Open AccessMethylotrophic growth of a mutant strain of the acetogenic bacterium Eubacterium limosum that uses acetate as co‐substrate in the absence of CO 2
Author(s) -
Loubiere Pascal,
Lindley Nicholas D.
Publication year - 1994
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1994.tb07237.x
Subject(s) - strain (injury) , methanol , ethanol , mutant , eubacterium , chemistry , biology , butyric acid , biochemistry , bacteria , microbiology and biotechnology , growth rate , chemostat , substrate (aquarium) , food science , organic chemistry , gene , genetics , ecology , geometry , mathematics , anatomy
A mutant strain (the CO 2 − strain) of the acetogenic bacterium Eubacterium limosum was isolated by nutritional selection on a medium containing methanol and acetate but lacking CO 2 . The ability of the CO 2 − strain to grow on methanol/acetate without CO 2 or other one‐carbon compounds was stable through several transfers in the presence of CO 2 . The phenotypic difference between the parent and the mutant strain was the ability to support sustained growth in the absence of CO 2 by consumption of acetate throughout the growth period. The maximal specific rate of acetate consumption (5 mmol C·g −1 ·h −1 ) was similar to that previously observed for a brief period early in the exponential growth phase of the parent strain but was maintained for a prolonged duration. The methanol consumption rate was considerably lower than in the presence of CO 2 and was similar to the rate of acetate consumption, hence maintaining equilibrated reducing equivalent pools. The maximal growth rate (0.08 h −1 ) was lower than that of the parent strain and the optimal pH for growth was 6.5 instead of 7.4 in the presence of CO 2 . These acidic conditions enhanced the toxic effect of butyric acid, resulting in a more pronounced inhibition of growth, as seen by the decrease in Y ATP proportional to the accumulated butyric acid.