Extracellular serine proteases by Acremonium sp. L1-4B isolated from Antarctica: Overproduction using cactus pear extract with response surface methodology

Bioprospecting of cellulases from marine fungi for macro-algal biomass degradation for biofuel application

The marine ecosystem, the largest on Earth, supports around 80 % of plant and animal species. Marine macroalgae, rich in polysaccharides like cellulose, remain underutilized despite their potential in a circular bioeconomy. Efficient valorization can promote sustainability, whereas mismanagement raises ecological concerns. Unlike lignocellulosic biomass, macroalgae lack lignin, making their processing unique. Global interest in macroalgae for biofuel applications is growing, particularly through polysaccharide-degrading biocatalysts like cellulases. Fungi, known for secreting extracellular cellulases and other enzymes, play a key role in biomass degradation. Marine fungi associated with macroalgae may possess enhanced enzymatic capabilities, enabling efficient algal polysaccharide breakdown. These fungi have immense potential in macroalgal biorefineries, facilitating the conversion of complex polysaccharides into oligosaccharides and monosaccharides for biofuels, pharmaceuticals, nutraceuticals, and cosmetics. Developing advanced bioprocessing technologies for marine fungi could provide robust cellulases that withstand industrial conditions, optimizing macroalgal biomass conversion. This review comprehensively examines cellulase production from marine fungi, their bioprocessing strategies, and their role in degrading macroalgal biomass. Additionally, other fungal enzymes and their industrial applications are briefly discussed. This study highlights the potential of marine fungi-derived cellulases in biofuel production, aligning with sustainable development goals and supporting global bioeconomic advancements.

A Review of the Biotechnological Potential of Cave Fungi: A Toolbox for the Future

The study of the intersection between biodiversity and biotechnology has revealed a rich source of innovations. Fungi, with their vast range of morphologies and lifestyles, thrive in various habitats, including caves. With impressive metabolic characteristics, they play a key role in producing essential biotechnological compounds for various economic sectors. This paper aims to consolidate evidence on the biotechnological potential of fungi isolated from caves, highlighting the urgency of conserving and exploring these ecosystems. For this purpose, we conducted a comprehensive literature search using scientific databases (SciELO, Medline Complete, Medline/PubMed, Web of Science, Scopus (Elsevier), and Google Scholar). We adopted an interdisciplinary approach by collecting information from 22 papers published between 2013 and 2024. Based on these data, our survey revealed broad potential, including antimicrobial compounds, antioxidants, antitumor agents, enzymes, and organic acids. We emphasize that accurately identifying and depositing fungal isolates in reference collections are crucial for reliable research and effective industrial applications, driving metabolic bioactivity and the production of substances with the potential to inhibit pathogens. Conserving and protecting the cave environment is imperative, considering its continuous potential for discovery and contribution to scientific advancement.

Application of fermentation for the valorization of residues from Cactaceae family

Cactaceae family is well-known for their adaptations to drought and arid environments. This family, formed by four subfamilies (Cactoideae, Opuntioideae, Pereskioideae, and Maihuenioideae) are known for being leafless stem succulent plants with numerous spines, and their commercial fruits, distinguished by their bright colors and their skin covered with bracts. Some of these species have been traditionally used in the food industry (e.g., pitaya, cactus, or prickly pear) or as pharmaceuticals to treat specific diseases due to their active properties. The processing of these fruits leads to different residues, namely pomace, skin, spines, and residues from cladodes; besides from others such as fruits, roots, flowers, mucilage, and seeds. In general, Cactaceae species produce large amounts of mucilage and fiber, although they can be also considered as a source of phenolic compounds (phenolic acids, flavonols and their glycosides), alkaloids (phenethylamines derived betalains), and triterpenoids. Therefore, considering their high content in fiber and fermentable carbohydrates, together with other target bioactive compounds, fermentation is a potential valorization strategy for certain applications such as enzymes and bioactive compounds production or aroma enhancement. This review will comprise the latest information about Cactaceae family, its potential residues, and its potential as a substrate for fermentation to obtain active molecules with application in the food industry.

Unconventional microbial proteases as promising tools for the production of bioactive protein hydrolysates

Enzymatic hydrolysis is the most prominent strategy to release bioactive peptides from different food proteins and protein-rich by-products. Unconventional microbial proteases (UMPs) have gaining increased attention for such purposes, particularly from the 2010s. In this review, we present and discuss aspects related to UMPs production, and their use to obtain bioactive protein hydrolysates. Antioxidant and anti-hypertensive potentials, commonly evaluated through in vitro testing, are mainly reported. The in vivo bioactivities of protein hydrolysates and peptides produced through UMPs action are highlighted. In addition to bioactivities, enzymatic hydrolysis acts by modulating the functional properties of proteins for potential food uses. The compiled literature indicates that UMPs are promising biocatalysts to generate bioactive protein hydrolysates, adding up to commercially available enzymes. From the recent interest on this topic, continuous and in-depth research is needed to advance toward the applicability and commercial utility of both UMPs and obtained hydrolysates.

Antarctic fungus proteases generate bioactive peptides from caseinate

The extracellular serine protease produced by Acremonium sp. L1-4B isolated from the Antarctic continent, was purified and used for the proteolysis of bovine and caprine sodium caseinate. Protein hydrolysates were evaluated in vitro to determine their antioxidant and antihypertensive potential, and later characterized by mass spectrometry. Bovine and caprine hydrolysates produced over 24 h showed a higher content of copper chelation (25.8 and 31.2% respectively), also at this time the ABTS^+• scavenging was 65.2% (bovine sample) and 67.5% (caprine sample), and bovine caseinate hydrolysate (8 h) exhibited higher iron chelation capacity (43.1%). Statistically (p < 0.05), caprine caseinate hydrolysates showed relatively higher antioxidant potential in this study. All hydrolysates showed antihypertensive potential; however peptides released from caprine caseinate after 8 h of hydrolysis were able to inhibit 75% of angiotensin-converting enzyme (ACE) activity. Nano-ESI-Q-TOF-MS/MS analysis prospected a total of 23 different peptide sequences in the bovine hydrolysate fraction, originated from the αS1- and β-casein chain, whilst in caprine hydrolysate, 31 sequences were detected, all from β-casein. The low molecular weight bovine and caprine hydrolysates obtained in this research have the potential to act in the prevention of disorders caused by oxidative reactions and in the regulation of blood pressure. These findings support the development of new functional food and nutraceutical formulations.

Biochemical and thermodynamic characteristics of a new serine protease from Mucor subtilissimus URM 4133

A protease from the fungus Mucor subtilissimus URM 4133, capable of producing bioactive peptides from goat casein, was purified. SDS-PAGE and zymography showed a molecular mass of 30 kDa. The enzyme was active and stable in a wide pH range (6.0–10.5) and (5.0–10.5), respectively. Optimum temperature was at 45–50 °C and stability was above 80 % (40 °C/2 h). Activity was not influenced by ions or organic substances (Triton, Tween, SDS and DMSO), but was completely inhibited by PMSF, suggesting that it belongs to the serine protease family. The Km and Vmax were 2.35 mg azocasein.mL-1 and 333.33 U.mg protein-1, respectively. Thermodynamic parameters of irreversible denaturation (40–60 °C) were enthalpy 123.63 – 123.46 kJ.mol-1, entropy 120.24–122.28 kJ.mol-1 and Gibbs free energy 85.97 – 82.45 kJ.mol-1. Any peptide sequences compatible with this protease were found after analysis by MALDI-TOF, which suggests that it is a new serine protease.

Cultivable fungi present in deep-sea sediments of Antarctica: taxonomy, diversity, and bioprospecting of bioactive compounds

We accessed the culturable mycobiota present in marine sediments at different depths in Antarctica Ocean. Acremonium fusidioides, Penicillium allii-sativi, Penicillium chrysogenum, Penicillium palitans, Penicillium solitum, and Pseudogymnoascus verrucosus were identified. Penicillium allii-sativi was the dominant species. At least one isolate of each species was capable to present antifungal, trypanocidal, leishmanicidal, antimalarial, nematocidal, or herbicidal activities. Penicillium produced extracts with strong trypanocidal and antimalarial activities, and the extracts of P. solitum and P. chrysogenum demonstrated strong antimalarial activities. Acremonium fusidioides and P. verrucosus displayed strong selective herbicidal properties. The ¹H NMR signals for extracts of A. fusidioides, P. chrysogenum, and P. solitum indicated the presence of highly functionalized secondary metabolites, which may be responsible for the biological activities detected. In the deep marine Antarctic sediments, we detected fungal assemblages in which the Penicillium species were found to be dominant and demonstrated capabilities to survive and/or colonise that poly-extreme habitat. Penicillium being a polyextremophile Antarctic species, exhibited strong biological activities and the presence of aromatic compounds in its extracts may indicate that they are wild ancient strains with high genetic and biochemical potentials that enable them to produce bioactive compounds which can be researched in further studies and used in the chemotherapy of neglected tropical diseases as well as in agriculture.

Cold-adapted enzymes produced by fungi from terrestrial and marine Antarctic environments

Antarctica is the coldest, windiest, and driest continent on Earth. In this sense, microorganisms that inhabit Antarctica environments have to be adapted to harsh conditions. Fungal strains affiliated with Ascomycota and Basidiomycota phyla have been recovered from terrestrial and marine Antarctic samples. They have been used for the bioprospecting of molecules, such as enzymes. Many reports have shown that these microorganisms produce cold-adapted enzymes at low or mild temperatures, including hydrolases (e.g. α-amylase, cellulase, chitinase, glucosidase, invertase, lipase, pectinase, phytase, protease, subtilase, tannase, and xylanase) and oxidoreductases (laccase and superoxide dismutase). Most of these enzymes are extracellular and their production in the laboratory has been carried out mainly under submerged culture conditions. Several studies showed that the cold-adapted enzymes exhibit a wide range in optimal pH (1.0-9.0) and temperature (10.0-70.0 °C). A myriad of methods have been applied for cold-adapted enzyme purification, resulting in purification factors and yields ranging from 1.70 to 1568.00-fold and 0.60 to 86.20%, respectively. Additionally, some fungal cold-adapted enzymes have been cloned and expressed in host organisms. Considering the enzyme-producing ability of microorganisms and the properties of cold-adapted enzymes, fungi recovered from Antarctic environments could be a prolific genetic resource for biotechnological processes (industrial and environmental) carried out at low or mild temperatures.

Optimized production and characterization of a detergent-stable protease from Lysinibacillus fusiformis C250R

In this study, we aimed to optimize the cultural and nutritional conditions for protease production by Lysinibacillus fusiformis strain C250R in submerged fermentation process using statistical methodology. The most significant factors (gruel, wheat bran, yeast extract, and FeSO₄) were identified by Plackett-Burman design. Response surface methodology (RSM) was used to determine the optimum levels of the screened factors and their interaction. Under the optimized conditions, protease yield 3100U/mL was 4.5 folds higher than those obtained by the use of the initial conditions (680U/mL). Additionally, a new extracellular 51kDa-protease, designated SAPLF, was purified and biochemically characterized from strain C250R. It shows optimum activity at 70°C and pH 10. Its half-life times at 70 and 80°C were 10 and 6-h, respectively. Irreversible inhibition of enzyme activity of SAPLF with serine protease inhibitors demonstrated that it belongs to the serine protease family. Interestingly, its catalytic efficiency was higher than that of SPVP from Aeribacillus pallidus strain VP3 and Alcalase Ultra 2.5L from Bacillus licheniformis. This study demonstrated that SAPLF has a high detergent compatibility and an excellent stain removal compared to Alcalase Ultra 2.5L; which offers an interesting potential for its application in the laundry detergent industry.