突出了海洋来源微生物通过生物技术应用解决塑料污染的潜力。重要性 sp. nov.的发现通过揭示在之前仅包含一个培养代表的研究较少的属中的一个新物种，推动了海洋微生物生态学的发展。这种细菌从受塑料污染的红树林中分离出来，体现了微生物对人为栖息地的适应性。其功能独特性通过一种系统发育上独特的聚对苯二甲酸乙二酯（PET）降解酶（Cut）得到强调，该酶形成了一个与所有已知塑料降解酶分开的进化分支。通过将分类学发现与功能基因组学相结合，本研究弥合了微生物多样性与生物技术潜力之间的差距。 作为一种分类学上新增加的物种以及进化上独特的酶的来源，其双重新颖性突出了探索研究不足的环境以应对塑料污染等全球挑战的重要性。
