Biosurfactants are surface-active compounds that have sparked interest in recent years because of their environmental advantages over conventional surfactants. The aim of this study was to investigate the production of biosurfactants by soil fungi isolated from the Amazon forest. Fungi colonies were isolated from soil samples and screened for biosurfactant production in submerged fermentation. In addition, the influences of bioprocess factors (carbon source, nitrogen source, pH, and fermentation time) were investigated. Finally, the biosurfactant produced was semipurified and submitted to stability tests. One hundred fungal cultures were obtained from the soil samples, identified by micromorphology, and submitted to screening for biosurfactant production. Sixty-one strains produced biosurfactants. The strainPenicillium8CC2 showed the highest emulsification index (54.2%). The optimized bioprocess conditions for biosurfactant production byPenicillium8CC2 were as follows: soybean oil, 20 g/L; yeast extract, 30 g/L; pH 9; duration of 9 days. The semipurified biosurfactant showed stability after heating at 100°C for 60 min and after the addition of 30% NaCl (w/v). Tween 80 (0.2% w/v), a conventional surfactant, was used as the control.

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.

Mushroom cultivation is an economically viable process for the conversion of various lignocellulosic residues. Recently in order to increase the feasibility of mushroom production, research has been carried out to investigate the use of residues as substrates and the possibility of obtaining two or more products in a single bioprocess. The aim of this study wasto investigate the potential of biomass residues from street markets in the city of Manaus (Amazonas, Brazil) as a substrate for the production of oyster mushroom and laccase. Pleurotus ostreatus was cultivated in the following biomass residues: a) peel from the fruit of Astrocaryum aculeatum Meyer, b) peel from the fruit of Bactris gasipaes Kunth, c) fibers from the endocarp of the fruit of Euterpe oleracea Mart. and d) peel from the fruit of Theobroma grandiflorum Schumann. The peel from the fruit of Bactris gasipaes was the best substrate to produce oyster mushroom (4.8 % biological efficiency -ratio between the fresh weight of the mushroom and the dry weight of the compost), and the peel from the fruit of Astrocaryum aculeatum was the best substrate for laccase production (21,766 U/Kg). The present work is important since it allowed us to demonstrate that two biomass residues from Amazonian plants could be utilized to produce mushrooms and laccases.