Juliana Aparecida dos Santos

Arbuscular mycorrhizal fungi (AMF) establish symbioses with most terrestrial plants, enhancing nutrient uptake, stress tolerance, and soil quality. We evaluated the use of Rhizophagus irregularis -based inoculants in cover crops and subsequent commercial crops in a no-till system and assessed their effects on soil biological attributes and crop yield. Three on-farm field experiments in different locations were conducted with common bean, okra, and corn cultivated after the winter cover crops. The assays were arranged in a randomized complete block design with a split-plot scheme and four replicates, with cover crop inoculation (black oats) as the main factor and crop inoculation in the subplot. The treatments included (i) inoculation in the cover crop and no inoculation in the main crop; (ii) no inoculation in the cover crop and inoculation in the main crop; (iii) inoculation in both crops; and (iv) no inoculation in either crop. Soil acid phosphatase activity, fluorescein diacetate hydrolysis, AMF spore density, and crop yield were measured at the end of each cycle, and the AMF community composition was characterized. The AMF inoculant increased the soil quality indicators (acid phosphatase activity and fluorescein diacetate hydrolysis). Inoculation of the cover crops did not replace the beneficial effects of direct inoculation on the yields of beans, okra, or corn. The results of the experiments in locations with different soils revealed that, overall, direct crop inoculation increased the yields of bean, okra, and corn by 30%, 33%, and 19%, respectively, and intensified soil enzyme activity, with no detectable effects on soil AMF community diversity or structure.

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 Leuconeurospora were characterized as psychrophilic, while the others were psychrotolerant. The Penicillium isolates were able to decolorize between 60 and 82% of IC. The isolates identified as Pseudogymnoascus showed 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 + Peniophora and 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.

Harsh and extreme environments, such as Antarctica, offer unique opportunities to explore new microbial taxa and biomolecules. Given the limited knowledge on microbial diversity, this study aimed to compile, analyze and compare a subset of the biobank of Antarctic fungi maintained at the UNESP’s Central of Microbial Resources (CRM-UNESP). A total of 711 isolates (240 yeasts and 471 filamentous fungi) from marine and terrestrial samples collected at King George Island (South Shetland Islands, Antarctica) were used with the primary objective of investigating their presence in both marine and terrestrial environments. Among the yeasts, 13 genera were found, predominantly belonging to the phylum Basidiomycota. Among the filamentous fungi, 34 genera were represented, predominantly from the phylum Ascomycota. The most abundant genera in the marine samples were Metschnikowia, Mrakia, and Pseudogymnoascus, while in the terrestrial samples, they were Pseudogymnoascus, Leucosporidium, and Mortierella. Most of the genera and species of the CRM-UNESP biobank of Antarctic fungi are being reported as an important target for biotechnological applications. This study showed the relevance of the CRM-UNESP biobank, highlighting the importance of applying standard methods for the preservation of the biological material and associated data (BMaD), as recommended in national and international standards.

Antarctic harsh conditions favor the development of microbial adaptations. In this study, a molecular approach was applied to identify/refine the taxonomy of five yeasts isolated from different Antarctic samples, which were tested against ranges of temperature, UV radiations, salinity, and pH. Based on sequencing and phylogenetic analysis, strain CRM 1839 was confirmed as Naganishia sp., and strains CRM 1874, CRM 1565, CRM 2571, and CRM 2576 were identified as Goffeauzyma gilvescens, Goffeauzyma gastrica, Candida atlantica, and Camptobasidium sp., respectively, being this last one possibly a new species. Growth at different temperatures indicates that these yeasts are psychrotolerant, with the exception of Camptobasidium sp., which presents psychrophilic characteristics. G. gastrica recovered from marine sediment showed the best results of resistance to UV radiation, being able to grow even after the exposure to UVB dose of 9144 J/m² and UVC dose of 6102 J/m². C. atlantica isolated from glacier soil showed high cellular growth from 3 to 10% NaCl. The majority of the strains produced higher biomass at pH 7; nevertheless, G. gilvescens showed higher biomass production at pH 9. The studied Antarctic-derived yeasts have adaptations to extreme conditions, which makes them useful for biotechnological applications and studies of extremophiles.