Water quality comparison between a supply network and household reservoirs in one of the oldest cities in Brazil.

Water is an essential good for human life. This study aimed to verify the effects of household reservoirs on the physicochemical and microbiological characteristics of water in the municipality of São Mateus, Brazil, founded on 21 September 1544. Samples were collected in 83 residences, two samples per residence, one from the supply network and another from the household reservoir, making a total of 166 samples. The pH values, the free residual chlorine content and the turbidity values were determined. For the microbiological analysis, the defined substrate technology was used, allowing the simultaneous detection and identification of total coliforms and Escherichia coli. The results showed that the samples from household reservoirs were more contaminated than those from the public supply network (p = 0.008). The high degree of microbiological contamination of the two groups may be directly associated to the reduced residual chlorine content in the samples, especially those from household reservoirs.

Bovicin HC5 and nisin reduce Staphylococcus aureus adhesion to polystyrene and change the hydrophobicity profile and Gibbs free energy of adhesion.

Staphylococcus aureus is an opportunistic pathogen often multidrug-resistant that not only causes a variety of human diseases, but also is able to survive on biotic and abiotic surfaces through biofilm communities. The best way to inhibit biofilm establishment is to prevent cell adhesion. In the present study, subinhibitory concentrations of the bacteriocins bovicin HC5 and nisin were tested for their capability to interfere with the adhesion of S. aureus to polystyrene. Subinhibitory dosages of the bacteriocins reduced cell adhesion and this occurred probably due to changes in the hydrophobicity of the bacterial cell and polystyrene surfaces. After treatment with bovicin HC5 and nisin, the surfaces became more hydrophilic and the free energy of adhesion (∆G(adhesion)) between bacteria and the polystyrene surface was unfavorable. The transcriptional level of selected genes was assessed by RT-qPCR approach, revealing that the bacteriocins affected the expression of some important biofilm associated genes (icaD, fnbA, and clfB) and rnaIII, which is involved in the quorum sensing mechanism. The conditioning of food-contact surfaces with bacteriocins can be an innovative and powerful strategy to prevent biofilms in the food industry. The results are relevant for food safety as they indicate that bovicin HC5 and nisin can inhibit bacterial adhesion and consequent biofilm establishment, since cell adhesion precedes biofilm formation.

Genome organization and assessment of high copy number and increased expression of pectinolytic genes from Penicillium griseoroseum: a potential heterologous system for protein production.

The fungus Penicillium griseoroseum has the potential for application on an industrial scale as a host for the production of homologous and heterologous proteins, mainly because it does not produce some mycotoxins or secrete proteases under the growth conditions for pectinase production. However, for the fungus to be used effectively as an expression heterologous system, an understanding of the organization of its genome, as well as the mechanisms of gene expression and protein production, is required. In the present study, the size of the P. griseoroseum genome was estimated to be 29.8-31.5 Mb, distributed among four chromosomes. An analysis of plg1 and pgg2 pectinolytic genes expression and copy number in recombinant multi-copy strains of P. griseoroseum demonstrated that an increase in the number of gene copies could increase enzyme production, but the transcription could be affected by the gene integration position. Placing a copy of the plg1 gene under the control of the gpd promoter of Aspergillus nidulans yielded a 200-fold increase in transcription levels compared to the endogenous gene, and two copies of the pgg2 gene produced an 1100-fold increase compared with the endogenous gene. These results demonstrated that transcription, translation, and protein secretion in the fungus P. griseoroseum respond to an increased number of gene copies in the genome. The processing capacity and efficiency of protein secretion in P. griseoroseum are consistent with our premise that this fungus can be used for the industrial-scale production of several enzymes.