Bioremediation of aniline aerofloat wastewater at extreme conditions using a novel isolate Burkholderia sp. WX-6 immobilized on biochar.

Aniline aerofloat (AAF) is a refractory organic pollutant in floatation wastewater. Little information is currently available on its biodegradation. In this study, a novel AAF-degrading strain named Burkholderia sp. WX-6 was isolated from mining sludge. The strain could degrade more than 80% of AAF at different initial concentrations (100-1000 mg/L) within 72 h. AAF degrading curves were fitted well with the four-parameter logistic model (R2 >0.97), with the degrading half-life ranging from 16.39 to 35.55 h. This strain harbors metabolic pathway for complete degradation of AAF and is resistant to salt, alkali, and heavy metals. Immobilization of the strain on biochar enhanced both tolerance to extreme conditions and AAF removal, with up to 88% of AAF removal rate in simulated wastewater under alkaline (pH 9.5) or heavy metal pollution condition. In addition, the biochar-immobilized bacteria removed 59.4% of COD in the wastewater containing AAF and mixed metal ions within 144 h, significantly (P < 0.05) higher than those by free bacteria (42.6%) and biochar (48.2%) only. This work is helpful to understand AAF biodegradation mechanism and provides viable references for developing practical biotreatment technique of mining wastewater.

[Microbial community structure analyzed by single-strand conformation polymorphism technique in sulfate-reducing reactor].

Analyses of microbial community structure and the relationships between Sulfate-Reducing Bacteria (SRBs) and Acidogenic Bacteria (ABs) in a completely stirred sulfate-reducing reactor were carried out by modified polymerase chain reaction-single-stranded conformation polymorphism (PCR-SSCP) targeted eubacterial 16S ribosomal RNA gene. A total of 13 bands were obtained and 6 of them (A1, A3, A4, A5, A9, A10) were sequenced. The sequences are similar to Leuconostoc mesenteroides (GenBank Access No. AY453065), some uncultured bacteria (AJ318147, AF227834, AJ576427), Ethanologenbacterium (AY434722), Clostridiaceae (AB084627), etc. In order to investigate the SRBs in the reactor,the active sludge was cultured on SRB-selected media and also did SSCP with the compound cultured bacteria. Two new bands appeared, one similar to Bacteroidetes (AB074606) and another similar to Desulfovibrio (Y12254, U42221). The experimental results indicate that the proportion of SRBs in the reactor is probably less than 1.5 percent. But the few SRBs play a very important role during the course of sulfate reduction via cooperation with acidogenic