ISSN:
1432-072X
Keywords:
Key wordsClostridium acetobutylicum
;
Lactate
;
utilization
;
Acetate utilization
;
Acetone-butanol
;
fermentation
;
Lactate dehydrogenase
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Clostridium acetobutylicum strain P262 utilized lactate at a rapid rate [600 nmol min–1 (mg protein)–1], but lactate could not serve as the sole energy source. When acetate was provided as a co-substrate, the growth rate was 0.05 h–1. Butyrate, carbon dioxide and hydrogen were the end products of lactate and acetate utilization, and the stoichiometry was 1 lactate + 0.4 acetate → 0.7 butyrate + 0.6 H2 + 1 CO2. Lactate-grown cells had twofold lower hydrogenase than glucose-grown cells, and the lactate-grown cells used acetate as an alternative electron acceptor. The cells had a poor affinity for lactate (Ks = 1.1 mM), and there was no evidence for active transport. Lactate utilization was catabolyzed by an inducible NAD-independent lactate dehydrogenase (iLDH) that had a pH optimum of 7.5. The iLDH was fivefold more active with d-lactate than l-lactate, and the K m for d-lactate was 3.2 mM. Lactate-grown cells had little butyraldehyde dehydrogenase activity, and this defect did not allow the conversion of lactate to butanol.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s002030050233
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