The role of an NAD-independent lactate dehydrogenase and acetate in the utilization of lactate byClostridium acetobutylicum strain P262 |
| |
Authors: | Francisco Diez-Gonzalez James B Russell Jean B Hunter |
| |
Institution: | (1) Agricultural Research Service, USDA and Section of Microbiology,Wing Hall, Cornell University, Ithaca, NY 14853, USA Tel. + 1-607-255-4508; Fax +1-607-255-3904, US;(2) Department of Food Science, Cornell University, Ithaca, NY 14853, USA, US;(3) Department of Agricultural and Biological Engineering, Cornell University, Ithaca, NY 14853, USA, US |
| |
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.
Received: 17 October 1994 / Accepted: 30 January 1995 |
| |
Keywords: | Clostridium acetobutylicum Lactate utilization Acetate utilization Acetone-butanol fermentation Lactate dehydrogenase |
本文献已被 SpringerLink 等数据库收录! |
|