Biofilm polymers: relationship between carbohydrate biopolymers from estuarine mudflats and unialgal cultures of benthic diatoms

Aquatic Microbial Ecology

B. J. Bellinger¹  A. S. Abdullahi M. R. Gretz G. J. C. Underwood¹ 

关键词: Diatoms;    Biofilms;    Microphytobenthos;    EPS;    Monosaccharide distribution;    Uronic acids;    Biopolymers;    Fractionation;   

DOI  :  10.3354/ame038169

学科分类：生物科学（综合）

来源: Inter-Research

【 摘 要 】

ABSTRACT: Benthic microalgae (microphytobenthos) are the dominant group of primary producers in many marine intertidal and subtidal habitats. Estuarine mudflat diatoms are thought to be major contributors of extracellular polymeric substances (EPS), whichare important for sediment stabilization and in benthic food chains. Biofilms from 6 sites in the Colne estuary, UK, were fractionated to isolate biopolymers (colloidal, colloidal EPS [cEPS], low molecular weight [LMW] carbohydrates, hot water [HW] andhot bicarbonate [HB] soluble) and the same techniques were applied to diatoms cultured from these sediments. At sites dominated by benthic diatoms, colloidal carbohydrate concentration and chlorophyll a were closely related. With increasingbiomass, the proportion of cEPS within the colloidal fraction decreased from 60 to 20%. Carbohydrate analysis revealed significant differences in monosaccharide and uronic acid composition of different carbohydrate fractions. Principal component analysis(PCA) of monosaccharide composition of HB polymers from both field and culture samples grouped closely along fucose and rhamnose vectors and formed 2 distinct clusters. HW and LMW fractions grouped along the glucose vector and cEPS polymers along thegalactose and arabinose vectors. These data indicate that the simple relationship between colloidal carbohydrate concentration and microphytobenthic biomass in biofilms masks a high degree of potential complexity within the sediment carbohydrate pool andin the different proportions of polymeric and nonpolymeric material between different biofilms. Comparing monosaccharide composition of extracts generated using the same protocol, natural assemblages showed close relationships with unialgal cultures,confirming the important role of diatom-derived polymers in mudflat ecology.

【 授权许可】

Unknown