Changes in glucose fermentation pathways by an enriched bacterial culture in response to regulated dissolved H2 concentrations. Issue 6 (18th April 2015)

• Record Type: Journal Article
• Authors: Zheng, Hang; Zeng, Raymond J.; Duke, Mikel C.; O'Sullivan, Cathryn A.; Clarke, William P.
• Is Part Of: Biotechnology and bioengineering. Volume 112:Issue 6(2015:Jun.)
• Page Start: 1177
• Page End: 1186
• Publication Date: 2015-04-18
• Subjects: Biotechnology -- Periodicals; Bioengineering -- Periodicals; 660.6
• DOI: 10.1002/bit.25525
• Languages: English
• ISSNs: 0006-3592

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>ABSTRACT</title> <sec id="bit25525-sec-0001" sec-type="section"> <p>It is well established that metabolic pathways in the fermentation of organic waste are primarily controlled by dissolved H<sub>2</sub> concentrations, but there is no reported study that compares observed and predicted shifts in fermentation pathways induced by manipulating the dissolved H<sub>2</sub> concentration. A perfusion system is presented that was developed to control dissolved H<sub>2</sub> concentrations in the continuous fermentation of glucose by a culture highly enriched towards <italic>Thermoanaerobacterium thermosaccharolyticum</italic> (86 ± 9% relative abundance) from an originally diverse consortia in the leachate of a laboratory digester fed with municipal solid waste. Media from a 2.5 L CSTR was drawn through sintered steel membrane filters to retain biomass, allowing vigorous sparging in a separate chamber without cellular disruption. Through a combination of sparging and variations in glucose feeding rate from 0.8 to 0.2 g/L/d, a range of steady state fermentations were performed with dissolved H<sub>2</sub> concentrations as low as an equivalent equilibrated H<sub>2</sub> partial pressure of 3 kPa. Trends in product formation rates were simulated using a H<sub>2</sub> regulation partitioning model. The model correctly predicted the direction of products redistribution in response to H<sub>2</sub> concentration changes and the acetate and butyrate formation rates when H<sub>2</sub> concentrations were less than 6 kPa. However, the model over‐estimated acetate, ethanol and butanol productions at the expense of butyrate production at higher H<sub>2</sub> concentrations. The H<sub>2</sub> yield at the lowest dissolved H<sub>2</sub> concentration was 2.67 ± 0.08 mol H<sub>2</sub>/mol glucose, over 300% higher than the yield achieved in a CSTR operated without sparging. Biotechnol. Bioeng. 2015;112: 1177–1186. © 2014 Wiley Periodicals, Inc.</p> </sec> </abstract>