The emergence of multidrug resistance in bacterial pathogens is a growing public health concern requiring solutions including the discovery of new antimicrobial drugs. Fungi have been used for decades as a source of antimicrobials. Ongoing screenings for newly characterized fungal strains producing antimicrobials include environments that are difficult to access like the deep sea, glaciers, wastewaters and environments polluted due to human activity. In the present study, fungal microorganisms were isolated from water samples taken from a polluted stream in the city of Manaus, AM, Brazil, and screened for antimicrobial effects against Escherichia coli. Using extracts from five isolates (Annulohypoxylon stygium WL1B5, Colletotrichum fructicola WL3B9, Clonostachys rosea WL5B18, Clonostachys rosea WL8B28 and Trichoderma harzianum WL9B49), antimicrobial activity against the reference strains Escherichia coli ATCC 25922 as well as E. coli NCTC 13353, an extended-spectrum beta-lactamase-positive strain, was observed. Inhibition zones ranged from 1 to 35.9 mm and a minimum inhibitory concentration of 400 µg/mL could be demonstrated. Assessments of the metabolites of Annulohypoxylon stygium WL1B5 allowed us to identify nodulisporone and daidzein, which have already been associated with antimicrobial activity. The findings confirm the feasibility of isolating fungal strains from polluted sites producing metabolites that can serve as potential future alternatives for the treatment of multidrug-resistant bacteria.

Since the classic studies of Alexander Flemming, Penicillium strains have been known as a rich source of antimicrobial substances. Recent studies have identified novel metabolites produced by Penicillium sclerotiorum that have antibacterial, antifouling and pharmaceutical activities. Here, we report the isolation of a P. sclerotiorum (LM 5679) from Amazonian soil and carry out a culture-based study to determine whether it can produce any novel secondary metabolite(s) that are not thus-far reported for this genus. Using a submerged culture system, secondary metabolites were recovered by solvent extract followed by thin-layer chromatography, nuclear magnetic resonance, and mass spectroscopy. One novel secondary metabolite was isolated from P. sclerotiorum (LM 5679); the phenolic compound 5-pentadecyl resorcinol widely known as an antifungal, that is produced by diverse plant species. This metabolite was not reported previously in any Penicillium species and was only found once before in fungi (that time, in a Fusarium). Here, we discuss the known activities of 5-pentadecyl resorcinol in the context of its mode-of-action as a hydrophobic (chaotropicity-mediated) stressor.

The fruit of Astrocaryum aculeatum G. Mey. are consumed by population in the Brazil Northern resulting fruit peels. These peels are rich in lignocellulose and fat. The present study investigated peels from the Astrocaryum aculeatum G. Mey. as a substrate for lipases production by solid state bioprocess. To reach this objective: 1) we isolated fungi from peels from the fruit of Astrocaryum aculeatum G. Mey; 2) we screened the isolates for lipase production (screening in petri dish and screening in submerged bioprocess), 3) we investigated the production of lipases by using peels from Astrocaryum aculeatum G. Mey as substrate. The isolates belonged to the genera Aspergillus (16), Penicillium (3) and Fusarium (1). These strains were submitted to petri dishes and submerged fermentation for lipases production, these experiments resulted in the selection of five strains belonging to the Aspergillus genera. The lipases produced by these five strains performed enzymatic transesterification; however, the lipases from the strain Aspergillus niger A2B1 produced the highest ester content. The utilisation of fruit peel from Astrocaryum aculeatum G. Mey. as the main substrate, fruit peel from Astrocaryum aculeatum G. Mey. oil (13%), moisture (70%) and 75 h of incubation were the optimal conditions identified for the production of lipases by Aspergillus niger A2B1(17.42 U/g) in solid state bioprocess (SSB).