Last years brought very fast development of molecular studies in fruit plants. Peach, because of its relatively small genome became a model plant for such studies. Genome maps, constructed on the base of molecular markers became in the last decade one of the main tools for studies of quantitative traits. Mapping of QTLs with molecular markers and improvement of quantitative traits is very important goal in plant breeding programmes. For fruit plants, especially for fruit trees elaboration of new, molecular techniques of early selection of seedlings that posses valuable traits became priority task of breeding programms. Such techniques enable selection several years earlier than in the case of classical selection in the field.

In this paper strains of filamentous fungi from Trichoderma genus for their ability to extracellular cellulases and xylanases biosynthesis were examined. Two strains were cultivated in liquid Mandels-Sternburg medium in presence of waste corn cobs as a main carbon source. The submerged cultures were carried out for 14 days and FPase, CMCase, xylanase activities and pH level were determined. The maximum synthesis of some hydrolases was observed in 10-14 days and their activities were depended on glucose (supplementary soluble carbon source) and pH. The xylanases biosynthesis was the highest and T. harzianum T33 strain produced maximum xylaneses activity (72,2 nKat·cm^-3).

Yarrowia lipolytica Wratislavia K1 strain was grown in nitrogen-limited aerobic cultures on pure glycerol, raw glycerol, glucose and mixture of glycerol and glucose. Two mixtures were used: first with pure glycerol and second with raw glycerol. Kinetic parameters of growth and citric acid production were determined. The highest biomass yield (Y_X/S=0.6 g∙g^-1) was obtained in the medium containing glucose as a carbon source. The highest citric acid concentration of 37.5 g∙dm^-3 and citric acid yield of 0.37 g∙g^-1 were reached with a medium containing pure glycerol. In all processes Y. lipolytica Wratislavia K1 strain produced sugar alcohols such as erythrytol and mannitol. The highest concentration of these polyols (erythrytol and mannitol) were determined in the culture containing pure glycerol, 19.3 g·dm^-3 and 10.1 g·dm^-3, respectively.