Biotrasformazioni di Acidi Biliari

In this PhD thesis a wide sampling of microrganisms from Ecuadorean slaughterhouses to use for biotransformations of the bile acids is reported. The aim of this project is the requirement both to have a different pathway to the chemical synthesis of ursodeoxycholic acid, active principle for gallstone solubilisation, and to recycle bile acids considered as “waste products”. In the first year the states of work of various slaughterhouses situated in the different Ecuadorean provinces have been studied. The Latacunga and Cayambe slaughterhouses have been selected to sample the microrganisms because of their poor sanitary conditions. This offers a higher chance to isolate microrganisms adapted to a “polluted environment” and with a potential ability to biotransform bile acids. The selection and purification of the microrganisms have been carried out in the labs of the Universidad Politecnica Salesiana of Quito (Ecuador). In the second year, a preliminary screening of the isolated microrganisms was carried out with various bile acids (i.e. deoxycholic, hyodeoxycholic, and cholic acid) in Biocatalysis and Biotransformations lab of the Department of Life Sciences and Biotechnologies of the University of Ferrara. The screening has demonstrated the ability of many microrganisms (bacteria and fungi) to give oxidation products of the various hydroxylic functions in C-3 and C-7 together with other unidentified products. In the third year, all the useful reactions have been repeated on preparative scale and the biotransformation products characterized by 1H e 13C NMR spectroscopy and Mass spectrometry. Among the microrganisms the strain MM B14, in particular, has been studied because of its ability to biotransform both deoxycholic and hyodeoxycholic acid giving various products and one of them unknown. The strain has been identified, sequencing his genomic DNA on a level of the sequence of the ribosomal RNA 16S, as Pseudomonas migulae. The new compound has been fully characterized. Other biotransformations are in progress. The research project will continue in Ecuador with new sampling to have new strains to test.