Frost fighters: unveiling the potential of microbial antifreeze proteins in biotech innovation.

Polar environments pose extreme challenges for life due to low temperatures, limited water, high radiation, and frozen landscapes. Despite these harsh conditions, numerous macro and microorganisms have developed adaptive strategies to reduce the detrimental effects of extreme cold. A primary survival tactic involves avoiding or tolerating intra and extracellular freezing. Many organisms achieve this by maintaining a supercooled state by producing small organic compounds like sugars, glycerol, and amino acids, or through increasing solute concentration. Another approach is the synthesis of ice-binding proteins, specifically antifreeze proteins (AFPs), which hinder ice crystal growth below the melting point. This adaptation is crucial for preventing intracellular ice formation, which could be lethal, and ensuring the presence of liquid water around cells. AFPs have independently evolved in different species, exhibiting distinct thermal hysteresis and ice structuring properties. Beyond their ecological role, AFPs have garnered significant attention in biotechnology for potential applications in the food, agriculture, and pharmaceutical industries. This review aims to offer a thorough insight into the activity and impacts of AFPs on water, examining their significance in cold-adapted organisms, and exploring the diversity of microbial AFPs. Using a meta-analysis from cultivation-based and cultivation-independent data, we evaluate the correlation between AFP-producing microorganisms and cold environments. We also explore small and large-scale biotechnological applications of AFPs, providing a perspective for future research.

Photoprotective compounds and radioresistance in pigmented and non-pigmented yeasts.

Ultraviolet radiation, continuously reaching our planet's surface, is a type of electromagnetic energy within the wavelength range of 10 to 400 nm. Despite essential for all life on Earth, ultraviolet radiation may have severe adverse cellular effects, including DNA dimerization and production of reactive oxygen species. Radioresistant microorganisms can survive under high doses of ultraviolet radiation, enduring the direct and indirect effects on nucleic acids and other biomolecules. The synthesis and accumulation of photoprotective compounds are among the main strategies employed by radioresistant yeast species to bear the harmful effects of ultraviolet radiation. A correlation between pigments and resistance to ultraviolet radiation has been widely recognized in these microorganisms; however, there is still some debate on this topic, with non-pigmented strains sometimes being more resistant than their pigmented counterparts. In this review, we explore the role of photoprotective compounds-specifically, melanin, carotenoids, and mycosporines-and compare the differences found in resistance between pigmented and non-pigmented yeasts. We also discuss the biotechnological potential of these photoprotective compounds, with special emphasis on those produced by non-pigmented yeast strains, such as phytoene and phytofluene. The use of "-omics" approaches should further unveil the radioresistance mechanisms of non-pigmented yeasts, opening new opportunities for both research and commercial applications. KEY POINTS: • Updated knowledge on photoprotective compounds from radioresistant yeasts. • Differences on radioresistance between pigmented and non-pigmented yeasts. • Future prospects over the study of non-pigmented photoprotective compounds.

The hidden rainbow: the extensive biotechnological potential of Antarctic fungi pigments.

The Antarctic continent is an extreme environment recognized mainly by its subzero temperatures. Fungi are ubiquitous microorganisms that stand out even among Antarctic organisms, primarily due to secondary metabolites production with several biological activities. Pigments are examples of such metabolites, which mainly occur in response to hostile conditions. Various pigmented fungi have been isolated from the Antarctic continent, living in the soil, sedimentary rocks, snow, water, associated with lichens, mosses, rhizospheres, and zooplankton. Physicochemical extreme environments provide a suitable setup for microbial pigment production with unique characteristics. The biotechnological potential of extremophiles, combined with concerns over synthetic pigments, has led to a great interest in natural pigment alternatives. Besides biological activities provided by fungal pigments for surviving in extreme environments (e.g., photoprotection, antioxidant activity, and stress resistance), it may present an opportunity for biotechnological industries. This paper reviews the biotechnological potential of Antarctic fungal pigments, with a detailed discussion over the biological role of fungal pigments, potential industrial production of pigments from extremophilic fungi, pigments toxicity, current market perspective and published intellectual properties related to pigmented Antarctic fungi.