Inhibition of Klebsiella pneumoniae carbapenemases by mycocins produced by Wickerhamomyces anomalus.

New alternatives have been under study as treatment due to the problem of multidrug-resistant bacteria. Among them, Wickerhamomyces anomalus mycocins have shown a great potential against several microorganisms since they have high antimicrobial activity, as well as they can be used as fast available nutrients and stand several extreme conditions. In this way, Klebsiella pneumoniae carbapenemases inhibition by mycocins produced by W. anomalus is important. Microdilution assays were carried out to evaluate strains inhibition in liquid medium and the test in solid medium were carried out. Toxicity was evaluated by both hemolysis and Artemia salina Leach tests. W. anomalus supernatant showed 2.36 U/mg ß-glucanases activity, and antimicrobial activity was evidenced in 100% Klebsiella pneumoniae carbapenemase strains up to 0.12 U/mg concentration. Besides, there was low toxicity in hemolysis and Artemia salina Leach tests. It is suggested that W. anomalus mycocins may be an alternative to develop new antimicrobial substances.

Susceptibility of Candida albicans Strains Isolated from Vaginal Secretion in Front of the Mycocins of Wickerhamomyces anomalus.

Mycocins are substances that have the potential to affect other sensitive yeasts or microorganisms. Wickerhamomyces anomalus is a yeast that produces mycocins that have great biotechnological potential, being highly competitive in many habitats, as it is adaptable to a wide range of environmental conditions. Thus, they are targets for studies in different areas, including the environment, industry, and medical sciences. Yeasts of the genus Candida are of great importance due to the high frequency with which they colonize and infect the human host. Yeast infections are often difficult to treat due to the acquisition of resistance against antifungals, leading to studies focusing in new treatment alternatives. This work aims to verify the inhibition of Candida albicans isolated from vaginal secretion by mycocins produced by Wickerhamomyces anomalus. Tests were carried out in solid medium and microdilution tests, where mycocins proved to be efficient in inhibiting the growth of C. albicans, hemolysis, and irritation in an organotypic model, which showed that the mycocins produced by W. anomalus are safe and non-irritating. Thus, the results of this work can provide scientific evidence for the application of mycocins in the production of new antifungal alternatives.

Yeast Mycocins: a great potential for application in health.

Mycocins have demonstrated inhibition of fungi, bacteria, parasites and viruses, in addition to being studied as epidemiological markers and in the development of vaccines. They are defined as extracellular proteins or glycoproteins with different activities, the main mechanism of action being the inhibition of ß-glucan synthesis in the cell wall of sensitive strains. Given the resistance problems created by several microorganisms to agents commonly used in clinical practice, the discovery of new substances with this purpose becomes essential. Mycocins have potential as anti-microbials because they show minimal toxicity and do not present resistance.

Antibiotic Activity of Wickerhamomyces anomalus Mycocins on Multidrug-Resistant Acinetobacter baumannii.

To evaluate the susceptibility of multidrug-resistant Acinetobacter baumannii to mycocins produced by Wickerhamomyces anomalus and to verify the cytotoxicity of these compounds. Three culture supernatants of W. anomalus (WA40, WA45, and WA92), containing mycocins (WA40M1, WA45M2, and WA92M3), were tested on A. baumannii using broth microdilution methods, solid medium tests, and cytotoxicity tests in human erythrocytes and in Artemia saline Leach. W. anomalus was able to produce high antimicrobial mycocins, as even at high dilutions, they inhibited A. baumannii. In a solid medium, it was possible to observe the inhibition of A. baumannii, caused by the diffusion of mycocins between agar. Finally, the three supernatants were not cytotoxic when tested on human erythrocytes and Artemia salina. According to the evidence in this study, the mycocins of W. anomalus have been effective and could be used in the development of new antimicrobial substances.

Repression of Proteases and Hsp90 Chaperone Expression Induced by an Antiretroviral in Virulent Environmental Strains of Cryptococcus neoformans.

This study evaluated the effect of the antiretroviral ritonavir on protease secretion in different strains of Cryptococcus neoformans isolated from the environment and investigated the expression of heat shock protein (Hsp90), classically described virulence factors in other yeast in the presence of the same antiretroviral. The presence of the enzyme was detected by the formation of a degradation of the halo around the colonies. The results were classified as follows: level 1 (without proteases), level 2 (positive for proteases), and level 3 (strongly positive for proteases). Total protein extract isolated from the cell walls of the 12 strains incubated in the absence and presence of ritonavir (0.3125 mg mL-1) were resolved by SDS-PAGE and analyzed by Western blot assays using an antiserum against Hsp90 from Blastocladiella emersonii. All strains tested showed inhibition of proteinase activity in the presence of ritonavir at 0.3125 to 1.25 mg mL-1. High levels of Hsp90 were observed in the absence of ritonavir (0.3125 mg mL-1), except for the non-virulent control cells. In contrast, in the presence of the antiretroviral, a drastic reduction in the expression of the chaperone was observed. The data suggest that ritonavir, in addition to containing viral replication, could inhibit the expression of virulence factors in opportunistic yeast, as proteases and Hsp90. According to our current knowledge, this is the first time that the inhibition of Hsp90 by an antiretroviral was reported for environmental isolates of C. neoformans.

Susceptibility of Candida albicans Isolated from Blood to Wickerhamomyces anomalous Mycocins.

The occurrence of infections caused by Candida albicans in developed and developing countries and their resistance to some available antifungal drugs have been viewed as causing a great problem to human health worldwide. In order to find new researched molecules, there are some mycoses secreted by yeasts, especially mycocins produced by Wickerhamomyces anomalus with a broad antimicrobial spectrum of activity. Thus, this trial aimed at evaluating mycocins' activity obtained from environmental W. anomalus cell wall compared to thirty C. albicans strains isolated from blood. Mycocins were extracted from cell walls of three W. anomalus strains (WA40, WA45, and WA92). The 400 µg mL-1 concentration of WA40M1, WA45M2, and WA92M3 mycocin extracts showed the following respective activity results: 96.6, 96.6, and 90.0 % C. albicans strains. WA45M2 and WA92M3 mycocin extracts showed some activity in 3.3 % of C. albicans strains at 50 µg mL-1 concentration. Mycocins extracted from cell walls of three W. anomalus strains named as WA40, WA45, and WA92 showed antifungal activity compared to C. albicans and low degree of hemolysis.