One-pot fermentation of agricultural residues to produce butanol and hydrogen by Clostridium strain BOH3

Abstract

a b s t r a c tSolventogenic Clostridium strains usually do not ferment lignocellulosic biomass directly due to insufficient expression of hydrolyzing enzymes. In this study, we show that a solventogenic Clostridium strain BOH3 is able to produce both butanol and hydrogen when it ferments mixtures of agricultural residues and oil cakes. In particular, fermentation of mixed rice bran and sesame oil cake gives the highest butanol and hydrogen concentrations. In an optimized agro-residual medium (OAM) containing 94.5 g/l of rice bran and 36.7 g/l of sesame oil cake, BOH3 produces 13.50 ± 0.12 g/l of butanol and 4.41 ± 0.04 l/l of hydrogen after 7 days. Because BOH3 excretes hydrolyzing enzymes such as cellulase (0.52 ± 0.08 U/ml), xylanase (4.10 ± 0.05 U/ml) and amylase (2.05 ± 0.12 U/ml) during fermentation, BOH3 is able to perform fermentation and saccharification simultaneously when rice bran and sesame oil cakes are used as substrates. This is the first report showing that direct fermentation of agricultural residues by using solventogenic Clostridia is possible.

Improvement of Biohydrogen Production from Dark Fermentation by Cocultures and Activated Carbon Immobilization

“…Previously many researches focused on pure culture fermentation, because the feedstock was consumed by only a single microbe without extra loss. − Nevertheless, plenty of disadvantages of pure culture fermentation could be observed. First, the degradation of macromolecular substrates requires a series of enzymes.…”

High level of 1,3‐propanediol production from crude glycerol by Clostridium strain BOH3: critical roles of inoculum and substrate concentration

“…Specific components were identified in the samples based on the increase in peak areas. For quantitative analysis of these products, standard curves were obtained by running known concentrations (0.25–25 g L −1 ) of standard solutions using the same method 51,52 …”

“…The GC was equipped with an RT®‐Msieve 5A (Restek, Bellefonte, PA, USA) porous layer open tubular column (30 m × 0.53 mm × 50 μm) with a thermal conductivity detector (TCD). Pure N 2 was used as the carrier gas at a flow rate of 8 mL min −1 , and the operational temperature of the column oven, injector module, and detector were set at 30 °C, 200 °C and 250 °C, respectively 45,51,52 . Finally, hydrogen (H 2 ) production (mL L −1 ) was calculated using the formula stated below 11 : …”

“…For quantitative analysis of these products, standard curves were obtained by running known concentrations (0.25-25 g L −1 ) of standard solutions using the same method. 51,52 Analysis of gaseous products: Using air-tight syringes, the gaseous samples were carefully drawn from the headspace of serum bottles as well as from the exit-gas outlet of the bioreactor. These gaseous samples were injected into a GC to estimate the percentage of hydrogen in the sample injected.…”

“…Pure N 2 was used as the carrier gas at a flow rate of 8 mL min −1 , and the operational temperature of the column oven, injector module, and detector were set at 30 °C, 200 °C and 250 °C, respectively. 45,51,52 Finally, hydrogen (H 2 ) production (mL L −1 ) was calculated using the formula stated below 11 :…”