In the present paper the research was focused on mutual interaction between three strains of Trichoderma and nine phytopathogenic moulds. Dual biotic test was made in media imitating natural environmental conditions (milled grain of four typical cereals), which was a modification of a standard procedure. Every tested and test-strain exploited cereals as the source of nutritive compounds to a different extent, which was exhibited by various growth speed and changes in interactions. The highest antagonistic ability was demonstrated for Trichoderma harziamum T33, which in many cases caused complete growth inhibition of tested moulds. Neither of the phytopathogenic strains had a negative influence on the T33 strain, in contrast to the rest of Trichoderma strains

In this research we investigated releasing of biofilm exopolymeric substance by three strains of Bacillus cereus species. We observed the difference in quality and quantity of produced exopolymers. The proportion between polysaccharides and proteins in EPS depended on the availability of carbon source in the culture environment and the presence of additional adhesion surface. Biological surfaces like poultry feathers stimulated releasing of polysaccharides by tested bacteria, however abiotic surfaces like glass plates induced protein’s releasing. In the proteins of biofilm by SDS polyacrylamide gel electrophoresis revealed the presence of additional fraction of proteins absent in control conditions. Production of exopolymeric matrix by bacteria is regulated by genetic mechanisms but it also highly depends on nutrient level and cultivating time.

The Lactobacillus brevis and Lactobacillus plantarum ATCC 4080 strains exhibited the highest magnesium binding activities (approximately: 5,82 mg Mg g^-1 and 3,29 mg Mg g^-1, respectively) in a medium containing magnesium in the form of salts such as magnesium acetate, with a magnesium concentration of 1,5 g dm^-3. Lb. brevis binded more magnesium than Lb. plantarum ATCC 4080 under the same culture conditions. The strains showed weaker growth during 24 h of culture in a medium to with 0,5–1,5 g Mg dm-3 was added, both in the form of sulfate and acetate of magnesium, in comparison with the control medium; however no decrease in their acidifying proprieties were observed.