Abstract
BackgroundThe need for new antibiotic drugs increases as pathogenic microorganisms continue to develop resistance against current antibiotics. We obtained samples from Antarctica as part of a search for new antimicrobial metabolites derived from filamentous fungi. This terrestrial environment near the South Pole is hostile and extreme due to a sparsely populated food web, low temperatures, and insufficient liquid water availability. We hypothesize that this environment could cause the development of fungal defense or survival mechanisms not found elsewhere.ResultsWe isolated a strain of Penicillium nalgiovense Laxa from a soil sample obtained from an abandoned penguin’s nest. Amphotericin B was the only metabolite secreted from Penicillium nalgiovense Laxa with noticeable antimicrobial activity, with minimum inhibitory concentration of 0.125 μg/mL against Candida albicans. This is the first time that amphotericin B has been isolated from an organism other than the bacterium Streptomyces nodosus. In terms of amphotericin B production, cultures on solid medium proved to be a more reliable and favorable choice compared to liquid medium.ConclusionsThese results encourage further investigation of the many unexplored sampling sites characterized by extreme conditions, and confirm filamentous fungi as potential sources of metabolites with antimicrobial activity.
Highlights
The discovery of penicillin based on observations made when Penicillium rubens and Staphylococcus aureus were co-cultured on the same agar plate was arguably the starting point of the Golden Era of Antibiotics [1,2]
A. fumigatus cultures were grown in the presence of the three selected Pathogen-associated molecular patterns (PAMPs) at various concentrations for seven days and the gliotoxin production in each case was compared to that of untreated control cultures
The addition of PAMPs to liquid cultures of A. fumigatus increased their secretion of gliotoxin by up to 65% after seven days of incubation
Summary
The discovery of penicillin based on observations made when Penicillium rubens and Staphylococcus aureus were co-cultured on the same agar plate was arguably the starting point of the Golden Era of Antibiotics [1,2]. P. rubens does not provide penicillin in sufficient quantities for mass production under conventional broth conditions. This problem was solved by the discovery of P. chrysogenum, which has much higher levels of constitutive penicillin production. To conserve nutrients and avoid self-toxicity as well as resistance development, organisms produce and secrete many antimicrobial agents on a facultative basis This is especially true for microorganisms such as fungi, which cannot rely as much on nutrient depots and cell-specialization. It is disputable that fungi secrete the full spectrum of antimicrobial agents in conventional laboratory growth conditions Methods for activating these pathways could be useful for finding new metabolites or increasing the secretion of known ones, which may be beneficial in drug discovery and production
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