초록
<P><B>Abstract</B></P> <P>In this study, an active photoheterotrophic growth of purple non-sulfur bacteria (PNSB) on Tris Acetate Phosphate Yeast extract (TAPY) medium is reported. TAPY medium is a modified TAP medium supplemented with filter sterilized yeast extract (0.3 g L<SUP>−1</SUP>) and vitamin B12. Heterotrophic growth of PNSB on nitrogen replete TAPY medium in dark could be obtained but much slower than that in light where cells could grow but without formation of pigments. The medium showed high potency for hydrogen production under nitrogen deprivation in light by <I>Rhodobacter sphaeroides</I> DSM 5864. Through using TAPY medium, 1 mole of acetate provided as glacial acetic acid produced 0.819 mole of hydrogen gas by <I>R. sphaeroides</I> on nitrogen deprived TAPY medium (initial pH 7 adjusted by HCl) with a maximum H<SUB>2</SUB> production rate of (0.669 mmol H<SUB>2</SUB> h<SUP>−1</SUP> L<SUP>−1</SUP>) obtained at 42 h after start of fermentation. Repeated-batch hydrogen production could be achieved with high efficiency for three cycles by supplementing the nitrogen deprived culture with filter sterilized sodium acetate at the end of the log hydrogen production phase of each cycle. The medium was also applicable for photoheterotrophic growth in light and heterotrophic growth in dark of other PNSB namely <I>Rhodobacter capsulatus</I> JCM-21090 and <I>Rhodospirillum rubrum</I> DSM 467. Although <I>R. rubrum</I> could actively grow on TAPY medium under nitrogen deprivation in light, it was the lowest in hydrogen production compared to <I>R. sphaeroides</I> and <I>R. capsulatus</I>. The active growth of <I>R. rubrum</I> on nitrogen deprived TAPY medium suggests its possible use for producing biodegradable plastic polymers better than hydrogen. The results suggest that it's possible to use TAPY medium for growth and producing variable bioproducts by PNSB in future studies and applications. The repeated-batch hydrogen production by <I>R. sphaeroides</I> on nitrogen deprived TAPY medium is promising for large-scale applications of hydrogen production industry by only sequential supply with sodium acetate to the culture for three rounds of batch fermentation. This is the first report in using TAPY medium for growth and hydrogen production by PNSB.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Tris-Acetate-Phosphate-Yeast-extract (TAPY) medium was modified from TAP medium. </LI> <LI> Purple non-sulfur bacteria (PNSB) actively grow photoheterotrophically on TAPY. </LI> <LI> N<SUB>2</SUB>-deprived TAPY medium used efficiently for H<SUB>2</SUB> production in light by <I>Rhodobacter.</I> </LI> <LI> <I>Rhodobacter sphaeroides</I> showed highest H<SUB>2</SUB> yield from TAPY compared to other PNSB. </LI> <LI> Repeated-batch H<SUB>2</SUB> production by <I>R. sphaeroides</I> could be efficiently achieved. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Photograph of <I>Rhodospirillum rubrum</I> DSM 467 (A), <I>Rhodobacter sphaeroides</I> DSM 5864 (B) and <I>Rhodobacter capsulatus</I> JCM-21090 (C) grown on nitrogen replete TAPY medium.</P> <P>[DISPLAY OMISSION]</P>