[Melanin pigments of the fungi Paecilomyces variotii and Aspergillus carbonarius]. / Melaninovye pigmenty gribov Paecilomyces variotii i Aspergillus carbonarius.

Pigments synthesized by micromycetes Paecilomyces variotii and Aspergillus carbonarius are true melanins. Copper ions and bicyclic phenolic compounds stimulated melaninogenesis, whereas benzotriazole inhibited this process. Precursors of melanin pigments were obtained and identified. p-Hydroxybenzoic acid was shown to be the main product of melanin degradation. Melanins of these fungi are concluded to belong to the dihydronaphthalene group.

[Effect of exogenous factors on extracellular alkaline ribonuclease synthesis in Bacillus mesentericus]. / Vliianie ékzogennykh faktorov na sintez vnekletochnoi shchelochnoi ribonukleazy Bacillus mesentericus.

Bacillus mesentericus was found to assimilate nucleic acids as a source of nitrogen and phosphorus. Nucleic acids added to the medium as a source of nitrogen or phosphorus stimulated synthesis of ribonuclease. When washed bacterial cells were incubated for a short period of time in a fresh nutrient medium containing RNA, synthesis of RNAase was also induced. Synthesis of the enzyme was inhibited by high concentrations of chloramphenicol and actinomycin D, and stimulated by low concentrations of actinomycin D. Therefore, alkaline RNAase is an inducible enzyme which participates in the nutrition processes of bacteria.

[Transmissive drug resistance and virulence of "epidemic" strains of S. typhimurium]. / Transmissivnaia lekarstvennaia ustoichivost' i virulentnost' "épidemicheskikh" shtammov S. typhimurium.

A total of 59 "epidemic" strains of S. typhimurium and 52 cultures isolated from the cases with sporadic diseases were studied with respect to the nature of their resistance to 10 antibiotics and virulence for albino mice under conditions of subcutaneous and oral inoculation. The virulence of the cultures isolated from the cases with sporadic diseases was higher in the strains sensitive to antibiotics. The "epidemic" strains were characterized by the lowest virulence for the mice and resistance to 8-10 antibiotics simultaneously with the transmissive nature of resistance to 1-5 drugs. The transmissive nature of resistance to antibiotics and its spectrum may serve an additional epidemiological marker of the strains.