[Role of phospholipids in the fractionation of stable sulfur isotopes during oxidation by Thiobacillus ferrooxidans].

The action of Thiobacillus ferrooxidans on elementary suhur was shown to be a step-wise process connected with the formation of its colloidal forms having a different isotope composition. Certain sulfur forms are in complex with phospholipids. Both exogenous and endogenous phospholipids are involved in the dissolving of sulfur and in the fractionation of its isotopes.

[Fractionation of stable isotopes of sulfur during its oxidation by Thiobacillus ferrooxidans].

The fractionation of sulfur isotopes was studied in the process of sulfur oxidation by Thiobacillus ferrooxidans. The isotope effect was observed at all stages of the bacterial growth during sulfur oxidation; as a result, residual sulfur became heavier whereas the fraction of colloidal sulfur and the fraction of sulfates became lighter. The isotope differences between the residual sulfur and the sulfates were greatest at the end of the lag phase (delta 34S = 0.

[Nitrogen transformation as a result of Pseudomonas denitrificans denitrification].

The energy process of nitrate reduction was studied in the typical soil denitrifying cultures of Pseudomonas denitrificans by mass spectrometry. These microorganisms differed in certain characteristics of the process from the cultures of sporogenic soil denitrifying bacteria belonging to the Bacillus genus. The rate of denitrification by Ps.

[Oxidation of nitrous oxide during decomposition of hydrogen peroxide by catalase].

Possible involvement of the catalase mechanism in the elimination of nitrous oxide was studied in model experiments. The concentration of N2O in the gaseous phase was found to decrease due to the decomposition of hydrogen peroxide by catalase. The concentration of NO increased accompanying the removal of N2O from the gaseous phase in the pressure of H2O2 and catalase.

[Use of a mass spectrometric method for studying the oxygen demand of suspensions of resting Bacillus anthracoides spores].

Oxygen assimilation by the spore suspensions of Bacillus anthracoides under sterile conditions was continuously registered by means of a modified mass-spectrometry technique using an original reaction vessel. The sensitivity of the technique is 2.10(-2) mcl O2 per 1 mg of dry biomass per hour.