Significance of diatom-derived polymers in carbon flow dynamics within estuarine biofilms determined through isotopic enrichment
Significance of diatom-derived polymers in carbon flow dynamics within estuarine biofilms determined through isotopic enrichment
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DOI：
10.3354/ame01287
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发表时间：
2009-01-01
影响因子：
1.4
通讯作者：
Gretz, M. R.
中科院分区：
文献类型：
--
作者：
Bellinger, B. J.;Underwood, G. J. C.;Gretz, M. R.
羽纹硅藻是泥质潮间带沉积物表面瞬时微生物生物膜的主要初级生产者。这些微藻产生大量的胞外聚合物（EPS），这对生物膜中观察到的内聚特性有显著贡献。碳水化合物的含量和组成的变化和持久性的硅藻EPS表现出脉冲追逐（NaHCO 3）-C-13标记和同位素富集的多糖和磷脂脂肪酸（PLFA）在科尔恩河口，英国，生物膜超过48小时的时间内同时检测。葡聚糖的显著同位素富集表明，大部分固定碳最初被隔离到细胞内的金藻胺聚糖中，并且标记碳也被迅速用于硅藻PLFA 20：5 omega 3和EPS的生产。EPS组分中的磷脂酰亚胺迅速富集，随后在4 h内通过异养利用EPS标记不同的细菌PLFA。硅藻和革兰氏阴性细菌PLFA和热水和热碳酸氢盐可溶性EPS组分的最大同位素富集发生在4小时后，在整个研究期间，革兰氏阳性细菌PLFA中的C-13标记增加。48小时后，PLFA仍然高度标记相对于生物膜衍生的多糖，表明持久性的生物膜内的生物体中的同化C通过时间和快速营业额的多糖池内的生物膜。耦合脉冲追踪同位素标记和同步跟踪的C-13在多糖和PLFA直接证明了生物膜自养和异养细菌之间的碳流和在这种交换的意义的生物膜衍生的碳水化合物。
Pennate diatoms are the main group of primary producers in transient microbial biofilms at the sediment surface in muddy intertidal systems. These microalgae produce a substantial quantity of extracellular polymeric substances (EPS) that contribute significantly to the cohesive properties observed in biofilms. Changes in carbohydrate content and composition and the persistence of diatom EPS were demonstrated with pulse-chase (NaHCO3)-C-13 labeling and simultaneous detection of isotopic enrichment in polysaccharides and phospholipid fatty acids (PLFAs) in Colne Estuary, UK, biofilms over a 48 h period. Significant isotopic enrichment of glucan indicated that a large proportion of fixed carbon was initially sequestered into intracellular chrysolaminaran, and labeled carbon was also quickly used for production of the diatom PLFA 20:5 omega 3 and EPS. Saccharides in the EPS fractions were enriched rapidly, followed by labeling of distinct bacterial PLFAs through heterotrophic utilization of EPS within 4 h. Maximal isotopic enrichment of diatom and Gram-negative bacterial PLFAs and hot water- and hot bicarbonate-soluble EPS fractions occurred after 4 h, and C-13-labeling increased in Gram-positive bacterial PLFAs throughout the study period. After 48 h, PLFAs remained highly labeled relative to diatom-derived polysaccharides, indicating persistence of assimilated C in organisms within the biofilms through time and rapid turnover of polysaccharide pools within the biofilms. Coupled pulse-chase isotopic labeling and simultaneous tracking of C-13 in polysaccharides and PLFAs directly demonstrated the flow of carbon between biofilm autotrophs and heterotrophic bacteria and the significance of diatom-derived carbohydrates in this exchange.