Use of<i> Mycobacterium austroafricanum</i> IFP 2012 in a MTBE-Degrading Bioreactor

Abstract

Mycobacterium austroafricanum IFP 2012 is able to slowly grow on methyl tert-butyl ether (MTBE), a fuel oxygenate widely used as a gasoline additive. The potential of M. austroafricanum IFP 2012 for aerobic MTBE degradation was investigated in the presence of a secondary carbon source, isopropanol. The strain was then tested for MTBE biodegradation at the laboratory-scale in a fixed-bed reactor using perlite as the matrix, and isopropanol was injected once a week to maintain M. austroafricanum IFP 2012 biomass inside the perlite bed. The biofilter was operated for 85 days at an influent flow rate of 20 ml/h by varying the MTBE concentration from 10 to 20 mg/l. The hydraulic retention time was fixed at 5 days. The removal of MTBE depended on the inlet MTBE concentration and a MTBE removal efficiency higher than 99% was obtained for MTBE concentrations up to 15 mg/l. A set of 16S rRNA gene primers specific for M. austroafricanum species was used to analyze the DNA extracted from the biofilter effluent in order to detect the presence of M. austroafricanum IFP 2012 and to estimate the effect of periodic injections of isopropanol on the release of the strain from the perlite bed. The results demonstrated that the injection of isopropanol served to maintain an active MTBE degrading biomass in the biofilter and that this system could be used to effectively treat MTBE contaminated groundwater.

Biodegradation of Methyl Tertiary Butyl Ether (MTBE) by a Microbial Consortium in a Continuous Up-Flow Packed-Bed Biofilm Reactor: Kinetic Study, Metabolite Identification and Toxicity Bioassays

“…In addition, Acuna-Askar et al [22] reported estimated volumetric MTBE removal rates of 5.35, 8.25 and 15.68 mg L -1 h -1 at volumetric MTBE loading rates of 6.09, 9.83 and 25 mg L -1 h -1 , respectively. Similarly, estimated volumetric MTBE removal rates of 1 mg L -1 h -1 and 0.124 mg L -1 h -1 at volumetric loading rates of 2 mg L -1 h -1 and 0.125 mg L -1 h -1 were reported by Waul et al [20] and Maciel et al [55], respectively.…”

“…in an up-flow, fixed-bed reactor operating at a HRT of 5 h. A microbial consortium was capable of removing 50% of approximately 160 mg MTBE L -1 in an up-flow, packed-bed reactor running at a HRT of 80 h [20]. Likewise, Mycobacterium austroafricanum IFP 2012 exhibited an MTBE removal efficiency higher than 99% in a fixed-bed reactor fed with a solution containing 15 mg MTBE L -1 and at an HRT of 120 h [55]. …”

Physiology of Mycobacteria

“…Mycobacteria also have possible industrial appplications. M. austroafricanuum is able to metabolize methyl tert-butyl ether which is often added to gasoline and could be used to treat contaminated ground water (Maciel et al ., 2008). …”

Biological and chemical analyses of a laboratory-scale biofilter for oxygenate bioremediation in simulated groundwater

“…Reactors that use biofilms can maintain high biomass concentrations and are meant to be more resistant to external environmental changes (Bryers and Characklis 1989;Wilson et al 1999); however, high biomass concentrations were not observed at the end of the experimental period. Co-metabolism such as alcohol injections observed in the work of Maciel et al (2008), or of alkanes, could help the microbial community grow better, leading to a higher MTBE removal rate. The use of an MTBE adsorption material described by Baus and Brauch (2007) for a packed biofilter such as the one described in this study may also favor microbial attachment and growth, as well as removing high levels of MTBE from the liquid flow.…”