Production of Buttery-Odor Compounds and Transcriptome Response in Leuconostoc gelidum subsp. gasicomitatum LMG18811^sup T^ during Growth on Various Carbon Sources

Leuconostoc gelidum subsp. gasicomitatum is a common spoilage bacterium in meat products packaged under oxygen-containing modified atmospheres. Buttery off-odors related to diacetyl/acetoin formation are frequently associated with the spoilage of these products. A whole-genome microarray study, together with gas chromatography (GC)-mass spectrometry (MS) analyses of the pathway end products, was performed to investigate the transcriptome response of L. gelidum subsp. gasicomitatum LMG18811T growing on semidefined media containing glucose, ribose, or inosine, which are essential carbon sources in meat. Generally, the gene expression patterns with ribose and inosine were quite similar, indicating that catabolism of ribose and nucleosides is closely linked. Diacetyl/acetoin concentrations as high as 110 or 470 μM were measured when growth was based on inosine or ribose, respectively. The gene expression results for pyruvate metabolism (upregulation of a-acetolactate synthase, downregulation of l-lactate dehydrogenase and pyruvate dehydrogenase) were as expected when diacetyl and acetoin were the end products. No diacetyl production (