Degradation of Brominated Organic Compounds (Flame Retardants) by a Four-Strain Consortium Isolated from Contaminated Groundwater

Abstract

Biodegradation of pollutants in the environment is directly affected by microbial communities and pollutant mixture at the site. Lab experiments using bacterial consortia and substrate mixtures are required to increase our understanding of these processes in the environment. One of the deficiencies of working with environmental cultures is the inability to culture and identify the active strains while knowing they are representative of the original environment. In the present study, we tested the aerobic microbial degradation of two brominated flame retardants, tribromo-neopentyl alcohol (TBNPA) and dibromo neopentyl glycol (DBNPG), by an assembled bacterial consortium of four strains. The four strains were isolated and plate-cultured from a consortium enriched from the impacted groundwater underlying the Neot Hovav industrial area (Negev, Israel), in which TBNPA and DBNPG are abundant pollutants. Total degradation (3–7 days) occurred only when the four-strain consortium was incubated together (25 °C; pH −7.2) with an additional carbon source, as both compounds were not utilized as such. Bacterial growth was found to be the limiting factor. A dual carbon–bromine isotope analysis was used to corroborate the claim that the isolated strains were responsible for the degradation in the original enriched consortium, thus ensuring that the isolated four-strain microbial consortium is representative of the actual environmental enrichment.

Keywords

• substrate mixtures
• assembled microbial consortium
• isotopic fractionation
• syntrophy
• simultaneous utilization
• brominated flame retardants