Conversion of gamma-butyrobetaine to L-carnitine by Achromobacter cycloclast.
L-Carnitine is an ubiquitous substance that plays a major role in the transportation of long-chain fatty acids. We investigated crucial factors that influence microbial conversion of gamma-butyrobetaine to L-carnitine using an Achromobacter cycloclast strain. Two-stage culture results showed that gamma-butyrobetaine induced enzymes essential for the conversion, which suggests that the precursor should be present in the initial cell growth stage. The addition of yeast extract enhanced L-carnitine production whereas inorganic nitrogen sources inhibited it. Under nitrogen-limiting conditions, the cells accumulated poly-beta-hydroxybutyrate instead of L-carnitine. Among the trace elements tested, nickel addition enhanced L-carnitine production by almost twice that of the control and copper strongly inhibited the conversion. L-Carnitine production was reduced when the medium contained inorganic salts of sodium, potassium, and calcium at a concentration greater than 2 g l(-1). A higher L-carnitine yield was achieved when cells were incubated in a lower culture volume. The optimal pH for L-carnitine production was 5 to 5.5, whereas that of growth was 7.0, indicating that a pH shift was required. Under optimal conditions, L-carnitine concentrations as high as 15 g l(-1) were obtained in 62 h with a 45% molar conversion yield.[1]References
- Conversion of gamma-butyrobetaine to L-carnitine by Achromobacter cycloclast. Naidu, G.S., Lee, I.Y., Cho, O.K., Park, Y.H. J. Ind. Microbiol. Biotechnol. (2001) [Pubmed]
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