The endophytic fungal community of the Amazonian medicinal plant Arrabidaea chica (Bignoniaceae) was evaluated based on the hypothesis that microbial communities associated with plant species in the Amazon region may produce metabolites with interesting bioactive properties. Therefore, the antimicrobial and antioxidant activities of the fungal extracts were investigated. A total of 107 endophytic fungi were grown in liquid medium and the metabolites were extracted with ethyl acetate. In the screening of fungal extracts for antimicrobial activity, the fungus identified as Botryosphaeria mamane CF2-13 was the most promising, with activity against E. coli, S. epidermidis, P. mirabilis, B. subtilis, S. marcescens, K. pneumoniae, S. enterica, A. brasiliensis, C. albicans, C. tropicalis and, especially, against S. aureus and C. parapsilosis (MIC = 0.312 mg/mL). Screening for antioxidant potential using the DPPH elimination assay showed that the Colletotrichum sp. CG1-7 endophyte extract exhibited potential activity with an EC₅₀ of 11 µg/mL, which is equivalent to quercetin (8 µg/mL). The FRAP method confirmed the antioxidant potential of the fungal extracts. The presence of phenolic compounds and flavonoids in the active extracts was confirmed using TLC. These results indicate that two of the fungi isolated from A. chica exhibit significant antimicrobial and antioxidant potential.

Pigments of fungal origin have aroused increasing interest in the food dye and cosmetic industries since the global demand for natural dyes has grown. Endophytic microorganisms are a source of bioactive compounds, and Amazonian plant species can harbor fungi with a wide range of biotechnological applications. Popularly known in Brazil as crajiru, Fridericia chica is a medicinal plant that produces a red pigment. In this study, a total of 121 fungi were isolated in potato dextrose agar from three plants. We identified nine pigment-producing endophytic fungi isolated from branches and leaves of F. chica. The isolates that showed pigment production in solid media were molecularly identified via multilocus analysis as Aspergillus welwitschiae, A. sydowii, Curvularia sp., Diaporthe cerradensis (two strains), Hypoxylon investiens, Neoscytalidium sp. (two strains) and Penicillium rubens. These isolates were subjected to submerged fermentation in two culture media to obtain metabolic extracts. The extracts obtained were analyzed in terms of their absorbance between 400 and 700 nm. The pigmented extract produced by H. investiens in medium containing yeast extract showed maximum absorbance in the red absorption range (UA₇₀₀ = 0.550) and significant antioxidant and antimicrobial activity. This isolate can thus be considered a new source of extracellular pigment.

Endophytic fungi are promising producers of phenolic compounds; however, the process of extracting these molecules from the culture medium is a crucial step for obtaining these metabolites. In this context, the best conditions for extracting phenolic compounds produced by Cophinforma mamane CF2-13, isolated from an Amazonian plant, were evaluated. The fungus was cultivated in a liquid medium to obtain its metabolites. The effects of the solvent, time, and temperature were investigated, as well as the use of ultrasound. The total phenolics and the antioxidant activity were assessed to define the best extraction conditions. The optimized extract was chemically characterized and used to analyze its potential in protecting olive oil from lipid oxidation. The best results were found using ethyl acetate at 20 °C for 2 h. These conditions led to 61.61 mg GAEq/g of extract of total phenolics, and an antioxidant capacity of 0.47, 0.45, and 0.29 mmol TEq/g of extract using the DPPH, ABTS, and FRAP methods, respectively. In addition, the optimized extract presented caffeic acid and was able to delay the lipid oxidation of olive oil. The potential of endophytic fungi to produce phenolic compounds is promising for the food industry since natural bioactive compounds have many benefits for human health.

Honey is a natural product produced by bees from the nectar of plants and has been widely used as a sweetener for centuries. In addition to its traditional use, it is also employed for other purposes due to its biological and nutraceutical properties. Although honey production is mostly associated with bees of the genus Apis, species from other genera, such as Melipona, also produce it, albeit on a smaller scale. The honey produced by these two genera shows significant differences in its composition. Moreover, distinct geographical localizations, which, consequently, have different flora, guide the chemical compositions of these samples. Regarding the Amazon region, the amount of knowledge about the honey samples from Melipona species is still scarce. In this context, the present study aimed to characterize the volatile compositions of honey from Melipona interrupta and Melipona seminigra, as well as from the floral sources available, in addition to evaluating their nutritional aspects, antioxidant activity, and antibacterial activity. The analysis of chemical composition was performed using gas chromatography coupled to mass spectrometry (GC-MS). Antioxidant activity was determined by DPPH and ABTS assays, while antimicrobial activity was tested against Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa, Proteus mirabilis, Staphylococcus epidermidis, Enterococcus faecalis, Salmonella enterica, Serratia marcescens, Bacillus subtilis, Candida albicans, Candida tropicalis, and Candida parapsilosis. The results allowed the identification of volatiles present in the honey and floral sources. The samples displayed moderate antioxidant activity and slightly antibacterial activity (MIC) of 75 μg/mL against two bacterial strains tested, demonstrating potential antimicrobial activity.

Produção de celulases por actinobactérias cultivadas em diferentes substratos / Production of cellulases by actinobacteria cultivated on different substrates

Background/Objectives: Antimicrobial resistance and biofilm-associated infections have intensified the search for new bioactive molecules from natural sources. This study evaluated the antibacterial activity, effects on biofilm biomass, preliminary cytotoxicity, and chemical profiles of ethyl acetate extracts obtained from Amazonian endophytic fungi against Staphylococcus aureus CCCD-S009. Methods: Ten fungal extracts were evaluated using broth microdilution and crystal violet-based biofilm assays. Additional experiments assessed biofilm biomass during formation and the reduction in preformed biofilm biomass at the minimum inhibitory concentration (MIC) and half the MIC (0.5× MIC). Complementary experiments with Talaromyces pinophilus CCM-UEA-F0408 included testing across multiple concentrations and qualitative microscopy. Cytotoxicity was evaluated in MRC-5 human fibroblasts, and chemical characterization included thin-layer chromatography, total phenolic content determination, and HPLC-PDA analysis of selected phenolic acids. Results: Nine extracts showed antibacterial activity, with Cophinforma mamane CCM-UEA-F0869 and Penicillium jenningsiae CCM-UEA-F0773 exhibiting the lowest MICs (312.5 µg/mL). Nine extracts reduced crystal violet-stained biofilm biomass during formation by more than 50%. At 0.5× MIC, reductions in biofilm biomass ranged from 73.40% to 86.94%. Removal of preformed biofilm biomass was less consistent and varied with extract concentration and exposure time. At 50 µg/mL, seven extracts maintained MRC-5 cell viability above 90%, whereas T. pinophilus CCM-UEA-F0695 and P. jenningsiae CCM-UEA-F0773 markedly reduced cell viability. Preliminary chemical analyses revealed differences among extracts, and targeted HPLC-PDA profiling indicated the presence of caffeic, 4-hydroxybenzoic, gallic, and vanillic acids in selected fungal extracts. Conclusions: Amazonian endophytic fungal extracts exhibited distinct antibacterial, biofilm-related, and cytotoxicity profiles. The reduction in biofilm biomass observed at sub-MICs supports further investigation of these extracts as potential sources of bioactive compounds. However, biofilm-specific effects cannot be distinguished from growth inhibition using the present assays alone.