Max Planck Institute for Marine Microbiology, Celsiusstraße 1, 28359, Bremen, Germany.
DOE Joint Genome Institute, 2800 Mitchell Drive, Walnut Creek, CA, 94598, USA.
ISME J. 2019 Nov;13(11):2800-2816. doi: 10.1038/s41396-019-0476-y. Epub 2019 Jul 17.
We investigated Bacteroidetes during spring algae blooms in the southern North Sea in 2010-2012 using a time series of 38 deeply sequenced metagenomes. Initial partitioning yielded 6455 bins, from which we extracted 3101 metagenome-assembled genomes (MAGs) including 1286 Bacteroidetes MAGs covering ~120 mostly uncultivated species. We identified 13 dominant, recurrent Bacteroidetes clades carrying a restricted set of conserved polysaccharide utilization loci (PULs) that likely mediate the bulk of bacteroidetal algal polysaccharide degradation. The majority of PULs were predicted to target the diatom storage polysaccharide laminarin, alpha-glucans, alpha-mannose-rich substrates, and sulfated xylans. Metaproteomics at 14 selected points in time revealed expression of SusC-like proteins from PULs targeting all of these substrates. Analyses of abundant key players and their PUL repertoires over time furthermore suggested that fewer and simpler polysaccharides dominated early bloom stages, and that more complex polysaccharides became available as blooms progressed.
我们在 2010 年至 2012 年期间调查了 2010 年至 2012 年期间在北海南部春季藻类大量繁殖期间的拟杆菌门，使用了 38 个深度测序的宏基因组的时间序列。初始分区产生了 6455 个箱，从中我们提取了 3101 个宏基因组组装基因组（MAG），其中包括 1286 个拟杆菌门 MAG，涵盖了大约 120 个主要未培养的物种。我们鉴定了 13 个优势、反复出现的拟杆菌门类群，它们携带一套有限的保守多糖利用基因座（PULs），这些 PULs可能介导了拟杆菌门藻类多糖的大部分降解。大多数 PULs 被预测靶向硅藻储存多糖褐藻淀粉、α-葡聚糖、富含α-甘露糖的底物和硫酸化木聚糖。在 14 个选定时间点的宏蛋白质组学揭示了针对所有这些底物的 PUL 靶向的 SusC 样蛋白的表达。对丰富的关键参与者及其 PUL 谱随时间的分析进一步表明，早期繁殖阶段的多糖种类较少且较简单，随着繁殖的进行，更多的多糖变得可用。
