Our society is facing the emergence of pathogenic bacteria and fungi resistant to available antimicrobials. WHO priority and critical pathogenic fungi include Aspergillus fumigatus, an azole-resistant fungus. A. fumigatus is a globally distributed ubiquitous environmental mould with high mortality rates in those with resistant infection [1]. To combat the problem, one of the keys is the discovery of new antimicrobials compounds, as well as the improvement of their production.

Through citizen science projects such as Tiny Earth [2] and other natural sources (compost, alkaline soils, trees, insects, etc.) we have isolated a few strains of actinomycetes, mainly from the genus Streptomyces [3-4] whose genome has been sequenced. These strains have a large genome in which a high number of biosynthetic gene clusters (BGCs) can be identified, thanks to bioinformatics programmes such as AntiSMASH v.6. [5]. This genomic mining together with genome annotation programs such as Prokka [6] and Rast allow us to search for genes of interest involved in antifungal compounds.

In addition to the in silico study, we have performed bioassays of some of the isolated Streptomyces strains against A. fumigatus. These assays have been performed using cultures of the isolated strains as well as extracts obtained from them. This enabled us to select the strain with the greatest antifungal potential for a more exhaustive study of its antifungal compounds in subsequent studies. Furthermore, we have performed dual cultures against plant pathogenic fungi of commercial interest to test the antifungal potential of our strains.

References

[1] WHO fungal priority pathogens list to guide research, development and public health action. Geneva: World Health Organization; 2022.

[2] https://swiusal.wixsite.com/micromundousal

[3] Marugán Cardiel, María. TFG, Universidad de Salamanca, 2019.

[4] Morante Gómara, Helena. TFG, Universidad de Salamanca, 2020.

[5] Blin et al. Nucleic Acids Research, 2023, gkad344. https://doi.org/10.1093/nar/gkad344.

[6] Seemann, Torsten. Bioinformatics 30, n.^o 14, (2014): 2068-69. https://doi.org/10.1093/bioinformatics/btu153.

[7] Brettin et al. Scientific Reports 5, n.^o 1 (2015): 8365. https://doi.org/10.1038/srep08365.