Απομόνωση μικροοργανισμού με δυνατότητα βιοδιάσπασης υψηλή συγκέντρωση γλυκερόλης

Abstract

The aim of the thesis was the isolation of a strain through microbial processes from various environmental samples, which have the ability to biodegrade high concentrations of glycerol into high added-value chemicals. Glycerol is the main by-product of biodiesel production at ratio 1 to 10, by the esterification of triglycerides found in various fats and fatty acids. During the last decade, the worldwide biodiesel industry experienced exponential growth in production rates and as a result the creation of large glycerol stocks which cannot be released into the environment. Combined with the lack of efficient use of glycerol in large quantities and the minimize of glycerol’s financial value to an extent of waste, there is a keen interest to explore new modes of exploitation. Succinic acid is a substance with various applications in many fields such as pharmaceutical, agricultural crops, in the food industry and the chemical industry. Due to the specialized usage, the rising cost of fossil raw materials and the difficulty of the production, glycerol is regarded as a high monetary value substance which can be produced biotechnological by microorganisms. The literature study showed that the isolation of such microorganism required the sampling of various environmental samples such as Fresh Fruits, Raw Glycerol, Primary Sludge, Secondary Sludge, Activated Sludge, Samples of microorganisms isolated from Oranges and from Beef Stomachs, which they showed a potential in bioconverting glycerol into succinic acid. Following the appropriate microbiological methods (Empowerment samples, plates, creating a pure culture plates, creating pure liquid culture, isolation of the microorganism) and analytical techniques (spectroscopy UV/Vis, High pressure liquid chromatography HPLC), was made possible the isolation of a strain derived from Beef Stomachs (B.S) This aerobic strain (B.S. B pH 7 pH 5.8) during the experiments showed a good adaptation and growth in high concentrations of glycerol (crude 500ml /L and pure 20ml /L), as well as great efficiency on the glycerol’s biodegradation into succinic acid and in lesser amounts various other substances. Additional experiments were performed in order to observe the microorganism’s development in a function of changes happened in the environmental conditions of incubation. Factors studied include changes in salinity, pH, glycerol’s concentration, temperature and the use of another nutritious substrate for studying the change in development. The results showed that the use of particular sulphates and phosphates salts ((NH4)2SO4 and K2HPO4.2H2O) or at a temperature of 30 oc can result the microorganism’s grown in a wide range of active acidity (pH 5.8-7) and give a great development. Also the experiments showed that the smaller amount of raw and pure glycerol is used, the faster is the growth. Moreover the use of some other more efficient nutrients (yeast extract) can change glycerol’s biodegradation time.