The parameters of pyruvic acid production by Yarrowia lipolytica A-10 strain from pure and crude glycerol at different C:N ratio (26.8 and 17.9) were compared. The highest pyruvic acid concentration was achieved in culture with C:N ratio 26.8, using crude glycerol as a substrate. After 92 hours of cultivation yeast produced 58.2 g∙dm^-3 of pyruvic acid with yield 0.39 g∙g^-1 and volumetric production rate 0.63 g∙dm^-3∙h^-1. Biomass from this process was separated from cultivation medium and determined for quantity of protein and intracellular fat. Cells of Yarrowia lipolytica A-10 were composed of 43.9% of protein and 10.42% of fat, in which unsaturated acids represented the majority of total fatty acids (linoleic acid, 18:2 – 33.94% and oleic acid, 18:1 – 30.98%).

The addition of various surfactants to the culture media increases the permeability of cell membranes in bacteria, yeast and filamentous fungi, thereby increasing the secretion of extracellular metabolites. The aim of this study was to evaluate the effect of Span 20 on erythritol production yield and the productivity of erythritol from crude glycerol by Yarowia lipolytica Wratislavia K1 in fed-batch culture. The addition of Span 20 to the culture media with crude glycerol as a carbon source (300 g∙dm^-3) caused about 10% increase in erythritol production, compared to the culture without surfactant. In the presence of Span 20 the yeast produced 166 g∙dm^-3 of erythritol, which corresponded to a productivity of 1.14 g∙dm^-3∙h^-1 and a yield of 0.55 g∙g^-1. The results of our study shown, that Span 20 may be use as a stimulating agent of erythritol production in an industrial scale. Moreover, Span 20 is cheap, non-toxic and well tolerated by organisms.

The article presents a relatively new area of studies – proteomics – which investigates the composition, structure and function of proteins and the interactions among proteins occurring in cells. Then the most important analytical techniques of proteomics are described: two-dimensional electrophoresis, matrix-assisted laser-desorption ionization time of flight (MALDI-TOF) and electrospray ionization (ESI) mass spectrometry techniques. In order to introduce issues related to proteomics, the examples of proteome microorganisms including specific pathogens (Staphylococcus aureus, Vibrio cholerae, Bacillus subtilis, Mycobacterium avium, Borrelia spp., Aspergillus flavus) are presented. Based on the results of the proteome, in this review the following applications of proteomic have been documented: species identification, the metabolism studies of microorganism and host-pathogen interactions and even the possibility of differentiating the enzymatic potential of the microorganisms utilizing lignocellulosic biomass. The potential of proteomic analysis was discussed in the summary of the article.