Division of Sustainable Energy and Environmental Engineering, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka, 565-0871, Japan.
Biodegradation. 2013 Jun;24(3):343-52. doi: 10.1007/s10532-012-9591-4. Epub 2012 Sep 18.
Plasmid-mediated bioaugmentation was demonstrated using sequencing batch reactors (SBRs) for enhancing 2,4-dichlorophenoxyacetic acid (2,4-D) removal by introducing Cupriavidus necator JMP134 and Escherichia coli HB101 harboring 2,4-D-degrading plasmid pJP4. C. necator JMP134(pJP4) can mineralize and grow on 2,4-D, while E. coli HB101(pJP4) cannot assimilate 2,4-D because it lacks the chromosomal genes to degrade the intermediates. The SBR with C. necator JMP134(pJP4) showed 100 % removal against 200 mg/l of 2,4-D just after its introduction, after which 2,4-D removal dropped to 0 % on day 7 with the decline in viability of the introduced strain. The SBR with E. coli HB101(pJP4) showed low 2,4-D removal, i.e., below 10 %, until day 7. Transconjugant strains of Pseudomonas and Achromobacter isolated on day 7 could not grow on 2,4-D. Both SBRs started removing 2,4-D at 100 % after day 16 with the appearance of 2,4-D-degrading transconjugants belonging to Achromobacter, Burkholderia, Cupriavidus, and Pandoraea. After the influent 2,4-D concentration was increased to 500 mg/l on day 65, the SBR with E. coli HB101(pJP4) maintained stable 2,4-D removal of more than 95 %. Although the SBR with C. necator JMP134(pJP4) showed a temporal depression of 2,4-D removal of 65 % on day 76, almost 100 % removal was achieved thereafter. During this period, transconjugants isolated from both SBRs were mainly Achromobacter with high 2,4-D-degrading capability. In conclusion, plasmid-mediated bioaugmentation can enhance the degradation capability of activated sludge regardless of the survival of introduced strains and their 2,4-D degradation capacity.
利用序列间歇式反应器（SBR）进行质粒介导的生物增强，通过引入铜绿假单胞菌 JMP134 和携带 2,4-二氯苯氧乙酸（2,4-D）降解质粒 pJP4 的大肠杆菌 HB101，来提高 2,4-D 的去除率。铜绿假单胞菌 JMP134(pJP4) 可以矿化和利用 2,4-D 进行生长，而大肠杆菌 HB101(pJP4) 由于缺乏降解中间产物的染色体基因，无法同化 2,4-D。SBR 中引入铜绿假单胞菌 JMP134(pJP4) 后，200mg/L 的 2,4-D 可以在 100%去除，此后引入菌株的存活率下降，2,4-D 的去除率在第 7 天下降到 0%。SBR 中引入大肠杆菌 HB101(pJP4) 后，2,4-D 的去除率较低，即低于 10%，直到第 7 天。第 7 天分离出的假单胞菌和无色杆菌的转导体株无法在 2,4-D 上生长。在第 16 天出现属于无色杆菌属、伯克霍尔德氏菌属、铜绿假单胞菌属和 Pandoraea 的 2,4-D 降解转导体后，两个 SBR 都以 100%的去除率开始去除 2,4-D。在第 65 天将进水 2,4-D 浓度提高到 500mg/L 后，SBR 中引入的大肠杆菌 HB101(pJP4) 仍能稳定去除超过 95%的 2,4-D。虽然 SBR 中引入的铜绿假单胞菌 JMP134(pJP4) 在第 76 天 2,4-D 去除率出现暂时下降 65%，但此后几乎达到 100%的去除率。在此期间，从两个 SBR 中分离出的转导体主要是具有高 2,4-D 降解能力的无色杆菌属。综上所述，质粒介导的生物增强可以提高活性污泥的降解能力，而不受引入菌株的生存能力及其 2,4-D 降解能力的影响。
