Relieving effects of glycine and methionine from acetic acid inhibition in Escherichia coli fermentation

Abstract

Among amino acids screened for their potential to relieve wild and recombinant Escherichia coli from the negative effects of acetic acid, glycine, and methionine showed a sparing effect. In the presence of 2 g/L of acetic acid, addition of 0.5 g/L of glycine or methionine resulted in either a complete recovery or a further enhancement in the specific growth rate, while the enhancement was significant but not fully complete in the presence of 4 g/L of acetic acid. The addition of 0.5 g/L of methionine alleviated the negative effect of acetic acid on recombinant E. Coli growth to produce more beta-lactamase, which was encoded by plasmid pUC18. In continuous fermentation the methionine effect on recombinant. E. coli metabolism depended on dilution rate; at high dilution rates, above 0.4 h(-1), the methionine addition enhanced beta-lactamase production and reduced acetic acid formation, while at low dilution rates, below 0.3 h (-1), the effect was reversed. In def-batch fermentation with wild-type E. Coli, cell growth rate and cell yield from glucose were enhanced with methionine addition, while the acetic acid concentration reached over 4 g/L.

Inhibition of Escherichia coli growth by acetic acid: a problem with methionine biosynthesis and homocysteine toxicity

“…Here we have confirmed the findings of an earlier study by Han et al (1993), which showed that methionine could relieve the acetate-mediated inhibition of growth of an E. coli culture. We have shown that the effects of methionine on acetate-mediated inhibition of growth can be replicated for other organic acids.…”

“…Methionine stimulated the growth rate of cells treated with up to 20 mM acetate at pH 6 (data not shown). In the earlier study (Han et al, 1993), glycine was also found to relieve growth inhibition, but we were unable to observe growth stimulation by this amino acid in E. coli Frag1 (data not shown).…”

“…Previous workers (Han et al, 1993) had reported that the accumulation of acetate in fermentation broth led to growth inhibition and that this inhibition could be reversed by the addition of methionine. To confirm these observations we grew E. coli Frag1 at pH 6 in minimal medium and in the presence of a range of organic acids, such that the growth rate was reduced to 50 % of the uninhibited control.…”

“…1). It has also been observed that methionine can relieve the inhibitory effects of acetate, which accumulates as a metabolic end product during fermentations with E. coli growing on glucose (Han et al, 1993). However, in this case no explanation for the relieving effect of methionine was offered.…”

Metabolite stress and tolerance in the production of biofuels and chemicals: Gene‐expression‐based systems analysis of butanol, butyrate, and acetate stresses in the anaerobe Clostridium acetobutylicum

“…Finally, genes in a putative operon orthologous to microbial methionine transporters (CAC0984-CAC0986) were differentially upregulated after acetate stress. Studies in E. coli have shown that acetate inhibition at 8-33 mM concentration can be relieved by the addition of methionine (Han et al, 1993;Roe et al, 2002). A result of acetate stress is accumulation of the toxic intermediate homocysteine (Roe et al, 2002).…”