Biofilms formed on humic substances: Response to flow conditions and carbon concentrations

Abstract

Stream biofilms are exposed to dynamic conditions of flow velocity and organic carbon availability. Thus, the aim of this study was to investigate the response of biofilms formed with and without humic substances (HSs) to an increase in flow velocity (0.04-0.10 ms(-1)) and HSs concentration (9.7+/-1.0 to 19.8+/-0.4 mgL(-1) C). The highest amount of biofilm, measured as volatile suspended solids and total countable cells, was observed at 0.10 m s(-1) without HSs. The bacterial community composition of the biofilm with HSs was characterized by sequences with high similarities (> or =97%) to the genus Dokdonella and to the genera Comamonas, Cupriavidus and, Ralstonia. Sequences retrieved from the biofilm without HSs presented high similarities (> or =97%) to the genus Sphingomonas and the genus Nitrosospira. Experimental results suggested that the presence of HSs under different concentrations and flow velocities did not significantly enhance the cell density of biofilms but influenced its microbial composition.

Response of heterotrophic stream biofilm ­communities to a gradient of resources

“…Additionally, aquatic microbial communities have known sens i tivities to varying carbon substrates. In stream biofilms, the abundance of cells from the domain bacteria and several phyla, sub-phyla, and species, shifted in response to the additions of glucose and to seasonal changes in available DOM (Olapade & Leff 2005, and the composition of the community changed rapidly in response to inoculation with a variety of simple and complex DOM substrates (Wu et al 2009, Rodrigues et al 2010. These studies also found that leaf leachate stimulated or suppressed various mem bers of the microbial community, indicating differential utilization of the potential DOM pools (Olapade & Leff 2005.…”

A flat microbial fuel cell for decentralized wastewater valorization: process performance and optimization potential

“…The diversity of the anode community was assessed by denaturing gradient gel electrophoresis (DGGE), as described by Rodrigues et al [36] Approximately 2 mL of a well-homogenized biofilm sample was frozen at the time of sampling and stored at −20 • C. Total genomic DNA was extracted using an UltraClean ™ Soil DNA Isolation Kit (MO BIO, Carlsbad, CA, USA) according to the protocol supplied by the manufacturer.…”

Influence of tetracycline on the microbial community composition and activity of nitrifying biofilms

“…Polymerase chain reactions (PCR) were conducted in a 50 lL reaction mixture according to Rodrigues et al (2010). For analysis of the total bacterial community by denaturing gradient gel electrophoresis (DGGE), a single round PCR was performed using the primers 338f and 518r, targeting the V3 region of the bacterial 16S rRNA gene (Supplementary Material (SM), Table SM-1).…”

“…DGGE analyzes of the PCR products were done as previously described (Rodrigues et al, 2010). Denaturant gradient from 30% to 60% was used.…”