Polyenic Antibiotics and Other Antifungal Compounds Produced by Hemolytic Streptomyces Species

Abstract

Streptomyces are of great interest in the pharmaceutical industry as they produce a plethora of secondary metabolites that act as antibacterial and antifungal agents. They may thrive on their own in the soil, or associate with other organisms, such as plants or invertebrates. Some soil-derived strains exhibit hemolytic properties when cultivated on blood agar, raising the question of whether hemolysis could be a virulence factor of the bacteria. In this work we examined hemolytic compound production in 23 β-hemolytic Streptomyces isolates; of these 12 were soil-derived, 10 were arthropod-associated, and 1 was plant-associated. An additional human-associated S. sp. TR1341 served as a control. Mass spectrometry analysis suggested synthesis of polyene molecules responsible for the hemolysis: candicidins, filipins, strevertene A, tetrafungin, and tetrin A, as well as four novel polyene compounds (denoted here as polyene A, B, C, and D) in individual liquid cultures or paired co-cultures. The non-polyene antifungal compounds actiphenol and surugamide A were also identified. The findings indicate that the ability of Streptomyces to produce cytolytic compounds (here manifested by hemolysis on blood agar) is an intrinsic feature of the bacteria in the soil environment and could even serve as a virulence factor when colonizing available host organisms. Additionally, a literature review of polyenes and non-polyene hemolytic metabolites produced by Streptomyces is presented.

Biocontrol Potential of Streptomyces odonnellii SZF-179 toward Alternaria alternata to Control Pear Black Spot Disease

“…UPLC-MS results showed that the active substance in SZF-179 against A. alternata was a class of polyene; however, polyene compounds are not very stable and difficult to purify [24]; so, using Saccharomyces cerevisiae as target, we tested the stability of SZF-179 fermentation broth under different temperatures and pHs. Temperature sensitivity experiment results showed that, when the temperature was below 50 • C, the active substance was relatively stable, and the size of the antifungal zone was the same as that in the control.…”