BIOCATALYTIC AND FERMENTATIVE APPROACHES FOR THE PRODUCTION OF ADDED VALUE COMPOUNDS USING WILD TYPE AND GENETICALLY MODIFIED ACETIC ACID BACTERIA

This PhD thesis is divided into four chapters that report the development of different microbial biocatalysts aimed at the valorization of food and biotechnological industrial by-products. The experimental parts are preceded by an introduction aimed to give a background on the impact of biocatalysis on green chemistry and, more generally on circular economy, together with a systematic review of the main molecular biology approaches employed to genetically engineer acetic acid bacteria. The second chapter reports the optimization of a biocatalytic system for the regioselective hydroxylation of different terpenes employing a Mycobacterium sp. CYP153A6 monoxygenase. In chapter 3 and in chapter 4 is described the development of different recombinant acetic acid bacteria strains, aimed at the production of highly added value products, such as perillic acid, starting from limonene, a cheap and highly available substrate derived from the agro-food industry. Limonene was employed as a pure compound (chapter 3) or via fermentation of orange peel wastes (chapter 4). The last chapter deals with the isolation and characterization of a bacterial cellulose (BC) producer strain, namely Komagataeibacter rhaeticus ENS9b, able to produce BC from acetate and crude glycerol, a by-product from the biodiesel production process.