Functional exploration of novel glycoside hydrolases in Fervidibacter sacchari PD1T

Few aerobic hyperthermophiles degrade polysaccharides. We describe the genome-enabled enrichment and isolation of an aerobic hyperthermophile, Fervidibacter sacchari, which was originally ascribed to candidate phylum Fervidibacteria. F. sacchari uses polysaccharides and monosaccharides as sole carbon sources from 65-87.5 °C, and its genome encodes 117 glycoside hydrolases (GHs) spanning 49 GH families, including 31 homologs of understudied GH109, GH177, and GH179 domains. Here, we analyzed the transcriptomes of F. sacchari cells grown on eight different sole carbon and energy sources (beta-glucan, chondroitin sulfate, corn stover, gellan gum, locust bean gum, starch, xanthan gum, and xyloglucan) to link glycoside hydrolase substrate to function, as well as identify potential regulatory mechanisms. These data will provide preliminary characterization of novel carbohydrate-active enzymes at high temperatures. To investigate differential expression of F. sacchari glycoside hydrolases, we grew, in triplicate, cells in media each containing one of eight different carbon sources (beta-glucan, chondroitin sulfate, corn stover, gellan gum, locust bean gum, starch, xanthan gum, and xyloglucan) to mid-exponential phase. Using RNA-seq, we identify highest expressed transcripts as well as most distinct transcriptomes based on carbon source during growth.

目前可降解多糖的需氧超嗜热菌（aerobic hyperthermophile）较为少见。本研究通过基因组辅助富集与分离技术，获得一株需氧超嗜热菌Fervidibacter sacchari，该菌株最初被归属于候选门费氏杆菌门（Fervidibacteria）。该菌株能够以多糖与单糖作为唯一碳源，生长温度区间为65~87.5℃；其基因组编码117种糖苷水解酶（glycoside hydrolases, GHs），隶属于49个GH家族，其中包含31个尚未被深入研究的GH109、GH177及GH179结构域同源蛋白。本研究针对以8种不同唯一碳源与能源（β-葡聚糖、硫酸软骨素、玉米秸秆、结冷胶、刺槐豆胶、淀粉、黄原胶及木葡聚糖）培养的F. sacchari细胞进行转录组分析，旨在建立糖苷水解酶底物与功能的对应关系，并挖掘潜在的调控机制。本研究所得数据将为高温条件下新型碳水化合物活性酶（carbohydrate-active enzymes）的初步表征提供参考依据。为探究F. sacchari糖苷水解酶的差异表达模式，我们将菌株接种于分别含有上述8种碳源的培养基中，每组设置3次生物学重复，培养至指数生长中期。通过RNA测序（RNA-seq），我们鉴定出表达量最高的转录本，并明确了不同碳源培养下菌株具有显著差异的转录组特征。