Biology Department and Institute of Marine Sciences, College of Science, Guangdong Provincial Key Laboratory of Marine Biotechnology, Shantou University, Shantou, 515063, China.
Biology Department and Institute of Marine Sciences, College of Science, Guangdong Provincial Key Laboratory of Marine Biotechnology, Shantou University, Shantou, 515063, China; Southern Marine Science and Engineering Guangdong Laboratory, Guangzhou, 511458, China.
Environ Res. 2022 Jun;209:112865. doi: 10.1016/j.envres.2022.112865. Epub 2022 Feb 2.
Marine group II euryarchaea (MGII) dominates the planktonic archaeal community in global surface seawater and is associated to particulate organic matters mainly composed of polysaccharides. However, the polysaccharides metabolism of MGII euryarchaea is unclear. In this study, the distribution and polysaccharides metabolism potential of MGII euryarchaea in the estuary were investigated. High-throughput sequencing of 16S rRNA genes showed that MGII euryarchaea was the predominant archaeal group in the Pearl River Estuary (PRE), and the relative abundance of MGII euryarchaea in particle-attached fraction was higher than that in free-living fractions. A total of 19 metagenome-assembled genomes (MAGs) were successfully reconstructed from metagenomic data, of which 10 MAGs were grouped as MGII euryarchaea according to phylogenomic analysis. Genes encoding a variety of carbohydrate-active enzymes (CAZymes) were found in MAGs/genomes of MGII euryarchaea. These CAZymes annotated in MAGs were capable of hydrolyzing many polysaccharides, including α-glucans, β-glucans, xylans, nitrogen-containing polysaccharides, and some insoluble galactans. The results also indicated that MGII euryarchaea has some unique enzymes that can hydrolyze starch, β-1,3-glucans, complex xylans, carrageenan, and agarose. Collectively, our results demonstrated that MGII euryarchaea has great polysaccharides hydrolysis potential and could play an important role in the carbon cycle of marine ecosystem.
海洋群 II 古菌（MGII）在全球表层海水中的浮游古菌群落中占主导地位，与主要由多糖组成的颗粒有机物有关。然而，MGII 古菌的多糖代谢途径尚不清楚。本研究调查了河口区 MGII 古菌的分布和多糖代谢潜力。16S rRNA 基因高通量测序显示，MGII 古菌是珠江口（PRE）的主要古菌群，颗粒结合态 MGII 古菌的相对丰度高于自由态。从宏基因组数据中成功重建了 19 个宏基因组组装基因组（MAG），其中 10 个 MAG 根据系统发育分析被归类为 MGII 古菌。MGII 古菌的 MAG/基因组中发现了多种碳水化合物活性酶（CAZymes）的编码基因。这些在 MAG 中注释的 CAZymes 能够水解多种多糖，包括α-葡聚糖、β-葡聚糖、木聚糖、含氮多糖和一些不溶性半乳糖。结果还表明，MGII 古菌具有一些独特的酶，可以水解淀粉、β-1,3-葡聚糖、复杂木聚糖、角叉菜胶和琼脂糖。总之，我们的研究结果表明，MGII 古菌具有很强的多糖水解潜力，可能在海洋生态系统的碳循环中发挥重要作用。
