ACTIVITY AND TOXICITY OF MYCOCINS PRODUCED BY Wickerhamomyces anomalus

Wickerhamomyces anomalus is a mycocin producer widely distributed in the environment and resistant to extreme conditions of pH, temperature and osmolarity. W. anomalus was the first yeast producing mycocins capable of inhibiting the growth of both eukaryotic and prokaryotic organisms. Its action is considered minimally toxic to human cells and of low potential to induce resistance to microorganisms, characteristics that make W. anomalus mycocins a candidate for medical application. This work aims to verify the antimicrobial action of the mycocin produced by W. anomalus against multiresistant Acinetobacter baumanniis strains. Wa 45 supernatant (GenBank KT580794) was assayed on A. baumannii by means of solid-half test from the check of the zone of inhibition and its toxicity was tested by the hemolysis test. A. baumannii strains were isolated from human biological samples from Cascavel-PR laboratories. In Petri dish, agar-agar was added and, after solidifying, nutrient agar and seeded A. baumannii strain. Orifices were made on the nutrient agar and then added 15 μl of supernatant. The plate was incubated at 36°C/48h. And in the erythrocyte cytotoxicity test, blood from a healthy individual was collected in a tube containing EDTA, which was centrifuged at 2000g for 10 min, and the cell mass was washed with PBS (Phosphate-buffered saline). Subsequently, a 4% suspension of erythrocytes in PBS was tested, which was tested under different concentrations of WA45 supernatant and incubated at 37°C/1h. After this period, the tubes were centrifuged at 2000g for 10 min and the supernatant was used to determine spectrophotometer absorption at 450 nm wavelength. The same procedure was done for Polymyxin B. In the inhibition zone test, it was possible to verify the diffusion of the mycocins of the supernatant in agar, forming a zone around the orifice where the same was pipetted. And in the erythrocyte cytotoxicity test, the low hemolytic action of mycocins was evidenced, this result resembles the levels of hemolysis caused by polymyxin B, therapy of choice in the treatment of A. baumannii infections. The mycocins of W. anomalus were effective and could be used in the development of new antimicrobial substances.