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...then converted to acetate with concomitant hydrogen peroxide, carbon dioxide, and ATP production (Fig. 1A) (20). Acetate becomes the major fermentation end product, leading to homoacetic fermentation =-=(18)-=-. This conversion is thought to play a role in pH homeostasis and survival during the stationary phase of growth under aerobic conditions (18, 20). The additional ATP generated through this pathway ca...

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...), as with lactobacilli, which can prevent pathogens causing bacterial vaginosis from colonizing the vagina by forming H 2O 2 (11). H 2O 2 could be produced via NADH oxidase, pyruvate oxidase, or Lox =-=(4, 20, 32)-=-. However, it was found in our study that S. oligofermentans, an oral streptococcus, produces large amounts of H 2O 2 not only from lactate but also from peptone (Fig. 1A) and from seven L-amino acids...

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...harp contrast to the situations of homologous proteins in other bacterial species: the activity of lactate oxidase in S. pyogenes (5, 29) and S. iniae (4) and that of pyruvate oxidase in L. plantarum =-=(6, 17, 21, 26, 28)-=- are all undetectable as long as glucose is available from the medium. Obviously, the practically constant expression of the spxB and lox genes represents a unique feature of S. pneumoniae. Characteri...

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...lactate as glucose becomes depleted and cells enter the stationary phase of growth. The pathway for lactate-toacetate conversion under these conditions has been shown to involve three enzymatic steps =-=(2, 6, 12, 20)-=-: oxidation of lactate to pyruvate by the NAD-dependent D- and L-lactate dehydrogenases (LDH), oxidative decarboxylation of pyruvate to acetyl-phosphate (acetyl�P) by pyruvate oxidase (POX), and depho...

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...ition, 50-ml aliquots were centrifuged at 5,000 � g for 10 min, and total RNA was extracted by the method of Anba et al. (1). Northern blot experiments were carried out as described by Lorquet et al. =-=(36)-=-, using a 710-bp probe that hybridizes with the larA ORF. This probe was obtained by PCR amplification with primers 104A1 and 104B1. DNA microarray analysis. The DNA microarrays applied in the present...

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...hate starvation conditions. Aside from the E. coli type of pyruvate oxidase, another type of pyruvate oxidase from two lactic acid bacteria, Lactobacillus delbrueckii (28) and Lactobacillus plantarum =-=(41, 48, 59, 60, 65)-=-, has been found and characterized. This type of enzyme * Corresponding author. Mailing address: Department of Microbiology and Biotechnology, University of Ulm, 89069 Ulm, Germany. Phone: 49 (0)731 5...

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..., 27), as with lactobacilli, which can prevent pathogens causing bacterial vaginosis from colonizing the vagina by forming H2O2 (11). H2O2 could be produced via NADH oxidase, pyruvate oxidase, or Lox =-=(4, 20, 32)-=-. However, it was found in our study that S. oligofermentans, an oral streptococcus, produces large amounts of H2O2 not only from lactate but also from peptone (Fig. 1A) and from seven L-amino acids (...

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...ition, 50-ml aliquots were centrifuged at 5,000 g for 10 min, and total RNA was extracted by the method of Anba et al. (1). Northern blot experiments were carried out as described by Lorquet et al. =-=(36)-=-, using a 710-bp probe that hybridizes with the larA ORF. This probe was obtained by PCR amplification with primers 104A1 and 104B1. DNA microarray analysis. The DNA microarrays applied in the present...

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...nce of genes predicted to encode PFL or genes that resemble the PDH-genes of other organisms does not preclude that a species still depends on pyruvate oxidase under aerobic conditions for the production of C2 and C1 components, analogous to what we concluded for L. johnsonii. Clear data to support this hypothesis are lacking, although CO2 dependency of L. plantarum was also reported to cause a characteristic growth stagnation under aerobic conditions [19]. In addition, another study showed that a pyruvate-oxidase deficient mutant of L. plantarum is hampered in its acetate production capacity [37,38], supporting the role of this enzyme in aerobic acetate supply in lactobacilli that have a broader genetic arsenal. The effect of deletion of pox in L. johnsonii confirms the role of POX in the generation of both C1 and C2 sources (CO2 and acetate) required for growth. However, a byproduct of pyruvate oxidation by POX is hydrogen peroxide, of which the accumulation induces oxidative stress that leads to premature growth arrest under aerobic conditions [24]. This brings us to the intriguing conclusion that oxygen appears to both benefit and harm L. johnsonii. Under aerobic conditions, clearly, ...

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... 1153 genome by homologous recombination. Stable knockouts of either poxB in Lactobacillus plantarum or pepO in Lactobacillus helveticus have been shown not to affect the phenotypes of these bacteria =-=(9, 23)-=-. Homologues of these genes, referred to as pox1 and pepO, were identified in the L. jensenii 1153 genome and used as integration sites for the optimized CV-N expression cassette via a single-crossove...