Transcriptional and Functional Analysis of Oxalyl-Coenzyme A (CoA) Decarboxylase and Formyl-CoA Transferase Genes from Lactobacillus acidophilus

Department of Food Science, North Carolina State University, Box 7624, Raleigh, NC 27695, USA.
Applied and Environmental Microbiology (Impact Factor: 3.67). 04/2006; 72(3):1891-9. DOI: 10.1128/AEM.72.3.1891-1899.2006
Source: PubMed


Oxalic acid is found in dietary sources (such as coffee, tea, and chocolate) or is produced by the intestinal microflora from
metabolic precursors, like ascorbic acid. In the human intestine, oxalate may combine with calcium, sodium, magnesium, or
potassium to form less soluble salts, which can cause pathological disorders such as hyperoxaluria, urolithiasis, and renal
failure in humans. In this study, an operon containing genes homologous to a formyl coenzyme A transferase gene (frc) and an oxalyl coenzyme A decarboxylase gene (oxc) was identified in the genome of the probiotic bacterium Lactobacillus acidophilus. Physiological analysis of a mutant harboring a deleted version of the frc gene confirmed that frc expression specifically improves survival in the presence of oxalic acid at pH 3.5 compared with the survival of the wild-type
strain. Moreover, the frc mutant was unable to degrade oxalate. These genes, which have not previously been described in lactobacilli, appear to be
responsible for oxalate degradation in this organism. Transcriptional analysis using cDNA microarrays and reverse transcription-quantitative
PCR revealed that mildly acidic conditions were a prerequisite for frc and oxc transcription. As a consequence, oxalate-dependent induction of these genes occurred only in cells first adapted to subinhibitory
concentrations of oxalate and then exposed to pH 5.5. Where genome information was available, other lactic acid bacteria were
screened for frc and oxc genes. With the exception of Lactobacillus gasseri and Bifidobacterium lactis, none of the other strains harbored genes for oxalate utilization.

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Available from: Maria Andrea Azcárate-Peril,
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    • "Lactobacilli have enjoyed widespread use as probiotics for many decades (Ouwehand et al., 2002). Increasing reports of oxalate-degrading lactic acid bacteria (Campieri et al., 2001; Federici et al., 2004; Lieske et al., 2005; Azcarate-Peril et al., 2006) suggested the existence of uncharacterised oxalatedegrading Lactobacillus species. In Lactobacillus acidophilus, a cluster of genes encoding the Oxc and Frc proteins involved in oxalate degradation was identified (Azcarate- Peril et al., 2006). "
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