Lactobacillus acidophilus JCM 1132 produces a heat-stable, two-component bacteriocin designated acidocin J1132 that has a narrow inhibitory spectrum. Maximum production of acidocin J1132 in MRS broth was detected at pH 5.0. Acidocin J1132 was purified by ammonium sulfate precipitation and sequential cation exchange and reversed-phase chromatographies. Acidocin J1132 activity was associated with two components, termed ␣ and . On the basis of N-terminal amino acid sequencing and the molecular masses of the ␣ and  components, it is interpreted that the compounds differ by an additional glycine residue in the  component. Both ␣ and  had inhibitory activity, and an increase in activity by the complementary action of the two components was observed. Acidocin J1132 is bactericidal and dissipates the membrane potential and the pH gradient in sensitive cells, which affect such proton motive force-dependent processes as amino acid transport. Acidocin J1132 also caused efflux of preaccumulated amino acid taken up via a unidirectional ATP-driven transport system. Secondary structure prediction revealed the presence of an amphiphilic ␣-helix region that could form hydrophilic pores. These results suggest that acidocin J1132 is a pore-forming bacteriocin that creates cell membrane channels through the ''barrel-stave'' mechanism.
Metabolic pathways of glucose during germination of Bacillus megaterium QM B1551 spores were studied by using specifically labeled glucose and gluconate. The Embden-Meyerhof pathway, the pentose cycle, and the direct oxidation route of glucose to gluconate (the gluconate pathway) were all operative at this stage; among those, gluconate accumulation was most predominant, especially in the early stage. Potassium fluoride, an enolase inhibitor, abolished the catabolism by the Embden-Meyerhof pathway totally without affecting gluconate accumulation. Under these conditions glucose was exclusively oxidized to gluconate. Gluconate thus accumulated could be metabolized further via phosphorylation by gluconate kinase. Remarkable gluconate accumulation was also demonstrated in several other spores requiring alanine as an effective germinant. NADH formed by the direct glucose oxidation may serve as a initial ATP source to phosphorylate glucose in germinating spores.Although glucose catabolism is not a prerequisite for triggering spore germination (4, 15, 22), it becomes detectable immediately after the initiation of germination (10,15,21,22). Oxygen consumption (4,7,8), ATP production (4, 12, 21), and other activities involved in energy metabolism (18,19) are also greatly enhanced by glucose catabolism in germinated (or germinating) spores. Previous studies (5-8, 12, 14, 21) suggest that three possible pathways are operative during germination, (i) the Embden-Meyerhof (EM) pathway, (ii) the pentose cycle, and (iii) a pathway which can oxidize glucose to gluconate without prior phosphorylation. The last pathway, which is catalyzed by glucose dehydrogenase (GDH, EC 1.1.1.47) coupling with NAD(P) reduction, is unique to spores; gluconate thus formed may be metabolized further, presumably by the pentose cycle or the EntnerDoudoroff pathway. This pathway is designated as the gluconate pathway in this study.Generally, to investigate metabolic pathways, the use of specifically labeled glucose seems to be of primary importance; nonetheless only a few attempts have been made in bacterial spores. As far as we know, a plausible determination was made only in Bacillus cereus T spores (6); Goldman and Blumenthal concluded the predominance of the EM pathway by using [1-14C]glucose and [6-14C]glucose. In Bacillus megaterium QM B1551 spores, the primary role of the EM pathway was also stressed by Komberg and his coworkers (12, 21), mainly based on the indirect findings. Contrary to this, we found a remarkable accumulation of gluconate in B. megaterium QM B1551 (10), which led us to make more extensive studies before drawing any definite conclusion.In this study we attempted to determine the possible pathways of glucose catabolism more directly, especially to evaluate the most predominant pathway during germination of B. megaterium QM B1551 spores. A possible role of the gluconate pathway in ATP production is also discussed. * Corresponding author. MATERIALS AND METHODSBacterial strains and spore production. Unless indicated otherwise, s...
The metabolism of L-tryptophan by Saccharomyces uvarum (carlsbergensis) was investigated by simultaneous measuring of fluxes through kynureninase, through transaminases and into protein using L-[methylene-14C] and L-[side chain-2,3-3H]tryptophan. In yeasts cultivated in synthetic medium (S medium), the flux into protein was predominant, closely followed by the flux leading to 2-3H liberation. The proportion of L-tryptophan metabolized via the latter flux increased over 10-fold (75% of total tryptophan metabolized) as the concentration of L-tryptophan was raised from 5 x 10(-5) to 5 x 10(-4) M. L-Tryptophan metabolized via the kynureninase flux was less than 5% of total tryptophan metabolized. In yeast extract-polypepton-glucose medium (YPG medium), more tryptophan was incorporated into protein than in the S medium. Contribution of the kynureninase flux remained very low. Tryptophan metabolism via each flux changed depending on the growth phase. 2-3H liberation was shown to be primarily due to tryptophol synthesis by high performance liquid chromatography (HPLC) and nuclear magnetic resonance (NMR), indole-3-acetic acid and kynurenic acid also contributing to 2-3H liberation but to a much lesser extent. 2-3H liberation increased dose-dependently at tryptophan concentration higher than 10(-5)M, while the kynureninase flux reached its plateau at 10(-5)M. Formation of tryptophol and indole-3-acetic acid via indole-3-pyruvic acid and indole-3-acetaldehyde with indole aldehyde as a by-product was confirmed using exogenous tryptophan metabolites with indole rings.
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