Enhancement of antibiotic and secondary metabolite detection from filamentous fungi by growth on nutritional arrays

Abstract

Aims: We asked to what extent does the application of the OSMAC (one strain, many compounds) approach lead to enhanced detection of antibiotics and secondary metabolites in fungi? Protocols for bacterial microfermentations were adapted to grow fungi in nutritional arrays. Methods and Results: Protocols for microfermentations of non‐sporulating fungi were validated using known antifungal‐producing fungi. Detection of antifungal activity was often medium dependent. The effects of medium arrays and numbers of strains on detection of antifungal signals were modelled by interpolation of rarefaction curves derived from matrices of positive and negative extracts. Increasing the number of fermentation media for any given strain increased the probability of detection of growth inhibition of Candida albicans. Increasing biodiversity increased detection of antifungal phenotypes, however, nutritional arrays could partly compensate for lost antibiotic phenotypes when biodiversity was limiting. Conclusions: Growth and extraction in microtiter plates can enable a discovery strategy emphasizing low‐cost medium arrays that can better exploit the metabolic potential of strains. Significance and Impact of the Study: Increasing fermentation parameters raise the probability of detecting bioactive metabolites from strains. The protocols can be used to pre‐select strains and their growth conditions for scale up that will most likely yield antibiotics and secondary metabolites.

Multicomponent Analysis of the Differential Induction of Secondary Metabolite Profiles in Fungal Endophytes

“…Mycelia discs were extruded from the "Transfer Tube" and crushed in the bottom of inocula tubes (25ˆ150 mm) containing 12 mL of SMYA and two cover glasses (22ˆ22 mm). Tubes were incubated on an orbital shaker (200 rpm; 1.5 cm throw), where rotation of the cover glasses continually sheared hyphae and mycelial disc fragments to produce nearly homogenous hyphal suspensions consisting of minute hyphal aggregates and fine mycelia pellets [27].…”

Evolution of Chemical Diversity in Echinocandin Lipopeptide Antifungal Metabolites

“…Fermentations of all these strains were potently active in antifungal screens; therefore, the pathways are operative. In our experience, their biosynthesis is not tightly regulated in the laboratory (12,65,89,90). The fungi also need mechanisms to manage their own toxic metabolites by exporting them from the site of synthesis, by excreting them through the plasma membrane, by transporting them into an internal compartmentalization, or by mechanistic resistance.…”

Bioprospecting microbial natural product libraries from the marine environment for drug discovery

“…For example, in the presence of different supplements, various acyl and phenyl a-L-rhamnopyranosides were produced by Streptomyces griseoviridis. 120 Bills et al 121 have used bacterial micro-fermentators for fungal growth in nutritional arrays, and the results indicate that the protocols can be used to pre-select strains and their growth conditions for scaling up. Development and testing of new culture media for the maximum expression of secondary metabolites is as important as genome-guided chemical diversity in the construction process of an MNPL.…”