초록
<P>Accumulation of carbon dioxide (CO<SUB>2</SUB>), associated with global temperature rise, and drastically decreasing fossil fuels necessitate the development of improved renewable and sustainable energy production processes. A possible route for CO<SUB>2</SUB> recycling is to employ autotrophic and hydrogenotrophic methanogens for CO<SUB>2</SUB>-based biological methane (CH<SUB>4</SUB>) production (CO<SUB>2</SUB>-BMP). In this study, the physiology and productivity of <I>Methanobacterium thermaggregans</I> was investigated in fed-batch cultivation mode. It is shown that <I>M. thermaggregans</I> can be reproducibly adapted to high agitation speeds for an improved CH<SUB>4</SUB> productivity. Moreover, inoculum size, sulfide feeding, pH, and temperature were optimized. Optimization of growth and CH<SUB>4</SUB> productivity revealed that <I>M. thermaggregans</I> is a slightly alkaliphilic and thermophilic methanogen. Hitherto, it was only possible to grow seven autotrophic, hydrogenotrophic methanogenic strains in fed-batch cultivation mode. Here, we show that after a series of optimization and growth improvement attempts another methanogen, <I>M. thermaggregas</I> could be adapted to be grown in fed-batch cultivation mode to cell densities of up to 1.56 g L<SUP>−1</SUP>. Moreover, the CH<SUB>4</SUB> evolution rate (MER) of <I>M. thermaggregans</I> was compared to <I>Methanothermobacter marburgensis</I>, the CO<SUB>2</SUB>-BMP model organism. Under optimized cultivation conditions, a maximum MER of 96.1 ± 10.9 mmol L<SUP>−1</SUP> h<SUP>−1</SUP> was obtained with <I>M. thermaggregans</I>—97% of the maximum MER that was obtained utilizing <I>M. marburgensis</I> in a reference experiment. Therefore, <I>M. thermaggregans</I> can be regarded as a CH<SUB>4</SUB> cell factory highly suited to be applicable for CO<SUB>2</SUB>-BMP.</P><P><B>Electronic supplementary material</B></P><P>The online version of this article (10.1007/s00253-018-9183-2) contains supplementary material, which is available to authorized users.</P>