Bioprospection of antibiotics and biofilm inhibitors from under-exploited filamentous fungi

Abstract

In the past century, antibiotics revolutionized the way infectious diseases were treated, saving millions of lives. However, bacteria, in particular these infectious, may develop antibiotic resistance in such a way that the speed of development of new drugs does not follows the development of resistance. Filamentous fungi have a vast, largely unexplored metabolome, giving them great potential for novel antibiotic discovery. The One Strain MAny Compounds (OSMAC) approach is a valuable tool in this regard and aims to vary culture conditions to obtain a wider range of metabolites. In this study, five under-explored fungal species were used, aiming to identify compounds with antibiotic or antibiofilm properties produced by them. They were grown in different culture media, under deep fermentation for 7 and 14 days, with changing conditions of aeration and agitation, and the resulting supernatants were tested for their antimicrobial activity against Gram-positive and Gram-negative bacteria using the disk diffusion method. All fungi grew on the different media and under the diverse process conditions. It was found that Coprinopsis spilospora metabolites inhibited Staphylococcus aureus growth and demonstrated antibiofilm properties. They reduced the biofilm in 30% in crystal violet staining, metabolic activity by 82% in Alamar blue test, and viable cells counts by 96% in CFU counting. Co-culture and disk diffusion test results also showed that this supernatant has a slight effect against Escherichia coli. The pioneer results obtained in the present study highlight the relevance of bioprospection for antibiotic discovery.