Thermophilic Methanotrophs From Kamchatka - Promising Biotechnological Tool For High-Temperature Processes

Abstract

Clone library analysis targeting to eubacterial 16S rRNA gene revealed that this culture was mainly consisted of fermentation bacteria such as Trichococcus sp. and Bacteroides sp.. Desulfitobacterium sp. known as facultative dechlorinator was also detected. Clone library analysis targeting to only 16S rRNA gene of Dehalococcoides sp. showed that almost all sequences in the library belong to Pinellas subgroup. Only Methanosarcina sp. was detected in clone library analysis targeting to archaeal 16S rRNA gene. From sequencing data of PCR products using specific primer for dehalogenase genes, this culture contains three dehalogenase genes, tceA, vcrA, and bvcA showing 99% similarity to those previously reported sequences. Copy number of these three genes in this consortium at different cultivation conditionswas analyzed by using real-time PCR. For example, in the culture of different initial cis-DCE concentration, these three typesofDehalococcoides sp. behaved independently and obvious differencewas observed. Generally, it is reported that each of these three genes may distribute in different types of Dehalococcoides sp. until now. So, our results agree with those reports. At low initial concentration of cis-DCE condition, copy number of all three dehalogenase genes was increased. But at comparatively high concentration of cis-DCE condition, only tceA was increased. This different distribution of these dehalogenase genes obviously affected dechlorination rate of VC. From this result, it is thought that distribution of these three types of Dehalococcoides sp. show great sensitivity to small changes of surrounding environments. Therefore, when we monitor bioremediation process, we should take into account not only increase of Dehalococcoides sp. but also these dehalogenase gene distribution profile to prospect complete dehalogenation.