Molecular characterisation of a versatile peroxidase from a Bjerkandera strain.

The cloning and sequencing of the rbpa gene coding for a versatile peroxidase from a novel Bjerkandera strain is hereby reported. The 1777 bp isolated fragment contained a 1698 bp peroxidase-encoding gene, interrupted by 11 introns. The 367 amino acid-deduced sequence includes a 27 amino acid-signal peptide. The molecular model, built via homology modelling with crystal structures of four fungal peroxidases, highlighted the amino acid residues putatively involved in manganese binding and aromatic substrate oxidation. The potential heme pocket residues (R44, F47, H48, E79, N85, H177, F194 and D239) include both distal and proximal histidines (H48 and H177). RBP possesses potential calcium-binding residues (D49, G67, D69, S71, S178, D195, T197, I200 and D202) and eight cysteine residues (C3, C15, C16, C35, C121, C250, C286, C316). In addition, RBP includes residues involved in substrate oxidation: three acidic residues (E37, E41 and D183)--putatively involved in manganese binding and H83 and W172--potentially involved in oxidation of aromatic substrates. Characterisation of nucleotide and amino acid sequences include RBP in versatile peroxidase group sharing catalytic properties of both LiP and MnP. In addition, the RBP enzyme appears to be closely related with the ligninolytic peroxidases from the Trametes versicolor strain.

Microflora evaluation of two agro-industrial effluents treated by the JACTO jet-loop type reactor system.

Jet-loop type reactors developed in our group have been successfully used for biological treatment of winery and olive oil wastewaters. The objective of the present work was to study the influence of the reactor hydrodynamics, causing high shear stress applied on the nozzle and its influence on the composition of the microbial population. Winery and olive oil industry effluents were treated and analysed. Microbial consortia were enriched and selected under different bio-treatment conditions of the effluents. In the case of the winery wastewaters, the isolates identified belong to the genera of Pseudomonas and Bacillus. Saccharomyces cerevisiae was also present in the consortia but no filamentous fungi were detected. In the case of the olive oil wastewaters, Bacillus megaterium 2 was the predominant microorganism. It was not detected any type of fungi.

Decolourisation of Remazol Brilliant Blue R via a novel Bjerkandera sp. strain.

A novel strain of Bjerkandera sp. (B33/3), with particularly high decolourisation activities upon Poly R-478 and Remazol Brilliant Blue R (RBBR) dyes, was isolated. The role of the ligninolytic extracellular enzymes produced by this strain on decolourisation of RBBR was studied in some depth. The basis of decolourisation is an enzyme-mediated process, in which the main enzyme responsible is a recently described peroxidase with capacity for oxidation of manganese, as well as veratryl alcohol and 2,6-dimethoxyphenol in a manganese-independent reaction.