Architecture and spatial organization in a triple‐species bacterial biofilm synergistically degrading the phenylurea herbicide linuron

Members of a triple‐species 3‐(3,4‐dichlorophenyl)‐1‐methoxy‐1‐methyl urea (linuron)‐mineralizing consortium, i.e. the linuron‐ and 3,4‐dichloroaniline‐degrading Variovorax sp. WDL1, the 3,4‐dichloroaniline‐degrading Comamonas testosteroni WDL7 and the N,O ‐dimethylhydroxylamine‐degrading Hyphomicrobium sulfonivorans WDL6, were cultivated as mono‐ or multi‐species biofilms in flow cells irrigated with selective or nonselective media, and examined with confocal laser scanning microscopy. In contrast to mono‐species biofilms of Variovorax sp. WDL1, the triple‐species consortium biofilm degraded linuron completely through apparent synergistic interactions. The triple‐species linuron‐fed consortium biofilm displayed a heterogeneous structure with an irregular surface topography that most resembled the topography of linuron‐fed mono‐species WDL1 biofilms, indicating that WDL1 had a dominating influence on the triple‐species biofilm architecture. This architecture was dependent on the carbon source supplied, as the biofilm architecture of WDL1 growing on alternative carbon sources was different from that observed under linuron‐fed conditions. Linuron‐fed triple‐species consortium biofilms consisted of mounds composed of closely associated WDL1, WDL7 and WDL6 cells, while this association was lost when the consortium was grown on a nonselective carbon source. In addition, under linuron‐fed conditions, microcolonies displaying associated growth developed rapidly after inoculation. These observations indicate that the spatial organization in the linuron‐fed consortium biofilm reflected the metabolic interactions within the consortium.