The effects of the use of protective agents (glycerol, sucrose, fructose, maltodextrin, concentration 4 and 8%) on the sacchcarolytic activity of baker’s yeast Saccharomyces cerevisiae during freeze-drying and storage were studied. A material was frozen at -30°C and freeze dried at 40°C/0,63 mbar during 20h. The positive influence on yeasts saccharolytic activity after drying, as compared to the drying without additives, was observed after the use of of 4% glycerol, 8% fructose, 4 and 8% maltodextrin. 8% maltodextrin was the best protective agent during drying and storage at 25°C.

Essential problem in biosynthesis of citric acid (CA) is the purity of process. Even low contamination by izocitric acid (ICA) perturbs crystallization. In the case of CA producers, selected from Yarrowia lipolytica A-101 yeasts strain, the amount of accumulated ICA from glucose, fructose or glycerol did not exceeded some %. The parent strain, on the same substrates, secretes over a dozen % of ICA and over 30% on hexadecane or fatty acids as substrates. The aim of the study was to evaluate kinetics of biosynthesis of CA and ICA by Y. lipolytica A-101 on hexadecane with three agitation rates (600, 300 and 150 rpm). The highest amount of acids (79,3 gL^-1) was obtained with the highest agitation rate (600 rpm). Accumulation of acids was significantly lower (8,5 gL^-1) with the lowest agitation rate (150 rpm). With two higher agitation rates, the amount of accumulated ICA was nearly 60% of the total acids amount. With low agitation rate mainly CA was secreted (70%). On glucose, tested strain secreted 31,7gL^-1 CA and the amount of ICA did not exceeded 10% of total acids .

The aim of conducted studies was to determine genetic and morphological variability of selected Davidia involucrata specimens from Western Pomerania and Berlin us- ing ISSR-PCR technique. The studies were carried out on the Davidia involucrata var. vilmoriniana growing in Germany in the Botanical Garden in Berlin-Dahlem and in Poland, in Pomerania: in the Dendrological Garden in Przelewice, Glinna and Central Cemetary in Szczecin. ISSR technique made it possible to determine genetic variability of the examined specimens. This was done by means of 6 out of 30 ISSR primers used in the experiment. Six primers (802, 807, 810, 819, 839, 840) generated in PCR reactions 64 amplicons, of which: 11 were monomorphic, 31 – polymorphic and 12 – genotype-specific. On average 1 primer generated 10 amplicons which ranged from 2550 to 270 bp.