(470e) Butanol and Hydrogen Production From Xylan By Clostridium Sp. BOH3: Simultaneous Saccharification and Fermentation

Title

Butanol
and hydrogen production from xylan by Clostridium sp. BOH3: simultaneous saccharification and fermentation

Abstract

Butanol
and hydrogen are recognized as fossil-fuel alternatives. They can be
simultaneously produced from anaerobic fermentation of simple sugars. Recently,
a new strain Clostridium sp. BOH3 was
observed to produce butanol and hydrogen from xylan.
While the most of solventogenic Clostridia spp. require simple fermentable sugars such as glucose
for the production of butanol, sp. BOH3 utilizes xylan (10 g/l) effectively because of its high level xylanase expression. In the present study, a medium is
designed for the production of xylanase, butanol and hydrogen using response surface methodology. The
medium is composed of two major components, xylan as
carbon source and ammonium sulphate as nitrogen source. With the help of
central composite design, the direct and interactive effects of xylan and ammonium sulphate on xylanase, butanol and hydrogen
production were analysed. The optimized medium, which supports maximum
production of xylanase, butanol
and hydrogen, contained 49.4 g/l of xylan and 19.8
g/l of ammonium sulphate. It supports the production of 6.1 U/ml of xylanase, 7.6 g/l of butanol and
16.2 ml/l.h of hydrogen. Apparently, simultaneous saccharification and fermentation (SSF) of xylan by using BOH3 is possible, thanks to the expression
of xylanse by BOH3. To improve this SSF process,
xylanase produced by BOH3 was purified by using one-step Q-anion column
chromatography and supplemented into the next batch. Every attempt of
purification yields 43±1.5% of enzyme, and its supplementation to the next
batch results the xylanase activity of 2.5±0.1 U/ml
at the beginning of fermentation. Due to this addition of xylanase,
production of butanol and hydrogen is increased to
16.05±0.5 g/l and 28.3±0.8 ml/l.h respectively. The butanol and hydrogen yields are increased to 0.33±0.01 g/g
and 0.58±0.008 ml/l.h/g respectively. These results suggest
that improved SSF process enhances the butanol and
hydrogen yield about 2 fold. This approach would also facilitate the effective
recycling of potential enzyme produced in the fermentation process.