荧光定量PCR解析酸性条件下丙酸氧化菌的演替

The succession of propionate-oxidizing bacteria at acidic conditions was analyzed by RT-PCR

采用实时荧光定量PCR技术考察了UASB酸性条件下丙酸氧化菌的演替规律.结果表明,至少有3种已鉴定的丙酸氧化菌(Pelotomaculum schinkii,P.propionicum和Smithella propionica)存在于UASB反应器中.在p H值为7.5~7.1时,P.schinkii是主要的丙酸氧化菌群,其数量为(5.0~5.8)×10~3 16SrRNA基因拷贝数/ngDNA,约占检测到丙酸氧化菌总数的90.6%以上.pH从7.1降到6.8导致S.propionica数量显著增加,P.schinkii和S.propionica成为优势菌群,其数量占丙酸氧化菌总数的88.9%.在pH6.5条件下,S.propionica(74.8%)成为优势丙酸氧化菌群.当p H￡6.0时,S.propionica和P.propionicum演替为优势丙酸氧化菌,表明这两种丙酸氧化菌具有较强的耐酸性.当p H￡6.0时,丙酸氧化菌总数随pH降低而明显减少,这可能是厌氧反应器在酸性条件下发生丙酸积累的根本原因之一.

Succession of propionate-oxidizing bacteria at acidic conditions was investigated in an upflow anaerobic sludge bed（UASB） reactor by quantitative real-time fluorescence polymerase chain reaction（q PCR）. The results showed that at least three identified species of propionate-oxidizing bacteria（Pelotomaculum schinkii, P. propionicum, and Smithella propionica） existed in the UASB system. P. schinkii was dominated at p H7.5~7.1 and its quantity was（5.0~5.8）×10~3 16SrDNA copies per ng DNA, accounting for above 90.6% of the total detectable propionate-oxidizing bacteria. p H decreased from 7.1 to 6.8 resulted in S. propionica was significantly increased. P. schinkii and S. propionica became dominant propionate-oxidizing bacteria and occupied 88.9%. S. propionica accounted for 74.8% in total detectable propionate-oxidizing bacteria at p H 6.5, whereas S. propionica and P. propionicum succeed to dominant propionate-oxidizing bacteria at pH≤6.0, indicating that S. propionica and P. propionicum were more acid resistant. In addition, the total number of propionate-oxidizing bacteria was gradually reduced at p H≤6.0. It might be one of the reasons for propionate accumulation at acidic conditions in anaerobic reactors.