Carbon source utilization profiles suggest additional metabolic interactions in a synergistic linuron-degrading bacterial consortium

Abstract

A bacterial triple-species consortium that synergistically metabolizes the phenylurea herbicide linuron was studied to determine whether synergy is extended toward the metabolism of other C-sources. The metabolic performance and range of the individual consortium members were compared with those of paired and three-species combinations in Biolog GN2 MicroPlate assays. The strain combinations showed an increase in the rate and extent of utilization of 80% of the C-sources that were utilized by either one or more of the individual consortium members and the additional utilization of eight C-sources for which oxidation was not observed for the individual strains. When one of the three strains was replaced by bacterial strains 'foreign' to the consortium, either belonging to the same genus or to other genera, mainly antagonistic effects occurred. The data suggest that the consortium members cooperate in the metabolism of C-sources in addition to linuron. This feature can contribute in consolidating consortium composition when linuron is absent or present at low concentrations.

Biofilm formation of a bacterial consortium on linuron at micropollutant concentrations in continuous flow chambers and the impact of dissolved organic matter

“…This agrees with a previous study in which the consortium's integrity, for example, the presence of strains WDL7‐Rfp and WDL1, remained when the consortium, after inoculation, was directly grown as a biofilm on DOM/citrate without linuron in the feed (Horemans et al ., ). This is explained by the earlier observation of synergism between consortium members during eDOM degradation (Horemans et al ., ) and single C‐substrates (Horemans et al ., ). Apparently, this multiple substrate synergism ensures integrity of the consortium and especially the balanced occurrence of WDL7‐Rfp and WDL1 in biofilms when linuron is not the major C‐source, for example, at micropollutant concentrations.…”

“…WDL6-Yfp was grown in minimal medium with nitrogen source (MMO) supplemented with 50 mg L À1 kanamycin and 1% methanol as C-source. Media were prepared as previously described (Horemans et al, 2013a). Bacterial cells for biofilm inoculation were harvested in late exponential phase at an OD 660 nm around 0.5-0.7 and washed three times with 10 mM MgSO 4 solution.…”

“…The consortium is therefore an ideal model for exploring micropollutant degradation by consortia in biofilms and for examining effects of environmental conditions such as DOM quality and quantity on micropollutant degradation. Interestingly, the consortium members appear also to interact in the degradation of DOM of environmental origin (eDOM) (Horemans et al, 2013b) of various quality and of various single carbon substrates besides linuron (Horemans et al, 2013a). Such interactions were observed to counteract detrimental effects of auxiliary carbon sources on linuron degradation in continuous biofilms as the integrity of the consortium was ensured (Horemans et al, 2013d).…”

Environmental Dissolved Organic Matter Governs Biofilm Formation and Subsequent Linuron Degradation Activity of a Linuron-Degrading Bacterial Consortium

“…strain WDL1, Hyphomicrobium sulfonivorans WDL6, and Comamonas testosteroni WDL7 synergistically degrade the phenylurea herbicide linuron (4) also shows synergism in the metabolism of various other carbon sources (18) and in the utilization of various environmental DOMs as carbon sources (19) in suspended cultures. It was hypothesized that this trait would contribute in consolidating the consortium's composition in periods where linuron is absent or present at poor concentrations.…”

“…Ϫ1 kanamycin and 1% methanol as the C source. Medium preparation was previously described (18). Bacterial cells were harvested in the late exponential phase at an optical density at 600 nm (OD 660 ) of around 0.5 to 0.7 and washed three times with a 10 mM MgSO 4 solution.…”