With the advent of the industrial revolution, the use of toxic compounds has grown exponentially, leading to a considerable pollution of the environment. Consequently, the development of more environmentally conscious technologies is an urgent need. Industrial biocatalysis appears as one potential solution, where a higher demand for more robust enzymes aims to replace toxic chemical catalysts. To date, most of the commercially available enzymes are of mesophilic origin, displaying optimal activity in narrow ranges of temperature and pH (i.e., between 20°C and 45°C, neutral pH), limiting their actual application under industrial reaction settings, where they usually underperform, requiring larger quantities to compensate loss of activity. In order to obtain novel biocatalysts better suited for industrial conditions, an efficient solution is to take advantage of nature by searching and discovering enzymes from extremophiles. These microorganisms and their macromolecules have already adapted to thrive in environments that present extreme physicochemical conditions. Hence, extremophilic enzymes stand out for showing higher activity, stability, and robustness than their mesophilic counterparts, being able to carry out reactions at nonstandard conditions. In this brief research report we describe three examples to illustrate a stepwise strategy for the development and production of commercial extremozymes, including a catalase from an Antarctic psychrotolerant microorganism, a laccase from a thermoalkaliphilic bacterium isolated from a hot spring and an amine-transaminase from a thermophilic bacterium isolated from a geothermal site in Antarctica. We will also explore some of their interesting biotechnological applications and comparisons with commercial enzymes.

Microorganisms present in Antarctica have to deal not only with cold temperatures but also with other environmental conditions, such as high UV radiation, that trigger the generation of reactive oxygen species. Therefore, Antarctic microorganisms must have an important antioxidant defense system to prevent oxidative damage. One of these defenses are antioxidant enzymes, such as catalase, which is involved in the detoxification of hydrogen peroxide produced under oxidative conditions. Here, we reported the isolation and partial characterization of an Antarctic bacterium belonging to the Serratia genus that was resistant to UV-C radiation and well-adapted to cold temperatures. This microorganism, denominated strain I1P, was efficient at decreasing reactive oxygen species levels produced after UV-C irradiation. Genomic and activity assays suggested that the enzymatic antioxidant defense mechanisms of strain I1P, especially its catalase enzyme, may confer UV resistance. This catalase was active in a wide range of temperatures (20–70 °C), showing optimal activity at 50 °C (at pH 7.0), a remarkable finding considering its psychrotolerant origin. In addition, this enzyme was thermostable, retaining around 60% of its activity after 6 h of incubation at 50 °C. The antioxidant defense systems of strain I1P, including its surprisingly thermoactive and thermostable catalase enzyme, make this microorganism a good source of biocompounds with potential biotechnological applications.

Microbial oxygenic photosynthesis in thermal habitats is thought to be performed by Bacteria in circumneutral to alkaline systems (pH > 6) and by Eukarya in acidic systems (pH < 3), yet the predominant oxygenic phototrophs in thermal environments with pH values intermediate to these extremes have received little attention. Sequencing of 16S and 18S rRNA genes was performed on samples from twelve hot springs in Yellowstone National Park (Wyoming, USA) with pH values from 3.0 to 5.5, revealing that Cyanobacteria of the genus Chlorogloeopsis and algae of the genus Cyanidioschyzon (phylum Rhodophyta) coexisted in ten of these springs. Cyanobacterial 16S rRNA genes were more abundant than rhodophyte 18S rRNA genes by 1–7 orders of magnitude, with rhodophyte template abundance approaching that of Cyanobacteria only at the most acidic sites. The ketocarotenoids echinenone and canthaxanthin were identified in samples from all but one spring yielding cyanobacterial sequences and are attributed to pigment synthesis by Cyanobacteria, whereas the absence of detectable chloroplast sequences affiliated with Cyanidioschyzon, pH and temperatures in excess of its limits for growth, and other observations collectively suggested these algae were inactive in many of the springs at the time of sampling. Fluctuations in the supply of meteoric water likely contribute to physicochemical variability in these springs, leading to transitions in microbial community composition. Spatial overlap, but perhaps not temporal overlap, in the habitat ranges of bacterial and eukaryal oxygenic phototrophs indicates that the notion of a sharp transition between these lineages with respect to pH is unwarranted.

Microalgae grow rapidly, require minimal space, can proliferate in non-agricultural land, do not compete with human food sources, and can be cultivated in a variety of environments, including wastewater. They are considered an ecological source of bioactive compounds, offering an environmentally friendly alternative to conventional industrial production methods, which are often resource-intensive. It is important to emphasize that both the species of microalgae and the specific culture conditions play a decisive role in the generation and storage of valuable bioactive compounds, which can act as biostimulants. Biostimulants are organic compounds or microorganisms capable of enhancing crop quality parameters by optimizing nutrient and water use efficiency, while also strengthening tolerance to abiotic stress. The aim of this article is to provide an updated understanding of biostimulants, their modes of action, and their role in regulating plant responses to abiotic stress. It further incorporates examples of successful trials that demonstrate the advantageous applications of microalgae-based biostimulants, while also addressing the barriers and limitations to their commercialization and integration into sustainable agricultural practices.

Microalgae are unicellular photosynthetic organisms with considerable genetic diversity and remarkable metabolic capacity, positioning them as sustainable cellular biorefineries. They can be cultivated in open or closed systems, influenced by physical and chemical variables such as light, temperature, and nutrient availability. These conditions modulate the synthesis of valuable biomolecules, including proteins, lipids, polysaccharides, and secondary metabolites. Microalgae are especially notable for their high protein content (up to 70% w/w in Spirulina sp.), polyunsaturated fatty acids (e.g., DHA and EPA), and β-glucans with bioactive properties. Choosing the correct extraction method (mechanical, enzymatic or combined) is very important to obtain and preserve the functionality of these compounds. Despite their biotechnological potential in functional foods, pharmaceuticals, and biofuels, industrial development faces challenges such as extraction efficiency, scalability, and regulatory approval. This review compiles current knowledge on the nutritional and bioactive potential of microalgae, highlights advances in extraction technologies and discusses their potential applications in health-oriented industrial innovation.

This dataset contains temperatures, pH values, conductivities, stable water isotope ratios, and major solute concentrations for 14 water samples collected from 12 moderately acidic hot springs in Yellowstone National Park, Wyoming, United States. Charge imbalance calculations, pH values calculated based on charge balance, and DIC speciation are also included. Additionally, semi-quantitative abundances for various pigments (chlorophylls, their degradation products, and carotenoids) and bulk carbon and nitrogen contents of the associated biofilms/sediments are also included. Quantitative abundances normalized to total nitrogen in the biofilms/sediments are provided for chlorophyll a, β-carotene, β-cryptoxanthin, and zeaxanthin. Ribosomal gene sequence abundances for Bacteria and Eukarya are also provided.