BioChem - DOS

Hydrogen production from starch by co-culture of Clostridium acetobutylicum and Rhodobacter sphaeroides in one step hybrid dark- and photofermentation in repeated fed-batch reactor

Bioresource technology : biomass, bioenergy, biowastes, conversion technologies, biotransformations, production technologies

Zagrodnik, R.; Łaniecki, M.

<P><B>Abstract</B></P> <P>Hydrogen production from starch by a co-culture hybrid dark and photofermentation under repeated fed-batch conditions at different organic loading rates (OLR) was studied. Effective cooperation between bacteria in co-culture during initial days was observed at controlled pH 7.0. However, at pH above 6.5 dark fermentation phase was redirected from H<SUB>2</SUB> formation towards production of formic acid, lactic acid and ethanol (which are not coupled with hydrogen production) with simultaneous lower starch removal efficiency. This resulted in decrease in the hydrogen production rate. The highest H<SUB>2</SUB> production in co-culture process (3.23LH<SUB>2</SUB>/L<SUB>medium</SUB> &ndash; after 11days) was achieved at OLR of 1.5g<SUB>starch</SUB>/L/day, and it was twofold higher than for dark fermentation process (1.59LH<SUB>2</SUB>/L<SUB>medium</SUB>). The highest H<SUB>2</SUB> yield in the co-culture (2.62molH<SUB>2</SUB>/mol<SUB>hexose</SUB>) was obtained at the OLR of 0.375g<SUB>starch</SUB>/L/day. Different pH requirements of bacteria were proven to be a key limitation in co-culture system.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Repeated fed-batch co-culture dark and photofermentation from starch was studied. </LI> <LI> pH above 6.5 strongly disfavored H<SUB>2</SUB> formation by dark fermentative bacteria. </LI> <LI> Photo bacteria prefer high acetate/butyrate ratio after dark fermentation process. </LI> <LI> Cooperation between dark and photobacteria at pH 7.0 was suppressed after few days. </LI> <LI> Redirection of dark fermentative metabolism led to low H<SUB>2</SUB> yields in the co-culture. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

2017

Elsevier

0960-8524

224

pp.298-306

10.1016/j.biortech.2016.10.060

http://click.ndsl.kr/servlet/OpenAPIDetailView?keyValue=05787966&target=NART&cn=NART77034323

Biohydrogen; Repeated fed-batch; Starch; Co-culture dark and photofermentation