Erythritol is a low calorie sucrose substitute, naturally occurring in fruit and honey. Erythritol is industrially produced by osmophilic yeast using fermentation process with glucose or sucrose and purification processes based on ion chromatography, decolorization and crystallization. High production costs from traditional carbon sources such as glucose and high costs of purification of erythritol cause to look for alternative low-cost technologies of sweetener production. The aim of this study was to develop the purification process of fermentation broth rich in erythritol, which was obtained from waste glycerol from biodiesel industry by Yarrowia lipolytica yeast. The parameters of purification process such as purity of crystals were investigated. As a result of two-stage crystallization process the crystals of erythritol with 99.5% of purity were obtained with the overall yield of the process of 91.5%. The costs of the production of erythritol might be decreased by using the fermentation process without salt addition and the purification without desalination.

The subject of the presented work were preliminary studies to obtain Trichoderma biopreparation, based on liquid culture medium. Cultures of filamentous fungi can be an alternative to solid state fermentation (SSF) in obtaining spore-based biopreparations, relevant in the protection of plants against phytopathogens. The study focused on the assessment of the biological value of 6 strains of Trichoderma cultured in liquid potato medium, complemented with lignocellulosic waste, such as beet, wheat bran and apple pomace. Out of the tested strains after the assessment of the hydrolytic activity level (cellulases, xylanases polygalacturonases, lichenases and laminarinases), 2 strains were selected for cultivation in bioreactors, intended for the obtaining of a biopreparation. After the cultures, biomass was centrifuged, along with the remains of the ligninocellulosic material, dried in a stream of hot air. Survival rate of spores was assessed, both, directly after drying and after 3 months of storage. The strain TRS40 was characterized by higher viability (72%) as compared with the TRS43 strain, which ensures activity of the biopreparation.

Nowadays cryopreservation is considered to be the most efficient method for the protection of plant genetic resources. The technology is attracting more and more attention among both research and commercial laboratories worldwide. However, it is a relatively new technique, which still requires a lot of exploration. The influence of cryopreservation on the plant material genetic stability is one of the most interesting aspects. Due to the high costs and complexity of specimens preparation, the histological and ultrastructural observations are performed infrequently. The contemporary research suggest, that meristematic cells with dense cytoplasm and low level of hydration are the most suitable for cryopreservation. More differentiated cells with larger vacuoles do not survive the storage in liquid nitrogen, although sometimes it is possible for the young parts of leaf primordia. Usually cryopreservation does not alter the cell structure. It is observed occasionally, however, that the pretreatment and dehydration steps may cause some more or less reversible changes (e.g. starch accumulation), which can affect the explant morphogenetic response/potential.

In the present day, the enzyme industry is looking for the highest activity. They can be obtained using methods of their mutagenesis. Site-directed mutagenesis techniques allow changes in a specific site in the amino acid sequence of proteins. These include the primer extension method, QuikChange PCR, MegaWhop PCR, GeneTailorT.Site-Directed Mutagenesis System, OmniChange PCR. These techniques can also be used to study the meaning of specific amino acids in the protein. In case we do not know which amino acids are best to replace, which would be best for the selected site, then we can use saturation mutagenesis. The following article describes these methods and how they can be used.

Residential buildings, during their lifetime, even while maintaining all available high-quality materials, are exposed to e.g. improper humidity or aeration engendering uncontrolled occupation by a variety of microorganisms, especially moulds. Besides the aspect of human health, such microorganisms must possess specific biochemical mechanisms, allowing them to colonize uncommon niches. The inquired 19 fungal strains, isolated from walls and slats of building interiors in Opole and Lower Silesia were tested for their enzymatic activities relevant from biotechnological point of view. It was demonstrated that the expression of cellulases (max 0.08 U/mg), xylanases (0.28 U/mg), polygalacturonases (0.018 U/mg), chitinases (0.048 U/mL) and laminarinases (0.43 U/mL) was inherent in the majority of the isolates.

The usefulness of Scepter^TM cell counter analyzer (produced by Merck) was tested to assess the physiological and morphological state of distillers’ yeast in conditions of ethanol stress. Yeast cells were divided into four size classes and on the basis of their structure, the physiological and morphological status of the analyzed yeast populations was determined. Measurements of the amount and size of yeast cells with the Scepter^TM cell counter are simple, fast and accurate. This device has a large application potential in ethanolic fermentation studies using yeast both in scientific research and in industrial plants.

The aim of the work was to present and compare the basic statistical parameters of titrimetric and HPLC methods of determination of oxalic acid concentration in fermentation liquid after A. niger cultivation on medium with sucrose as a carbon source. Both methods were tested with oxalic, citric and gluconic acids standards. Moreover, the HPLC analysis was done in order to determine the constitution of the fermentation liquid after biomass removing before and after calcium oxalate precipitation. Presented results show that both methods are linear, precise and accurate in the tested range. The reaction of oxalic acid with calcium chloride effects in over 99.8% precipitation of the oxalate in the fermentation broth sample, but the co-precipitation of citrate and gluconate in maximum amount of 3.4 g⋅dm^-3 occurs. Despite that the titrimetric method is reliable and still used to determine the concentration of oxalic acid in liquids.

By using genetic engineering to improve yeast strains, it is often necessary to distinguish the transformants obtained. The purpose of the study was to compile a RAPD-PCR assay with four microsatellite primers: (GTG)₅ , (GAC)₅ , (GACA)₄ and M13, and phylogenetic analysis for differentiation of yeast strains Yarrowia lipolytica obtained by homologous or heterologous transformation with a transgenic SUC2 from Saccharomyces cerevisiae under the control of the XPR2 promoter and flanked by URA3 gene fragments from Y.lipolytica. For several transformants, the presence of the SUC2 gene was confirmed by PCR with specific primers and hybridization probe. The phylogenetic analysis of 20 strains was performed on the basis of a dendrogram, prepared with similarity matrices obtained from RAPD-PCR results. The applied technique with one exception enabled the homologous and heterologous transformants to be grouped into two separate clusters with 79% of similarity. The first group included the parent strain Y.lipolytica A-101 and 10 of 11 Suc⁺Ura⁺ clones (B56-5, B60-4, B14-6, B10A-5, B7-6, B59-3, KLON1, KLON10, B58-2, B61-5). The second group (except for strain B62-1 with Suc⁺ Ura⁺ phenotype) included clones B1-1, B9-2, A50 presented Suc^-Uraphenotype.

The aim of this study was to investigate the efficiency of flax transformation performed via Agrobacterium rhizogenes. The work presents the preliminary data obtained after transformation of flax (Linum usitatissimum L.) of oil (Opal) and fibrous (Nike) cultivars, which was performed with A. rhizogenes strain ATCC 15834. Applied method for transformation was injection of bacteria suspension to flax explants. The results indicate that the used strain of bacteria was virulent to both tested flax cultivars. The highest efficiency of transformation was noticed for Nike cultivar, in which the transformation frequency reached 82%.

The human digestive system is the site of colonization of over 500 different species of bacteria. The number and diversity of bacteria is relatively small in the stomach and increases as the food moves towards the small intestine, ileum and colon. Disorders in the microflora of the human gastrointestinal tract are closely related to lifestyle, diet, pharmacotherapy, exposure to stress and age. In the aging organism there are many changes, both related to the physiology of individual systems and to the psychological aspect. One of them concerns changes in the quantitative and qualitative composition of gastrointestinal microbiota. The work presents and characterizes the most important factors affecting dysfunctions in the digestive system of older people. In the case of quantitative and qualitative disturbances in the gastrointestinal microbiota, the use of liquid probiotic preparation, the effect of which has been investigated and presented in the following work, has a positive effect.

An alternative to eating highly processed food is fermented food, which has been used for centuries in traditional Polish cuisine, but also in the world. The probiotic microorganisms contained in this type of food determine the proper functioning of the digestive system, but also as the latest research indicated of the central nervous system. Fermented products should be more widely disseminated, not only for valuable flavors, but also because of proven health significance.

A beer recipe with a 50% share of unmalted sorghum and an addition of smoked malts was developed. The research material was the grain of two sorghum cultivars (white and red) and barley malts: pilsen, smoked with cherry wood and smoked with beech wood. Two yeast strains Saccharomyces cerevisiae were used in the fermentation of worts: Safale US-05 and Safbrew WB-06. 12 variants of beers consisting of different types of malt, sorghum grain and yeast strain were prepared. The sorghum variety and barley malts did not affect the physico-chemical parameters of beers. All received beers were characterized by good fermentation, higher in variants fermented by yeast WB-06. In the sensory assessment, the tasters positively distinguished beer with the addition of smoked beech malt.