AUTHOR=He Lian , Wang Yaya , You Le , Khin Yadana , Tang Joseph K.-H. , Tang Yinjie J. 

TITLE=Glycine Cleavage Powers Photoheterotrophic Growth of Chloroflexus aurantiacus in the Absence of H2

JOURNAL=Frontiers in Microbiology

VOLUME=Volume 6 - 2015

YEAR=2015

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2015.01467

DOI=10.3389/fmicb.2015.01467

ISSN=1664-302X

ABSTRACT=Chloroflexus aurantiacus is an anoxygenic phototrophic bacterium. Its unique CO2 fixation pathway and primitive light-harvesting antenna complexes have attracted extensive research attentions. In this work, we investigated the photoheterotrophic growth of C. aurantiacus J-10-fl using acetate (at 55 oC and without H2(g)). The results indicate that glycine can promote anaerobic biomass production in a minimal medium by 3~5 folds. Via 13C-metabolite analysis, we observed that glycine was involved in serine synthesis. Instead of being used as a major carbon source, glycine was degraded to produce C1 units and NAD(P)H. Tracer experiments also suggest that photoheterotrophic cultures growing with a exogenous glycine source exhibited capabilities of assimilating CO2 via multiple routes (including the 3-hydroxypropionate pathway). Finally, glycylglycine, a commonly used culture buffer, could also release glycine via thermal or enzymatic degradation to significantly enhance photoheterotrophic growth of C. aurantiacus.