Isolation and cultivation of methanogenic archaea from serpentinization system at Chimaera Seeps, Turkey

Abstract: A methanogenic archaeon was successfully isolated from iron-rich environmental samples from the Chimaera seeps in Turkey by cultivation in anoxic media supplemented with H2/CO2 and an antibiotic, namely erythromycin. The morphological features of this methanogen were non-motile rod cells approximately 1.7 – 8.5 μm in length and 0.3 – 0.4 μm in width and occurred most frequently as singular cells or aggregated in small clusters but were also observed in filamentous structure. The morphology corresponds with the species Methanobacterium oryzae found in rice fields in Philippines. Moreover, based on 16S rRNA gene sequence, this isolate in earlier studies showed 98.6 % sequence similarity to this M. Oryzae species. In similarity to this species, the obtained isolate from this study showed the ability to utilise H2 as electron donor and CO2 as carbon source to produce CH4, which also simulates the energy resources at the onshore low-temperature serpentinization system at the Chimaera seeps in Turkey. Hence, this study proposes that the Chimaera site can hosts hydrogenotrophic methanogens and provides with a biotic influx of CH4 and not only abiotically produced CH4. Besides, this study also suggests that there might exist a correlation between iron-rich sites and the isolated methanogen.