UMR 6250 CNRS - ULR LIENSs, UFR Sciences, Bâtiment Marie Curie, Université de La Rochelle, Avenue Michel Crépeau, 17042, La Rochelle, France.
Microb Ecol. 2012 Jan;63(1):157-69. doi: 10.1007/s00248-011-9959-8. Epub 2011 Oct 15.
The main goal of this work was to study the dynamics and biochemical composition of extracellular polysaccharides (ECPS), a fraction of the extracellular polymeric substances (EPS) produced during the development of a microphytobenthic biofilm in a European intertidal mudflat (Marennes-Oléron Bay, France) during winter. Microphytobenthic biomass was surveyed during four consecutive emersion periods to confirm the biofilm growth. Bacteria abundance was also checked considering the importance of heterotrophic bacteria observed by various authors in the dynamics of EPS. Various colorimetric assays, coupled to biochemical chromatographic analysis, were used to characterize the three main fractions of extracted EPS: colloidal, bound, and residual. The monosaccharide distribution of colloidal ECPS highlighted their role of carbon source for bacteria (>50% of glucose) even if no increase of colloidal carbohydrate amounts was observed during the tidal exposure. Bound ECPS were composed of deoxy or specific sugars (30% rhamnose) and uronic acids (18% galacturonic acid). Their levels and dynamics could be correlated to the development of the microphytobenthic biofilm, enhancing the stabilization of the sediment or increasing binding forces accordingly. Residual fractions, containing refractory bound ECPS and other internal polymeric substances, were composed of various carbohydrates. The high ratio of glucose in these fractions (18% to 43%) was interesting, as it was once attributed to colloidal sugars due to poor extraction procedures. Finally, the presence of inositol (15%) was significant since no author has highlighted it before, knowing that inositol is a major growth factor for heterotrophic bacteria.
本研究的主要目的是研究冬季法国马朗恩-奥雷隆湾（Marennes-Oléron Bay）潮间带泥滩上微藻生物膜发育过程中胞外多糖（ECPS）的动态变化和生化组成，ECPS 是胞外聚合物物质（EPS）的一个组成部分。在连续四个暴露期内对微藻生物量进行了调查，以确认生物膜的生长。还检查了细菌丰度，因为许多作者观察到 EPS 动态中异养细菌的重要性。采用各种比色分析方法，结合生化色谱分析，对提取的 EPS 的三个主要部分（胶体、结合和残留）进行了表征。胶体 ECPS 的单糖分布突出了其作为细菌碳源的作用（>50%为葡萄糖），即使在潮汐暴露期间胶体碳水化合物的含量没有增加。结合 ECPS 由脱氧糖或特定糖（30%鼠李糖）和糖醛酸（18%半乳糖醛酸）组成。它们的水平和动态变化可以与微藻生物膜的发育相关联，从而增强沉积物的稳定性或相应地增加结合力。含有难降解结合 ECPS 和其他内部聚合物物质的残留部分由各种碳水化合物组成。这些部分中葡萄糖的高比例（18%至 43%）很有趣，因为之前由于提取程序不完善，它曾被归因于胶体糖。最后，肌醇（15%）的存在很重要，因为以前没有作者强调过这一点，而肌醇是异养细菌的主要生长因子。
