Bacteria are becoming increasingly resistant to antibiotics, leading to untreatable infections and constituting a major public health hazard (Lewis, 2013). This problem is further increased by the reduction in the number of effective antibiotics to tackle resistant strains (Penesyan et al. 2015), so the search for new compounds is seen as a vital priority. Our study consisted in the analysis of four different environmental strains of Penicillium spp., with screening for their extracellular metabolites for potential antimicrobial activity. Several methods were combined and tested for metabolite production and extraction. The strains were grown on: solid media (I-potato dextrose agar and II-malt extract agar), broth (malt extract broth with III-0 and IV-5% NaCl), and V-tapwater; extractions were performed using three different solvents: A-methanol, B-butanol and C-ethyl acetate. All extracts were tested on three different model organisms: Micrococcus luteus, Escherichia coli and Mycobacterium smegmatis. These are models for Gram-positive and Gram-negative bacteria, and for Tuberculosis. The extracts were compared and analysed in order to determine minimal inhibitory concentrations for each of the microorganisms tested. This research presents preliminary results on the development of potential new chemical compounds to help us circumvent the problem of drug resistance. Lewis, K., 2013. Platforms for antibiotic discovery. Nature reviews Drug discovery, 12(5), pp.371–387. Penesyan, A., Gillings, M. and Paulsen, I.T., 2015. Antibiotic discovery: combatting bacterial resistance in cells and in biofilm communities. Molecules, 20(4), pp.5286–5298.
- Penicillium spp