Comparison of the behavior of fungal and plant cell wall during gastrointestinal digestion and resulting health effects: A review

Genome-wide identification of the MYB gene family and FfMYB13 regulation analysis in cell wall synthesis underlying tissue toughening process of yellow Flammulina filiformis stipes

MYB transcription factors (TFs) play important roles in fungal growth, development, stress response, and secondary metabolism. Cell wall glycan remodeling induced by oxidative damage levels is vital for stipe quality during mature stage of yellow Flammulina filiformis fruiting bodies. In this study, we identified 15 F. filiformis MYB (FfMYB) that are ranging from 28.43 kDa-172.3 kDa, with an average of 73.51 kDa. These FfMYB genes were unevenly distributed among six chromosomes. Phylogenetic analysis indicated that 15 FfMYBs were closely related to existing model fungi, while they were more distant from Arabidopsis thaliana. Based on expression analysis, a MYB TF termed FfMYB13 were isolated and identified as a potential regulator binding the promoter of Ff-FeSOD1, which was negatively correlated with tissue toughening of yellow F. filiformis stipes. The data of DAP-seq analysis suggested that the downstream target genes of FfMYB13 were significantly enriched in cell wall metabolism. The result of EMSA and dual luciferase report experiments demonstrated that FfMYB13 served as an upstream transcriptional regulatory factor that activates four cell wall synthesis metabolism related genes, FfKRE6, Ffgas1, FfHYD-1, and FfGFA1. Moreover, FfMYB13 might negatively influence tissue toughening in the inhibition of oxidative damage by activating Ff-FeSOD1.

Fungal β-1, 3-glucanosyltransferases: A comprehensive review on classification, catalytic mechanism and functional role

β-1,3-Glucans form the major carbohydrate component of fungal cell walls, playing a vital role in cell viability, stress response, virulence, and even healthy functions such as immuno-enhancement. The elongation and branching of β-1,3-glucans is a mystery. More evidence proved the β-1, 3-glucantransferases belonging to GH72 or GH17 family to branch and remodel the synthesized linear β-1, 3-glucan chain by cleaving its internal β-1, 3-linkage and transfer the cleaved fragment to the nonreducing end of another β-1, 3-glucan acceptor. The present review summarized the comprehensive advances of β-1, 3-glucantransferases including their structures such as catalytic and non-catalytic protein domains, catalytic mechanisms and roles in cell wall formation, cell separation and cell viability to provide the references for understanding and guiding the biosynthesis and production regulation of functional β-1, 3-glucans with high-branched or elongated structures.

Formation and Characterization of Mycelium-Potato Protein Hybrid Materials for Application in Meat Analogs or Substitutes

There is increasing interest in the development of meat analogs due to growing concerns about the environmental, ethical, and health impacts of livestock production and consumption. Among non-meat protein sources, mycoproteins derived from fungal fermentation are emerging as promising meat alternatives because of their natural fibrous structure, high nutritional content, and low environmental impact. However, their poor gelling properties limit their application in creating meat analogs. This study investigated the potential of creating meat analogs by combining mycoprotein (MCP), a mycelium-based protein, with potato protein (PP), a plant-based protein, to create hybrid products with meat-like structures and textures. The PP-MCP composites were evaluated for their physicochemical, rheological, textural, and microstructural properties using electrophoresis, differential scanning calorimetry, dynamic shear rheology, texture profile analysis, confocal fluorescence microscopy, and scanning electron microscopy analyses. The PP-MCP hybrid gels were stronger and had more fibrous structures than simple PP gels, which was mainly attributed to the presence of hyphae fibers in mycelia. Dynamic shear rheology showed that the PP-MCP hybrids formed irreversible heat-set gels with a setting temperature of around 70 °C during heating, which was attributed to the unfolding and aggregation of the potato proteins. Confocal and electron microscopy analyses showed that the hybrid gels contained a network of mycelia fibers embedded within a potato protein matrix. The hardness of the PP-MCP composites could be increased by raising the potato protein content. These findings suggest that PP-MCP composites may be useful for the development of meat analogs with more meat-like structures and textures.

Recent insights into glucans biosynthesis and engineering strategies in edible fungi

Fungal α/β-glucans have significant importance in cellular functions including cell wall structure, host-pathogen interactions and energy storage, and wide application in high-profile fields, including food, nutrition, and pharmaceuticals. Fungal species and their growth/developmental stages result in a diversity of glucan contents, structures and bioactivities. Substantial progresses have been made to elucidate the fine structures and functions, and reveal the potential molecular synthesis pathway of fungal α/β-glucans. Herein, we review the current knowledge about the biosynthetic machineries, including: precursor UDP-glucose synthesis, initiation, elongation/termination and remodeling of α/β-glucan chains, and molecular regulation to maximally produce glucans in edible fungi. This review would provide future perspectives to biosynthesize the targeted glucans and reveal the catalytic mechanism of enzymes associated with glucan synthesis, including: UDP-glucose pyrophosphate phosphorylases (UGP), glucan synthases, and glucanosyltransferases in edible fungi.

Novel fungal alternative proteins from Penicillium limosum for enhancing structural and functional properties of plant-based meat analogues

Fungal proteins are excellent novel protein resources due to their high nutritional value and biological activity. In this study, a non-toxic strain of Penicillium limosum with a high biomass yield, protein, and essential amino acid contents, was isolated from wheat Qu (solid-state fermentation starter culture). Pea protein isolate (PPI) and P. limosum mycelial protein powder were extruded to prepare high-moisture meat analogues (HMMA), and their structural and functional properties were evaluated. Compared with 100% PPI, the addition of 5% mycoprotein enhanced the viscosity, gelling properties, chewiness, fibrous degree and in vitro protein digestibility (68.65%) of HMMA. Protein aggregates formed during high temperature extrusion, which increased the oil absorption capacity of HMMA (5% MY substitution). Conversely, their water absorption capacity indices were reduced by 5%. These findings provide a theoretical basis for the functional application of novel fungal alternative proteins.

In vitro protein digestion and carbohydrate colon fermentation of microbial biomass samples from bacterial, filamentous fungus and yeast sources

This study evaluated the nutritional quality of different microbial biomass samples by assessing their protein digestibility and carbohydrate fermentability in the colon using in vitro methods. Four microbial samples were produced: one hydrogen-oxidizing bacterial strain (Nocardioides nitrophenolicus KGS-27), two strains of filamentous fungi (Rhizopus oligosporus and Paecilomyces variotii), and one yeast strain (Rhodotorula babjevae). The microorganisms were grown in bioreactors, harvested and dried before analysis. The commercial fungal product Quorn was used as a reference. The protein digestibility of the microbial samples was analysed using the INFOGEST in vitro model, followed by quantification of N-terminal amine groups. An in vitro faecal fermentation experiment was also performed to evaluate the degradation of carbohydrates in microbial biomass samples and formation of short-chain fatty acids (SCFA). The fungal biomass samples had higher protein hydrolysis (60-75 %) than the bacterial sample (12 %) and Quorn (45 %), while the yeast biomass had the highest protein digestibility (85 %). Heat-treatment of the biomass significantly reduced its protein digestibility. Total dietary fibre (DF) content of fungal biomass was 31 - 43 %(DW), mostly insoluble, whereas the bacterial biomass contained mainly soluble DF (total DF: 25.7 %, of which 23.5 % were soluble and 2.2 % insoluble). After 24 h of colonic in vitro fermentation, SCFA production from the biomass of Paecilomyces, Quorn and Rhodotorula was similar to that of wheat bran, while 17 % and 32 % less SCFA were produced from the biomass of Rhizopus and the bacterial strain, respectively. Further studies are needed to clarify the reasons for the observed differences in protein digestibility and DF fermentability, especially regarding the cell wall structures and role of post-processing.

Colonic in vitro fermentation of mycoprotein promotes shifts in gut microbiota, with enrichment of Bacteroides species

Mycoprotein is a fungal-derived ingredient used for meat alternative products whose fungal cell walls are rich in dietary fibre (β-glucans and chitin) and defines its structure. Several health benefits have been reported after mycoprotein consumption, however, little is known about the impact of mycoprotein fermentation on the gut microbiota. This study aims to identify changes in microbiome composition and microbial metabolites during colonic fermentation of mycoprotein following simulated upper gastrointestinal digestion. Changes in microbial populations and metabolites produced by the fermentation of mycoprotein fibre were investigated and compared to a plant (oat bran) and an animal (chicken) comparator. In this model fermentation system, mycoprotein and oat showed different but marked changes in the microbial population compared to chicken, which showed minimal differentiation. In particular, Bacteroides species known for degrading β-glucans were found in abundance following fermentation of mycoprotein fibre. Mycoprotein fermentation resulted in short-chain fatty acid production comparable with oat and chicken at 72 h. Significantly higher branched-chain amino acids were observed following chicken fermentation. This study suggests that the colonic fermentation of mycoprotein can promote changes in the colonic microbial profile. These results highlight the impact that the unique structure of mycoprotein can have on digestive processes and the gut microbiota.

Designing healthier and more sustainable ultraprocessed foods

The food industry has been extremely successful in creating a broad range of delicious, affordable, convenient, and safe food and beverage products. However, many of these products are considered to be ultraprocessed foods (UPFs) that contain ingredients and are processed in a manner that may cause adverse health effects. This review article introduces the concept of UPFs and briefly discusses food products that fall into this category, including beverages, baked goods, snacks, confectionary, prepared meals, dressings, sauces, spreads, and processed meat and meat analogs. It then discusses correlations between consumption levels of UPFs and diet-related chronic diseases, such as obesity and diabetes. The different reasons for the proposed ability of UPFs to increase the risk of these chronic diseases are then critically assessed, including displacement of whole foods, high energy densities, missing phytochemicals, contamination with packaging chemicals, hyperpalatability, harmful additives, rapid ingestion and digestion, and toxic reaction products. Then, potential strategies to overcome the current problems with UPFs are presented, including reducing energy density, balancing nutritional profile, fortification, increasing satiety response, modulating mastication and digestion, reengineering food structure, and precision processing. The central argument is that it may be possible to reformulate and reengineer many UPFs to improve their healthiness and sustainability, although this still needs to be proved using rigorous scientific studies.

Nutritional, Textural, and Sensory Attributes of Protein Bars Formulated with Mycoproteins

Research accumulated over the past decades has shown that mycoprotein could serve as a healthy and safe alternative protein source, offering a viable substitute for animal- and plant-derived proteins. This study evaluated the impact of substituting whey protein with fungal-derived mycoprotein at different levels (10%, 20%, and 30%) on the quality of high-protein nutrition bars (HPNBs). It focused on nutritional content, textural changes over storage, and sensory properties. Initially, all bars displayed similar hardness, but storage time significantly affected textural properties. In the early storage period (0-5 days), hardness increased at a modest rate of 0.206 N/day to 0.403 N/day. This rate dramatically escalated from 1.13 N/day to 1.36 N/day after 5 days, indicating a substantial textural deterioration over time. Bars with lower mycoprotein levels (10%) exhibited slower hardening rates compared with those with higher substitution levels (20% and 30%), pointing to a correlation between mycoprotein content and increased bar hardness during storage. Protein digestibility was assessed through in vitro gastric and intestinal phases. Bars with no or low-to-medium levels of mycoprotein substitution (PB00, PB10, and PB20) showed significantly higher digestibility (40.3~43.8%) compared with those with the highest mycoprotein content (PB30, 32.9%). However, digestibility rates for all mycoprotein-enriched bars were lower than those observed for whey-protein-only bars (PB00, 84.5%), especially by the end of the intestinal digestion phase. The introduction of mycoprotein enriched the bars' dietary fiber content and improved their odor, attributing a fresh mushroom-like smell. These findings suggest that modest levels of mycoprotein can enhance nutritional value and maintain sensory quality, although higher substitution levels adversely affect texture and protein digestibility. This study underscores the potential of mycoprotein as a functional ingredient in HPNBs, balancing nutritional enhancement with sensory acceptability, while also highlighting the challenges of textural deterioration and reduced protein digestibility at higher substitution levels.

The Tissue Browning and Concomitant Toughening of Yellow Flammulina filiformis Stipes Is Caused by Oxidative Damage-Mediated Metabolic Disorder and Cell Wall Glycan Remodeling

The browning and associated toughening of fruiting body stipes are the main causes of declines in the commercial production of yellow Flammulina filiformis. The dynamic metabolic changes from the top to bottom stipe sections of yellow F. filiformis fruiting bodies were investigated by integrating physiological, transcriptomic, and metabolomic analyses. The results indicated that oxidative stress levels gradually increased accompanying the degree of tissue browning and toughening from the top to bottom sections of F. filiformis stipes. In-depth analysis showed that there were remarkable changes in the expression of genes, and the content of metabolites correlated with the primary and secondary metabolism of F. filiformis stipes. Interestingly, the expression levels of genes participating in chitosan biosynthesis and the degree of deacetylation of chitosan increased from top to bottom in F. filiformis stipes, implying that cell wall glycan remodeling may contribute to concomitant toughening of the browning of F. filiformis stipes.

A Review of Plant-Based Drinks Addressing Nutrients, Flavor, and Processing Technologies

Plant-based drinks have garnered significant attention as viable substitutes for traditional dairy milk, providing options for individuals who are lactose intolerant or allergic to dairy proteins, and those who adhere to vegan or vegetarian diets. In recent years, demand for plant-based drinks has expanded rapidly. Each variety has unique characteristics in terms of flavor, texture, and nutritional composition, offering consumers a diverse range of choices tailored to meet individual preferences and dietary needs. In this review, we aimed to provide a comprehensive overview of the various types of plant-based drinks and explore potential considerations including their nutritional compositions, health benefits, and processing technologies, as well as the challenges facing the plant-based drink processing industry. We delve into scientific evidence supporting the consumption of plant-based drinks, discuss their potential roles in meeting dietary requirements, and address current limitations and concerns regarding their use. We hope to illuminate the growing significance of plant-based drinks as sustainable and nutritious alternatives to dairy milk, and assist individuals in making informed choices regarding their dietary habits, expanding potential applications for plant-based drinks, and providing necessary theoretical and technical support for the development of a plant-based drink processing industry.

Designing healthier plant-based foods: Fortification, digestion, and bioavailability

Many consumers are incorporating more plant-based foods into their diets as a result of concerns about the environmental, ethical, and health impacts of animal sourced foods like meat, seafood, egg, and dairy products. Foods derived from animals negatively impact the environment by increasing greenhouse gas emissions, land use, water use, pollution, deforestation, and biodiversity loss. The livestock industry confines and slaughters billions of livestock animals each year. There are concerns about the negative impacts of some animal sourced foods, such as red meat and processed meat, on human health. The livestock industry is a major user of antibiotics, which is leading to a rise in the resistance of several pathogenic microorganisms to antibiotics. It is often assumed that a plant-based diet is healthier than one containing more animal sourced foods, but this is not necessarily the case. Eating more fresh fruits, vegetables, nuts, and whole grain cereals has been linked to improved health outcomes but it is unclear whether next-generation plant-based foods, such as meat, seafood, egg, and dairy analogs are healthier than the products they are designed to replace. Many of these new products are highly processed foods that contain high levels of saturated fat, sugar, starch, and salt, and low levels of micronutrients, nutraceuticals, and dietary fibers. Moreover, they are often rapidly digested in the gastrointestinal tract because processing disrupts plant tissues and releases the macronutrients. Consequently, it is important to formulate plant-based foods to reduce the levels of nutrients linked to adverse health effects and increase the levels linked to beneficial health effects. Moreover, it is important to design the food matrix so that the macronutrients are not digested and absorbed too quickly, but the micronutrients are highly bioavailable. In this article, we discuss how next-generation plant-based foods can be made healthier by controlling their nutrient profile, digestibility, and bioavailability.

Loss of Phosphomannose Isomerase Impairs Growth, Perturbs Cell Wall Integrity, and Reduces Virulence of Fusarium oxysporum f. sp. cubense on Banana Plants

Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4) causes Fusarium wilt of banana, necessitating urgent measures to control this disease. However, the molecular mechanisms underlying Foc TR4 virulence remain elusive. Phosphomannose isomerase is a key enzyme involved in the biosynthesis of GDP mannose, an important precursor of fungal cell walls. In this study, two phosphomannose isomerases were identified in the Foc TR4 genome, of which only Focpmi1 was highly expressed throughout all developmental stages. Generated null mutants in Foc TR4 showed that only the ΔFocpmi1 mutant required exogenous mannose for growth, indicating that Focpmi1 is the key enzyme involved in GDP mannose biosynthesis. The Focpmi1 deficient strain was unable to grow without exogenous mannose and exhibited impaired growth under stress conditions. The mutant had reduced chitin content in its cell wall, rendering it vulnerable to cell wall stresses. Transcriptomic analysis revealed up- and down-regulation of several genes involved in host cell wall degradation and physiological processes due to the loss of Focpmi1. Furthermore, Focpmi1 was also found to be crucial for Foc TR4 infection and virulence, making it a potential antifungal target to address the threats posed by Foc TR4.

Alternative dietary protein sources to support healthy and active skeletal muscle aging

To mitigate the age-related decline in skeletal muscle quantity and quality, and the associated negative health outcomes, it has been proposed that dietary protein recommendations for older adults should be increased alongside an active lifestyle and/or structured exercise training. Concomitantly, there are growing environmental concerns associated with the production of animal-based dietary protein sources. The question therefore arises as to where this dietary protein required for meeting the protein demands of the rapidly aging global population should (or could) be obtained. Various non-animal-derived protein sources possess favorable sustainability credentials, though much less is known (compared with animal-derived proteins) about their ability to influence muscle anabolism. It is also likely that the anabolic potential of various alternative protein sources varies markedly, with the majority of options remaining to be investigated. The purpose of this review was to thoroughly assess the current evidence base for the utility of alternative protein sources (plants, fungi, insects, algae, and lab-grown "meat") to support muscle anabolism in (active) older adults. The solid existing data portfolio requires considerable expansion to encompass the strategic evaluation of the various types of dietary protein sources. Such data will ultimately be necessary to support desirable alterations and refinements in nutritional guidelines to support healthy and active aging, while concomitantly securing a sustainable food future.

Delivery of Phenolic Compounds, Peptides and β-Glucan to the Gastrointestinal Tract by Incorporating Dietary Fibre-Rich Mushrooms into Sorghum Biscuits

Sorghum biscuits were enriched with mushroom powders (Lentinula edodes, Auricularia auricula and Tremella fuciformis) at 5%, 10% and 15% substitution levels. An in vitro gastrointestinal digestion was used to evaluate the effect of this enrichment on the phenolic content and soluble peptide content as well as antioxidant activities of the gastric or intestinal supernatants (bio-accessible fractions), and the remaining portions of phenolic compounds, antioxidants and β-glucan in the undigested residue (non-digestible fraction). The phenolic content of the gastric and intestinal supernatants obtained from digested mushroom-enriched biscuits was found to be higher than that of control biscuit, and the phenolic content was positively correlated to the antioxidant activities in each fraction (p < 0.001). L. edodes and T. fuciformis enrichment increased the soluble protein content (small peptide) of sorghum biscuits after in vitro digestion. All mushroom enrichment increased the total phenolic content and β-glucan content of the undigested residue and they were positively correlated (p < 0.001). The insoluble dietary fibre of biscuits was positively correlated with β-glucan content (p < 0.001) of undigested residue. These findings suggested that enriching food with mushroom derived dietary fibre increases the bioavailability of the non-digestible β-glucan and phenolic compounds.