Polysaccharides and Proteins Added to Flowing Drinking Water at Microgram-per-Liter Levels Promote the Formation of Biofilms Predominated by Bacteroidetes and Proteobacteria

Abstract

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 g 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 g 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.

Biofilm Composition and Threshold Concentration for Growth of Legionella pneumophila on Surfaces Exposed to Flowing Warm Tap Water without Disinfectant

“…Cloning and sequencing of the 16S rRNA gene insert (ca. 650 bp) for identification of the predominating uncultured bacteria were performed as described previously (49). Counts of colonies with identical appearances on R 2 A agar were recorded as percentages of the total colony count.…”

“…Counts of colonies with identical appearances on R 2 A agar were recorded as percentages of the total colony count. Bacteria from predominating colonies were isolated, and the 16S rRNA genes of the isolates were amplified by PCR using primers 8f and 1392r (Biolegio, the Netherlands) (49). Fragments of approximately 1,030 bp were sequenced by using primer 8f.…”

“…The ATP concentrations (a measure of active biomass) of the suspension and the feed water were measured using a bioluminescence assay as described elsewhere (48). Membrane filtration (0.22-m pore size) followed by the application of a FastDNA Spin kit for soil (MP Biomedicals) was used for the isolation of the DNAs of the microorganisms in the biofilm suspension as described previously (49). The concentrations of V. vermiformis and Acanthamoeba spp.…”

Isolation and Complete Genome Sequence of Algibacter alginolytica sp. nov., a Novel Seaweed-Degrading Bacteroidetes Bacterium with Diverse Putative Polysaccharide Utilization Loci

“…They have been found in various marine habitats, including coastal sediments (3), coastal waters (4, 5), hydrothermal vents (6, 7), and open ocean waters (8-10). In previous studies, marine Bacteroidetes have been reported as important contributors to the utilization of biopolymers such as polysaccharides and proteins (2,(11)(12)(13)(14). As a result, marine Bacteroidetes are assumed to play an important role in the degradation of algae.…”

The effect of light intensity and shear stress on microbial biostabilization and the community composition of natural biofilms

“…Besides the complex competition for nitrogen and phosphorus between diatoms and bacteria, the amount of available organic carbon apparently strongly affects the entire biofilm food web. 81 Recent studies have given insights into highly specialized EPS utilization by bacteria 82 and discovered a strong regulatory role of these EPSs produced by diatoms upon bacterial development and activity. 83 In the context of nutrient limitation, the morphology of the microbes can be a decisive factor.…”