Biorefining via solid-state fermentation of rice and sunflower by-products employing novel monosporic strains from Pleurotus sapidus

Nutritional profiling and in silico analysis of pharmacological activities from local rice Pulu Mandoti fermented with Pleurotus spp

Pulu Mandoti, a local red rice (Oryza sativa L.) variety popular among Sulawesi residents, has gained recognition for its perceived health benefits, especially as a preferred dietary option for individuals with diabetes or those seeking to prevent obesity. Given the increasing consumption of mushrooms, particularly Pleurotus species, renowned for their nutritional and medicinal attributes, this study delves into the transformative effects of Pleurotus spp. fermentation on Pulu Mandoti, the indigenous rice variety. Proximate analysis disclosed elevated dry matter (91.99 ± 0.61%), crude protein (8.55 ± 0.15%), and crude fat (1.34 ± 0.05%) in Pleurotus cystidiosus fermentation compared to Pleurotus ostreatus and Pleurotus djamor. Concurrently, antioxidant and antidiabetic activities were notably improved in all Pleurotus fermentations. Pulu Mandoti fermented with P. cystidiosus outperformed other treatments, aligning with molecular docking results pinpointing 11-Eicosenoic acid, methyl ester, and butylated hydroxytoluene as optimal interactors with antioxidant receptors 5O0x and 2CKJ. Butylated hydroxytoluene demonstrated interactions with the antidiabetic receptor 2QV4, along with 9-Octadecenoic acid, methyl ester. These compounds, previously unreported in Pleurotus, displayed promising attributes as antioxidants and antidiabetic agents. Furthermore, the investigation delved into the fatty acid profiles, emphasizing the diverse range of potential bioactive compounds in fermented Pulu Mandoti. The findings of this research present a potential functional food rich in natural antioxidants and antidiabetic compounds, highlighting the yet undiscovered capabilities of Pleurotus spp. fermentation in augmenting the nutritional composition and bioactivity of indigenous rice varieties, specifically Pulu Mandoti.

Potential and Restrictions of Food-Waste Valorization through Fermentation Processes

Food losses (FL) and waste (FW) occur throughout the food supply chain. These residues are disposed of on landfills producing environmental issues due to pollutants released into the air, water, and soil. Several research efforts have focused on upgrading FL and FW in a portfolio of added-value products and energy vectors. Among the most relevant research advances, biotechnological upgrading of these residues via fermentation has been demonstrated to be a potential valorization alternative. Despite the multiple investigations performed on the conversion of FL and FW, a lack of comprehensive and systematic literature reviews evaluating the potential of fermentative processes to upgrade different food residues has been identified. Therefore, this article reviews the use of FL and FW in fermentative processes considering the composition, operating conditions, platforms, fermentation product application, and restrictions. This review provides the framework of food residue fermentation based on reported applications, experimental, and theoretical data. Moreover, this review provides future research ideas based on the analyzed information. Thus, potential applications and restrictions of the FL and FW used for fermentative processes are highlighted. In the end, food residues fermentation must be considered a mandatory step toward waste minimization, a circular economy, and the development of more sustainable production and consumption patterns.

Mushroom Production in the Southern Cone of South America: Bioeconomy, Sustainable Development and Its Current Bloom

A Sustainable Development Goals (SDGs) based analysis is presented here for business development of the production of edible and medicinal mushrooms using agro-wastes in the Southern Cone of South America. This circular economy approach using edible and medicinal mushroom production on lignocellulosic residues is discussed by analysing both its advantages and drawbacks. Among its main benefits, it is notable that mushroom cultivation using lignocellulosic residues promotes innovation aimed at environmental sustainability, facilitating diversification of the labour supply and the transfer of science to the socio-cultural sphere, which also increases the availability of healthy foods. However, there are some bottlenecks in the process, such as the continuous supply chain of substrates for fungal growth, the lack of equipment and infrastructure for the implementation of cultivation systems in extreme habitats, as well as authorization requirements and other limitations related to a non-fungiphilic culture society. Therefore, this chapter tries to provide key tools for establishing sustainable guidelines for the procurement of local healthy food and other products derived from mushroom cultivation using agricultural residues in the region, which might bloom due to an SDGs-based circular economy approach.

Production of an Anise- and Woodruff-like Aroma by Monokaryotic Strains of Pleurotus sapidus Grown on Citrus Side Streams

The production of natural flavors by means of microorganisms is of great interest for the food and flavor industry, and by-products of the agro-industry are particularly suitable as substrates. In the present study, Citrus side streams were fermented using monokaryotic strains of the fungus Pleurotus sapidus. Some of the cultures exhibited a pleasant smell, reminiscent of woodruff and anise, as well as herbaceous notes. To evaluate the composition of the overall aroma, liquid/liquid extracts of submerged cultures of a selected monokaryon were prepared, and the volatiles were isolated via solvent-assisted flavor evaporation. Aroma extract dilution analyses revealed p-anisaldehyde (sweetish, anisic- and woodruff-like) with a flavor dilution factor of 2¹⁸ as a character impact compound. The coconut-like, herbaceous, and sweetish smelling acyloin identified as (2S)-hydroxy-1-(4-methoxyphenyl)-1-propanone also contributed to the overall aroma and was described as an aroma-active substance with an odor threshold in air of 0.2 ng L⁻¹ to 2.4 ng L⁻¹ for the first time. Supplementation of the culture medium with isotopically substituted l-tyrosine elucidated this phenolic amino acid as precursor of p-anisaldehyde as well as of (2S)-hydroxy-1-(4-methoxyphenyl)-1-propanone. Chiral analysis via HPLC revealed an enantiomeric excess of 97% for the isolated product produced by P. sapidus.

Preparation of porous carbon based on partially degraded raw biomass by Trichoderma viride to optimize its toluene adsorption performance

Volatile organic compounds (VOCs), which are usually organic compounds with boiling point in the range of 50 to 260°C, pose a serious threat to human health and ecological environment. In order to find an adsorbent with excellent adsorption effect on VOCs, activated carbon was prepared from corn bran partially degraded by Trichoderma viride, and the adsorption performance of the optimized porous carbon materials on toluene was studied. Physical and chemical properties (such as specific surface area, pore size distribution, and surface functional groups) of the activated carbon were characterized by scanning electron microscope (SEM), N₂ adsorption/desorption experiences, Fourier-transform infrared (FTIR), and Raman and X-ray diffraction (XRD). The results showed that the specific surface area of corn bran reached 1896 m²/g and the total pore volume was 1.04 cm³/g after 15 days of microbial pretreatment. Dynamic simulation of adsorption experiment found that the saturated adsorption capacity of the pretreated carbon material was 237 mg/g at 100 ppm toluene concentration, which was 1.58 times of that of corn bran without microbial pretreatment. Generally, the improvement of adsorption performance may be mainly attributed to the increase of specific surface area, pore volume and the decrease of surface acidic groups.

Ganoderma sessile is a fast polysaccharide producer among Ganoderma species

The selection of fast-growing and high-yield-producing strains is required to satisfy the market demand on fungal food supplements. To that aim, three strains deposited in our collection as G. lucidum and G. oregonense were screened for polysaccharide production and biomass yield. Ganoderma strains deposited as G. lucidum were identified as G. sessile and G. lingzhi by nuc rDNA internal transcribed spacer ITS1-5.8S-ITS2 (ITS) and translation elongation factor 1-α (TEF1-α) phylogenies. The identity of G. oregonense was confirmed by molecular phylogeny and biogeography. Additionally, mycelial antagonism confirmed species differentiation, and strains were further distinguished by morphology and protein profiles. Biomass and polysaccharide yields of G. sessile were clearly different from those of G. lingzhi and G. oregonense in both liquid culture and solid-state fermentation. The maximum polysaccharide yield (4.52 ± 0.83 g L^-1) for G. sessile was obtained from submerged cultures at day 9. G. sessile also achieved the highest linear growth in lignocellulosic solid substrates. Consequently, basidiomata were successfully obtained by solid-state fermentation in polypropylene bags, whereas G. lingzhi and G. oregonense mushrooms were not produced in artificial solid substrates. G. sessile, a species frequently collected in America, showed to be a promising polysaccharide producer for the manufacture of dietary supplements.

Monokaryotic Pleurotus sapidus Strains with Intraspecific Variability of an Alkene Cleaving DyP-Type Peroxidase Activity as a Result of Gene Mutation and Differential Gene Expression

The basidiomycete Pleurotus sapidus produced a dye-decolorizing peroxidase (PsaPOX) with alkene cleavage activity, implying potential as a biocatalyst for the fragrance and flavor industry. To increase the activity, a daughter-generation of 101 basidiospore-derived monokaryons (MK) was used. After a pre-selection according to the growth rate, the activity analysis revealed a stable intraspecific variability of the strains regarding peroxidase and alkene cleavage activity of PsaPOX. Ten monokaryons reached activities up to 2.6-fold higher than the dikaryon, with MK16 showing the highest activity. Analysis of the PsaPOX gene identified three different enzyme variants. These were co-responsible for the observed differences in activities between strains as verified by heterologous expression in Komagataella phaffii. The mutation S371H in enzyme variant PsaPOX_high caused an activity increase alongside a higher protein stability, while the eleven mutations in variant PsaPOX_low resulted in an activity decrease, which was partially based on a shift of the pH optimum from 3.5 to 3.0. Transcriptional analysis revealed the increased expression of PsaPOX in MK16 as reason for the higher PsaPOX activity in comparison to other strains producing the same PsaPOX variant. Thus, different expression profiles, as well as enzyme variants, were identified as crucial factors for the intraspecific variability of the PsaPOX activity in the monokaryons.

Aspergillus oryzae Fermented Rice Bran: A Byproduct with Enhanced Bioactive Compounds and Antioxidant Potential

Rice bran (RB) is a byproduct of the rice industry (milling). For the fermentation process and to add value to it, RB was sprayed with fungal spores (Aspergillus oryzae MTCC 3107). The impact of fermentation duration on antioxidant properties was studied. Total phenolic content (TPC) determined using the Folin–Ciocalteu method, increased during fermentation until the 4th day. The antioxidant activity analyzed using the 2,2 Diphenyl–1′ picrylhydrazyl (DPPH) assay, total antioxidant activity (TAC), 2,2′-azinobis 3-ethylbenzothiazoline-6-sulfonic acid (ABTS⁺) assay, reducing power assay (RPA) and hydroxyl free radical scavenging activity (HFRSA) for fermented rice bran (FRB) were determined and compared to unfermented rice bran (URB). TAC, DPPH, ABTS⁺ and RPA of FRB increased till 4th day of fermentation, and then decreased. The specific bioactive constituents in extracts (Ethanol 50%) from FRB and URB were identified using high performance liquid chromatography (HPLC). HPLC confirmed a significant (p < 0.05) increase in gallic acid and ascorbic acid. On the 4th day of fermentation, the concentrations of gallic acid and ascorbic acid were 23.3 and 12.7 µg/g, respectively. The outcome of present investigation confirms that antioxidant potential and TPC of rice bran may be augmented using SSF.

Fermentation as an Alternative Process for the Development of Bioinsecticides

Currently, insect pest control is carried out through the application of synthetic insecticides which have been related to harmful effects on both human and environmental health, as well as to the development of resistant pest populations. In this context, the development of new and natural insecticides is necessary. Agricultural and forestry waste or by-products are very low-cost substrates that can be converted by microorganisms into useful value-added bioactive products through fermentation processes. In this review we discuss recent discoveries of compounds obtained from fermented substrates along with their insecticidal, antifeedant, and repellent activities. Fermentation products obtained from agricultural and forestry waste are described in detail. The fermentation of the pure secondary metabolite such as terpenes and phenols is also included.

Valorization of Vegetable Food Waste and By-Products Through Fermentation Processes

There is a general interest in finding new ways of valorizing fruit and vegetable processing by-products. With this aim, applications of industrial fermentation to improve nutritional value, or to produce biologically active compounds, have been developed. In this sense, the fermentation of a wide variety of by-products including rice, barley, soya, citrus, and milling by-products has been reported. This minireview gives an overview of recent fermentation-based valorization strategies developed in the last 2 years. To aid the designing of new bioprocesses of industrial interest, this minireview also provides a detailed comparison of the fermentation conditions needed to produce specific bioactive compounds through a simple artificial neural network model. Different applications reported have been focused on increasing the nutritional value of vegetable by-products, while several lactic acid bacteria and Penicillium species have been used to produce high purity lactic acid. Bacteria and fungi like Bacillus subtilis, Rhizopus oligosporus, or Fusarium flocciferum may be used to efficiently produce protein extracts with high biological value and a wide variety of functional carbohydrates and glycosidases have been produced employing Aspergillus, Yarrowia, and Trichoderma species. Fermentative patterns summarized may guide the production of functional ingredients for novel food formulation and the development of low-cost bioprocesses leading to a transition toward a bioeconomy model.

Effects of mixed agro-residues (corn crop waste) on lignin-degrading enzyme activities, growth, and quality of Lentinula edodes

Using agro-residues in bioreactors to produce mushrooms is an important component of eco-agriculture. Here, we tested the cultivation of Lentinula edodes with corn cob (CC) and corn straw (CS), and then evaluated the resulting enzyme activities, agronomic traits, textures and nutrient compositions of mushrooms. Laccase (T1 formula, 3.26 g U⁻¹) and carboxymethyl cellulase (T3 formula, 1.01 g U⁻¹) activities were the highest at the time for a complete substrate colonization stage (TCSC), while acidic xylanase activity was the highest (CK formula, 4.05 g U⁻¹) in the mushroom block to color-turned (TMBCT) stage. The biological efficiency of growth on the T6 formula was 8.82% higher than growth on the CK formula, wherein the low C/N ratio of the substrate had an obvious negative effect on yield while the mass ratio of pileus (MRP) of fruiting bodies did not change with mixed substrates. No significant differences were observed in mineral composition for CK formulas, but corn crop waste (CCW) formulas exhibited more optimal nutritional contents. A formula containing more corn cob and sawdust (SD) (sum of at least 70%) as the substrate can produce fruiting bodies with good hardness. These results indicate that the use of corn cobs as the main ingredient, mixed with sawdust and corn straw to grow L. edodes provides a more efficient use of agro-residues for growth. Thus, mixed agro-residue formulas have exceptional advantages in texture, nutrition of fruiting bodies, and yields.

Using agro-residues in bioreactors to produce mushrooms is an important component of eco-agriculture.

Biotransformation of rice and sunflower side-streams by dikaryotic and monokaryotic strains of Pleurotus sapidus: Impact on phenolic profiles and bioactive properties

Fungi are known to modify the properties of lignocellulosic materials during solid-state fermentation (SSF). In this study, agricultural side-streams (sunflower seed hulls, rice husks and rice straw) were used as substrates for SSF with dikaryotic and monokaryotic strains of Pleurotus sapidus. The phenolic profiles of the mentioned substrates were characterized by LC-DAD/ESI-MSⁿ pre- and post- fermentation. Moreover, antioxidant, cytotoxic and antimicrobial activities were screened against oxidizable cellular substrates, tumour and primary cell lines, and different bacteria and fungi, respectively. The concentration of phenolic compounds in the crop side-streams was reduced after fermentation with both strains of the fungus. The fermented extracts also displayed lower antioxidant and cytotoxic activities and had no hepatotoxicity. The antimicrobial activity depended upon the crop side-stream and/or SSF conditions. These results indicate that P. sapidus represent a good candidate to modify the phenolic fraction presents in crop side-streams with a consequent decrease in its bioactivities. However, the SSF with P. sapidus strains play an interesting role in the detoxification of plant materials which can be used for different applications according to the "reduce - reuse - recycle" concept contributing with the sustainable land use and circular economy.