Applied Microbiology: Open Access
Open Access
ISSN: 2471-9315
+44 1300 500008
ISSN: 2471-9315
+44 1300 500008
Sofia Esquivel-Elizondo
Arizona State University, USA
Posters & Accepted Abstracts: Appli Micro Open Access
Fermentation of CO or syngas (CO with H2 and/or CO2) can lead to the production of commodity chemicals, including acetate and ethanol. Research has focused on enhancing syngas-conversion by pure cultures to ethanol. However, since syngas composition depends on the feedstock gasified, different substrates, such as CO:CO2, CO:H2 and CO:CO2:H2, have been used in various studies. Despite increased ethanol/acetate ratios achieved with these different syngas mixtures, the effect of CO2 and H2 in the metabolism of carboxidotrophs is not understood. This research focused on understanding how CO, CO2 and/or H2 affect the microbial community structure and function. Two carboxidotrophs (SVCO-15 and SVCO-16) were isolated after long-term enrichment of sludge with CO at increasing partial pressure (PCO). Fermentation of CO, CO:H0, CO:CO2, and CO:CO2:H2 by the CO-enrichment culture and the isolates was tested. Increasing PCO enriched for Clostridiales. CO2 and H2 influenced the microbial community structure in the CO-enrichment culture at different stages of CO-fermentation (lag, exponential or stationary phase), but did not affect its overall function or CO-consumption rates. Based on Phylogeny, SVCO-15 is 99% similar to Acetobacterium wieringae, and SVCO-16 is a new species within Pleomorphomonas. Contrary to the mixed-culture, syngas mixtures affected function of the isolates. SVCO-15 produced mainly ethanol from CO and CO:H2, while acetate was the main product in the presence of CO2. CO-conversion by SVCO- 16 produced H2:CO2 and was inhibited by external CO2/H2. Pure cultures are important for fundamental studies. However, mixedcultures are promising in large-scale syngas applications because of their flexibility and functional redundancy.
Email: svesquiv@asu.edu