Formation of acetaldehyde from 2-deoxy-D-ribose-5- phosphate in lactic acid bacteria

Abstract

Acetaldehyde can be formed from 2-deoxyribose-5-phosphate by organisms which contain the enzyme deoxyriboaldolase. This enzyme is thought to be involved in the degradation rather than the synthesis of DNA (Sable, 1966). Thymidine which is formed by the breakdown of DNA is degraded by the enzymes thymidine phosphorylase and deoxyribomutase to 2-deoxyribose-5-phosphate (Hoffee, 19686; Hoffee & Robertson, 1969;Hoffmann & Lampen, 1952; Munch-Petersen, 1968 a, b). Although the presence of deoxyriboaldolase is widespread among bacterial species, its presence and activity are not essential for growth of the organism. Mutants of Escherichia coli (Munch-Petersen, 1968a) which lack this enzyme are known.J This paper describes the activity and properties of the deoxyriboaldolase in lactic acid bacteria and the possible breakdown of thymidine to acetaldehyde in these organisms. MATEEIALS AND METHODSThe lactic acid bacteria examined, media, growth conditions, and the preparation of cell-free extracts have been described previously (Lees & Jago, 1976). When required, the pH of the growth medium was maintained at a constant value by the addition of 10 M-NaOH controlled by a magnetic valve (Radiometer, Model MNV1, Copenhagen, Denmark) connected to a titrator (Radiometer, Model TTTllb).Deoxyriboaldolase (E.C. 4.1.2.4) activity, measured in the direction of synthesis of 2-deoxyribose-5-phosphate, was estimated by the method of Racker (1952). The reaction mixture, total volume 2-6 ml, contained: 15/nnoles of fructose-1,6-diphosphate; 52 /imoles of acetaldehyde (or water); 50 fondles of triethanolamine-HCl buffer, pH 6-5; 30 fig aldolase (optional) and 0-25 ml (c. 4 mg protein) of a bacterial cell-free extract. The reaction mixtures were incubated for 30 min at 37 °C before the reaction was stopped by the addition of 0-5 ml]of 20 % (w/v) TCA. Deoxyribose phosphate was estimated in 1 ml samples by the diphenylamine method (Racker, 1952).When deoxyriboaldolase activity was assayed in the direction of breakdown of 2-deoxyribose-5-phosphate (forming acetaldehyde and glyceraldehyde-3-phosphate), the reaction mixture was added to the outer well of a Conway microdiffusion unit and the acetaldehyde formed was absorbed into semicarbazide in the centre well and

Nucleotide metabolism and its control in lactic acid bacteria

“…It should further be noted that several of the salvage genes found at the preserved positions in S. thermophilus seem to be disrupted (e.g., xpt , pdp , and deoC ). Lack of a functional deoC gene has previously been found by enzyme analysis in 3 out of 4 strains of S. thermophilus [142]. Very scarce data are available with regard to the regulation of gene expression of the salvage enzymes in L. lactis .…”

An overview of formation and roles of acetaldehyde in winemaking with emphasis on microbiological implications

“…The amount of acetaldehyde formed by dairy LAB varies with species and strain, and is usually less than 30 mg L Ϫ1 (Kneifel et al, 1992). Acetaldehyde is produced by dairy LAB from the metabolism of glucose (Lees & Jago, 1976a), 2-deoxy-D-ribose-5-phosphate (Lees & Jago, 1977) and threonine (Lees & Jago, 1976b;Wilkins et al, 1986aWilkins et al, , 1986bMarshall & Cole, 1983;Marranzini et al, 1989;Rysstad et al, 1990;Grozeva et al, 1994). These acetaldehyde precursors are also present in wine, and it will be of practical value to ascertain if wine LAB can form acetaldehyde from these substrates.…”

Effect of oxidoreduction potential on aroma biosynthesis by lactic acid bacteria in nonfat yogurt

“…The proteolytic system of LAB degrades casein into its constituent amino acids, which can then be converted into flavor compounds (Marilley and Casey, 2004;Smit et al, 2005;Ardö, 2006;Liu et al, 2008). Three main metabolic pathways have been shown to lead to the formation of acetaldehyde ( Figure 1a; Ott et al, 2000a): reduction of glucose through the glycolytic pathway (Lees and Jago, 1976a), 2-deoxyribose-5-phosphate by the degradation of DNA (Lees and Jago, 1977;Raya et al, 1986a), and threonine aldolase (Lees and Jago, 1976b;Raya et al, 1986b). For diketones (Figure 1a), the condensation of pyruvate and activated acetaldehyde leads to 2-acetolactate, and the condensation of 2-ketobutyrate and activated acetaldehyde leads to 2-aceto-hydroxybutyrate (Ramos et al, 1994).…”