An overview of fungal biopolymers: bioemulsifiers and biosurfactants compounds production

A review of the fungal polysaccharides as natural biopolymers: Current applications and future perspective

As a unique natural resource, fungi are a sustainable source of lipids, polysaccharides, vitamins, proteins, and other nutrients. As a result, they have beneficial medicinal and nutritional properties. Polysaccharides are among the most significant bioactive components found in fungi. Increasing research has revealed that fungal polysaccharides (FPS) contain a variety of bioactivities, including antitumor, antioxidant, immunomodulatory, anti-inflammatory, hepatoprotective, cardioprotective, and anti-aging properties. However, the exact knowledge about FPS and their applications related to their future possibilities must be thoroughly examined to enhance a better understanding of this sustainable biopolymer source. Therefore, FPS' biological applications and their role in the food and feed industry, agriculture, and cosmetics applications were all discussed in this work. In addition, this review highlighted the mode of action of FPS on human diseases by regulating gut microbiota and discussed the mechanism of FPS as antioxidants in the living cell. The structure-activity connections of FPS were also highlighted and explored. Moreover, future perspectives were listed to pave the way for future studies of FPS applications. Hence, this study can be a scientific foundation for future FPS research and industrial applications.

Bio-stimulating effect of endophytic Aspergillus flavus AUMC 16068 and its respective ex-polysaccharides in lead stress tolerance of Triticum aestivum plant

Heavy metal accumulation is one of the major agronomic challenges that has seriously threatened food safety. As a result, metal-induced phytotoxicity concerns require quick and urgent action to retain and maintain the physiological activities of microorganisms, the nitrogen pool of soils, and the continuous yields of wheat in a constantly worsening environment. The current study was conducted to evaluate the plant growth-promoting endophytic Aspergillus flavus AUMC 16,068 and its EPS for improvement of plant growth, phytoremediation capacity, and physiological consequences on wheat plants (Triticum aestivum) under lead stress. After 60 days of planting, the heading stage of wheat plants, data on growth metrics, physiological properties, minerals content, and lead content in wheat root, shoot, and grains were recorded. Results evoked that lead pollution reduced wheat plants' physiological traits as well as growth at all lead stress concentrations; however, inoculation with lead tolerant endophytic A. flavus AUMC 16,068 and its respective EPS alleviated the detrimental impact of lead on the plants and promoted the growth and physiological characteristics of wheat in lead-contaminated conditions and also lowering oxidative stress through decreasing (CAT, POD, and MDA), in contrast to plants growing in the un-inoculated lead polluted dealings. In conclusion, endophytic A. flavus AUMC 16,068 spores and its EPS are regarded as eco-friendly, safe, and powerful inducers of wheat plants versus contamination with heavy metals, with a view of protecting plant, soil, and human health.

Diversity and enzymatic, biosurfactant and phytotoxic activities of culturable Ascomycota fungi present in marine sediments obtained near the South Shetland Islands, maritime Antarctica

We studied the culturable fungal community recovered from deep marine sediments in the maritime Antarctic, and assessed their capabilities to produce exoenzymes, emulsifiers and metabolites with phytotoxic activity. Sixty-eight Ascomycota fungal isolates were recovered and identified. The most abundant taxon recovered was the yeast Meyerozyma guilliermondii, followed by the filamentous fungi Penicillium chrysogenum, P. cf. palitans, Pseudeurotium cf. bakeri, Thelebolus balaustiformis, Antarctomyces psychrotrophicus and Cladosporium sp. Diversity indices displayed low values overall, with the highest values obtained at shallow depth, decreasing to the deepest location sampled. Only M. guilliermondii and P. cf. palitans were detected in the sediments at all depths sampled, and were the most abundant taxa at all sample sites. The most abundant enzymes detected were proteases, followed by invertases, cellulases, lipases, carrageenases, agarases, pectinases and esterases. Four isolates showed good biosurfactant activity, particularly the endemic species A. psychrotrophicus. Twenty-four isolates of P. cf. palitans displayed strong phytotoxic activities against the models Lactuca sativa and Allium schoenoprasum. The cultivable fungi recovered demonstrated good biosynthetic activity in the production of hydrolytic exoenzymes, biosurfactant molecules and metabolites with phytotoxic activity, reinforcing the importance of documenting the taxonomic, ecological and biotechnological properties of fungi present in deep oceanic sediments of the Southern Ocean.

Exploring fungal bioemulsifiers: insights into chemical composition, microbial sources, and cross-field applications

The demand for emulsion-based products is crucial for economic development and societal well-being, spanning diverse industries such as food, cosmetics, pharmaceuticals, and oil extraction. Formulating these products relies on emulsifiers, a distinct class of surfactants. However, many conventional emulsifiers are derived from petrochemicals or synthetic sources, posing potential environmental and human health risks. In this context, fungal bioemulsifiers emerge as a compelling and sustainable alternative, demonstrating superior performance, enhanced biodegradability, and safety for human consumption. From this perspective, the present work provides the first comprehensive review of fungal bioemulsifiers, categorizing them based on their chemical nature and microbial origin. This includes polysaccharides, proteins, glycoproteins, polymeric glycolipids, and carbohydrate-lipid-protein complexes. Examples of particular interest are scleroglucan, a polysaccharide produced by Sclerotium rolfsii, and mannoproteins present in the cell walls of various yeasts, including Saccharomyces cerevisiae. Furthermore, this study examines the feasibility of incorporating fungal bioemulsifiers in the food and oil industries and their potential role in bioremediation events for oil-polluted marine environments. Finally, this exploration encourages further research on fungal bioemulsifier bioprospecting, with far-reaching implications for advancing sustainable and eco-friendly practices across various industrial sectors.

Advancements in biosurfactant production using agro-industrial waste for industrial and environmental applications

The adverse effects of waste generation on the environment and public health have raised global concerns. The utilization of waste as a raw material to develop products with enhanced value has opened up novel prospects for promoting environmental sustainability. Biosurfactants obtained from agro-industrial waste are noteworthy due to their sustainability and environmental friendliness. Microorganisms have been employed to generate biosurfactants as secondary metabolites by making use of waste streams. The utilization of garbage as a substrate significantly reduces the expenses associated with the process. Furthermore, apart from reducing waste and offering alternatives to artificial surfactants, they are extensively employed in bioremediation, food processing, agriculture, and various other industrial pursuits. Bioremediation of heavy metals and other metallic pollutants mitigated through the use of bacteria that produce biosurfactants which has been the more recent research area with the aim of improving its quality and environmental safety. Moreover, the production of biosurfactants utilizing agricultural waste as a raw material aligns with the principles of waste minimization, environmental sustainability, and the circular economy. This review primarily focuses on the production process and various types of biosurfactants obtained from waste biomass and feedstocks. The subsequent discourse entails the production of biosurfactants derived from various waste streams, specifically agro-industrial waste.

Natural surfactant mediated bioremediation approaches for contaminated soil

The treatment of environmental pollution by employing microorganisms is a promising technology, termed bioremediation, which has several advantages over the other established conventional remediation techniques. Consequently, there is an urgent inevitability to develop pragmatic techniques for bioremediation, accompanied by the potency of detoxifying soil environments completely. The bioremediation of contaminated soils has been shown to be an alternative that could be an economically viable way to restore polluted soil. The soil environments have long been extremely polluted by a number of contaminants, like agrochemicals, polyaromatic hydrocarbons, heavy metals, emerging pollutants, etc. In order to achieve a quick remediation overcoming several difficulties the utility of biosurfactants became an excellent advancement and that is why, nowadays, the biosurfactant mediated recovery of soil is a focus of interest to the researcher of the environmental science field specifically. This review provides an outline of the present scenario of soil bioremediation by employing a microbial biosurfactant. In addition to this, a brief account of the pollutants is highlighted along with how they contaminate the soil. Finally, we address the future outlook for bioremediation technologies that can be executed with a superior efficiency to restore a polluted area, even though its practical applicability has been cultivated tremendously over the few decades.

Evidence of Small Fungal Cysteine-Rich Proteins Acting as Biosurfactants and Self-Assembling into Large Fibers

Fungi produce surface-active proteins, among which hydrophobins are the most characterized and attractive also for their ability to form functional amyloids. Our most recent findings show that these abilities are shared with other classes of fungal proteins. Indeed, in this paper, we compared the characteristics of a class I hydrophobin (Vmh2 from Pleurotus ostreatus) and an unknown protein (named PAC3), extracted from the marine fungal strain Acremonium sclerotigenum, which does not belong to the same protein family based on its sequence features. They both proved to be good biosurfactants, stabilizing emulsions in several conditions (concentration, pH, and salinity) and decreasing surface tension to a comparable value to that of some synthetic surfactants. After that, we observed for both Vmh2 and PAC3 the formation of giant fibers without the need for harsh conditions or long incubation time, a remarkable ability herein reported for the first time.

Differences in the Production of Extracellular Polymeric Substances (EPS) and Other Metabolites of Plenodomus (Leptosphaeria) Infecting Winter Oilseed Rape (Brassica napus L.)

Species of the genus Plenodomus (Leptosphaeria) are phytopathogens of the Brassicaceae family, which includes oilseed rape. The spores of these fungi spread by airborne transmission, infect plants, and cause crop losses. The secondary metabolism of P. lingam and P. biglobosus was studied and compared, with the main focus being on the ability to produce Extracellular Polymeric Substances (EPS). In spite of the 1.5-2-fold faster growth rate of P. biglobosus on Czapek-Dox and other screening media, the average yield of EPS in this fungus was only 0.29 g/L, compared to that of P. lingam (0.43 g/L). In turn, P. biglobosus showed a higher capacity to synthesise IAA, i.e., 14 µg/mL, in contrast to <1.5 µg/mL produced by P. lingam. On the other hand, the P. lingam strains showed higher β-glucanase activity (350-400 mU/mL), compared to 50-100 mU/mL in P. biglobosus. Invertase levels were similar in both species (250 mU/mL). The positive correlation between invertase activity and EPS yield contrasted with the absence of a correlation of EPS with β-glucanase. Plenodomus neither solubilised phosphate nor used proteins from milk. All strains showed the ability to synthesise siderophores on CAS agar. P. biglobosus exhibited the highest efficiency of amylolytic and cellulolytic activity.

A review of the role of biosurfactants in the biodegradation of hydrophobic organopollutants: production, mode of action, biosynthesis and applications

The increasing influence of human activity and industrialization has adversely impacted the environment via pollution with organic contaminants, which are minimally soluble in water. These hydrophobic organopollutants may be present in sediment, water or biota and have created concern due to their toxic effects in mammals. The ability of microorganisms to degrade pollutants makes their use the most effective, inexpensive and ecofriendly method for environmental remediation. Microorganisms have the ability to produce natural surfactants (biosurfactants) that increase the bioavailability of hydrophobic organopollutants, which enables their use as carbon and energy sources. Due to microbial diversity in production, and the biodegradability, nontoxicity, stability and specific activity of the surfactants, the use of microbial surfactants has the potential to overcome problems associated with contamination by hydrophobic organopollutants.This review provides an overview of the current state of knowledge regarding microbial surfactant production, mode of action in the biodegradation of hydrophobic organopollutants and biosynthetic pathways as well as their applications using emergent strategy tools to remove organopollutants from the environment. It is also specified for the first time that biosurfactants are produced either as growth-associated products or secondary metabolites, and are produced in different amounts by a wide range of microorganisms.

Biosurfactant-Producing Mucor Strains: Selection, Screening, and Chemical Characterization

Biosurfactants are amphiphilic molecules with surface tension reducing activities. Among biosurfactant producers, fungi have been identified as promising organisms. While many studies have investigated biosurfactant production in fungal species from the Ascomycota and Basidiomycota phyla, less is known concerning species from the Mucoromycota phylum. In this context, the aim of this study was to screen and optimize biosurfactant production in 24 fungal strains, including seven Mucor, three Lichtheimia, and one Absidia species. After cultivation in a medium stimulating surfactant production, the surface activity of cell-free supernatants was measured using both oil spreading and parafilm M tests. Among them, five Mucor strain cell-free supernatants belonging to M. circinelloides, M. lanceolatus, M. mucedo, M. racemosus, and M. plumbeus, showed oil repulsion. Then, the impact of the medium composition on surfactant production was evaluated for eight strains. Three of them, i.e., Mucor circinelloides UBOCC-A-109190, Mucor plumbeus UBOCC-A-111133, and Mucor mucedo UBOCC-A-101353 showed an interesting surfactant production potential, reducing the medium surface tension to 36, 31, and 32 mN/m, respectively. A preliminary characterization of the surfactant molecules produced by these strains was performed and showed that these compounds belonged to the glycolipid family.

Optimization of Exopolysaccharide (EPS) Production by Rhodotorula mucilaginosa sp. GUMS16

Exopolysaccharides (EPSs) are important biopolymers with diverse applications such as gelling compounds in food and cosmetic industries and as bio-flocculants in pollution remediation and bioplastics production. This research focuses on enhancing crude EPS production from Rhodotorula mucilaginosa sp. GUMS16 using the central composite design method in which five levels of process variables of sucrose, pH, and ammonium sulfate were investigated with sucrose and ammonium sulfate serving as carbon and nitrogen sources during microbial incubation. The optimal crude EPS production of 13.48 g/100 mL was achieved at 1 g/100 mL of sucrose concentration, 14.73 g/100 mL of ammonium sulfate at pH 5. Variations in ammonium sulfate concentrations (1.27–14.73 g/100 mL) presented the most significant effects on the crude EPS yield, while changes in sucrose concentrations (1–5 g/100 mL) constituted the least important process variable influencing the EPS yield. The Rhodotorula mucilaginosa sp. GUMS16 may have the potential for large-scale production of EPS for food and biomedical applications.

Submerged cultivation, characterization and in vitro antitumor activity of polysaccharides from Schizophyllum radiatum

Production of polysaccharides by white-rot-fungi in submerged cultivation has several advantages due to process control. This work deals with the submerged cultivation, extraction and antitumor activity of polysaccharides from a wild strain of Schizophyllum radiatum isolated from a tropical forest of Colombia. The mushroom was cultivated in laboratory conditions, and classified by classical and molecular taxonomy. Submerged cultivation was performed in a bioreactor of 5 L using a ligninolytic residue as substrate. The fermentation conditions were 30 ± 1 °C, pH 4.5, 300 rpm and 1.5 vvm of air for 4 days. The yields were 16.8 g/L (w/v) of biomass, and after extraction, 0.6 g/L of water-soluble exopolysaccharide (SEPS) and 2.01 % (w/w) of water-soluble intrapolysaccharide (SIPS) were obtained. In each extract total carbohydrate, glucans and protein contents were determined. Also, nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffractometry (XRD), high performance liquid chromatography with refraction index detection (HPLC-RI), high performance gel permeation chromatography (HPGPC) and Nuclear Magnetic Resonance (NMR) analysis were performed. Results indicated that SEPS and SIPS are heteropolysaccharides with amorphous structure and high molecular weights. Antitumor and immunostimulant activity was evaluated in different cancer cell lines. The results suggest these polysaccharides have direct and indirect antitumor activity activating immune cells such as macrophages. These findings enhance our knowledge about new sources of fungal metabolites that serve as adjuvant, cheaper and less harmful alternatives to cancer treatment.

Extraction and characterization of polysaccharide-enriched fractions from Phoma dimorpha mycelial biomass

Ultrasound-assisted extraction (UAE) and pressurized hot water extraction (PHWE) were tested as advanced clean methods to obtain polysaccharides from Phoma dimorpha mycelial biomass. These methods were compared to conventional extraction (hot water extraction, HWE) in terms of polysaccharides-enriched fractions (PEF) yield. A central composite rotational design was performed for each extraction method to investigate the influence of independent variables on the yield and to help the selection of the condition with the highest yield using water as an extraction solvent. The best extraction condition of PEF yielded 12.02 wt% and was achieved when using UAE with direct sonication for 30 min under the intensity of 75.11 W/cm² and pulse factor of 0.57. In the kinetic profiles, the highest yield (15.28 wt%) was obtained at 50 °C under an ultrasound intensity of 75.11 W/cm² and a pulse factor of 0.93. Structural analysis of extracted polysaccharide was performed using Fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and thermal property. The water solubility index, water holding capacity, and emulsification index of PEF were 31.3 ± 1.5%, 138.1 ± 3.2%, and 62.9 ± 2.3%, respectively. The submerged fermentation demonstrates the huge potential of Phoma dimorpha to produce polysaccharides with bioemulsifying properties as a biotechnologically cleaner alternative if compared to commercial petroleum-derived compounds. Furthermore, UAE and PHWE are green technologies, which can be operated at an industrial scale for PEF extraction.