Search

Cold-adapted microorganisms can produce enzymes with activity at low and mild temperatures, which can be applied to environmental biotechnology. This study aimed to characterize 20 Antarctic fungi to identify their genus (ITS rDNA marker) and growth temperatures and evaluate their ability to decolorize and detoxify the textile dye indigo carmine (IC). An individual screening was performed to assess the decolorization and detoxification of IC by the isolates, as well as in consortia with other fungi. The isolates were affiliated with seven ascomycete genera: Aspergillus(n= 4), Cosmospora(n= 2), Leuconeurospora(n= 2), Penicillium(n= 3), Pseudogymnoascus(n= 6), Thelebolus(n= 2), and Trichoderma(n= 1). The two isolates from the genus Leuconeurosporawere characterized as psychrophilic, while the others were psychrotolerant. The Penicilliumisolates were able to decolorize between 60 and 82% of IC. The isolates identified as Pseudogymnoascusshowed the best detoxification capacity, with results varying from 49 to 74%. The consortium using only Antarctic ascomycetes (C1) showed 45% of decolorization, while the consortia with the addition of basidiomycetes (C1 + Peniophoraand C1 + Pholiota) showed 40% and 50%, respectively. The consortia C1 with the addition of the basidiomycetes presented a lower toxicity after the treatments. In addition, a higher fungal biomass was produced in the presence of dye when compared with the experiment without the dye, which can be indicative of dye metabolization. The results highlight the potential of marine-derived Antarctic fungi in the process of textile dye degradation. The findings encourage further studies to elucidate the degradation and detoxification pathways of the dye IC by these fungal isolates.

The Antarctic continent is a reservoir of new genetic resources to the bioprospection of microorganisms adapted to the polar conditions and capable to produce molecules with differentiated properties. Biosurfactants are a promising alternative to replace synthetic surfactants due to their eco-friendly characteristics and the possibility of being produced from raw materials, such as lignocellulosic biomass. The aim of the current study was to evaluate the biosurfactants produced by Antarctic yeast strains using detoxified sugarcane straw hemicellulosic hydrolysate (DSSHH). Therefore, the biosurfactant production, using xylose as the carbon source, was first evaluated in semi-defined medium and subsequently in DSSHH. The Naganishia adelliensesL95 showed the highest emulsification index (52%) and total xylose consumption (40 g.L−1) in DSSHH. The biosurfactant produced by the yeast strain L95 was partially characterized, and its emulsion remained stable under low-temperature conditions (0 and 4 °C), at high salt concentration (10%), and alkaline condition. The screening of yeasts for the attainment of natural products that have potential biotechnological applications is of great importance. The results showed the potential of L95 to produce biosurfactants in DSSHH.

In this study, L-asparaginase and biosurfactants production by yeasts isolated from marine and terrestrial Antarctic environments was investigated. L-asparaginase production was determined by assessing enzyme activity and biosurfactants production was evaluated according to fermentation parameters and biosurfactant characteristics, including those determined by FTIR. Biosurfactant analysis results revealed all 14 yeast tested presented at least one characteristic of biosurfactant or bioemulsification activity. The yeasts Meyerozyma guilliermondiiL21, Candida glaebosaL75, Cryptococcus victoriaeL92 and Leucosporidium scottiL120 presented the greatest potential to produce biosurfactant and were selected for additional testing related to biosurfactants production and evaluation of L-asparaginase production. Additional tests found critical micellar concentration (CMC) values of 500–700 mg/L and high stability (pH 2–12, salinity of 0.5–10% and temperature of 20–100°C); the highest productivity was 0.17 and 0.28 g/L·h, respectively, for Candida glaebosaL75 and Leucosporidiumscotti L120. Also, the use of polyurethane as solid-state fermentation (SSF) support proved to be useful in L-asparaginase production; all selected yeasts yielded at least 0.9 U/g of inert support and Leucosporidium scottiL120 was the most efficient, providing 1.4 U/g support. The evaluation of Antarctic yeast confirmed their potential to produce L-asparaginase and biosurfactants, demonstrated L-asparaginase production by yeasts via SSF and revealed satisfactory production of biosurfactants by yeasts from poorly explored cold environments.

Plant pathogens cause great economic losses in agriculture. To reduce damage, chemical pesticides have been frequently used, but these compounds in addition to causing risks to the environment and health, its continuous use has given rise to resistant phytopathogens, threatening the efficiency of control methods. One alternative for such a problem is the use of natural products with high antifungal activity and low toxicity. Here, we present the production, isolation, and identification of cyclopaldic acid, a bioactive compound produced by Penicilliumsp. CRM 1540, a fungal strain isolated from Antarctic marine sediment. The crude extract was fractionated by reversed-phase chromatography and yielded 40 fractions, from which fraction F17 was selected. We used 1D and 2D Nuclear Magnetic Resonance analysis in DMSO-d6and CDCl3, together with mass spectrometry, to identify the compound as cyclopaldic acid C11H10O6(238 Da). The pure compound was evaluated for antimicrobial activity against phytopathogenic fungi of global agricultural importance, namely: Macrophomina phaseolina, Rhizoctonia solani,and Sclerotinia sclerotiorum. The antifungal assay revealed the potential of cyclopaldic acid, produced by Penicilliumsp. CRM 1540, as a leading molecule against M. phaseolinaand R. solani, with more than 90% of growth inhibition after 96h of contact with the fungal cells using 100 µg mL−1, and more than 70% using 50 µg mL−1.

Xylarenones C−E (2−4), three new eremophilane sesquiterpenes, have been isolated from solid substrate cultures of a Camarops-like endophytic fungus isolated from Alibertia macrophylla. The structures were elucidated by analysis of spectroscopic data. Compounds were evaluated in subtilisin and pepsin protease assays, and compound 2showed potent inhibitory activity against both proteases.