aureus . Modified after Marilley et al. [19] Additionally, pyruvate or citrate are starting materials for the formation of short-chain flavor compounds such as acetoin, 2,3-butanedione, 1-butanol, 2-propanol, acetic acid, acetaldehyde and ethanol through glycolytic, lactate converting and non-glycolytic carbohydrates fermentations or fermentations of nitrogenous compounds [44]. The catabolism

of pyruvate (presented on Figure 3) seems to play an important role in case of S. aureus since the products of this metabolic selleck chemicals pathway were found in the headspace of this bacterium in our study and also by other researchers, inter alia ethanol, acetaldehyde, acetic acid [11] and acetoin [6, 40]. Figure 3 Simplified scheme of pyruvate www.selleckchem.com/products/cobimetinib-gdc-0973-rg7420.html metabolism via EVP4593 mouse glycolytic fermentations and lactate converting

fermentations, modified after Michal et al.[44]. Exclusively, pathways which lead to the production of VOCs significantly released by S. aureus in this study (underlined with solid line) are presented, including acetoin (3-hydroxy-2-butanone), acetaldehyde, ethanol, 1-butanol, acetone, 2-propanol. In case of P. aeruginosa the metabolism of amino acids rather than glycolysis of carbohydrates yields pyruvate as starting material (significantly released or taken up products are underlined with dotted line). Detailed investigation of the subspecies of the genus Staphylococcus shows that

acetoin is produced by the subspecies aureus and not by the subspecies anaerobius. On the other hand, Pseudomonads are described as organisms with strictly respiratory metabolism mostly with oxygen and in some species nitrate as terminal electron acceptor [45], hence the release of alcohols and acids from these microorganisms is not expected. Indeed, carboxylic acids were not observed to be released by P. aeruginosa in our in vitro study, but a very week production of 2-butanol and substantially stronger almost of ethanol and 3-methyl-1-butanol were found. These may be related to altered activity of aldehyde- and alcoholdehydrogenase as reported by Nosova et al. [46] while the metabolism of amino acids [44] rather than glycolysis of carbohydrates via Entner-Doudoroff pathway [1] yields pyruvate as starting material under conditions applied in our study. Nevertheless, it seems that the most dominant metabolic process in P. aeruginosa cultures is the catabolism of organic compounds such as aldehydes as carbon and energy sources. The versatile nutritional requirements of Pseudomonas are commonly known and some of its subspecies utilize over 100 different compounds of diverse chemical classes what makes them particularly important organisms of bioremediation in environment (degradation of oil spills, pesticides and other xenobiotics) [1, 47].