The strain of Absidia coerulea 93 was used to investigate the transformations of C₁₈ steroids: 19-nortestosterone and its 17α-alkyl and ethynyl derivatives. 19-nortestosterone and its 17α-alkyl derivatives were transformed, forming hydroxylated products. It was found that the position of the introduced hydroxyl group depended on the structure of the substrate: 19-nortestosterone underwent hydroxylation at C15, whereas 19-nortestosterone 17α-alkyl derivatives were predominantly hydroxylated at 7α-position. Besides hydroxylation introduction of double bond C6-C7 was observed. It was noticed that 19-nortestosterone 17α-ethynyl derivatives were not transformed in Absidia coerulea culture.

Crude glycerol from biodiesel industry, containing 350 g∙dm^-3 of glycerol, was used as a substrate for citric acid production by acetate negative mutant of Yarrowia lipolytica Wratislavia AWG7 in fed-batch experiment. This strain produced 133,4 g∙dm^-3 of citric acid and 2,7 g∙dm^-3 of isocitric acid, unwanted product in this process, in 140 h of cultivation. As a results the volumetric citric acid production rate and the citric acid yield reached 0,95 g∙dm^-3h^-1 and 0,67 g∙g^-1, respectively. The total amount of other organic acids such as malic, fumaric and α-ketoglutaric acid produced by the Wratislavia AWG7 strain no exceed 6 g∙dm^-3.Polioles such as erythritol and as well as mannitol were produced in this process also. Concentration of these by-products at the and of process were 9,8 i 2,7 g∙dm^-3, respectively.

The purpose of this study was to evaluate the ability of five strains of yeasts Yarrowia lipolytica JII1a, JII1b, JII1c, PII6a, PII6b, isolated from Polish mould cheese, to secrete extracellular proteolytic and lipolytic enzymes. After their cultivation for 48 hours in media containing different carbon and nitrogen sources the level of population growth as well as the activities of proteolitic enzymes (at pH 3,0 and 7,5 against hemoglobin and casein, respectively) and lipolytic enzymes (against butter oil and tributyrine) were determined. It was shown that investigated strains of Y. lipolytica exhibited different growth and enzyme biosynthesis pattern depending on the carbon and nitrogen source present in medium. Populations of all studied strains reached the level of 1,5-2,1 ∙ 10⁸ cells mL^-1 in medium containing glucose and casein as the carbon and nitrogen sources, respectively. Substitution of glucose by plant oils resulted in decrease of their growth. Similar effect was observed when casein was substituted by more simple nitrogen sources. The exception was strain JII1 c, which growth was not affected by nitrogen component replacement. The changes in composition of growth medium influenced on the biosynthesis level of hydrolytic enzymes. The presence of glucose stimulated the production of extracellular aspartic proteinase. Also whey proteins favoured the biosynthesis of this proteinase. Whereas applying of the olive oil enhanced biosynthesis of serine proteinase. The presence of plant oils, including olive oil, in growth medium promoted the secretion of lipolytic enzymes.