Aerobic MTBE biodegradation in the presence of BTEX by two consortia under batch and semi-batch conditions

Abstract

This study explores the effect of microbial consortium composition and reactor configuration on methyl tert-butyl ether (MTBE) biodegradation in the presence of benzene, toluene, ethylbenzene and p-xylenes(BTEX). MTBE biodegradation was monitored in the presence and absence of BTEX in duplicate batch reactors inoculated with distinct enrichment cultures: MTBE only (MO-originally enriched on MTBE) and/or MTBE BTEX (MB-originally enriched on MTBE and BTEX). The MO culture was also applied in a semi-batch reactor which received both MTBE and BTEX periodically in fresh medium after allowing cells to settle. The composition of the microbial consortia was explored using a combination of 16S rRNA gene cloning and quantitative polymerase chain reaction targeting the known MTBE-degrading strain PM1T. MTBE biodegradation was completely inhibited by BTEX in the batch reactors inoculated with the MB culture, and severely retarded in those inoculated with the MO culture (0.18+/-0.04 mg/L-day). In the semi-batch reactor, however, the MTBE biodegradation rate in the presence of BTEX was almost three times as high as in the batch reactors (0.48+/-0.2 mg/L-day), but still slower than MTBE biodegradation in the absence of BTEX in the MO-inoculated batch reactors (1.47+/-0.47 mg/L-day). A long lag phase in MTBE biodegradation was observed in batch reactors inoculated with the MB culture (20 days), but the ultimate rate was comparable to the MO culture (0.95+/-0.44 mg/L-day). Analysis of the cultures revealed that strain PM1T concentrations were lower in cultures that successfully biodegraded MTBE in the presence of BTEX. Also, other MTBE degraders, such as Leptothrix sp. and Hydrogenophaga sp. were found in these cultures. These results demonstrate that MTBE bioremediation in the presence of BTEX is feasible, and that culture composition and reactor configuration are key factors.

Degradation of a Mixture of Hydrocarbons, Gasoline, and Diesel Oil Additives by Rhodococcus aetherivorans and Rhodococcus wratislaviensis

“…The presence of the eth genes in the Rhodococcus strains with fuel ether degradation capacities that are cited above was not detected with R. wratislaviensis IFP 2016. The simultaneous presences of BTEXs and MTBE had a negative impact on the MTBE degradation rate (nearly fivefold lower) as previously reported (12,27,40,47), whereas no negative effect was shown on strain UC1, a strain closely related to the well-known Methylibium petroleiphilum PM1 (39). The negative effect of the presence of BTEXs on MTBE biodegradation has consequences for the environmental fate of MTBE in contaminated aquifers.…”

Role of Microorganisms in Permeable Reactive Bio-Barriers (PRBBs) for Environmental Clean-Up: A Review

“…Hydrocarbons have been widely degraded by a variety of microorganisms in both conditions whether aerobic or anaerobic having different electron acceptors (Kleinsteuber et al, 2012;Hyman, 2013). Hydrogenophaga flava ENV735 was identified to degrade both TBA and MTBE in pure culture as well as enriched both in bioreactors and in microcosms (Raynal and Pruden, 2008;Bastida et al, 2010). It has observed by many researchers that Hydrogenophaga was able to degrade PAH with a mixture of toluene and benzene as a carbon source and BTEX contaminated groundwater as a source of innoculum (Aburto andPeimbert, 2011, Martin et al, 2012).…”

Effect of benzene and ethylbenzene on the transcription of methyl-tert-butyl ether degradation genes of Methylibium petroleiphilum PM1

“…The effect of BTEX compounds on MTBE biodegradation rates has been evaluated in several studies with varying results (Deeb & Alvarez-Cohen, 2000;Deeb et al, 2001;Lee & Cho, 2009;Lin et al, 2007;Pruden et al, 2001Pruden et al, , 2003Pruden & Suidan, 2004;Raynal & Pruden, 2008;Sedran et al, 2002). MTBE degradation in Pseudomonas aeruginosa was inhibited in the presence of BTEX compounds (Lin et al, 2007).…”

“…MTBE degradation in Pseudomonas aeruginosa was inhibited in the presence of BTEX compounds (Lin et al, 2007). In a bioreactor study with a mixed culture consortium enriched on either MTBE or benzene prior to inoculation, MTBE degradation was significantly negatively impacted in the presence of all four BTEX compounds, and the microbial community composition of this consortium associated with MTBE degradation was significantly different in the presence versus absence of BTEX (Raynal & Pruden, 2008). At a field site where the activity of aquifer microorganisms was stimulated using oxygen release compounds, MTBE degradation occurred only after a significant reduction in BTEX concentrations (Koenigsberg et al, 1999).…”