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Title: Carbon monoxide fermentation by Eubacterium limosum KIST612
Author: Chang, I. S.
Awarding Body: University of Wales Swansea
Current Institution: Swansea University
Date of Award: 2000
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Carbon monoxide (CO)-utilising acetogens were enriched and the isolate KIST612 was selected for its abilities to tolerate high CO and acetate concentration. The isolate KIST612 was identified as Eubacterium limosum based on the morphological and biochemical characteristics. E. limosum KIST612 produced acetate and butyrate from CO. The optimum temperature and pH for the growth and organic acids formations were 37°C and 7.0, respectively. This bacterium was cultivated on phosphate-buffered basal medium (PBBM) with CO as the sole energy and carbon source. In a batch fermentation using a serum vial, E. limosum KIST612 grew at the initial growth rate of 0.15-0.16 h-1 with Ks for dissolved CO of 0.14 mM. When sufficient CO was supplied using a bubble column reactor, the maximum growth rate of E. limosum KIST612 was 0.23 h-1. The bacterial growth rate was reduced in the presence of acetate. A membrane reactor was employed to allow cell recycling continuous sparging CO fermentation to organic acid product removal. The reactor system used was a bubble column type reactor, and the overall volumetric CO mass transfer coefficient (kLa) of the reactor was 72 h-1. When the dry cell weight was 5.25 g/L in the reactor, the bacterial cell concentration did not increase at a CO partial pressure lower than 74 kPa, though CO was consumed with organic acid produced. At this stage, supply of CO mass transfer rate was lower than CO requirement to support maximum cell growth, but higher than that to maintain culture. Since CO was supplied higher than maintenance requirement under atmospheric CO pressure, bacterial cell concentration increased to 9.5 g/L.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available