School of Ecology & Environment, Hainan Tropical Ocean University, Sanya, Hainan, China.
School of Marine Science & Technology, Zhejiang Ocean University, Zhoushan, Zhejiang, China.
PLoS One. 2021 Nov 18;16(11):e0256013. doi: 10.1371/journal.pone.0256013. eCollection 2021.
Ruditapes philippinarum conglutination mud (RPM) is a typical waste by-product from manila clam R. philippinarum aquaculture. However, RPM from the clam at an aquaculture farm in Zhoushan, China, has been newly reported as a promising natural bioflocculant resource that contains effective flocculating polysaccharides from the clam associated bacteria. With an intent to figure out whether RPM flocculation activity is ubiquitous to the manila clam across a wide geographical range or only the Zhoushan location, and to explore the flocculation production basis and ultimately widen its exploitation scope, in this study, an extensive survey of RPMs from four representative locations along the coast of China was performed to determine their flocculation activity, polysaccharide constitution and bacterial community composition. Frozen preserved RPM samples from Zhoushan, Dalian, Weihai and Zhanjiang exhibited comparable flocculation activities (FRs) ranging from 61.9±2.4% to 73.2±0.9% at dosage of 8 g·L-1; while fresh RPMs from Zhoushan exhibited a much higher flocculation activity of 91.34±1.18% than its frozen counterpart. Polysaccharide extracts from the four locations showed similar monosaccharide constitutions to some extent. The geographical distribution led to certain variation in bacterial community structures. The similarity clustering of the polysaccharide compositions coincided with that of bacterial community structures from RPMs, suggesting that polysaccharides and respective bacterial communities might be the foundation of the flocculation activity for all RPMs. The overlapping OTUs across all the RPMs accounted for 44.6-62.22% of the overall sequences in each sample and contained the vast majority of the most abundant OTUs (Operational Taxonomic Units), forming a common "core microbiome" that is probably responsible for polysaccharide production and flocculation activity development.
菲律宾蛤仔粘连泥（RPM）是一种典型的菲律宾蛤仔（Ruditapes philippinarum）养殖副产物。然而，中国舟山养殖农场的蛤仔粘连泥最近被报道为一种有前途的天然生物絮凝剂资源，其中含有来自蛤仔相关细菌的有效絮凝多糖。为了确定 RPM 絮凝活性是否在广泛的地理范围内普遍存在于菲律宾蛤仔中，或者只是在舟山地区存在，以及探索絮凝生产基础，并最终扩大其开发范围，本研究对中国沿海四个代表性地区的 RPM 进行了广泛调查，以确定其絮凝活性、多糖组成和细菌群落组成。舟山、大连、威海和湛江冷冻保存的 RPM 样品在 8 g·L-1剂量下表现出相当的絮凝活性（FR），范围为 61.9±2.4%至 73.2±0.9%；而舟山新鲜的 RPM 表现出更高的絮凝活性，为 91.34±1.18%。四个地点的多糖提取物在某种程度上具有相似的单糖组成。地理位置导致细菌群落结构存在一定的变化。多糖组成的相似聚类与 RPM 中细菌群落结构的聚类相吻合，表明多糖和相应的细菌群落可能是所有 RPM 絮凝活性的基础。所有 RPM 之间重叠的 OTUs 占每个样品总序列的 44.6-62.22%，并包含绝大多数最丰富的 OTUs（操作分类单元），形成一个共同的“核心微生物组”，可能负责多糖的产生和絮凝活性的发展。
