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Davide Zannoni

Alma Mater Honorary Professor

Alma Mater Studiorum - Università di Bologna


Keywords: Metalloids PCBs Monooxygenases Bioremediation Xenobiotics Bacterial energetics Butane Phototrophs Metals Bacteria

Research lines: This specific research line aims to clone and characterize, genetically and physiologically, the carrier involved in the a-specific mechanism though which the toxic oxyanion tellurite is taken up by facultative photosynthetic bacteria; 2. This second research line aims to determine the toxicity levels of selenite under various physiological growth conditions along with the setting up of a rapid and innovative methodology to determine the cytosolic uptake of this oxyanion in order to understand the interaction between selenite and the microrganism. 3. The aim of this project is to develop a method to determine metal(lloid)s and antibiotics susceptibility in bacterial biofilms and planktonic cells; 4. This lines involves a series of procedures to study the co-metabolic degradation under aerobic conditions of alyphatic chlorinated hydrocarbons (vinyl cloride, chloroform, ethylene chloride, chloethane) in bacteria growing on buthane and propane.

1. The phototrophic bacterium Rhodobacter capsulatus is particularly resistant to the toxic oxyanion tellurite. The cytotoxic action of this metalloid is due to the pro-oxidant activity of this metalloid. Preliminary data indicate that tellurite get into cells by means of an uncharacterized acetate carrier. This project aims to clone and characterized, both genetically and physiologically, this carrier. Cloning will be performed on the basis of a bioinformatics approach using the data presently available in silico or, alternatively, by means of orthodox techniques such as mutagenesis or mutants screening. The carrier functional analysis will be based on tellurite resistance and kinetic parameters along with carrier expression level as a function of growth conditions.


2. Phototrophic bacteria are particularly resistant to toxic oxyanions which are included into group VI A of the periodic table. A few years ago, our research group started a study on the bacterial response against the toxic effects of tellurite in Rhodobacter capsulatus.  Along with tellurite, oxyanions such as selenite and selenate are toxic to bacteria and eukaryotes. Selenium, unlike tellurium, is a fundamental micro-elements in metabolisms of living organisms. Further, the oxyanion selenite have an impact on the environment which is much higher than tellurite. Aim of this project is to determine the level of toxicity of selenite under various physiological growth conditions along with setting up a rapid and innovative method to measure the cytosolic uptake of selenite. These data will be necessary to understand the interaction between selenite and bacterial cells.


3. Biofilms are microbial communities adherent to a solid surface which is included into a polymeric exocellular matrix. In spite of the fact that biofilms represent the predominant bacterial form in nature, studies devoted to understand the effects of metals, metalloids and other toxic compounds on biofilms are lacking. This research line will be focused on the development of a methodology to determine bacterial susceptibility against metals, metalloids and antibiotics in both biofilms and planktonic cells. Furthermore, several other aspects will be examined such as: a) RNA-messenger transcription levels; b) protein synthesis; c) phenotypic features of biofilms made by Pseudomononas pseudoalcaligenes KF707 in the presence or absence of meta(lloid)s or antibiotics.


4. This research line, which will be undertaken in collaboration with DICMA-UniBo, involves a study on the co-metabolic degradation of chlorinated aliphatic hydrocarbons (vinyl chloride, chloroform, chloroethylene, chloroethane) by bacteria growing on propane and butane. This research will be directed toward the molecular analysis of bacterial communities by T-RFLP analysis and 16S-DNA sequencing; further, bacterial species belonging to Rhodococcus genus and isolated from bacterial consortia degrading propane and butane will also be analyzed as far as concern their content in monooxygenases. In addition to isolation and sequencing of the genes coding for the monooxygense subunits, their expression as a function of various growth substrates and metabolic pathways will be examined.

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