Chemotactic and adhesive properties of Azotobacter vinelandii and Bacillus subtilis | Хемотаксисные и адгезивные свойства Azotobacter vinelandii и Bacillus subtilis

Effectiveness of introduced microorganisms action on plants depends on their chemotactic and adhesive properties. The adhesion of bacteria Azotobacter vinelandii IMV B-7076 (strain 1) and Bacillus subtilis IMV B-7023 (strain 2) in monoculture and bikulture (ratio 1:1) was under study. In an experiment seedlings obtained from sterile seeds of tomato, cucumber, spring wheat and cabbage were used. It is shown that the smallest number of Azotobacter was attached to the roots of wheat, and the largest - to the roots of cabbage. The intensity of adhesion of monocultures studied bacteria on the roots of cucumber varied slightly, and in the mixed suspension it was reduced. Chemotaxis of bacteria was studied by capillary method, evaluating the effect of temperature and pH on the process. Experimental capillaries filled with solutions of 0.1 M glucose were prepared on the basis of buffer solutions containing K and R. The optimum for chemotaxis of strain 1 and strain 2 were pH 7-8 and 6-7, t 20-30, and 30 deg. C respectively. The data can be explained by differences in surface structures of bacteria and features of the conformational changes in proteins, chemotaxis receptors at different pH values. With the increase of pH also increased the number of adhesived bacteria. It is proved that this process is driven by an increase in the speed of their movement. Adhesive properties of bacteria changed in the presence of clay minerals montmorillonite (MR) and palygorskite (OL), which contributed to the bacterial suspension for 30 minutes before their contact with the roots. The addition of MR to the suspension of strain 2 in doses of 100 and 500 mg/L increased the adhesion of bacteria in the 1.75 and 1.48 times respectively. Higher doses (1000-10 000 mg/L) inhibited the process. MR increased the adhesion of bacteria strain 1 in all concentrations studied. The introduction of PR in the number of 10-10 000 mg/L led to a decrease in the number of adhesived bacterial strain 2, and in the number of 10-100 mg/l - strain 1. At the same time, the PR for the content of 500-10 000 mg/l stimulated the adhesion of a strain 1.