Aerobic degradation of methyl tert-butyl ether by a Proteobacteria strain in a closed culture system

Comparative analysis of bacterial diversity in two hot springs in Hefei, China

Hot springs are extreme ecological environments of microbes. The study is the first comparative analysis of bacterial diversity of Tangchi and Bantang hot spring water samples collected in Hefei, China, which is conducive to the further development and utilization of microbial resources in hot springs. Illumina MiSeq system was utilized to sequence and analyze the bacterial 16S rRNA gene from hot spring water samples by bioinformatics, to probe into the bacterial abundance and diversity of two hot springs in Hefei. Results revealed that prevalent bacterial phyla in Tangchi hot spring were Bacillota and Aquificota, and the prevalent bacterial genus was Hydrogenobacter; prevalent phyla in Bantang hot spring were Pseudomonadota followed by Actinobacteriota, and prevalent genera were CL500-29_marine_group and Polynucleobacter. More species and higher evenness in Bantang hot spring than those in Tangchi hot spring. In MetaCyc pathway analysis, the major pathways of metabolism existed in the bacteria from the two hot springs were 'pyruvate fermentation to isobutanol (engineered)', 'acetylene degradation', 'carbon fixation pathways in prokaryotes', 'nitrate reduction I (denitrification)', 'methanogenesis from acetate', 'superpathway of glucose and xylose degradation', etc.

Interaction of tetrahydrofuran and methyl tert-butyl ether in waste gas treatment by a biotrickling filter bioaugmented with Piscinibacter caeni MQ-18 and Pseudomonas oleovorans DT4

Bioaugmented biotrickling filter (BTF) seeded with Piscinibacter caeni MQ-18, Pseudomonas oleovorans DT4, and activated sludge was established to investigate the treatment performance and biodegradation kinetics of the gaseous mixtures of tetrahydrofuran (THF) and methyl tert-butyl ether (MTBE). Experimental results showed an enhanced startup performance with a startup period of 9 d in bioaugmented BTF (25 d in control BTF seeded with activated sludge). The interaction parameter I_2,1 of control (7.462) and bioaugmented BTF (3.267) obtained by the elimination capacity-sum kinetics with interaction parameter (EC-SKIP) model indicated that THF has a stronger inhibition of MTBE biodegradation in the control BTF than in the bioaugmented BTF. Similarly, the self-inhibition EC-SKIP model quantified the positive effects of MTBE on THF biodegradation, as well as the negative effects of THF on MTBE biodegradation and the self-inhibition of MTBE and THF. Metabolic intermediate analysis, real-time quantitative polymerase chain reaction, biofilm-biomass determination, and high-throughput sequencing revealed the possible mechanism of the enhanced treatment performance and biodegradation interactions of MTBE and THF.

Aerobic degradation of methyl tert-butyl ether in a closed symbiotic system containing a mixed culture of Chlorella ellipsoidea and Methylibium petroleiphilum PM1

The contamination of groundwater by methyl tert-butyl ether (MTBE) is one of the most serious environmental problems around the world. MTBE degradation in a closed algal-bacterial symbiotic system, containing a mixed culture of Methylibium petroleiphilum PM1 and Chlorella ellipsoidea, was investigated. The algal-bacterial symbiotic system showed increased MTBE degradation. The MTBE-degradation rate in the mixed culture (8.808 ± 0.007 mg l(-1) d(-1)) was higher than that in the pure bacterial culture (5.664 ± 0.017 mg l(-1) d(-1)). The level of dissolved oxygen was also higher in the mixed culture than that in the pure bacterial culture. However, the improved efficiency of MTBE degradation was not in proportional to the biomass of the alga. The optimal ratio of initial cell population of bacteria to algae was 100:1. An immobilized culture of mixed bacteria and algae also showed higher MTBE degradation rate than the immobilized pure bacterial culture. A mixed culture with algae and PM1 immobilized separately in different gel beads showed higher degradation rate (8.496 ± 0.636 mg l(-1) d(-1)) than that obtained with algae and PM1 immobilized in the same gel beads (5.424 ± 0.010 mg l(-1) d(-1)).

Degradation of methyl tert-butyl ether by gel immobilized Methylibium petroleiphilum PM1

Cells of Methylibium petroleiphilum PM1 were immobilized in gel beads to degrade methyl tert-butyl ether (MTBE). Calcium alginate, agar, polyacrylamide and polyvinvyl alcohol were screened as suitable immobilization matrices, with calcium alginate demonstrating the fastest MTBE-degradation rate. The rate was accelerated by 1.8-fold when the beads had been treated in physiological saline for 24h at 28 degrees C. MTBE degradation in mineral salts medium (MSM) was accompanied by the increase of biomass. The half-life of MTBE-degradation activity for the encapsulated cells stored at 28 degrees C was about 120 h, which was obviously longer than that of free cells (approximately 36 h). Efficient reusability of the beads up to 30 batches was achieved in poor nutrition solution as compared to only 6 batches in MSM. The immobilized cells could be operated in a packed-bed reactor for degradation of 10 mg L(-1) MTBE in groundwater with more than 99% removal efficiency at hydraulic retention time of 20 min. These results suggested that immobilized cells of PM1 in bioreactor might be applicable to a groundwater treatment system for the removal of MTBE.