Utilizzo di Lactobacillus plantarum per la defenolizzazione di sottoprodotti oleari da utilizzare come biomasse per la produzione di biogas

The aim of this work is the use of olive industry by-products (olive residues, wet pomace, olive mill wastewater and alkaline wastewater derived from debittering Seville method for table olives) to produce renewable energy sources (biogas), through the optimization of pre-digestion phase using biotechnology processes, where the main role is played by microorganisms. The addition of biomasses with a high content of simple and complex phenol compounds holds a high bacteriostatic action against many bacterial species especially the methanogenic bacteria, leading to reduce the production of methane. The contribution of not treated biomasses with a high content of cellulose, pectin and lignin leads to an increase of processing times. Biochemical and molecular tests were carried out to select bacterial strains to use in fermentation trials. A special attention has been focused on three bacterial strains isolated from olive fruits skin of different origin trees, present in the Col lect ion of Microorganisms of the CRA OLI (Lactobacillus plantarum B28, L. plantarum B51 and L. plantarum B124). Oleuropeinolytic activity was assessed by inoculation of these strains in MRS Broth without glucose, added 1% of oleuropein (w/v). Products degradation analysis was performed by HPLC apparatus and adjusting to the specific case, method COI /T.20/Doc. n. 29. November 2009 “Determination of biophenols in olive oils by HPLC”. Oleuropein demolition was followed checking up the formation of hydroxytyrosol. It was tested, besides, both the capacity of growing/fermentation of the bacterial strains in highly acid, in neutral and in strong basic environments that characterize the several starting matrices, and the tolerance at different temperature that could occur during the storage (T 4- 15°C) or inside the digester (T>40°C).