Sack Eveline L W, van der Wielen Paul W J J, van der Kooij Dick
KWR Watercycle Research Institute, Nieuwegein, The Netherlands.
Appl Environ Microbiol. 2014 Apr;80(8):2360-71. doi: 10.1128/AEM.04105-13. Epub 2014 Jan 31.
Biopolymers are important substrates for heterotrophic bacteria in (ultra)oligotrophic freshwater environments, but information about their utilization at microgram-per-liter levels by attached freshwater bacteria is lacking. This study aimed at characterizing biopolymer utilization in drinking-water-related biofilms by exposing such biofilms to added carbohydrates or proteins at 10 μg C liter(-1) in flowing tap water for up to 3 months. Individually added amylopectin was not utilized by the biofilms, whereas laminarin, gelatin, and caseinate were. Amylopectin was utilized during steady-state biofilm growth with simultaneously added maltose but not with simultaneously added acetate. Biofilm formation rates (BFR) at 10 μg C liter(-1) per substrate were ranked as follows, from lowest to highest: blank or amylopectin (≤6 pg ATP cm(-2) day(-1)), gelatin or caseinate, laminarin, maltose, acetate alone or acetate plus amylopectin, and maltose plus amylopectin (980 pg ATP cm(-2) day(-1)). Terminal restriction fragment length polymorphism (T-RFLP) and 16S rRNA gene sequence analyses revealed that the predominant maltose-utilizing bacteria also dominated subsequent amylopectin utilization, indicating catabolic repression and (extracellular) enzyme induction. The accelerated BFR with amylopectin in the presence of maltose probably resulted from efficient amylopectin binding to and hydrolysis by inductive enzymes attached to the bacterial cells. Cytophagia, Flavobacteriia, Gammaproteobacteria, and Sphingobacteriia grew during polysaccharide addition, and Alpha-, Beta-, and Gammaproteobacteria, Cytophagia, Flavobacteriia, and Sphingobacteriia grew during protein addition. The succession of bacterial populations in the biofilms coincided with the decrease in the specific growth rate during biofilm formation. Biopolymers can clearly promote biofilm formation at microgram-per-liter levels in drinking water distribution systems and, depending on their concentrations, might impair the biological stability of distributed drinking water.
生物聚合物是（超）贫营养淡水环境中异养细菌的重要底物，但关于附着在淡水细菌上的每升微克水平生物聚合物利用情况的信息尚缺。本研究旨在通过在流动自来水中将与饮用水相关的生物膜暴露于添加量为10 μg C升⁻¹的碳水化合物或蛋白质中长达3个月，来表征生物聚合物的利用情况。单独添加的支链淀粉未被生物膜利用，而海带多糖、明胶和酪蛋白酸盐则被利用。在稳态生物膜生长期间，支链淀粉在同时添加麦芽糖时被利用，但在同时添加乙酸盐时未被利用。每种底物在10 μg C升⁻¹时的生物膜形成速率（BFR）从低到高排序如下：空白或支链淀粉（≤6 pg ATP cm⁻² 天⁻¹）、明胶或酪蛋白酸盐、海带多糖、麦芽糖、单独的乙酸盐或乙酸盐加支链淀粉，以及麦芽糖加支链淀粉（980 pg ATP cm⁻² 天⁻¹）。末端限制性片段长度多态性（T-RFLP）和16S rRNA基因序列分析表明，主要利用麦芽糖的细菌在随后的支链淀粉利用中也占主导地位，表明存在分解代谢阻遏和（细胞外）酶诱导。在麦芽糖存在下支链淀粉加速的BFR可能是由于支链淀粉与附着在细菌细胞上起诱导作用的酶有效结合并被其水解所致。在添加多糖期间，噬细胞菌纲、黄杆菌纲、γ-变形菌纲和鞘脂杆菌纲生长，在添加蛋白质期间，α-、β-和γ-变形菌纲、噬细胞菌纲、黄杆菌纲和鞘脂杆菌纲生长。生物膜中细菌种群的演替与生物膜形成过程中比生长速率的降低相一致。生物聚合物能够在饮用水分配系统中以每升微克水平明显促进生物膜形成，并且根据其浓度，可能会损害分配的饮用水的生物稳定性。
