Biomass and Biopolymer Production using Vegetable Wastes as Cheap Substrates for Extremophiles

Abstract

Waste biomass is continuously generated in huge amounts by cultivation, harvest, selection and industrial transformation of fruits, vegetables and crops that are exploited for production of foods, chemicals, fertilizers and bioenergy. The management and the proper disposal of such biomass (whose levels in Italy reach about 22,000,000 t/y) is a worldwide problem both in environmental and in economical terms. On this basis we investigated a possible strategy of valorization of these residues, with particular regard to some agro-industry wastes and crop residues. Agro-industrial wastes included tomato and lemon processing wastes, fennel and carrot selection residues that are produced by some of the most important activities of Italian food industry sector. Crop residues selected for this study included giant roots and cardoon residues, that are two lignocellulosic cultures that in recent year attracted attention in relation to their potential use in bioenergy (bioethanol, biodiesel) production. All the wastes were tested as growth media in batch fermentation (BF) and dialysis fermentation (DF) modes for the production of biotechnologically useful microorganisms, namely two thermophilic species and two halophilic species. All the wastes afforded appreciable microbial biomass production and moreover they positively affected also production of enzymes and biopolymers by the studied extremophiles. The results obtained encourage to exploit such wastes as zero cost fermentation media for biotechnologically useful microorganisms, thus also providing an alternative and less environmental impacting method for vegetable wastes management.