Anti-CandidaProperties of Urauchimycins from Actinobacteria Associated withTrachymyrmexAnts

Abstract

After decades of intensive searching for antimicrobial compounds derived from actinobacteria, the frequency of isolation of new molecules has decreased. To cope with this concern, studies have focused on the exploitation of actinobacteria from unexplored environments and actinobacteria symbionts of plants and animals. In this study, twenty-four actinobacteria strains isolated from workers of Trachymyrmex ants were evaluated for antifungal activity towards a variety of Candida species. Results revealed that seven strains inhibited the tested Candida species. Streptomyces sp. TD025 presented potent and broad spectrum of inhibition of Candida and was selected for the isolation of bioactive molecules. From liquid shake culture of this bacterium, we isolated the rare antimycin urauchimycins A and B. For the first time, these molecules were evaluated for antifungal activity against medically important Candida species. Both antimycins showed antifungal activity, especially urauchimycin B. This compound inhibited the growth of all Candida species tested, with minimum inhibitory concentration values equivalent to the antifungal nystatin. Our results concur with the predictions that the attine ant-microbe symbiosis may be a source of bioactive metabolites for biotechnology and medical applications.

Microbial secondary metabolites and their impacts on insect symbioses

“…have also been isolated from fungus-growing ants and their fungus gardens and were hypothesized to function as protective symbionts [47][48][49][50][51][52][53]. However, current data indicates that these microbes are neither abundant [31 ,37-39,48] nor widely distributed throughout the symbiosis despite their in vitro bioactivities and in one case in situ visualization [53].…”

“…Unless such dispersal is frequent, the encounter rate between symbiotic and non-symbiotic microbes will be too low to consistently correlate with any effect on these communities even if strong bioactivity occurs in a single example, therefore leaving Koch's postulates unfulfilled. These dynamics may best describe microbes that have been isolated infrequently from the fungus-growing ant symbiosis [47][48][49][50][51][52][53]. However, immigration of external microbes may provide selection for broad-spectrum antibiotics to be produced by genuine symbionts, for example, as postulated for beewolves and entomopathogenic nematodes [13,19 ].…”

Imaging mass spectrometry and MS/MS molecular networking reveals chemical interactions among cuticular bacteria and pathogenic fungi associated with fungus-growing ants

“…weberi antimycin A2antimycin A3antimycin A3 Trachymyrmex sp. Streptomyces sp. TD025.Five Candida speciesurauchimycin AFour Candida species 35 urauchimycin BSix Candida speciesThe table summarizes compounds that are produced by the bacteria associated with fungus growing ant’s species pointing out the activity against the fungal pathogen, Escovopsis . …”

Actinomicetos con actividad anti-Candida aisladas de hormigas cortadoras de hojas Atta cephalotes (Formicidae: Myrmicinae: Attini)

“…Existen diversos estudios que confirman la eficacia de los extractos de actinomicetos obtenidos a partir de acetato de etilo, reportándose una destacada actividad antifúngica frente a C. albicans. Mendes et al (23) determinaron la actividad de extractos de acetato de etilo de actinomicetos asociados a hormigas Trachymyrmex frente a C. albicans, con resultados similares. Asimismo, Narayana et al…”