Virulence determinants in genetically heterogeneous populations of Aeromonads recovered from an urban lagoon.

The diversity and distribution of Aeromonas spp. associated with virulence profiles from the Rodrigo de Freitas Lagoon were investigated using phylogenetic analysis of gyrB/rpoB gene sequences for speciation. The concatenated gyrB/rpoB gene sequences clustered into five species: Aeromonas punctata/caviae (n = 37), A. hydrophila (n = 10), A. dhakensis (n = 16), A. jandaei (n = 1) and A. enteropelogenes/trota (n = 3). The virulence genes (atc/aerA/hlyA/asp/amp) resulted in 19 virulence profiles, distributed heterogeneously among the five Aeromonas species. Out of the 67 isolates, 16% presented five distinct profiles carrying four virulence genes and 7% showed all genes investigated. The hemolytic genes were detected as follows: act 54% (37/67), aerA 36% (24/67), hlyA 26% (18/67) and proteolytic genes such as asp 36% (24/57) and amp in 85% (57/67) were widely distributed in lagoon sampling stations. Meanwhile, 88% (59/67) and 92% (62/67) of the isolates showed hemolytic and proteolytic activity, respectively. Our results demonstrated that concatenated sequences of the gyrB and rpoB genes showed to be an adequate approach for the Aeromonas speciation and prevalence. The high heterogeneity of virulence genes among the species resulted in several virulence profiles, as well as high percentages of hemolytic and proteolytic activity, demonstrating the necessity of further epidemiological surveys of Aeromonas species pathogenicity in an aquatic recreational lagoon.

Keratinolytic activity of Bacillus subtilis LFB-FIOCRUZ 1266 enhanced by whole-cell mutagenesis.

Discarded feathers represent an important residue from the poultry industry and are a rich source of keratin. Bacillus subtilis LFB-FIOCRUZ 1266, previously isolated from industrial poultry wastes, was used in this work and, through random mutation using ethyl methanesulfonate, ten strains were selected based on the size of their degradation halos. The feather degradation was increased to 115% and all selected mutants showed 1.4- to 2.4-fold increase in keratinolytic activity compared to their wild-type counterparts. The protein concentrations in the culture supernatants increased approximately 2.5 times, as a result of feather degradation. The mutants produced more sulfide than the wild-type bacteria that produced 0.45 µg/ml, while mutant D8 produced 1.45 µg/ml. The best pH for enzyme production and feather degradation was pH 8. Zymography showed differences in the intensity and molecular mass of some bands. The peptidase activity of the enzyme blend was predominantly inhibited by PMSF and EDTA, suggesting the presence of serine peptidases. HPTLC analysis evidenced few differences in band intensities of the amino acid profiles produced by the mutant peptidase activities. The mutants showed an increase in keratinolytic and peptidase activities, demonstrating their biotechnological potential to recycle feather and help to reduce the environmental impact.

Detection of human fecal contamination by nifH gene quantification of marine waters in the coastal beaches of Rio de Janeiro, Brazil.

The identification of fecal pollution in aquatic ecosystems is one of the requirements to assess the possible risks to human health. In this report, physicochemical parameters, Escherichia coli enumeration and Methanobrevibacter smithii nifH gene quantification were conducted at 13 marine waters in the coastal beaches of Rio de Janeiro, Brazil. The pH, turbidity, dissolved oxygen, temperature, and conductivity, carried out by mobile equipment, revealed varied levels due to specific conditions of the beaches. The bioindicators' enumerations were done by defined substrate method, conventional, and real-time PCR. Six marine beach sites (46 %) presenting E. coli levels in compliance with Brazilian water quality guidelines (<2500 MPN/100 mL) showed nifH gene between 5.7 × 109 to 9.5 × 1011 copies. L-1 revealing poor correlation between the two approaches. To our knowledge, this is the first inquiry in qPCR using nifH gene as a biomarker of human-specific sources of sewage pollution in marine waters in Brazil. In addition, our data suggests that alternative indicator nifH gene could be used, in combination with other markers, for source tracking studies to measure the quality of marine ecosystems thereby contributing to improved microbial risk assessment.

Fecal pollution source tracking in waters intended for human supply based on archaeal and bacterial genetic markers.

The determination of fecal pollution sources in aquatic ecosystems is essential to estimate associated health risks. In this study, we evaluate eight microbial source tracking (MST) markers including host-specific Bacteroidales and Methanobrevibacter spp. for discrimination between human, bovine, equine, and swine fecal contamination in waters intended for human supply. Overall, the novel host-specific archaeal and bacterial primers proposed in this study demonstrated high sensitivity and specificity. Markers for the Archaea domain were more prevalent in the fecal and water samples studied. We conclude that the investigations regarding the sources of fecal pollution in public water supplies can contribute to improve the quality of human health. To our knowledge, this is the first analysis using both archaeal and bacterial fecal MST markers on tropical water bodies of Rio de Janeiro city, Brazil.