Applied and Environmental Microbiology vol:79 issue:15 pages:4534-4542
It was examined whether biofilm growth on dissolved organic matter (DOM) of a three-species consortium whose members synergistically degrade the phenylurea herbicide linuron, affected the consortium’s integrity and subsequent linuron-degrading functionality. Citrate as a model DOM as well as three environmental DOM (eDOM) of different quality were used. Biofilms developed with all DOM formulations and the three species were retained in the biofilm. However, biofilm biomass, species composition, architecture and co-localization of member strains depended on DOM and its biodegradability. To assess the linuron-degrading functionality, biofilms were subsequently irrigated with linuron at 10 mg L-1 or 100 µg L-1. Instant linuron degradation, the time needed to attain maximal linuron degradation and hence the total amount of linuron removed depended on both the DOM used for growth and the linuron concentration. At 10 mg L-1, final linuron degradation efficiency was as high as previously observed without DOM except for biofilms fed with humic acids which did not degrade linuron. At 100 µg L-1 linuron, DOM grown biofilms degraded linuron less efficient than without DOM. The amount of linuron removed was more correlated with biofilm species composition than with biomass or structure. Based on visual observations, co-localization of consortium members in biofilms after the DOM feed appears essential for instant linuron-degrading activity and might explain the differences in overall linuron degradation. The data show that DOM quality determines biofilm structure and composition of the pesticide-degrading consortium in periods with DOM as main C-source and can affect subsequent pesticide-degrading activity; especially at micropollutant concentrations.