17 Sep 2012
For those who are familiar with the strong and mostly unpleasant odour of sulfur-containing compounds, it may come as a surprise that such compounds are also the source of many of the characteristic flavours of much-loved fermented dairy products like cheese and yoghurt. Important flavour components such as dimethyl sulfide (DMS) and methanethiol are formed during the fermentation process when lactic acid bacteria break down the sulfur-containing amino acids cysteine and methionine.
To the dairy industry, insight into the regulation of this degradation process may offer clues to a rational control of flavour profiles of dairy products. To this end, Mengjin Liu (FrieslandCampina Research) and colleagues from academia including NBIC Faculty members Roland Siezen and Christof Francke, performed a genome-wide in silico analysis to systematically evaluate the regulatory interactions that control the expression of genes associated with cysteine and methionine metabolism in all sequenced species of the order Lactobacillales. The results suggest that the reaction network can be subdivided into five modules, with the family Streptococcaceae appearing to have a distinctly different modular composition compared to the three other families. The authors propose to include the reaction network built on their analysis into a quantitative metabolic network model, in order to develop rational strategies towards flavour control strategies in fermented food products.
Liu M, Prakash C, Nauta A, Siezen RJ, Francke C
Computational analysis of cysteine and methionine metabolism and its regulation in dairy starter and related bacteria.
J Bacteriol. 2012 Jul;194(13):3522-33