title: Oxalate-degrading activity in Bifidobacterium animalis subsp. lactis: impact of acidic conditions on the transcriptional levels of the oxalyl coenzyme A (CoA) decarboxylase and formyl-CoA transferase genes.
abstract: Oxalic acid occurs extensively in nature and plays diverse roles, especially in pathological processes. Due to its highly oxidizing effects, hyperabsorption or abnormal synthesis of oxalate can cause serious acute disorders in mammals and can be lethal in extreme cases. Intestinal oxalate-degrading bacteria could therefore be pivotal in maintaining oxalate homeostasis and reducing the risk of kidney stone development. In this study, the oxalate-degrading activities of 14 bifidobacterial strains were measured by a capillary electrophoresis technique. The oxc gene, encoding oxalyl-coenzyme A (CoA) decarboxylase, a key enzyme in oxalate catabolism, was isolated by probing a genomic library of Bifidobacterium animalis subsp. lactis BI07, which was one of the most active strains in the preliminary screening. The genetic and transcriptional organization of oxc flanking regions was determined, unraveling the presence of two other independently transcribed open reading frames, potentially responsible for the ability of B. animalis subsp. lactis to degrade oxalate. pH-controlled batch fermentations revealed that acidic conditions were a prerequisite for a significant oxalate degradation rate, which dramatically increased in cells first adapted to subinhibitory concentrations of oxalate and then exposed to pH 4.5. Oxalate-preadapted cells also showed a strong induction of the genes potentially involved in oxalate catabolism, as demonstrated by a transcriptional analysis using quantitative real-time reverse transcription-PCR. These findings provide new insights into the characterization of oxalate-degrading probiotic bacteria and may support the use of B. animalis subsp. lactis as a promising adjunct for the prophylaxis and management of oxalate-related kidney disease.
authors.affiliation: Department of Pharmaceutical Sciences, University of Bologna, Via Belmeloro 6, Bologna, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Turroni
authors.forename: Claudia
authors.initials: C
authors.lastname: Bendazzoli
authors.forename: Samuele C F
authors.initials: SC
authors.lastname: Dipalo
authors.forename: Marco
authors.initials: M
authors.lastname: Candela
authors.forename: Beatrice
authors.initials: B
authors.lastname: Vitali
authors.forename: Roberto
authors.initials: R
authors.lastname: Gotti
authors.forename: Patrizia
authors.initials: P
authors.lastname: Brigidi
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis*; D001644:Bifidobacterium / Q000378:metabolism*; D002262:Carboxy-Lyases / Q000096:biosynthesis* / Q000235:genetics; D015256:Coenzyme A-Transferases / Q000096:biosynthesis*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D020536:Enzyme Activators / Q000378:metabolism*; D015870:Gene Expression; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D023061:Gene Order; D008969:Molecular Sequence Data; D010070:Oxalates / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D020536:Enzyme Activators; D010070:Oxalates; D015256:Coenzyme A-Transferases; C064813:formyl-coenzyme A transferase; D002262:Carboxy-Lyases; C059418:oxalyl CoA decarboxylase