Comparative study of single cultures and a consortium of white rot fungi for polychlorinated biphenyls treatment.

AIMS: To evaluate the mycoremediation of polychlorinated biphenyls (PCBs) by either single cultures or binary consortia of Pleurotus pulmonarius LBM 105 and Trametes sanguinea LBM 023. METHODS AND RESULTS: PCBs tolerance, removal capacity, toxicity reduction and ligninolytic enzyme expression were assessed when growing single culture and binary consortium of fungus in 217 mg l-1 of a technical mixture of Aroclor 1242, 1254 and 1260 in transformer oil. A decrease in tolerance and variation in ligninolytic enzyme secretion were observed in PCB-amended solid media. Pleurotus pulmonarius LBM 105 mono-culture was able to remove up to 95·4% of PCBs, whereas binary consortium and T. sanguinea LBM 023 could biodegrade about 55% after 24 days. Significant detoxification levels were detected in all treatments by biosorption mechanism. CONCLUSIONS: Pleurotus pulmonarius LBM 105 in single culture had the best performance regarding PCBs biodegradation and toxicity reduction. Ligninolytic enzyme secretion changed in co-culture. SIGNIFICANCE AND IMPACT OF THE STUDY: The evaluation of PCBs bioremediation effectiveness of basidiomycetes consortium in terms of PCB removal, toxicity and ligninolytic enzyme production to unravel the differences between using individual cultures or consortium has not been reported. The results from this study enable the selection of P. pulmonarius LBM 105 mono-culture to bioremediate PCBs as it showed higher efficiency compared to binary consortium with T. sanguinea LBM 023 for potential decontamination of PCB-contaminated transformer oil.

Isolation of a laccase-coding gene from the lignin-degrading fungus Phlebia brevispora BAFC 633 and heterologous expression in Pichia pastoris.

AIMS: Isolate and characterize a laccase-encoding gene (lac I) of Phlebia brevispora BAFC 633, as well as cloning and expressing cDNA of lac I in Pichia pastoris. And to obtain a purified and characterized recombinant laccase to analyse the biotechnological application potential. METHODS AND RESULTS: Lac I was cloned and sequenced, it contains 2447 pb obtained by PCR and long-distance inverse PCR. Upstream of the structural region of the laccase gene, response elements such as metals, antioxidants, copper, nitrogen and heat shock were found. The coding region consisted of a 1563-pb ORF encoding 521 amino acids. Lac I was functionally expressed in P. pastoris and it was shown that the gene cloned using the α-factor signal peptide was more efficient than the native signal sequence, in directing the secretion of the recombinant protein. Km and highest kcat /Km values towards ABTS, followed by 2,6-dimethylphenol, were similar to other laccases. Lac I showed tolerance to NaCl and solvents, and nine synthetic dyes could be degraded to different degrees. CONCLUSIONS: Lac I-encoding gene could be successfully sequenced having cis-acting elements located at the regulatory region. It was found that lac I cDNA expressed in P. pastoris using the α-factor signal peptide was more efficient than the native signal sequence. The purified Lac I exhibited high tolerance towards NaCl and various solvents and degraded some recalcitrant synthetic dyes. SIGNIFICANCE AND IMPACT OF THE STUDY: The cis-acting elements may be involved in the transcriptional regulation of laccase gene expression. These results may provide a further insight into potential ways of optimizing fermentation process and also open new frontiers for engineering strong promoters for laccase production. The Lac I stability in chloride and solvents and broad decolorization of synthetic dyes are important for its use in organic synthesis work and degradation of dyes from textile effluents respectively.

[Phosphotyrosine phosphatase SHP-1, somatostatin and prostate cancer]. / Fosfotirosina fosfatasa SHP-1, somatostatina y cáncer de próstata.

We review the mechanisms involved in prostatic growth based on androgens and product of neuroendocrine secretion, with special reference to the role of somatostatin (SS) in the inhibition of neoplastic growth. Our contributions in the field confirm the antiproliferative effect of SS on the prostate is mediated by phosphotyrosine phosphatase SHP-1, that is present in human prostate. This enzyme plays a role in the control of prostatic cell proliferation and in the progression of prostate cancer. Besides, we consider its presence may determine the therapeutic potential of SS in the control of prostate cancer.