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Featured Application: Single-cell protein is a type of protein derived from fungi and it has gained attention as a meat substitute due to its high protein content, low fat content, and specific texture. However, this type of protein can be used in the development of functional foods as well as additive to high-protein products, protein bars, shakes, snacks, dairy alternatives, etc. In recent years, there has been an increasing demand for new sources of protein, both for human and animal nutrition. In addition to alternative sources of protein, such as algae or edible insects, protein obtained from yeast and mold biomass is becoming more and more important. The main fungal protein producers are the yeasts Saccharomyces cerevisiae, Kluyveromyces marxianus, Candida utilis, Yarrowia lipolytica, and the molds Fusarium venenatum, Aspergillus oryzae, and Monascus purpureus. The production of fungal protein has many advantages, including the ability to regulate the amino acid composition, high protein content in dry matter, the possibility of production in a continuous process, independence from climatic factors, and the possibility of using waste substrates as ingredients of media. One of the disadvantages is the high content of nucleic acids, which generates the need for additional purification procedures before use in food. However, a number of enzymatic, chemical, and physical methods have been developed to reduce the content of these compounds. The paper presents the current state of knowledge about fungal producers, production and purification methods, the global market, as well as opportunities and challenges for single-cell protein (SCP) production. [ABSTRACT FROM AUTHOR]

Increasing global consumption of protein over the last five decades, coupled with concerns about the impact on emissions of animal‐based protein production, has created interest in alternative protein sources. Microbial proteins (MPs), derived through the fermentation of agro‐industrial byproducts, present a promising option. This review assesses a century of advancements in this domain. We conducted a comprehensive review and meta‐analysis, examining 347 relevant research papers to identify trends, technological advancements, and key influencing factors in the production of MP. The analysis covered the types of feedstocks and microbes, fermentation methods, and the implications of nucleic acid content on the food‐grade quality of proteins. A conditional inference tree model and Bayesian factor were used to ascertain the impact of various parameters on protein content. Out of all the studied parameters, such as type of feedstock (lignocellulose, free sugars, gases, and others), type of fermentation (solid, liquid, gas), type of microbe (bacteria, fungi, yeast, and mix), and operating parameters (temperature, time, and pH), the type of fermentation and microbe were identified as the largest influences on protein content. Gas and liquid fermentation demonstrated higher protein content, averaging 52% and 42%, respectively. Among microbes, bacterial species produced a higher protein content of 51%. The suitable operating parameters, such as pH, time, and temperature, were also identified for different microbes. The results point to opportunities for continued innovation in feedstock, microbes, and regulatory alignment to fully realize the potential of MP in contributing to global food security and sustainability goals. [ABSTRACT FROM AUTHOR]

Chlorella vulgaris (Chlorophyta) stands out as a promising microalga for single-cell protein production, particularly due to its potential to address the need for affordable nutrition in less-developed regions. Given this context, the quest for more economic fertilization methods is essential. Among the viable alternatives, hydroponic fertilizer (HF) emerges as a widely available option, particularly in regions such as Indonesia. Typically, HF is supplied in two distinct forms, powdered Mix-A and Mix-B, to prepare the stock solutions. This study investigates the impact of varying concentrations and stock solution ratios on both the growth rate and biomass yield of C. vulgaris. Additionally, an economic analysis of cultivation activities is conducted, with a specific focus on comparing the feasibility of utilizing hydroponic fertilizer against conventional methods. The findings reveal that specific ratios and concentrations of the tested growth media outperform standard media in promoting the growth rate and biomass yield of cultivated C. vulgaris. Furthermore, the economic analysis assesses two primary cost components: fertilizer and energy. All tested hydroponic media offered a more cost-effective cultivation solution compared to conventional methods, primarily attributed to the lower cost of the hydroponic fertilizers.

The escalating global demand for protein and the imperative to meet sustainable development goals have driven the emergence of biotransformation platforms, with methanotrophs showing significant potential in this field. In this paper, the metabolism, nutritional requirements, cultivation strategies, and bioreactors of methanotrophs are reviewed. Integrating upstream and downstream technologies is also advocated to advance the development of methanotroph biotransformation platforms toward a circular economy model. The advancements in utilizing biogas as a viable carbon source and wastewater as a nitrogen source are discussed, emphasizing the need for detailed quality control and safety assessments to ensure the suitability of single-cell protein as animal feed. In general, by integrating advanced nutrient recovery technologies to define new process routes, methanotroph biotransformation platforms can bring better environmental benefits by reducing carbon emissions and saving resources. Shifting to renewable energy is crucial for achieving environmental sustainability. By using renewable energy to power microbial fermentation, biomass dehydration, and waste recycling, the platform can offset high energy consumption and attain significant market competitiveness with traditional protein sources.

The present work examined the production of single-cell protein (SCP) by a newly isolated strain of Kluyveromyces marxianus EXF-5288 under increased lactose concentration of deproteinized cheese whey (DCW) and different temperatures (in °C: 20.0, 25.0, 30.0 and 35.0). To the best of the authors' knowledge, this is the first report examining the ability of Kluyveromyces marxianus species to produce SCP at T = 20.0 °C. Different culture temperatures led to significant differences in the strain's growth, while maximum biomass and SCP production (14.24 ± 0.70 and 6.14 ± 0.66 g/L, respectively) were observed in the cultivation of K. marxianus strain EXF-5288 in shake-flask cultures at T = 20.0 °C. Increased DCW lactose concentrations (35.0–100.0 g/L) led to increased ethanol production (Ethmax = 35.5 ± 0.2 g/L), suggesting that K. marxianus strain EXF-5288 is "Crabtree-positive". Batch-bioreactor trials shifted the strain's metabolism to alcoholic fermentation, favoring ethanol production. Surprisingly, K. marxianus strain EXF-5288 was able to catabolize the produced ethanol under limited carbon presence in the medium. The dominant amino acids in SCP were glutamate (15.5 mg/g), aspartic acid (12.0 mg/g) and valine (9.5 mg/g), representing a balanced nutritional profile [ABSTRACT FROM AUTHOR]

In recent years, single-cell protein (SCP) has been considered a promising aquaculture feed to cope with the growing issue of food security. SCP is derived from microbes including algae, yeasts, and bacteria. Algae and yeasts have been comprehensively studied as SCP sources in the last few years. However, their large-scale application is not yet economical. Recently, the use of purple non-sulfur bacteria (PNSB) has been realized as a sustainable source of SCP. PNSB display unique metabolic features that distinguish them from other SCP sources. They can grow under various light and electron donor/acceptor conditions, can use a variety of low-cost carbon sources, give high substrate yield under their preferred photoheterotrophic growth mode, and demonstrate anti-pathogenic properties. They also use the infrared region of light that enables their straightforward enrichment under non-axenic conditions. Despite the unique characteristics of PNSB, their use as SCP has not been widely reported. This review provides comprehensive knowledge about different factors that influence the quality and quantity of SCP produced from PNSB. The effects of key factors including light, redox conditions, trace metals, carbon substrate, and substrate availability are discussed. Special focus is given to the use of PNSB as SCP in aquaculture and PNSBs concomitant role in improving water quality. This information would expand knowledge and enhance understanding to utilize PNSB as an alternative SCP source for aquaculture feed. [ABSTRACT FROM AUTHOR]

Transformer‐based models have revolutionized single cell RNA‐seq (scRNA‐seq) data analysis. However, their applicability is challenged by the complexity and scale of single‐cell multi‐omics data. Here a novel single‐cell multi‐modal/multi‐task transformer (scmFormer) is proposed to fill up the existing blank of integrating single‐cell proteomics with other omics data. Through systematic benchmarking, it is demonstrated that scmFormer excels in integrating large‐scale single‐cell multimodal data and heterogeneous multi‐batch paired multi‐omics data, while preserving shared information across batchs and distinct biological information. scmFormer achieves 54.5% higher average F1 score compared to the second method in transferring cell‐type labels from single‐cell transcriptomics to proteomics data. Using COVID‐19 datasets, it is presented that scmFormer successfully integrates over 1.48 million cells on a personal computer. Moreover, it is also proved that scmFormer performs better than existing methods on generating the unmeasured modality and is well‐suited for spatial multi‐omic data. Thus, scmFormer is a powerful and comprehensive tool for analyzing single‐cell multi‐omics data. [ABSTRACT FROM AUTHOR]

Scalable, low-cost biofuel and biochemical production can accelerate progress on the path to a more circular carbon economy and reduced dependence on crude oil. Rather than producing a single fuel product, lignocellulosic biorefineries have the potential to serve as hubs for the production of fuels, production of petrochemical replacements, and treatment of high-moisture organic waste. A detailed techno-economic analysis and life-cycle greenhouse gas assessment are developed to explore the cost and emission impacts of integrated corn stover-to-ethanol biorefineries that incorporate both codigestion of organic wastes and different strategies for utilizing biogas, including onsite energy generation, upgrading to bio-compressed natural gas (bioCNG), conversion to poly(3-hydroxybutyrate) (PHB) bioplastic, and conversion to single-cell protein (SCP). We find that codigesting manure or a combination of manure and food waste alongside process wastewater can reduce the biorefinery's total costs per metric ton of CO2 equivalent mitigated by half or more. Upgrading biogas to bioCNG is the most cost-effective climate mitigation strategy, while upgrading biogas to PHB or SCP is competitive with combusting biogas onsite.

Yeast biomass, a brewery by-product of the world's substantial alcohol beverage industry, finds successful applications in the fodder industry and food additive production. This is attributed to its rich nutritional profile that comprises high protein and vitamin content. Nonetheless, in small-scale breweries, yeast slurries present a significant challenge, as the quantities obtained are insufficient to attract the attention of the food industry. The disposal of yeast contributes substantially to the organic load of wastewater (approximately 40%) and elevates water consumption (3–6 hL/hL of beer), consequently escalating production costs and environmental impact. In recent years, diverse potential applications of products derived from yeast biomass have emerged, encompassing the substitution of sera in cell culture media, the fortification of animal feed with vitamins and selenium, the utilization of beta-glucan in low-fat food products, and the development of functional foods incorporating yeast-derived peptides. These peptides exhibit the potential to safeguard the gastric mucosa, prevent hypertension, and address neurodegenerative disorders. The rising demand for value-added products derived from yeast underscores the potential profitability of processing yeast from small breweries. Due to the high equipment costs associated with yeast biomass fractionation, the establishment of specialized facilities in collaboration with multiple small breweries appears to be the most optimal solution. [ABSTRACT FROM AUTHOR]

With rapid growth of global population, meeting the increasing demand for food has become a significant challenge. This challenge is further compounded by limited arable land and the necessity to address the nutritional needs of both humans and animals. However, the utilization of straw biomass, which is readily available as an agricultural by‐product, presents a sustainable solution to this problem. Microbial fermentation has emerged as a highly effective method for converting non‐food biomass into protein, particularly known as single‐cell protein (SCP). Compared to traditional protein sources, SCP production through microbial fermentation is rapid and efficient, and requires minimal land resources. This review provides a comprehensive review of the research advancements in SCP from agricultural biomass, including pretreatment methods, microbial strains, and fermentation processes involved in the bioconversion of straw biomass. Due to the complexity of straw‐based biomass (SBB), it is essential to customize industrial strains and optimize the fermentation process to achieve the highest protein yield and productivity. Additionally, improving the compatibility between tailored processes and cost‐effective industrial strains can lead to the production of protein substitutes that are not only highly nutritious but also economically viable. Hence, the application of SCP derived from SBB presents a dual solution by reducing the need for managing agricultural residues and providing a sustainable source of protein. However, the production of SCP from SBB also has some limitations, such as protein‐synthesis efficiency, production cost, and difficulty to scale‐up the production process. In the future, there is great potential for significant advancements in the targeted conversion of SBB into protein by customizing high‐performance microbial strains. Several sensor and machine learning technologies will predict and monitor real‐time dynamic changes in the fermentation process of SBB, offering an opportunity to improve the production of sustainable SCP in an environmentally friendly and precise manner. [ABSTRACT FROM AUTHOR]

Alternative protein sources are gaining attraction in food industry and consumers. Proteins obtained by single-cell organisms, such as torula yeast, are of enormous interest, as they are highly scalable, efficient, and sustainable, and the production costs are comparably low. Nevertheless, proteins obtained from yeasts are still mostly known and studied for feed applications, despite their nutritional, functional, and sensory benefits for various food applications. Testing consumer acceptance of products, especially products containing alternative proteins provides insights into, e.g., market success, consumer perception, and optimization potential. In this study, the development of two vegan spread powders, high in protein and containing torula yeast as an alternative protein source, is introduced. The result of food product development using torula yeast were "Leberwurst"-style (14.7% protein) and a "Balkan"-style (9.7% protein) spreads both meeting the criteria "at least 20% kcal from proteins of total product kcal" and thus claimable as "high-protein." The application of the alternative protein from torula yeast within the final products was studied by a consumer acceptance test (n = 123) within three different countries (Germany, Iceland, and Sweden). Consumers also rated their trust in food production actors, the food industry in particular, and their willingness to try new foods. Overall, both spreads received acceptance values in the range of "like slightly." It is noticeable that the consumers liked the spread "Balkan style" more than "Leberwurst"-style. The background variables revealed higher neophobic characteristics of Icelandic consumers compared with Swedish or German consumers. However, German consumers felt transparency, and communication was missing, but Icelandic consumers, in general, had more trust in the overall food value chain. This knowledge allows for the development of strategies that address cultural-specific barriers and capitalize on cultural values that promote openness to culinary innovation. The identification of cultural variations in consumer preferences emphasizes the need for customized approaches to product development and marketing. These findings could have implications for businesses and policymakers in understanding and catering to the preferences and concerns of consumers in these respective countries. Businesses might benefit from emphasizing transparency and improving communication strategies. This could involve providing clear information about the sourcing, production, and other aspects of the food value chain. [ABSTRACT FROM AUTHOR]

The increase in world population has led to an increase in global food demand, which is estimated to grow by 35–56% from 2010 to 2050. As a result, the risk of hunger is also expected to rise. Protein consumption between 2000 and 2018 rose by 40% worldwide and is expected to increase at 9.3% cumulative annual growth rate in the near future. Hence, there is a huge demand and potential market available for human and animal protein. Therefore, newer and more protein sources will be required to meet the longer food value chains. Hence, a microbial protein produced using waste biomass could offer socio‐economic benefits and consumer acceptance owing to its vegetarian nature. Moreover, waste biomass‐based proteins are environmentally benign and very good ingredients in food and feed. Dry microbial protein, described as single‐cell protein, grown on agricultural residue, has been considered as a potent source of protein for both humans and animals. Thus, single‐cell protein will open up new opportunities to meet the growing protein demands for humans and animals. Microbially produced beer, cheese and yogurt are all examples of microbial protein sources for humans and animals. The feedstock, like agriculture residue, is relatively cheap and could be a potential source for large‐scale protein production in the future. [ABSTRACT FROM AUTHOR]

The rapidly increasing population and climate change pose a great threat to our current food systems. Moreover, the high usage of animal-based and plant-based protein has its drawbacks, as these nutritional sources require many hectares of land and water, are affected by seasonal variations, are costly, and contribute to environmental pollution. Single-cell proteins (SCPs) are gaining a lot of research interest due to their remarkable properties, such as their high protein content that is comparable with other protein sources; low requirements for land and water; low carbon footprint; and short production period. This review explores the use of food waste as a sustainable feedstock for the advancement of SCP processes. It discusses SCP studies that exploit food waste as a substrate, alongside the biocatalysts (bacteria, fungi, yeast, and microalgae) that are used. The operational setpoint conditions governing SCP yields and SCP fermentation routes are elucidated as well. This review also demonstrates how the biorefinery concept is implemented in the literature to improve the economic potential of "waste-to-protein" innovations, as this leads to the establishment of multiproduct value chains. A short section that discusses the South African SCP scenario is also included. The technical and economic hurdles facing second-generation SCP processes are also discussed, together with future perspectives. Therefore, SCP technologies could play a crucial role in the acceleration of a "sustainable protein market", and in tackling the global hunger crisis. [ABSTRACT FROM AUTHOR]

Abstract Transformer‐based models have revolutionized single cell RNA‐seq (scRNA‐seq) data analysis. However, their applicability is challenged by the complexity and scale of single‐cell multi‐omics data. Here a novel single‐cell multi‐modal/multi‐task transformer (scmFormer) is proposed to fill up the existing blank of integrating single‐cell proteomics with other omics data. Through systematic benchmarking, it is demonstrated that scmFormer excels in integrating large‐scale single‐cell multimodal data and heterogeneous multi‐batch paired multi‐omics data, while preserving shared information across batchs and distinct biological information. scmFormer achieves 54.5% higher average F1 score compared to the second method in transferring cell‐type labels from single‐cell transcriptomics to proteomics data. Using COVID‐19 datasets, it is presented that scmFormer successfully integrates over 1.48 million cells on a personal computer. Moreover, it is also proved that scmFormer performs better than existing methods on generating the unmeasured modality and is well‐suited for spatial multi‐omic data. Thus, scmFormer is a powerful and comprehensive tool for analyzing single‐cell multi‐omics data.

Abstract Single-cell protein (SCP) production in the methylotrophic yeast Pichia pastoris has the potential to achieve a sustainable protein supply. However, improving the methanol fermentation efficiency and reducing carbon loss has been a long-standing challenge with far-reaching scientific and practical implications. Here, comparative transcriptomics revealed that PAS_0305, a gene directly associated with cell wall thickness under methanol stress, can be used as a target for unlocking cell wall sensors. Intracellular trehalose accumulation confirmed that cell wall sensors were activated after knocking out PAS_0305, which resulted in increased cell wall permeability. Genome-wide signal perturbations were transduced through the HOG module and the CWI pathway, which was confirmed to connected by Pbs2-Mkk. As a consequence of CWI pathway activation, ΔPAS_0305 elicited a rescue response of cell wall remodeling by increasing the β-1,3-glucan content and decreasing the chitin/mannose content. Remarkably, perturbations in global stress signals led to a fine-tuning of the metabolic network of ΔPAS_0305, resulting in a superior phenotype with highest crude protein and methanol conversion rate of 67.21% and 0.46 gDCW/g. Further genome-scale metabolic models were constructed to validate the experimental results, confirming that unlocking cell wall sensors resulted in maximized flux from methanol towards SCP and effectively addressing the issue of carbon loss in methanol fermentation. This work sheds new light on the potential of manipulating cellular signaling pathways to optimize metabolic networks and achieve exceptional phenotypic characteristics, providing new strategies for constructing versatile cell factories in P. pastoris.

In recent years, there has been an increasing demand for new sources of protein, both for human and animal nutrition. In addition to alternative sources of protein, such as algae or edible insects, protein obtained from yeast and mold biomass is becoming more and more important. The main fungal protein producers are the yeasts Saccharomyces cerevisiae, Kluyveromyces marxianus, Candida utilis, Yarrowia lipolytica, and the molds Fusarium venenatum, Aspergillus oryzae, and Monascus purpureus. The production of fungal protein has many advantages, including the ability to regulate the amino acid composition, high protein content in dry matter, the possibility of production in a continuous process, independence from climatic factors, and the possibility of using waste substrates as ingredients of media. One of the disadvantages is the high content of nucleic acids, which generates the need for additional purification procedures before use in food. However, a number of enzymatic, chemical, and physical methods have been developed to reduce the content of these compounds. The paper presents the current state of knowledge about fungal producers, production and purification methods, the global market, as well as opportunities and challenges for single-cell protein (SCP) production.

Integration of first- and second-generation ethanol production is a strategy to strengthen the economic viability of individual processes and the overall viability of biorefineries. The sharing of storage, fermentation, distillation, and energy infrastructure is an important advantage of process integration. Furthermore, integration contributes to the utilization and valorization of all products and by-products, which is key to the success of a biorefinery. Selenium-enriched yeasts have aroused great interest as mineral sources for their high bioavailability and low toxicity. This study aimed to evaluate the effect of selenium on yeast cell growth and production of ethanol and xylitol from hydrolyzed hemicellulosic biomass and sugarcane molasses. For this, cultures were enriched with sodium selenite at concentrations ranging from 1 to 20 mg/L. A miniaturization protocol was used to simulate biorefinery production of first-generation ethanol. The yeasts Spathaspora passalidarum and Kluyveromyces marxianus were able to grow under all tested conditions. The maximum specific growth rate, lag time, and biomass production were influenced by selenium concentration. S. passalidarum provided the best fermentation results, with 77.9% ethanol fermentation efficiency, 24.7% xylitol fermentation efficiency, 0.25 g/g glycerol yield, and 3.3 g cell biomass production. K. marxianus accumulated 122.92 mg selenium/kg biomass, whereas S. passalidarum had a maximum accumulation of 37.40 mg selenium/kg biomass. Yeasts also accumulated other minerals. Therefore, S. passalidarum has great potential as a biological platform and the results of this work could be useful for supporting the development of integrated processes to produce ethanol-, xylitol-, glycerol-, and selenium-enriched yeast products. [ABSTRACT FROM AUTHOR]

Single-cell protein (SCP) production in the methylotrophic yeast Pichia pastoris has the potential to achieve a sustainable protein supply. However, improving the methanol fermentation efficiency and reducing carbon loss has been a long-standing challenge with far-reaching scientific and practical implications. Here, comparative transcriptomics revealed that PAS_0305, a gene directly associated with cell wall thickness under methanol stress, can be used as a target for unlocking cell wall sensors. Intracellular trehalose accumulation confirmed that cell wall sensors were activated after knocking out PAS_0305, which resulted in increased cell wall permeability. Genome-wide signal perturbations were transduced through the HOG module and the CWI pathway, which was confirmed to connected by Pbs2-Mkk. As a consequence of CWI pathway activation, ΔPAS_0305 elicited a rescue response of cell wall remodeling by increasing the β-1,3-glucan content and decreasing the chitin/mannose content. Remarkably, perturbations in global stress signals led to a fine-tuning of the metabolic network of ΔPAS_0305, resulting in a superior phenotype with highest crude protein and methanol conversion rate of 67.21% and 0.46 gDCW/g. Further genome-scale metabolic models were constructed to validate the experimental results, confirming that unlocking cell wall sensors resulted in maximized flux from methanol towards SCP and effectively addressing the issue of carbon loss in methanol fermentation. This work sheds new light on the potential of manipulating cellular signaling pathways to optimize metabolic networks and achieve exceptional phenotypic characteristics, providing new strategies for constructing versatile cell factories in P. pastoris. [ABSTRACT FROM AUTHOR]

Summary: Aquaculture has been challenged to explore alternative proteins to develop efficient feed formulations that foster a sustainable future growth. Largemouth bass (LMB) are economically important cultured fish with a high demand for protein. One of the traditional ingredients used to develop protein diets is fish meal (FM). With the aquaculture industry expanding, the FM price climbs with broadening the imbalance between the supply and requirement. Hence, there is a requisite to explore novel alternative proteins sources. In this review, we summarised recent knowledge about the alternative sources of proteins with potential to partially or fully substitute FM in LMB feed and the shortcomings of present alternative proteins. We also highlight the challenges faced for LMB feed in the substitution of FM with alternative proteins, which need more in‐depth investigations in the future. [ABSTRACT FROM AUTHOR]

Although Pichia pastoris was successfully used for heterologous gene expression for more than twenty years, many factors influencing protein expression remain unclear. Here, we optimized the expression of a thermophilic endoglucanase from Thermothielavioides terrestris (TtCel45A) for cost-effective production in Pichia pastoris. To achieve this, we established a multifactorial regulation strategy that involved selecting a genome-editing system, utilizing neutral loci, incorporating multiple copies of the heterologous expression cassette, and optimizing high-density fermentation for the co-production of single-cell protein (SCP). Notably, even though all neutral sites were used, there was still a slight difference in the enzymatic activity of heterologously expressed TtCel45A. Interestingly, the optimal gene copy number for the chromosomal expression of TtCel45A was found to be three, indicating limitations in translational capacity, post-translational processing, and secretion, ultimately impacting protein yields in P. pastoris. We suggest that multiple parameters might influence a kinetic competition between protein elongation and mRNA degradation. During high-density fermentation, the highest protein concentration and endoglucanase activity of TtCel45A with three copies reached 15.8 g/L and 9640 IU/mL, respectively. At the same time, the remaining SCP of P. pastoris exhibited a crude protein and amino acid content of up to 59.32% and 46.98%, respectively. These findings suggested that SCP from P. pastoris holds great promise as a sustainable and cost-effective alternative for meeting the global protein demand, while also enabling the production of thermophilic TtCel45A in a single industrial process. [ABSTRACT FROM AUTHOR]

Alternative protein sources are gaining attraction in food industry and consumers. Proteins obtained by single-cell organisms, such as torula yeast, are of enormous interest, as they are highly scalable, efficient, and sustainable, and the production costs are comparably low. Nevertheless, proteins obtained from yeasts are still mostly known and studied for feed applications, despite their nutritional, functional, and sensory benefits for various food applications. Testing consumer acceptance of products, especially products containing alternative proteins provides insights into, e.g., market success, consumer perception, and optimization potential. In this study, the development of two vegan spread powders, high in protein and containing torula yeast as an alternative protein source, is introduced. The result of food product development using torula yeast were “Leberwurst”-style (14.7% protein) and a “Balkan”-style (9.7% protein) spreads both meeting the criteria “at least 20% kcal from proteins of total product kcal” and thus claimable as “high-protein.” The application of the alternative protein from torula yeast within the final products was studied by a consumer acceptance test (n = 123) within three different countries (Germany, Iceland, and Sweden). Consumers also rated their trust in food production actors, the food industry in particular, and their willingness to try new foods. Overall, both spreads received acceptance values in the range of “like slightly.” It is noticeable that the consumers liked the spread “Balkan style” more than “Leberwurst”-style. The background variables revealed higher neophobic characteristics of Icelandic consumers compared with Swedish or German consumers. However, German consumers felt transparency, and communication was missing, but Icelandic consumers, in general, had more trust in the overall food value chain. This knowledge allows for the development of strategies that address cultural-specific barriers and capitalize on cultural values that promote openness to culinary innovation. The identification of cultural variations in consumer preferences emphasizes the need for customized approaches to product development and marketing. These findings could have implications for businesses and policymakers in understanding and catering to the preferences and concerns of consumers in these respective countries. Businesses might benefit from emphasizing transparency and improving communication strategies. This could involve providing clear information about the sourcing, production, and other aspects of the food value chain.

The present work examined the production of single-cell protein (SCP) by a newly isolated strain of Kluyveromyces marxianus EXF-5288 under increased lactose concentration of deproteinized cheese whey (DCW) and different temperatures (in °C: 20.0, 25.0, 30.0 and 35.0). To the best of the authors’ knowledge, this is the first report examining the ability of Kluyveromyces marxianus species to produce SCP at T = 20.0 °C. Different culture temperatures led to significant differences in the strain’s growth, while maximum biomass and SCP production (14.24 ± 0.70 and 6.14 ± 0.66 g/L, respectively) were observed in the cultivation of K. marxianus strain EXF-5288 in shake-flask cultures at T = 20.0 °C. Increased DCW lactose concentrations (35.0–100.0 g/L) led to increased ethanol production (Ethmax = 35.5 ± 0.2 g/L), suggesting that K. marxianus strain EXF-5288 is “Crabtree-positive”. Batch-bioreactor trials shifted the strain’s metabolism to alcoholic fermentation, favoring ethanol production. Surprisingly, K. marxianus strain EXF-5288 was able to catabolize the produced ethanol under limited carbon presence in the medium. The dominant amino acids in SCP were glutamate (15.5 mg/g), aspartic acid (12.0 mg/g) and valine (9.5 mg/g), representing a balanced nutritional profile

Methanotrophic bacteria that possess a unique ability of using methane as a sole source of carbon and energy have attracted considerable attention as potential producers of a single-cell protein. So far, this biotechnology implied using freshwater methanotrophs, although many regions of the world have limited freshwater resources. This study aimed at searching for novel methanotrophs capable of fast growth in saltwater comparable in composition with seawater. A methane-oxidizing microbial consortium containing Methylomarinum- and Methylotuvimicrobium-like methanotrophs was enriched from sediment from the river Chernavka (water pH 7.5, total salt content 30 g L−1), a tributary river of the hypersaline Lake Elton, southern Russia. This microbial consortium, designated Ch1, demonstrated stable growth on natural gas in a bioreactor in media with a total salt content of 23 to 35.9 g L−1 at a dilution rate of 0.19–0.21 h−1. The highest biomass yield of 5.8 g cell dry weight (CDW)/L with a protein content of 63% was obtained during continuous cultivation of the consortium Ch1 in a medium with a total salt content of 29 g L−1. Isolation attempts resulted in obtaining a pure culture of methanotrophic bacteria, strain Ch1-1. The 16S rRNA gene sequence of strain Ch1-1 displayed 97.09–97.24% similarity to the corresponding gene fragments of characterized representatives of Methylomarinum vadi, methanotrophs isolated from marine habitats. The genome of strain Ch1-1 was 4.8 Mb in size and encoded 3 rRNA operons, and about 4400 proteins. The genome contained the gene cluster coding for ectoine biosynthesis, which explains the ability of strain Ch1-1 to tolerate high salt concentration. [ABSTRACT FROM AUTHOR]

Yeast biomass, a brewery by-product of the world’s substantial alcohol beverage industry, finds successful applications in the fodder industry and food additive production. This is attributed to its rich nutritional profile that comprises high protein and vitamin content. Nonetheless, in small-scale breweries, yeast slurries present a significant challenge, as the quantities obtained are insufficient to attract the attention of the food industry. The disposal of yeast contributes substantially to the organic load of wastewater (approximately 40%) and elevates water consumption (3–6 hL/hL of beer), consequently escalating production costs and environmental impact. In recent years, diverse potential applications of products derived from yeast biomass have emerged, encompassing the substitution of sera in cell culture media, the fortification of animal feed with vitamins and selenium, the utilization of beta-glucan in low-fat food products, and the development of functional foods incorporating yeast-derived peptides. These peptides exhibit the potential to safeguard the gastric mucosa, prevent hypertension, and address neurodegenerative disorders. The rising demand for value-added products derived from yeast underscores the potential profitability of processing yeast from small breweries. Due to the high equipment costs associated with yeast biomass fractionation, the establishment of specialized facilities in collaboration with multiple small breweries appears to be the most optimal solution.

The rapidly increasing population and climate change pose a great threat to our current food systems. Moreover, the high usage of animal-based and plant-based protein has its drawbacks, as these nutritional sources require many hectares of land and water, are affected by seasonal variations, are costly, and contribute to environmental pollution. Single-cell proteins (SCPs) are gaining a lot of research interest due to their remarkable properties, such as their high protein content that is comparable with other protein sources; low requirements for land and water; low carbon footprint; and short production period. This review explores the use of food waste as a sustainable feedstock for the advancement of SCP processes. It discusses SCP studies that exploit food waste as a substrate, alongside the biocatalysts (bacteria, fungi, yeast, and microalgae) that are used. The operational setpoint conditions governing SCP yields and SCP fermentation routes are elucidated as well. This review also demonstrates how the biorefinery concept is implemented in the literature to improve the economic potential of “waste-to-protein” innovations, as this leads to the establishment of multiproduct value chains. A short section that discusses the South African SCP scenario is also included. The technical and economic hurdles facing second-generation SCP processes are also discussed, together with future perspectives. Therefore, SCP technologies could play a crucial role in the acceleration of a “sustainable protein market”, and in tackling the global hunger crisis.

Tofu wastewater can be utilized as a substrate for microorganisms that produce single-cell proteins (SCPs). Because different microorganisms have different cellular components, the composition of SCPs varies. Electro-stimulation has the potential to speed up fermentation and increase product yield. The goal of this study was to find the best way to produce SCPs from Aspergillus awamori, Rhizopus oryzae, and Saccharomyces cerevisiae in the tofu wastewater substrate using electro-stimulation. The experimental method was used in the study, the data were analyzed using independent t-test statistical analysis, and the best treatment was identified using the effective index method. This treatment consisted of producing SCP with electro-stimulation of −1.5 V and without electro-stimulation for 72 h for the yeast and 96 h for the mold at 25 °C in tofu wastewater that had already been conditioned to a pH of 5. The parameters measured included measurement of population of microorganism, change in pH, dry biomass weight, carbohydrate content, and protein content. Electro-stimulation reduced the optimum fermentation time of A. awamori SCP from 56 to 32 h, resulting in 0.0406 g/50 mL of dry biomass, 30.09% carbohydrate content, and 6.86% protein content. Meanwhile, the optimal fermentation time on R. oryzae and S. cerevisiae were not accelerated by electro-stimulation. The best treatment was A. awamori without electro-stimulation, which produced 0.0931 g/50 mL of dry biomass, 20.29% carbohydrate, and 7.55% protein.

The demand for cheap, healthy, and sustainable alternative protein sources has turned research interest into microbial proteins. Mycoproteins prevail due to their quite balanced amino acid profile, low carbon footprint and high sustainability potential. The goal of this research was to investigate the capability of Pleurotus ostreatus to metabolize the main sugars of agro-industrial side streams, such as aspen wood chips hydrolysate, to produce high-value protein with low cost. Our results indicate that P. ostreatus LGAM 1123 could be cultivated both in a C-6 (glucose)- and C-5(xylose)-sugar-containing medium for mycoprotein production. A mixture of glucose and xylose was found to be ideal for biomass production with high protein content and rich amino acid profile. P. ostreatus LGAM 1123 cultivation in a 4 L stirred-tank bioreactor using aspen hydrolysate was achieved with 25.0 ± 3.4 g L−1 biomass production, 1.8 ± 0.4 d−1 specific growth rate and a protein yield of 54.5 ± 0.5% (g/100 g sugars). PCA analysis of the amino acids revealed a strong correlation between the amino acid composition of the protein produced and the ratios of glucose and xylose in the culture medium. The production of high-nutrient mycoprotein by submerged fermentation of the edible fungus P. ostreatus using agro-industrial hydrolysates is a promising bioprocess in the food and feed industry. [ABSTRACT FROM AUTHOR]

To meet the growing global demand for gluconic acid as a cement and concrete retarder, inexpensive and abundant lignocellulosic materials are regarded as the most suitable alternatives to starchy materials. However, their enzymatic hydrolysate contains not only glucose but also xylose, which negatively affects the performance of gluconic acid as a retarder. Notably, glucose is preferentially bio-oxidized into gluconic acid by Gluconobacter oxydans, but gluconic acid cannot be metabolized by Candida tropicalis. Given this, an artificially designed biological cascade process, respectively employing Gluconobacter oxydans and Candida tropicalis, was established to successfully carry out glucose conversion into gluconic acid, and xylose into a single-cell protein, using the enzymatic hydrolysate of corncobs as a feedstock. This sequential fermentation process produced 95.8 g/L gluconic acid and 9.0 g/L single-cell protein from one liter of the enzymatic hydrolysate that initially contained 98.1 g/L of glucose and 25.4 g/L of xylose. The mass-balance calculation showed that approximately 280 grams of gluconic acid and 27 grams of the single-cell protein could be harvested from 1000 grams of the corncob feedstock. The results suggest that the above-mentioned two-step bioconversion method is efficient in utilizing glucose and xylose from lignocellulosic hydrolysates. [ABSTRACT FROM AUTHOR]

Microorganisms have the potential to produce nutrient‐rich products that can be consumed as food or feed. The protein‐rich powder derived from heat treatment of the whole‐cell biomass of polyhydroxybutyrate‐deficient Cupriavidus necator, a metabolically versatile organism that uses elements found in the air, is an example of such a product. To assess the safety of the protein powder for use as a nutritional ingredient in human food, in accordance with internationally accepted standards, its genotoxic potential and repeated‐dose oral toxicity were investigated. A bacterial reverse mutation test, an in vitro mammalian chromosomal aberration test, and an in vivo mammalian micronucleus test were performed. No evidence of mutagenicity or genotoxicity was found. Additionally, a 90‐day repeated‐dose oral toxicity study in rats was completed, in which a total of 100 male and female Wistar rats were exposed by gavage to daily doses of 1000, 2000, or 3000 mg/kg bw/day of the test material. Following 90 days of continuous exposure, no mortality or treatment‐related adverse effects were observed and no target organs were identified. Therefore, a no observed adverse effect level was determined at 3000 mg/kg bw/day, the highest dose tested. The whole‐cell biomass of polyhydroxybutyrate‐deficient Cupriavidus necator is protein rich. The derived protein concentrate has the potential for use as an environmentally sustainable nutrient‐dense food ingredient. Therefore, we assessed the genotoxic potential and oral toxicity of the heat‐treated and powdered product, in preclinical safety studies. No evidence of genotoxicity or mutagenicity was found. In a 90‐day repeated‐dose oral toxicity study, a no observed adverse effect level in rats of 3000 mg/kg bw/day, the highest feasible dose, was determined. [ABSTRACT FROM AUTHOR]

Rapeseed meal (RM) is produced in large quantities as a byproduct of oil extraction from rapeseeds. However, the efficient utilization of RM as animal feed is limited by its low metabolizable energy, poor palatability, and high levels of fiber and anti-nutritional components. Here, we investigate the potential of enriching RM with single-cell protein through fermentation with conventional and unconventional yeasts. The process of simultaneous saccharification and fermentation improved the parameters of the waste biomass, especially the protein content, while reducing the amount of crude fiber and enhancing the biotransformation of isoflavone compounds present in the waste. Fermentation yielded the highest protein gain for the Saccharomyces cerevisiae Ethanol Red strain (ΔN = 2.38%) at a biomass load of 12.5 g and for Scheffersomyces stipitis (ΔN = 2.34%) at an enzyme dose of 0.125 mL/10 g DM. The crude fiber content (CF) was reduced by 2.55–7.18%. The simultaneous saccharification and fermentation (SSF) process resulted in the conversion of isoflavones to forms with fewer adverse effects and a lower estrogenic activity. The results show the potential of using RM as a substrate for making a nutritionally improved feed components. [ABSTRACT FROM AUTHOR]

Microalgae can contribute to food security through the sustainable production of proteins and lipids, which are required to meet population growth and address environmental challenges. Cellular agriculture is developing with emerging bioprocesses based on solar energy, photovoltaics, H 2 , C1 carbon sources, and sugar as feedstocks. Different trophic modes – autotrophy, heterotrophy, and mixotrophy – have been successfully explored for microalgae. The production of microalgae has tripled in the last 5 years. The genetic toolbox for industrially relevant phototrophic strains expanded tremendously in the last 5 years. The urge for food security and sustainability has advanced the field of microalgal biotechnology. Microalgae are microorganisms able to grow using (sun)light, fertilizers, sugars, CO 2 , and seawater. They have high potential as a feedstock for food, feed, energy, and chemicals. Microalgae grow faster and have higher areal productivity than plant crops, without competing for agricultural land and with 100% efficiency uptake of fertilizers. In comparison with bacterial, fungal, and yeast single-cell protein production, based on hydrogen or sugar, microalgae show higher land-use efficiency. New insights are provided regarding the potential of microalgae replacing soy protein, fish oil, and palm oil and being used as cell factories in modern industrial biotechnology to produce designer feed, recombinant proteins, biopharmaceuticals, and vaccines. [ABSTRACT FROM AUTHOR]

Yarrowia lipolytica is a promising feed additives. Here, we aimed to produce extracellular lipases and single-cell proteins (SCPs) at high levels simultaneously through fed-batch fermentation of engineered Y. lipolytica. The parameters for 500 mL shake flask cultures were optimized with a single factorial design. The resultant activity of lipase reached 880.6 U/mL after 84 h of fermentation, and 32.0 g/L fermentation broth of dry SCP was obtained at 120 h. To attain high SCP and lipase productivity, the high-density fed-batch fermentation of Y. lipolytica was scaled up in 10 L, 30 L, and 100 L fermentors. Using glycerol as the sole carbon source, the lipase activity peaked to 8083.3 U/mL, and the final dry SCP weight was 183.1 g/L at 94.6 h in 10 L fermentors. The extracellular lipase activity and SCP weight reached 11,100.0 U/mL and 173.3 g of dry SCP/L at 136 h in 30 L fermentors, respectively. Following 136 h of fed-batch fermentation, the extracellular lipase activity and dry SCP weight reached 8532.0 U/mL and 170.3 g/L in 100 L fermentors, respectively. A balance between the lipase secretion and growth of Y. lipolytica recombinant strain was achieved, indicating that an efficient fermentation strategy could promote further scale-up for industrial SCP production from engineered Y. lipolytica. [ABSTRACT FROM AUTHOR]

Most polyethylene terephthalate (PET) plastic waste is landfilled or pollutes the environment. Additionally, global food production must increase to support the growing population. This article explores the feasibility of using microorganisms in an industrial system that upcycles PET into edible microbial protein powder to solve both problems simultaneously. Many microorganisms can utilize plastics as feedstock, and the resultant microbial biomass contains fats, nutrients, and proteins similar to those found in human diets. While microbial degradation of PET is promising, biological PET depolymerization is too slow to resolve the global plastic crisis and projected food shortages. Evidence reviewed here suggests that by coupling chemical depolymerization and biological degradation of PET, and using cooperative microbial communities, microbes can efficiently convert PET waste into food. Innovative solutions are needed to resolve the ongoing global issues of excess plastic waste and food insecurity. Polyethylene terephthalate (PET) polymers can be depolymerized and biodegraded by naturally occurring microorganisms, although rates of degradation are too slow to independently form the foundation of a biotechnological process and help to resolve the global plastic crisis. Chemical depolymerization of PET can deconstruct plastics into aromatic building blocks. Microorganisms can more rapidly break down the aromatic building blocks of PET after chemical depolymerization, greatly improving rates of biodegradation. Single-cell protein (SCP) is a food source that is derived from microbial cells. Microbial cells grown on waste products offer a promising source of alternative protein and other nutrients. [ABSTRACT FROM AUTHOR]

Microbial proteins, i.e., single-cell proteins or microbial biomass, can be cultivated for food and animal feed due to their high protein content and the fact that they represent a rich source of carbohydrates, minerals, fats, vitamins, and amino acids. Another advantage of single-cell proteins is their rapid production due to the growth rate of microorganisms and the possibility of using agro-industrial waste, residues and by-products for production through this renewable technology. Agro-industrial residues and by-products represent materials obtained from various processes in agriculture and agriculture-related industries; taking into account their composition and characteristics, as well as vast amounts, they have an enormous potential to generate sustainable bioproducts, such as microbial proteins. This review aims to summarize contemporary scientific research related to the production of microbial proteins on various agro-industrial residues and by-products, as well as to emphasize the current state of production of single-cell proteins and the importance of their production to ease the food crisis and support sustainable development. [ABSTRACT FROM AUTHOR]

There is a growing demand for nutritional, functional, and eco-friendly dairy products, which has increased the need for research regarding alternative and sustainable protein sources. Plant-based, single-cell (SCP), and recombinant proteins are being explored as alternatives to dairy proteins. Plant-Based Proteins (PBPs) are commonly used to replace total dairy protein. However, PBPs are generally mixed with dairy proteins to improve their functional properties, which makes them dependent on animal protein sources. In contrast, single-Cell Proteins (SCPs) and recombinant dairy proteins are promising alternatives for dairy protein replacement since they provide nutritional components, essential amino acids, and high protein yield and can use industrial and agricultural waste as carbon sources. Although alternative protein sources offer numerous advantages over conventional dairy proteins, several technical and sensory challenges must be addressed to fully incorporate them into cheese and yogurt products. Future research can focus on improving the functional and sensory properties of alternative protein sources and developing new processing technologies to optimize their use in dairy products. This review highlights the current status of alternative dairy proteins in cheese and yogurt, their functional properties, and the challenges of their use in these products.

Although Pichia pastoris was successfully used for heterologous gene expression for more than twenty years, many factors influencing protein expression remain unclear. Here, we optimized the expression of a thermophilic endoglucanase from Thermothielavioides terrestris (TtCel45A) for cost-effective production in Pichia pastoris. To achieve this, we established a multifactorial regulation strategy that involved selecting a genome-editing system, utilizing neutral loci, incorporating multiple copies of the heterologous expression cassette, and optimizing high-density fermentation for the co-production of single-cell protein (SCP). Notably, even though all neutral sites were used, there was still a slight difference in the enzymatic activity of heterologously expressed TtCel45A. Interestingly, the optimal gene copy number for the chromosomal expression of TtCel45A was found to be three, indicating limitations in translational capacity, post-translational processing, and secretion, ultimately impacting protein yields in P. pastoris. We suggest that multiple parameters might influence a kinetic competition between protein elongation and mRNA degradation. During high-density fermentation, the highest protein concentration and endoglucanase activity of TtCel45A with three copies reached 15.8 g/L and 9640 IU/mL, respectively. At the same time, the remaining SCP of P. pastoris exhibited a crude protein and amino acid content of up to 59.32% and 46.98%, respectively. These findings suggested that SCP from P. pastoris holds great promise as a sustainable and cost-effective alternative for meeting the global protein demand, while also enabling the production of thermophilic TtCel45A in a single industrial process.

Abstract With the increase in population growth and environmental pollution, the daily protein supply is facing great challenges. Single-cell protein (SCP) produced by microorganism fermentation is a good alternative for substituting plant- and animal-derived proteins. In this study, Paracoccus communis MA5 isolated from soil previously demonstrated an excellent ability to synthesize SCP directly from sodium formate. To investigate the central metabolic network of formic acid assimilation and protein synthesis, genome-scale analyses were performed. Genomic analysis showed that complete tetrahydrofolate cycle-, serine cycle-, glycolytic pathway-, tricarboxylic acid (TCA) cycle- and nitrogen metabolism-relevant genes were annotated in the genome. These pathways play key roles in the conversion of formic acid into proteins. Transcriptional analysis showed that sodium formate stress could stimulate the metabolic pathway in response to environmental stress, but weaken the sulfur metabolic pathway to inhibit amino acid synthesis, resulting in a decrease in protein content (30% vs 44%). However, under culture conditions with ammonium sulfate, metabolic pathways associated with protein synthesis were accelerated, causing an increase in protein content (53% vs 44%); while the tetrahydrofolate cycle associated with formic acid assimilation was inhibited, causing a 62.5% decrease in growth rate (OD600: 0.21 vs 0.56). These results provide evidence of protein synthesis from sodium formate in strain MA5 at the gene level and lay a theoretical foundation for the optimization of fermentation systems using formic acid as a carbon source. Graphical Abstract

Photoautohydrogenotrophic enrichments of wastewater treatment microbiomes were performed to obtain hypothetically high-potential specialist species for biotechnological applications. From these enrichment cultures, ten photoautohydrogenotrophic species were isolated: six Rhodopseudomonas species , three Rubrivivax members and Rhodobacter blasticus. The performance of these isolates was compared to three commonly studied, and originally photoheterotrophically enriched species (Rhodopseudomonas palustris, Rhodobacter capsulatus and Rhodobacter sphaeroides), designated as reference species. Repeated subcultivations were applied to improve the initial poor performance of the isolates (acclimation effect), which resulted in increases in both maximum growth rate and protein productivity. However, the maximum growth rate of the reference species remained 3–7 times higher compared to the isolates (0.42–0.84 d−1 at 28 °C), while protein productivities remained 1.5–1.7 times higher. This indicated that H 2 -based enrichment did not result in photoautohydrogenotrophic specialists, suggesting that the reference species are more suitable for intensified biomass and protein production. On the other hand, the isolates were able to provide equally high protein quality profiles as the references species, providing full dietary essential amino acid matches for human food. Lastly, the effect of metabolic carbon/electron switching (back and forth between auto- to heterotrophic conditions) initially boosted µ max when returning to photoautohydrogenotrophic conditions. However, the switch negatively impacted lag phase, protein productivities and pigment contents. In the case of protein productivity, the acquired acclimation was partially lost with decreases of up to 44 % and 40 % respectively for isolates and reference species. Finally, the three reference species, and specifically Rh. capsulatus , remained the most suitable candidate(s) for further biotechnological development. [Display omitted] • Ten photoautohydrogenotrophic species were enriched from water treatment microbiomes. • Repeated subcultivation improved maximum growth rates and protein productivities. • Metabolic carbon/electron switches decreased protein productivity and pigment content. • All tested purple bacteria could provide full human dietary protein matches. • Photoheterotrophically enriched species act as photoautohydrogenotrophic specialist. [ABSTRACT FROM AUTHOR]

There is a wide range of algae species originating from a variety of freshwater and saltwater habitats. These organisms form nutritional organic products via photosynthesis from simple inorganic substances such as carbon dioxide. Ruminants can utilize the non-protein nitrogen (N) and the cell walls in algae, along with other constituents such as minerals and vitamins. Over recent decades, awareness around climate change has generated new interest into the potential of algae to suppress enteric methane emissions when consumed by ruminants and their potential to sequester atmospheric carbon dioxide. Despite the clear potential benefits, large-scale algae-livestock feedstuff value chains have not been established due to the high cost of production, processing and transport logistics, shelf-life and stability of bioactive compounds and inconsistent responses by animals under controlled experiments. It is unlikely that algal species will become viable ingredients in extensive grazing systems unless the cost of production and practical systems for the processing, transport and feeding are developed. The algae for use in ruminant nutrition may not necessarily require the same rigorous control during the production and processing as would for human consumption and they could be grown in remote areas or in marine environments, minimizing competition with cropping, whilst still generating high value biomass and capturing important amounts of atmospheric carbon. This review will focus on single-cell algal species and the opportunistic use of algal by-products and on-site production. [ABSTRACT FROM AUTHOR]

Single‐cell protein (SCP) derived from methanotrophic bacteria has significant potential as a fishmeal alternative in aquafeeds. However, SCP has known palatability issues, to overcome these issues tuna hydrolysate and garlic powder were tested as palatability enhancers against basal diets without these additives. This study tested the inclusion of SCP at four dietary levels of 0%, 10%, 20% and 30%, representing 0%, 25%, 50% and 75% fishmeal replacement in juvenile yellowtail kingfish (Seriola lalandi) (YTK) diets. YTK were fed these diets in triplicate over 35 days. Compared with the control diet, fish fed the SCP10% diet ate less feed, but had equal growth and subsequently an improved FCR. Feed intake decreased with increasing SCP inclusion, and the palatability enhancers were ineffective at improving intake. Despite the significant reduction in feed intake, FCR was equal across all SCP inclusion levels, demonstrating that the reduced growth performance at these higher inclusion levels was a function of only the reduced intake. Data showing equal protein retention efficiency and apparent digestibility coefficients across diets support this finding. This study showed that SCP derived from methanotrophic bacteria can replace 25% of fishmeal in a 400 g/kg FM diet and suggests if palatability issues can be overcome then higher inclusion of SCP could be achieved in YTK diets. [ABSTRACT FROM AUTHOR]

Rice husk contains high contents of cellulose, lignin, and inorganic compounds, which can be recovered and utilized in a variety of useful applications. In this study, rice husk was refined using a multistage process for producing nano- and bioproducts. To begin, the material was treated with dilute sulfuric acid for obtaining a pentose solution, which was then used for Candida utilis yeast fermentation. In the next stage, the pre-hydrolyzed rice husk was treated with an alkaline solution under regular pulping conditions to break down all chemical bonds between the substances in the material. Subsequently, cellulose was extracted for nanocellulose production, while lignin and silica were isolated via acid precipitation. Proper conditions for these processes were established. Under suitable conditions, about 55.0% of the rice husk was effectively utilized. Over 75.0% of the rice husk pentosan was converted into xylose and arabinose for single-cell protein fermentation. Lignin was mostly transformed into lower molecular weight compounds or single substances, resulting in a recovery rate of about 17.0%. The precipitation's pH for silica and lignin recovery was 8.5 and 3.0, respectively. The findings of this work provide an effective solution for the utilization of agricultural residue and contribute significantly to the sustainable development. [Display omitted] • Producing single-cell protein from rice husk derived xylose. • Developing a novel method for preparing nanocellulose. • Establishing optimal pH for the sequential precipitation and separation of nanosilica and lignin. [ABSTRACT FROM AUTHOR]

In the current study, several non-conventional yeast strains were screened and adapted to produce single-cell protein (SCP) at high productivities and yields from wasted date molasses (WDM). Among the tested yeasts, Hanseniaspora guilliermondii JQ690237, Hanseniaspora uvarum JQ690236, Issatchenkia orientalis JQ690240, and Cyberlindnera fabianii JQ690242 emerged as the highest producers of biomass during small-scale batch experiments, leading to yields up to 700 g dry biomass/kg of WDM after 48 h of incubation. It was shown that the supplementation of the WDM medium with either organic or inorganic nitrogen sources, enhanced significantly the bioconversion efficiency of WDM into single-cell protein, with H. guilliermondii and I. orientalis exhibiting the highest production of biomass, with a protein content of up to 54.3%. The scaling up of the process confirmed its efficiency, indicating that newly isolated yeasts are promising SCP producers for possible industrial exploitation of the specific waste toward animal feed. [ABSTRACT FROM AUTHOR]