Enzymatic Bioprospecting of Fungi Isolated from a Tropical Rainforest in Mexico

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.

Trichoderma virens XZ11-1 producing siderophores inhibits the infection of Fusarium oxysporum and promotes plant growth in banana plants

BACKGROUND

Banana Fusarium wilt caused by Fusarium oxysporum f. sp. cubense is a soil-borne fungal disease. Especially, tropical Race 4 (Foc TR4) can infect almost Cavendish subgroup and has a fatal threat to banana industry. Use of antagonistic microbes to manage soil-borne pathogen is viewed as a promising strategy.

RESULTS

Strain XZ11-1 isolated from tropical rainforest has the production ability of high siderophore. By the analysis of physiological and biochemical profiles, construction of phylogenetic tree, and comparative results from the NR database, strain XZ11-1 was identified as Trichoderma virens. A relative content of 79.45% siderophores was produced in the optimized fermentation solution, including hydroxamate and carboxylate-type siderophores. Siderophores were key for inhibiting the growth of Foc TR4 by competing for environmental iron. Similarly, T. virens XZ11-1 also had antagonistic activities against 10 phytopathogenic fungi. Pot experiments demonstrated that T. virens XZ11-1 could colonize in the root system of banana plants. The symbiotic interaction not only improve plant resistance to Foc TR4, but also enhance iron absorption of roots to promote plant growth by secreting siderophores.

CONCLUSIONS

T. virens XZ11-1 with the high-yield siderophores was isolated and identified. The strain could effectively inhibit the infection of Foc TR4 in banana roots and promote plant growth. It is a promising biocontrol agent for controlling fungal disease.

Ex Situ Conservation, DNA Barcoding and Enzymatic Potential Evaluation of Macrofungi (Basidiomycota, Ascomycota) from Vietnam

The diversity and resource potential of macroscopic fungi in tropical regions remain understudied. Vietnam, being in a biodiversity hotspot, has a large number of new fungal species that are of interest for biotechnology and medicine. The presence of a large number of protected areas in Vietnam creates favorable opportunities for the study and ex situ conservation of tropical biodiversity. From 2012 to 2023, 785 strains of macrofungi from National Parks of Vietnam were preserved in the LE-BIN collection, 327 of which were barcoded with the sequences deposited in the NCBI GenBank. A taxonomic analysis demonstrated that many of the preserved isolates are potentially new or poorly studied species, representing a useful resource for taxonomical studies and a search for new medicinal mushrooms. More than 180 strains were studied for the first time for growth rate and enzymatic activities. Of these, 53 strains showed high growth rate, 43-high cellulolytic activity, 73-high oxidative enzymes activity, and 27 showed high proteolytic activity, making them promising candidates for biotechnological and medical applications and opening new opportunities for sustainable biomass management, discovery of new enzymes and bioactive substances, development of new drugs and efficient plant waste treatment technologies. The results confirm the importance of the ex situ conservation of fungal diversity in tropical regions as a valuable source for scientific and commercial applications and suggest certain new active strains for biotechnological study.

Scrutinizing harsh habitats endophytic fungi and their prospective effect on water-stressed maize seedlings

Drought constitutes a significant abiotic stressor that hinders plant growth and productivity in many countries. Habitat-adapted endophytic fungi offer an environmentally sustainable approach to address this issue by promoting plant development and enhancing resilience against abiotic stresses. In this study, 30 endophytic fungal isolates were recovered from some wild plants in the extreme habitats of Port Said Governorate, Egypt, and evaluated for their drought tolerance using polyethylene glycol (PEG-6000). Only eight isolates demonstrated drought tolerance properties and were further evaluated for their plant growth-promoting biochemical activities and ability to improve maize germination under simulated drought conditions. All eight isolates exhibited enzyme activity for endo-1,4-β-glucanase, amylase, and pectinase, and most displayed significant nutrient mobilization, with siderophores production ranging from 4 to 89%, ammonia production from 1 to 7 μmol/ml, and phosphate solubilization from 129 to 256 µg/ml. Additionally, all isolates showed strong antioxidant activity and high total phenolic content, with some also producing notable levels of indole acetic acid (IAA) and gibberellic acid (GA3) as plant growth hormones. Coating maize grains with spore suspensions of the eight fungal isolates, in general, significantly increased their germination parameters and seedling vigor in vitro under 8% PEG-6000. This enhancement was particularly pronounced with Neurospora sitophila (P8L4M1) and Penicillium tardochrysogenum (P15L4M1), which increased the vigor of maize seedlings by approximately 308% compared to untreated control. Molecular identification of P8L4M1 and P15L4M1 was performed by amplifying the 28S rRNA gene. This study disclosed unique endophytic fungal isolates with promising potential for enhancing drought resistance in maize.

Bioprospecting of endophytic fungi from semidesert candelilla (Euphorbia antisyphilitica Zucc): Potential for extracellular enzyme production

Endophytic microbial communities colonize plants growing under various abiotic stress conditions. Candelilla (Euphorbia antisyphilitica Zucc.) is a shrub that develops functionally in arid and semi-arid zones of Mexico; these conditions generate an association between the plant and the microorganisms, contributing to the production of enzymes as a defense mechanism for resistance to abiotic stress. The objective of this research was to isolate and identify endophyte fungi of candelilla and bioprospection of these endophytic fungi for enzyme production using candelilla by-products. Fungi were isolated and identified using ITS1/ITS4 sequencing. Their potency index (PI) was evaluated in producing endoglucanase, xylanase, amylase, and laccase. Fermentation was carried out at 30°C for 8 days at 200 rpm, with measurements every 2 days, using candelilla by-products as substrate. All fungi exhibited higher cellulase, amylase, and laccase activities on the 2nd, 6th, and 8th day of fermentation, respectively, of fermentation. The fungus Aspergillus niger ITD-IN4.1 showed the highest amylase activity (246.84 U/mg), the genus Neurospora showed the highest cellulase activity, reaching up to 13.45 FPU/mg, and the strain Neurospora sp. ITD-IN5.2 showed the highest laccase activity (3.46 U/mg). This work provides the first report on the endophytic diversity of E. antisyphilitica and its potential role in enzyme production.

Molecular identification and lipolytic potential of filamentous fungi isolated from residual cooking oil

Filamentous fungi, microorganisms that develop and are located in different habitats, are considered important producers of enzymes and metabolites with potential for the biotechnology industry. The objective of this work was to isolate and identify filamentous fungi that grow in used oil. Two fungal species were characterised through their morphology and molecular identification. The DNA of each extracted strain was amplified by PCR using primers ITS1 and ITS4, obtaining sequences that were later in GenBank (NCBI). A white coloured strain (HB) with a cottony, white, hyaline morphology and irregular borders was observed; so too, a brown colony (HC) with a sandy surface, a well-defined border of beige colour in early growth until it became a dark brown colour. The identity result by homology of the sequences in the BLASTn database was 100% and 99.55%, indicating that they correspond to Cladosporiumtenuissimum and Fomitopsismeliae, respectively. Finally, the results in lipolytic activity show greater potential for Fomitopsismeliae with 0.61 U/l in residual oil. Thus, it is important to highlight the potential of this type of waste to favour the prospection of microorganisms for a sustainable alternative for future studies of biological conversion.

Inactivation of siderophore iron-chelating moieties by the fungal wheat root symbiont Pyrenophora biseptata

We investigated the ability of four plant and soil-associated fungi to modify or degrade siderophore structures leading to reduced siderophore iron-affinity in iron-limited and iron-replete cultures. Pyrenophora biseptata, a melanized fungus from wheat roots, was effective in inactivating siderophore iron-chelating moieties. In the supernatant solution, the tris-hydroxamate siderophore desferrioxamine B (DFOB) underwent a stepwise reduction of the three hydroxamate groups in DFOB to amides leading to a progressive loss in iron affinity. A mechanism is suggested based on the formation of transient ferrous iron followed by reduction of the siderophore hydroxamate groups during fungal high-affinity reductive iron uptake. P. biseptata also produced its own tris-hydroxamate siderophores (neocoprogen I and II, coprogen and dimerum acid) in iron-limited media and we observed loss of hydroxamate chelating groups during incubation in a manner analogous to DFOB. A redox-based reaction was also involved with the tris-catecholate siderophore protochelin in which oxidation of the catechol groups to quinones was observed. The new siderophore inactivating activity of the wheat symbiont P. biseptata is potentially widespread among fungi with implications for the availability of iron to plants and the surrounding microbiome in siderophore-rich environments.

Eco-friendly detoxification of hazardous Congo red dye using novel fungal strain Trametes flavida WTFP2: Deduced enzymatic biomineralization process through combinatorial in-silico and in-vitro studies

Growing textile industry is a major global concern, owing to the presence of recalcitrant hazardous pollutants, like synthetic dyes in discharged effluents. To explore new bioresources for mycoremediation, a high laccase-producing novel white-rot fungus (WRF), Trametes flavida WTFP2, was employed. T. flavida is an underexplored member of Polyporales. Using bioinformatic tools, 8 different cis-acting RNA elements were identified in the 5.8 S ITS gene sequence, where CRISPR (CRISPR-DR15), sRNA (RUF1), and snoRNA (ceN111) are uniquely present. Molecular docking was adopted to predict the catalytic interaction of chosen toxic diazo colorant, Congo red (CR), with four dye-degrading enzymes (laccase, lignin peroxidase, azoreductase, and aryl alcohol oxidase). With 376.41 × 10³ U/L laccase production, novel WRF exhibited dye-decolorization potential. WTFP2 effectively removed 99.48 ± 0.04% CR (100 mg/L) and demonstrated remarkable recyclability and persistence in consecutive remediation trials. Mycelial dye adsorption was not only substantial driver of colorant elimination; decolorization using active T. flavida was regulated by enzymatic catalysis, as outlined by in-vitro growth, induction of extracellular enzymes, and FESEM. Fifteen metabolites were identified using HRLCMS-QTOF, and novel CR degradation pathway was proposed. Furthermore, microbial and phyto-toxicity tests of metabolites suggested complete detoxification of toxic dye, making the process clean, green, and economically sustainable.

Isolation and characterization of wood-decomposing basidiomycetes from the Andean Forest in Boyacá, Colombia

This study explores the biotechnological potential of lignocellulolytic fungi collected in an oak forest. Fungal collections were obtained from natural reserves located in Boyacá-Colombia, ranging from 2700 to 3000 m.a.s.l. Twenty-three strains were isolated on malt agar, molecular characterization was performed, and ligninolytic and cellulolytic enzymatic activities were screened. Several white-rot fungi of biotechnological importance were identified as follows: Trametes sp., Trametes versicolor, Trametes villosa, Pycnoporus sanguineus, Bjerkandera adjusta, Lentinula boryana, Panus conchatus, Antrodia neotropica, Brunneoporus malicola, Laetiporus gilbertsonii, Stereum sp., Ganoderma sp., and Dichomitus sp. The strains T. versicolor 0554 and 0583, T. villosa 0562, and B. adusta 0556 showed the highest response in the qualitative enzymatic assays. These strains were used to determine their ability to decolorate the dyes aniline blue and Congo red, and it was found that T. villosa 0562 reached a level of decolorization close to 90% after 48 h of submerged culture. The fungal strains obtained here could offer alternatives to develop a process to accomplish sustainable development objectives.