L. Sergio

Selection of non-conventional yeasts and their use in immobilized form for the bioremediation of olive oil mill wastewaters.

The yeast population dynamics in olive wastewaters (OMW), sampled in five mills from Salento (Apulia, Southern Italy), were investigated. Three hundred yeasts were isolated in five industrial mills and identified by molecular analysis. Strains belonging to Geotrichum, Saccharomyces, Pichia, Rhodotorula and Candida were detected. Five G. candidum strains were able to grow in OMW as the sole carbon source and to reduce phenolics, chemical oxygen demand (COD) and antimicrobial compounds. One G. candidum isolate was selected for whole-cell immobilization in calcium alginate gel. The COD and phenolic reduction obtained with immobilized cells showed a 2.2- and 2-fold increase compared to the removal obtained with free cells, respectively. The immobilization system enhanced yeast oxidative activity by avoiding the presence of microbial protease in treated OMW. To our knowledge, this is the first report on G. candidum whole-cell immobilization for OMW bioremediation.

Purification, biochemical characterization and cloning of a new cationic peroxidase isoenzyme from artichoke.

A cationic soluble peroxidase isoenzyme (CysPrx) has been purified and characterized from artichoke (Cynara cardunculus subsp. scolymus (L.) Hegi) leaves by combination of aqueous two phase extraction, ion exchange chromatography, and gel filtration. The purification fold was 149 and the activity recovery 5.5%. CysPrx was stable from 5 to 45 °C with a pH optimum around 5.5; the pI was 8.3 and the MW of 37.7 ± 1.5 kDa. MALDI-TOF MS analysis provided partial peptide sequences and resolved CysPrx isoenzyme into two putative isoforms. The presence of these isoforms was confirmed by the isolation of full-length cDNA encoding CysPrx that generate two slightly different sequences coding for two putative CysPrx: CysPrx1 and CysPrx2. The obtained MS peptides showed a 35% coverage with 100% identity with the two CysPrx deduced protein sequences. A molecular modeling analysis was carried out to predict in silico the protein structure and compare it with other plant Prx structures. Considering that CysPrx is quite stable, the study carried out in this paper will offer new insights for the production of the recombinant protein for utilization of CysPrx as an alternative Prx for food technology, biomedical analysis and bioremediation.