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Summary: Fluorescent pseudomonads produce and secrete a siderophore termed pyoverdine to capture iron when it becomes scarce. The molecular basis of pyoverdine secretion is only partially understood. Here, we investigate the role of the putative PvdRT‐OpmQ and MdtABC‐OpmB efflux systems in pyoverdine secretion in the soil bacterium Pseudomonas putida KT2440. Expression from the respective promoters is stimulated by iron limitation albeit to varying degrees. Deletion of pvdRT‐opmQ leads to reduced amounts of pyoverdine in the medium and decreased growth under iron limitation. Deletion of mdtABC‐opmB does not affect growth. However, when both systems are deleted, strong effects on growth and pyoverdine secretion (yellow colony phenotype, less pyoverdine in medium, more pyoverdine in the periplasm) are observed. Overexpression of pvdRT‐opmQ causes the opposite effect. These results provide first evidence for an involvement of the multidrug efflux system MdtABC‐OpmB in pyoverdine secretion. In addition, the PvdRT‐OpmQ system was shown to contribute to pyoverdine secretion in P. putida KT2440, extending previous investigations on its role in Pseudomonas species. Since the double deletion mutant still secrets pyoverdine, at least one additional efflux system participates in the transport of the siderophore. Furthermore, our results suggest a contribution of both efflux systems to ampicillin resistance. [ABSTRACT FROM AUTHOR]

The eftA gene in Bacillus subtilis has been suggested to be involved in the oxidation/reduction reactions during fatty acid metabolism. Interestingly etfA deletion in B. subtilis results in impairment in CaCO3 precipitation on the biofilm. Comparisons between the wild type B. subtilis 168 and its etfA mutant during in vitro CaCO3 crystal precipitation (calcite) revealed changes in phospholipids membrane composition with accumulation of up to 10% of anteiso-C17:0 and 11% iso-C17:0 long fatty acids. Ca2+ nucleation sites such as dipicolinic acid and teichoic acids seem to contribute to the CaCO3 precipitation. etfA mutant strain showed up to 40% less dipicolinic acid accumulation compared with B. subtilis 168, while a B. subtilis mutant impaired in teichoic acids synthesis was unable to precipitate CaCO3. In addition, B. subtilis etfA mutant exhibited acidity production leading to atypical flagella formation and inducing extensive lateral growth on the biofilm when grown on 1.4% agar. From the ecological point of view, this study shows a number of physiological aspects that are involved in CaCO3 organomineralization on biofilms. [ABSTRACT FROM AUTHOR]

Backgound: The virulence factors of the Vibrio cholerae non-O1, non-O139 strains are not clearly known. The strain of septicemic origin NN1 Vibrio cholerae non-O1, non-O139 was sequenced previously by the Illumina platform. A fragment of the pathogenicity island VPaI-7 of V. parahaemolyticus was detected in its genome., Aim: To detect the virulence genes vcsN2, vcsC2, vcsV2, vspD, toxR2 y vopF in Chilean strains of V. cholerae non-O1, non-O139., Methods: A total of 9 Chilean strains of clinical origin of Vibrio cholerae non-O1, non-O139 isolated between 2006-2012 were analyzed by conventional PCR assays for type III secretion genes encoded on that island: vcsN2, vcsC2, vcsV2, vspD, toxR2 and vopF. Additionally, the presence of the virulence genes hylA and rtxA was determined. In addition, REP-PCR and ERIC-PCR assays were performed., Results: most (6/9) Chilean V. cholerae non-O1, non-O139 strains contain the type III secretion genes vcsN2, vcsC2, vcsV2, vspD, toxR2 and vopF, encoded in an island of pathogenicity. In addition, all (9/9) the strains contain the virulence genes hylA and rtxA., Conclusion: These results strongly suggest the possibility that those strains possess an important virulence potential in humans.