Title

Volatile sulfur-containing compounds from methionine metabolism in genetically modified Lactobacillus helveticus CNRZ 32 strains

Document Type

Contribution to Book

Journal/Book Title/Conference

Flavor of Dairy Products

Editor

K. R. Caldwaller, M. A. Drake, and R. J. McGorrin

Publisher

American Chemical Union

Publication Date

2007

First Page

205

Last Page

213

DOI

10.1021/bk-2007-0971.ch012

Abstract

Cystathionine-β-lyase (CBL) catalyzes the conversion of methionine to methanethiol, dimethyl disulfide and dimethyl trisulfide. These three compounds are collectively referred to as volatile sulfur compounds (VSC). Two strains ofLactobacillus helveticus CNRZ32 were evaluated for VSC production; wild-type and a genetically modified variant that produced elevated levels CBL. Whole cell suspensions and cell free extracts were incubated in buffer (pH 6.0) with methionine substrate; furfuryl alcohol was added as an internal standard. Results demonstrated that the modified strain produced ~2-fold higher levels of VSC, primarily dimethyl disulfide. In parallel, NMR was used to substantiate a lyase-mediated pathway by tracking metabolites of uniformly labeled13C methionine (17.5mM).

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