The aim of the present study was to determine the effect of medium components and culture conditions on the activity of alanyl and phenyloanalyl aminopeptidases synthesised by Pseudomonas sp. It was observed that the enzymatic activity is dependent on the composition of the culture medium. The high level of the aminopeptidase activity was achieved on the second day of growth at pH 6.8 at 27 ˚C in the mineral medium enriched with 1% of tryptone. The enrichment of the culture medium with some carbohydrates and mineral salts resulted in the increase of the activity level for both enzymes. The presence of 4% glucose in the medium resulted in a fall of the phenyloanalylaminopeptidases’ activity. In the medium with inorganic carbon and nitrogen, relatively low enzymatic activity was observed.

Two species of fungi: Sclerophoma pythiophila and Epithyrium resinae occurring on forest trees were used as bioreagents in transformations of steroid substrates. The fungi have been shown to oxidize steroid hormone – testosterone and anabolic agents – 19-nortestosterone and 1-dehydrotestosterone. S. pythiophila and E. resinae, were also used to investigate the transformations of testosterone and 19-nortestosterone esters: propionate, isobutyrate testosterone and propionate, phenylopropionate 19-nortestosterone. Besides 17β oxidation, which was observed in all examined substrates, additionally in E. resinae culture, selective reduction of C1-C2 double bond in 1-dehydrotestosterone was observed. Hydrolysis reactions for all testosterone and 19-nortestosterone esters was noticed.

The production of selected extracellular enzymes by Trichoderma reesei M-7 on two different media containing either sweet whey in combination with 4% lactose or solely 4% lactose was examined and compared. It was found that the activity of cellulases expressed as FPU (filter paper unit) in both media differed and was unfavourable for whey containing medium. On the contrary, reverse results were observed for other examined enzymes i.e protease, laminarinase and chitinase which had higher activities on whey then on lactose medium. Furthermore, it was observed that the lactic acid concentration in the cultures of whey medium did not inhibit the secretion of cellulolytic enzymes independent of the initial pH values of the media. One of the reasons for low secretion of cellulolytic and xylanolytic enzymes by Trichoderma reesei M-7 on whey media could be explained by the high level of proteolytic activity which probably caused proteolysis of both cellulases and xylanases. Besides, the acidity of undiluted whey was below 5,5 and thus could inhibit the growth of Trichoderma reesei M-7. The application of whey for successful production of cellulases and xylanases by the examined strain needs identification of factors leading to low secretion of these enzymes and modification of the medium composition of whey.

The aim of the studies was to estimate microbiological contamination of rabbit ground meat samples differently confectioned: vacuum packaged (VP), packaged in modified atmosphere (MAP) and in normal atmosphere (NP). Enumeration of total aerobe mesophile microflora, indicator and physiological groups of bacteria, and Brochotrix thermosphacta was effectuated in the samples directly after packaging and during their storage at 4 ^oC. The number of aerobe mesophile bacteria determined after packaging was 10⁴-10⁵ cfu · g^-1 of meat, and was independent of the packaging gases. During the refrigerated storage, in all samples the growth of bacteria was enhanced and in VP samples the growth of anaerobic bacteria and B. thermosphacta was induced. MAP and VP diminished the rate of growth of bacteria, and the MAP prolonged the lag phase, specially of B. thermosphacta. Therefore, the atmosphere of packaging is important in the term of microbiological meat quality and the packaging system must be considered as one of critical control points of the production of rabbit ground meat.

In this paper we focus on the capability to biosynthesis extra and intracellular lipases by 8 strains of Geotrichum candidum. We value activities against two different substrates: olive oil (JL_O) and glycerol tributyrate (JL_T). As a carbon source in the medium we used rapeseed oil, glucose, and residue oil – waste from fatty industry (1% of each). All tested strains show differentiation in the volume of intra and extracellular lipase activity, according to carbon source in medium, but also kind of substrate in enzymatic tests and also incubation time. Rapeseed oil was the most effective carbon source in lipase synthesis and Geotrichum candidum X5 strain showed the highest extracellular activity of lipase (260 JL_OmL^-1) in given conditions.

The aim of the work was to examine ability of Y. lipolytica A-101 yeast to accumulation of selenium and chromium in biomass during biomass production process in media containing crude rapeseed oil. In shaking cultures limiting growth of Y. lipolytica A-101 yeast concentration of selenium 6 mgdm^-3 Se (IV) and chromium 80 mgdm^-3 Cr (III) was obtained. Yeast of Y. lipolytica A-101 was cultivated in batch culture in stirred tank reactor, containing chemically defined medium, supplemented with selenium or chromium. The results showed that level of selenium or chromium accumulation was dependent on microelements concentration. It was found that elevated concentrations of Se (IV) and Cr (III) in the environment caused a reduction both biomass production, productivity and biomass yield of Y. lipolytica A-101. Concentrations 4 mgdm^-3 Se (IV) and 40 mgdm^-3 Cr (III) was obtained as the best concentrations for Y. lipolytica A-101 biomass production on lipid media.

The aim of the present study was to examine different yeast species ability to utylise glycerol in the pH range from 3.5 to 6.5. Growth kinetics and yield biomass of selected yeast strains in stirred tank reactor on pH 3.5-4.0 media with raw glycerol from a bio-diesel production unit was investigated, also. An automated turbidimetry, Bioscreen C, was used to monitor yeast growth on pure glycerol in the pH range from 3.5 to 6.5. The growth of the yeast was kinetically monitored throughout the incubation period and various growth curves parameters were used as quantitative indicators of yeast growth. Yarrowia lipolytica ATCC 8661 UV’1 strain growth parameters were the highest values and was not dependent on the pH media (ΔOD = 1,70-1,75 i WEW = 3077-3360). Biomass production processes were cerried out with the best growing strains at the pH 3.5-4.0 (Y. lipolytica ATCC 8661 UV’1, Candida robusta ATCC 60 559, C. utilis ATCC 60 558 and C. tropicalis ATCC 60 557). Technological parameters (biomass yield, protein content, productivity and total yield) showed that the best biomass producer from raw glycerol was Y. lipolytica ATCC 8661 UV’1 strain.