Growth of hydrogenotrophic methanogen Methanoculleus bourgensis MAB1 in the presence of dunite.

Abstract

This study investigated the long-term potential of low-temperature serpentinization of dunite to support the growth of the hydrogenotrophic methanogen Methanoculleus bourgensis strain MAB1. Incubation experiments were conducted for over 800 days, using dunite powder as the sole energy source, with and without the addition of nickel, an essential cofactor for methanogenesis. The results indicated that hydrogen released from dunite was sufficient to sustain methanogen growth, but the process was slow, with methane production beginning only after approximately 300 days. The release of toxic metals from dunite, particularly zinc, appeared to inhibit methanogen growth over time, leading to the cessation of methane production after 528 days and likely the lysing of the methanogenic cells. The study suggests that hydrogen availability, rather than nickel, is the limiting factor for methanogen growth in these conditions.