The role of single cell protein in cellular agriculture

Challenges and innovations in food and water availability for a sustainable Mars colonization

In recent years, extensive research has been dedicated to Mars exploration and the potential for sustainable interplanetary human colonization. One of the significant challenges in ensuring the survival of life on Mars lies in the production of food as the Martian environment is highly inhospitable to agriculture, rendering it impractical to transport food from Earth. To improve the well-being and quality of life for future space travelers on Mars, it is crucial to develop innovative horticultural techniques and food processing technologies. The unique challenges posed by the Martian environment, such as the lack of oxygen, nutrient-deficient soil, thin atmosphere, low gravity, and cold, dry climate, necessitate the development of advanced farming strategies. This study explores existing knowledge and various technological innovations that can help overcome the constraints associated with food production and water extraction on Mars. The key lies in utilizing resources available on Mars through in-situ resource utilization. Water can be extracted from beneath the ice and from the Martian soil. Furthermore, hydroponics in controlled environment chambers, equipped with nutrient delivery systems and waste recovery mechanisms, have been investigated as a means of cultivating crops on Mars. The inefficiency of livestock production, which requires substantial amounts of water and land, highlights the need for alternative protein sources such as microbial protein, insects, and in-vitro meat. Moreover, the fields of synthetic biology and 3-D food printing hold immense potential in revolutionizing food production and making significant contributions to the sustainability of human life on Mars.

Waste to protein: A systematic review of a century of advancement in microbial fermentation of agro-industrial byproducts

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.

Protein transition: focus on protein quality in sustainable alternative sources

The current consumption trends, combined with the expected demographic growth in the coming years, call for a protein transition, i.e., the partial substitution of animal protein-rich foods with foods rich in proteins produced in a more sustainable way. Here, we have discussed some of the most common and promising protein sources alternative to animal proteins, namely: legumes, insects, and microorganisms (including microalgae and fungi). The primary objective was to assess their nutritional quality through the collection of digestible indispensable amino acid score (DIAAS) values available in the scientific literature. Protein digestibility corrected amino acid score (PDCAAS) values have been used where DIAAS values were not available. The ecological impact of each protein source, its nutritional quality and the potential applications in traditional foods or novel food concepts like meat analogues are also discussed. The data collected show that DIAAS values for animal proteins are higher than all the other protein sources. Soybean proteins, mycoproteins and proteins of some insects present relatively high DIAAS (or PDCAAS) values and must be considered proteins of good quality. This review also highlights the lack of DIAAS values for many potentially promising protein sources and the variability induced by the way the proteins are processed.

Protein Nutrition: Understanding Structure, Digestibility, and Bioavailability for Optimal Health

This review discusses different protein sources and their role in human nutrition, focusing on their structure, digestibility, and bioavailability. Plant-based proteins, such as those found in legumes, nuts, and seeds, may contain anti-nutritional factors that impact their bioavailability apart from structural and compositional differences from animal proteins. Animal proteins are generally highly digestible and nutritionally superior to plant proteins, with higher amino acid bioavailability. Alternative protein sources are also processed in different ways, which can alter their structure and nutritional value, which is also discussed.

In vitro genotoxicological evaluation of protein-rich powder derived from Xanthobacter sp. SoF1

One way of limiting the environmental impact of food production and improving food security is to replace part of the animal- or plant-based protein in the human diet with protein sourced from microorganisms. The recently discovered bacterium Xanthobacter sp. SoF1 (VTT-E-193585) grows autotrophically using carbon dioxide gas as the only carbon source, yielding protein-rich biomass that can be processed further into a powder and incorporated into various food products. Since the safety of this microbial protein powder for human consumption had not been previously assessed, its genotoxic potential was evaluated employing three internationally recognized and standardized studies: a bacterial reverse mutation test, an in vitro chromosomal aberration assay in human lymphocytes, and an in vitro micronucleus test in human lymphocytes. No biologically relevant evidence of genotoxicity or mutagenicity was found.

From sustainable feedstocks to microbial foods

Climate change-induced alterations in weather patterns, such as frequent and severe heatwaves, cold waves, droughts, floods, heavy rain and storms, are reducing crop yields and agricultural productivity. At the same time, greenhouse gases arising from food production and supply account for almost 30% of anthropogenic emissions. This vicious circle is producing a global food crisis. Sustainable food resources and production systems are needed now, and microbial foods are one possible solution. In this Perspective, we highlight the most promising technologies, and carbon and energy sources, for microbial food production.

Current trends and possibilities of typical microbial protein production approaches: a review

Global population growth and demographic restructuring are driving the food and agriculture sectors to provide greater quantities and varieties of food, of which protein resources are particularly important. Traditional animal-source proteins are becoming increasingly difficult to meet the demand of the current consumer market, and the search for alternative protein sources is urgent. Microbial proteins are biomass obtained from nonpathogenic single-celled organisms, such as bacteria, fungi, and microalgae. They contain large amounts of proteins and essential amino acids as well as a variety of other nutritive substances, which are considered to be promising sustainable alternatives to traditional proteins. In this review, typical approaches to microbial protein synthesis processes were highlighted and the characteristics and applications of different types of microbial proteins were described. Bacteria, fungi, and microalgae can be individually or co-cultured to obtain protein-rich biomass using starch-based raw materials, organic wastes, and one-carbon compounds as fermentation substrates. Microbial proteins have been gradually used in practical applications as foods, nutritional supplements, flavor modifiers, and animal feeds. However, further development and application of microbial proteins require more advanced biotechnological support, screening of good strains, and safety considerations. This review contributes to accelerating the practical application of microbial proteins as a promising alternative protein resource and provides a sustainable solution to the food crisis facing the world.

A comprehensive report on valorization of waste to single cell protein: strategies, challenges, and future prospects

The food insecurity due to a vertical increase in the global population urgently demands substantial advancements in the agricultural sector and to identify sustainable affordable sources of nutrition, particularly proteins. Single-cell protein (SCP) has been revealed as the dried biomass of microorganisms such as algae, yeast, and bacteria cultivated in a controlled environment. Production of SCP is a promising alternative to conventional protein sources like soy and meat, due to quicker production, minimal land requirement, and flexibility to various climatic conditions. In addition to protein production, it also contributes to waste management by converting it into food and feed for both human and animal consumption. This article provides an overview of SCP production, including its benefits, safety, acceptability, and cost, as well as limitations that constrains its maximum use. Furthermore, this review criticizes the downstream processing of SCP, encompassing cell wall disruption, removal of nucleic acid, harvesting of biomass, drying, packaging, storage, and transportation. The potential applications of SCP, such as in food and feed as well as in the production of bioplastics, emulsifiers, and as flavoring agents for baked food, soup, and salad, are also discussed.

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.

Ruminations on sustainable and safe food: Championing for open symbiotic cultures ensuring resource efficiency, eco-sustainability and affordability

Microbes are powerful upgraders, able to convert simple substrates to nutritional metabolites at rates and yields surpassing those of higher organisms by a factor of 2 to 10. A summary table highlights the superior efficiencies of a whole array of microbes compared to conventionally farmed animals and insects, converting nitrogen and organics to food and feed. Aiming at the most resource-efficient class of microbial proteins, deploying the power of open microbial communities, coined here as 'symbiotic microbiomes' is promising. For instance, a production train of interest is to develop rumen-inspired technologies to upgrade fibre-rich substrates, increasingly available as residues from emerging bioeconomy initiatives. Such advancements offer promising perspectives, as currently only 5%-25% of the available cellulose is recovered by ruminant livestock systems. While safely producing food and feed with open cultures has a long-standing tradition, novel symbiotic fermentation routes are currently facing much higher market entrance barriers compared to axenic fermentation. Our global society is at a pivotal juncture, requiring a shift towards food production systems that not only embrace the environmental and economic sustainability but also uphold ethical standards. In this context, we propose to re-examine the place of spontaneous or natural microbial consortia for safe future food and feed biotech developments, and advocate for intelligent regulatory practices. We stress that reconsidering symbiotic microbiomes is key to achieve sustainable development goals and defend the need for microbial biotechnology literacy education.

Designing sustainable circular bioeconomy solutions for the pulse industry: The case of crude pea starch as a substrate for single cell protein production

Valorization of crude pea starch has become a key focus in the pea industry's sustainability pursuit. This study aimed to explore the circularity potential of crude pea starch as a nutrient-dense substrate for the solid-state cultivation of yeast (Saccharomyces cerevisiae) Single Cell Protein (SCP). Following the ISO 2006:14040/44 standard, a life cycle assessment (LCA) was performed to ascertain the environmental performance and operational dynamics of baseline and scenario pea starch-based yeast SCP process designs and identify optimal design considerations. Results demonstrated a higher relative contribution to the toxicity categories, with a relatively less contribution to global warming and land use. The distribution and media enrichment processes were identified as the hotspots, contributing about 32-55 % and 40-56 % to global warming and land use, respectively. Generally, train and air freight were more sustainable than lorry freight, respective of mileage and mass. Regarding system alteration, eliminating the media enrichment process could offset about 26 % of land footprint, with a similar trend for most impact categories. Process benchmarking showed up to a 3-fold reduction in global warming impacts relative to soybean meal, and about 71 % offset relative to fishmeal. Consequential LCA showed a general sustainability preference for substituting the aquacultural feeds with pea starch-based SCP, with a stronger emphasis on fishmeal substitution. Overall, these findings highlight the potential of the proposed SCP design as a sustainable upcycling solution with substitutionary potentials for conventional food and feeds, recommending further exploration in value and wealth creation.

Manipulation of co-pelletization for Chlorela vulgaris harvest by treatment of Aspergillus niger spore

The co-pelletization of microalgae with filamentous fungi was a promising approach for microalgae harvest. However, the real conditions of microalgae growth limited the arbitrary optimization of co-pellets formation with filamentous fungi. Therefore, it is urgent to develop an approach to manipulate the co-pelletization through treatment of A. niger spores. In this study, Aspergillus niger and Chlorella vulgaris were used as the model species of filamentous fungi and microalgae to investigate co-pellets formation using A. niger spores after by different pH solutions treatment, swelling, snailase treatment. The importance of spore treatments on C. vulgaris harvest in sequence was claimed based on response surface methodology analysis. The pH solutions treatment, swelling, snailase treatment of A. niger spore contributed 21.0%, 10.5%, 40.7% of harvest ratio of C. vulgaris respectively, which guided the application of spore treatment into co-pelletization. Treatment of spore was showed as an efficient approach to manipulate co-pelletization for microalgae harvest in diverse microalgae condition. This results promoted the application of co-pelletization technology in microalgae harvest of various conditions.

Microbial gas fermentation technology for sustainable food protein production

The development of novel, sustainable, and robust food production technologies represents one of the major pillars to address the most significant challenges humanity is going to face on earth in the upcoming decades - climate change, population growth, and resource depletion. The implementation of microfoods, i.e., foods formulated with ingredients from microbial cultivation, into the food supply chain has a huge potential to contribute towards energy-efficient and nutritious food manufacturing and represents a means to sustainably feed a growing world population. This review recapitulates and assesses the current state in the establishment and usage of gas fermenting bacteria as an innovative feedstock for protein production. In particular, we focus on the most promising representatives of this taxon: the hydrogen-oxidizing bacteria (hydrogenotrophs) and the methane-oxidizing bacteria (methanotrophs). These unicellular microorganisms can aerobically metabolize gaseous hydrogen and methane, respectively, to provide the required energy for building up cell material. A protein yield over 70% in the dry matter cell mass can be reached with no need for arable land and organic substrates making it a promising alternative to plant- and animal-based protein sources. We illuminate the holistic approach to incorporate protein extracts obtained from the cultivation of gas fermenting bacteria into microfoods. Herein, the fundamental properties of the bacteria, cultivation methods, downstream processing, and potential food applications are discussed. Moreover, this review covers existing and future challenges as well as sustainability aspects associated with the production of microbial protein through gas fermentation.

The Administration of Inactivated and Stabilized Whole-Cells of Saccharomyces cerevisiae to Gestating Sows Improves Lactation Efficiency and Post-Weaning Antimicrobial Use

Increasingly hyperprolific sows and the need to reduce antibiotics represent challenges in pig farming. The aim of this work was to determine the effects of a postbiotic obtained from inactivated and stabilized whole-cells of Saccharomyces cerevisiae, administered during the sow's gestation, on the performance of the mother and litter. Maternal feed intake, productive parameters, colostrum quality and post-weaning piglets' health were assessed, including antibiotic consumption. The trial involved 183 sows, divided into two groups: (1) sows fed with a daily supplementation of postbiotic during gestation (n = 90); (2) sows without any supplement (n = 93). Piglets were followed up at two different post-weaning sites. The lactation efficiency of the treated sows improved by +5.9% (41.3 ± 11.4 vs. 35.4 ± 11.6%; p = 0.011). Lactating piglets' mortality was lower in the treated group (25.1 ± 16.7 vs. 28.8 ± 14.4%; p = 0.048). The same tendency was shown in both the weaning sites, together with a reduced antibiotic consumption in weaning site 1 (0.72 ± 0.25 vs. 1.22 ± 0.30 DDDvet/PCU; p = 0.047). The results suggest the role of this postbiotic administered to the mother in improving the health status of the piglets. Furthermore, lactation efficiency is suggested as an interesting parameter for assessing the efficiency of farming.

Inverse metabolic engineering for improving protein content in Saccharomyces cerevisiae

Production of Saccharomyces cerevisiae-based single cell protein (SCP) has recently received great attention due to the steady increase in the world's population and environmental issues. In this study, an inverse metabolic engineering approach was applied to improve the production of yeast SCP. Specifically, an S. cerevisiae mutant library, generated using UV-random mutagenesis, was screened for three rounds to isolate mutants with improved protein content and/or concentration. The #1021 mutant strain exhibited a respective 31% and 23% higher amino acid content and concentration than the parental S. cerevisiae D452-2 strain. Notably, the content, concentration, and composition of amino acids produced by the PAN2* strain, with a single nucleotide polymorphism in PAN2 coding for a catalytic subunit of the poly(A)-nuclease (PAN) deadenylation complex, were virtually identical to those produced by the #1021 mutant strain. In a glucose-limited fed-batch fermentation, the PAN2* strain produced 19.5 g L-1 amino acids in 89 h, which was 16% higher than that produced by the parental D452-2 strain. This study highlights the benefits of inverse metabolic engineering for enhancing the production titer and yield of target molecules without prior knowledge of rate-limiting steps involved in their biosynthetic pathways.

From anaerobic digestion to single cell protein synthesis: A promising route beyond biogas utilization

The accumulation of a large amount of organic solid waste and the lack of sufficient protein supply worldwide are two major challenges caused by rapid population growth. Anaerobic digestion is the main force of organic waste treatment, and the high-value utilization of its products (biogas and digestate) has been widely concerned. These products can be used as nutrients and energy sources for microorganisms such as microalgae, yeast, methane-oxidizing bacteria(MOB), and hydrogen-oxidizing bacteria(HOB) to produce single cell protein(SCP), which contributes to the achievement of sustainable development goals. This new model of energy conversion can construct a bioeconomic cycle from waste to nutritional products, which treats waste without additional carbon emissions and can harvest high-value biomass. Techno-economic analysis shows that the SCP from biogas and digestate has higher profit than biogas electricity generation, and its production cost is lower than the SCP using special raw materials as the substrate. In this review, the case of SCP-rich microorganisms using anaerobic digestion products for growth was investigated. Some of the challenges faced by the process and the latest developments were analyzed, and their potential economic and environmental value was verified.

Inactivation of poly(3-hydroxybutyrate) (PHB) biosynthesis in 'Knallgas' bacterium Xanthobacter sp. SoF1

Aerobic hydrogen-oxidizing 'Knallgas' bacteria are promising candidates for microbial cell factories due to their ability to use hydrogen and carbon dioxide as the sole energy and carbon sources, respectively. These bacteria can convert atmospheric CO₂ to chemicals which could help to mitigate climate change by replacing fossil fuel-based chemicals. A known method to enhance the product yield is to disrupt competing metabolic pathways in the host organism. One such pathway in many 'Knallgas' bacteria is polyhydroxybutyrate (PHB) biosynthesis. In this study, the PHB biosynthesis genes of a non-model 'Knallgas' bacterium Xanthobacter sp. SoF1 were identified. Consequently, the phaA, phaB and phaC genes were individually deleted and the resulting knockouts were evaluated for their ability to produce PHB in autotrophic shake flask and small-scale bioreactor cultivations. The results demonstrate that PHB production was inactivated in the phaC1 knockout strain, which advances the development of Xanthobacter sp. SoF1 as a production host.

Mycoprotein as chicken meat substitute in nugget formulation: Physicochemical and sensorial characterization

The aim of this study was to replace chicken breast by mycoprotein in nuggets and optimizing the sensory and technological properties. In the first step of the study, 14 formulations were prepared by mixture design to evaluate the impact of three binding agents (as independent variables): soy protein isolate, phosphate, and carrageenan on sensory properties. Then, the optimized formulation of mycoprotein nugget (with higher acceptability) was characterized and compared to chicken nugget (control) from texture, color, and physicochemical aspects. The texture attributes including hardness, springiness, cohesiveness, and chewiness of the optimized sample (1.37 kg, 0.70 mm, 0.56, and 0.53 kg.mm) had no significant difference (p > .05) compared to control. Based on the results, optimized sample had a lower lightness and yellowness (a*, b*, and L* were 3.06, 18.62, and 59.23, respectively) rather than the similar value of the control (2.20, 21.27, and 79.10, respectively), which indicated carrageenan did not lead to any significant impact (p > .05) on the color. Also, mycoprotein nugget showed 33% lower cooking loss in comparison to control. Moisture, protein, lipid, and ash in optimized sample were 57.9 ± 1.9, 24.1 ± 1.0, 13.2 ± 1.2, and 2.1 ± 0.5, respectively. Investigation on physicochemical properties shows an acceptable characterization in optimized sample in comparison to control. The results of this study present an opportunity to produce nonmeat nuggets with similar texture and acceptable sensory and technological characteristics by using mycoprotein as meat alternative. The production of mycoprotein is eco-friendly, not dependent on climate (flood and drought) and landscape limitation, which is an important aspect in meat alternatives in the near future.

Toward optimal use of biomass as carbon source for chemical bioproduction

Biomass is widely identified as a promising, renewable replacement for fossil feedstocks in the production of energy, fuels, and chemicals. However, the sustainable supply of biomass is limited. Economic and ecological criteria support prioritization of biomass as a carbon source for organic chemicals; however, utilization for energy currently dominates. Therefore, to optimize the use of available biomass feedstock, biorefining development must focus on high carbon efficiencies and enabling the conversion of all biomass fractions, including lignin and fermentation-derived CO₂. Additionally, novel technological platforms should allow the incorporation of nontraditional, currently underutilized carbon feedstocks (e.g. manure) into biorefining processes. To this end, funneling of waste feedstocks to a single product (e.g. methane) and subsequent conversion to chemicals is a promising approach.

Microbial meat: A sustainable vegan protein source produced from agri-waste to feed the world

In the modern world, animal and plant protein may not meet the sustainability criteria due to their high need for arable land and potable water consumption, among other practices. Considering the growing population and food shortage, finding alternative protein sources for human consumption is an urgent issue that needs to be solved, especially in developing countries. In this context, microbial bioconversion of valuable materials in nutritious microbial cells represent a sustainable alternative to the food chain. Microbial protein, also known as single-cell protein (SCP), consist of algae biomass, fungi or bacteria that are currently used as food source for both humans and animals. Besides contributing as a sustainable source of protein to feed the world, producing SCP, is important to reduce waste disposal problems and production costs meeting the sustainable development goals. However, for microbial protein as feed or food to become an important and sustainable alternative, addressing the challenges of raising awareness and achieving wider public regulatory acceptance is real and must be addressed with care and convenience. In this work, we critically reviewed the potential technologies for microbial protein production, its benefits, safety, and limitations associated with its uses, and perspectives for broader large-scale implementation. We argue that the information documented in this manuscript will assist in developing microbial meat as a major protein source for the vegan world.

Bioeconomy and net-zero carbon: lessons from Trends in Biotechnology, volume 1, issue 1

Many biotechnology applications tend to be for low production volumes and relatively high-value products such as insulin and vaccines. More difficult to perfect at scale are bioprocesses for high-volume products with lower value, especially if the target product is a reduced chemical such as a solvent or a plastic. Historically, industrial microbiology succeeded under special circumstances when fossil feedstocks were either unavailable or expensive. Inevitably, as these circumstances relaxed, bioprocesses struggled to compete with petrochemistry. Why try to compete? Fossil resources will be phased out in the coming decades in the struggle with climate change. To reach net-zero carbon by 2050 will require all sectors to transition, not only energy and transportation. This may herald a new opportunity for industrial bioprocesses with much better tools.

Recent progress and challenges in biotechnological valorization of lignocellulosic materials: Towards sustainable biofuels and platform chemicals synthesis

Lignocellulosic materials (LCM) have garnered attention as feedstocks for second-generation biofuels and platform chemicals. With an estimated annual production of nearly 200 billion tons, LCM represent an abundant source of clean, renewable, and sustainable carbon that can be funneled to numerous biofuels and platform chemicals by sustainable microbial bioprocessing. However, the low bioavailability of LCM due to the recalcitrant nature of plant cell components, the complexity and compositional heterogeneity of LCM monomers, and the limited metabolic flexibility of wild-type product-forming microorganisms to simultaneously utilize various LCM monomers are major roadblocks. Several innovative strategies have been proposed recently to counter these issues and expedite the widespread commercialization of biorefineries using LCM as feedstocks. Herein, we critically summarize the recent advances in the biological valorization of LCM to value-added products. The review focuses on the progress achieved in the development of strategies that boost efficiency indicators such as yield and selectivity, minimize carbon losses via integrated biorefinery concepts, facilitate carbon co-metabolism and carbon-flux redirection towards targeted products using recently engineered microorganisms, and address specific product-related challenges, to provide perspectives on future research needs and developments. The strategies and views presented here could guide future studies in developing feasible and economically sustainable LCM-based biorefineries as a crucial node in achieving carbon neutrality.

Biotechnological Production of Sustainable Microbial Proteins from Agro-Industrial Residues and By-Products

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.

A Comparative Photographic Review on Higher Plants and Macro-Fungi: A Soil Restoration for Sustainable Production of Food and Energy

The Kingdom of Plantae is considered the main source of human food, and includes several edible and medicinal plants, whereas mushrooms belong to the Kingdom of fungi. There are a lot of similar characteristics between mushrooms and higher plants, but there are also many differences among them, especially from the human health point of view. The absences of both chlorophyll content and the ability to form their own food are the main differences between mushrooms and higher plants. The main similar attributes found in both mushrooms and higher plants are represented in their nutritional and medicinal activities. The findings of this review have a number of practical implications. A lot of applications in different fields could be found also for both mushrooms and higher plants, especially in the bioenergy, biorefinery, soil restoration, and pharmaceutical fields, but this study is the first report on a comparative photographic review between them. An implication of the most important findings in this review is that both mushrooms and plants should be taken into account when integrated food and energy are needed. These findings will be of broad use to the scientific and biomedical communities. Further investigation and experimentation into the integration and production of food crops and mushrooms are strongly recommended under different environmental conditions, particularly climate change.

Potential use of microbial engineering in single-cell protein production

Single-cell proteins (SCPs) have been widely used in human food and animal feed applications, still, there are challenges in their production and commercialization. Recently, advances in microbial synthetic biology, genomic engineering, and biofoundry technologies have offered capabilities to effectively and rapidly engineer microorganisms for improving the productivity, nutritional, and functional quality of SCPs. In this review, we discuss various synthetic biology, genomic engineering, and biofoundry tools that can be harnessed for SCP production and genetic modification. We also describe the current and potential applications of genetic modification in producing intermediate feedstocks, as well as biomass-based and multifunctional SCPs. Finally, we discuss the technological and policy-control related challenges encountered when deploying genetic modification in SCP production for animal feed and human food applications.