Showing papers in "Critical Reviews in Biotechnology in 2021"

Valorization of fruits and vegetable wastes and by-products to produce natural pigments.

Abstract: Synthetic pigments from petrochemicals have been extensively used in a wide range of food products. However, these pigments have adverse effects on human health that has rendered it obligatory to the scientific community in order to explore for much safer, natural, and eco-friendly pigments. In this regard, exploiting the potential of agri-food wastes presumes importance, extracted mainly by employing green processing and extraction technologies. Of late, pigments market size is growing rapidly owing to their extensive uses. Hence, there is a need for sustainable production of pigments from renewable bioresources. Valorization of vegetal wastes (fruits and vegetables) and their by-products (e.g. peels, seeds or pomace) can meet the demands of natural pigment production at the industrial levels for potential food, pharmaceuticals, and cosmeceuticals applications. These wastes/by-products are a rich source of natural pigments such as: anthocyanins, betalains, carotenoids, and chlorophylls. It is envisaged that these natural pigments can contribute significantly to the development of functional foods as well as impart rich biotherapeutic potential. With a sustainability approach, we have critically reviewed vital research information and developments made on natural pigments from vegetal wastes, greener extraction and processing technologies, encapsulation techniques and potential bioactivities. Designed with an eco-friendly approach, it is expected that this review will benefit not only the concerned industries but also be of use to health-conscious consumers.

Biotechnological basis of microbial consortia for the removal of pesticides from the environment.

Abstract: The application of microbial strains as axenic cultures has frequently been employed in a diverse range of sectors. In the natural environment, microbes exist as multispecies and perform better than monocultures. Cell signaling and communication pathways play a key role in engineering microbial consortia, because in a consortium, the microorganisms communicate via diffusible signal molecules. Mixed microbial cultures have gained little attention due to the lack of proper knowledge about their interactions with each other. Some ideas have been proposed to deal with and study various microbes when they live together as a community, for biotechnological application purposes. In natural environments, microbes can possess unique metabolic features. Therefore, microbial consortia divide the metabolic burden among strains in the group and robustly perform pesticide degradation. Synthetic microbial consortia can perform the desired functions at naturally contaminated sites. Therefore, in this article, special attention is paid to the microbial consortia and their function in the natural environment. This review comprehensively discusses the recent applications of microbial consortia in pesticide degradation and environmental bioremediation. Moreover, the future directions of synthetic consortia have been explored. The review also explores the future perspectives and new platforms for these approaches, besides highlighting the practical understanding of the scientific information behind consortia.

Can omics deliver temperature resilient ready-to-grow crops?

Abstract: Plants are extensively well-thought-out as the main source for nourishing natural life on earth. In the natural environment, plants have to face several stresses, mainly heat stress (HS), chilling stress (CS) and freezing stress (FS) due to adverse climate fluctuations. These stresses are considered as a major threat for sustainable agriculture by hindering plant growth and development, causing damage, ultimately leading to yield losses worldwide and counteracting to achieve the goal of "zero hunger" proposed by the Food and Agricultural Organization (FAO) of the United Nations. Notably, this is primarily because of the numerous inequities happening at the cellular, molecular and/or physiological levels, especially during plant developmental stages under temperature stress. Plants counter to temperature stress via a complex phenomenon including variations at different developmental stages that comprise modifications in physiological and biochemical processes, gene expression and differences in the levels of metabolites and proteins. During the last decade, omics approaches have revolutionized how plant biologists explore stress-responsive mechanisms and pathways, driven by current scientific developments. However, investigations are still required to explore numerous features of temperature stress responses in plants to create a complete idea in the arena of stress signaling. Therefore, this review highlights the recent advances in the utilization of omics approaches to understand stress adaptation and tolerance mechanisms. Additionally, how to overcome persisting knowledge gaps. Shortly, the combination of integrated omics, genome editing, and speed breeding can revolutionize modern agricultural production to feed millions worldwide in order to accomplish the goal of "zero hunger."

Strategies for antimicrobial peptide coatings on medical devices: a review and regulatory science perspective

Abstract: Indwelling and implanted medical devices are subject to contamination by microbial pathogens during surgery, insertion or injection, and ongoing use, often resulting in severe nosocomial infections. Antimicrobial peptides (AMPs) offer a promising alternative to conventional antibiotics to reduce the incidence of such infections, as they exhibit broad-spectrum antimicrobial activity against Gram-negative and Gram-positive bacteria, microbial biofilms, fungi, and viruses. In this review-perspective, we first provide an overview of the progress made in this field over the past decade with an emphasis on the local release of AMPs from implant surfaces and immobilization strategies for incorporating these agents into a wide range of medical device materials. We then provide a regulatory science perspective addressing the characterization and testing of AMP coatings based on the type of immobilization strategy used with a focus on the US market regulatory niche. Our goal is to help narrow the gulf between academic studies and preclinical testing, as well as to support a future literature base in order to develop the regulatory science of antimicrobial coatings.

Silicon in mitigation of abiotic stress-induced oxidative damage in plants.

Abstract: Accumulation of reactive oxygen species (ROS), and their destructive effects on cellular organelles are the hallmark features of plants exposed to abiotic stresses. Plants are well-equipped with defensive mechanisms like antioxidant systems to deal with ROS-induced oxidative stress. Silicon has been emerged as an important regulator of plant protective mechanisms under environmental stresses, which can be up-taken from soil through a system of various silicon-transporters. In plants, silicon is deposited underneath of cuticles and in the cell wall, and help plant cells reduce deleterious effects of stresses. Furthermore, silicon can provide resistance to ROS-toxicity, which often accounts for silicon-mediated improvement of plant tolerance to different abiotic constraints, including salinity, drought, and metal toxicity. Silicon enhances the ROS-detoxification ability of treated plants by modulating the antioxidant defense systems, and the expression of key genes associated with oxidative stress mitigation and hormone metabolism. Silicon also displays additive roles in ROS-elimination when supplied with other external stimuli. Here, we discuss recent findings on how silicon is able to modulate antioxidant defense of plants in response to oxidative stress triggered by different abiotic constraints. We also review interactions of silicon with other signaling molecules, including nitric oxide, ROS, polyamines, and phytohormones in the mediation of plant protection against abiotic stress-induced oxidative damage.

Drought stress-induced physiological mechanisms, signaling pathways and molecular response of chloroplasts in common vegetable crops.

Abstract: Drought stress is one of the most adverse abiotic stresses that hinder plants' growth and productivity, threatening sustainable crop production. It impairs normal growth, disturbs water relations and reduces water-use efficiency in plants. However, plants have evolved many physiological and biochemical responses at the cellular and organism levels, in order to cope with drought stress. Photosynthesis, which is considered one of the most crucial biological processes for survival of plants, is greatly affected by drought stress. A gradual decrease in CO2 assimilation rates, reduced leaf size, stem extension and root proliferation under drought stress, disturbs plant water relations, reducing water-use efficiency, disrupts photosynthetic pigments and reduces the gas exchange affecting the plants adversely. In such conditions, the chloroplast, organelle responsible for photosynthesis, is found to counteract the ill effects of drought stress by its critical involvement as a sensor of changes occurring in the environment, as the first process that drought stress affects is photosynthesis. Beside photosynthesis, chloroplasts carry out primary metabolic functions such as the biosynthesis of starch, amino acids, lipids, and tetrapyroles, and play a central role in the assimilation of nitrogen and sulfur. Because the chloroplasts are central organelles where the photosynthetic reactions take place, modifications in their physiology and protein pools are expected in response to the drought stress-induced variations in leaf gas exchanges and the accumulation of ROS. Higher expression levels of various transcription factors and other proteins including heat shock-related protein, LEA proteins seem to be regulating the heat tolerance mechanisms. However, several aspects of plastid alterations, following a water deficit environment are still poorly characterized. Since plants adapt to various stress tolerance mechanisms to respond to drought stress, understanding mechanisms of drought stress tolerance in plants will lead toward the development of drought tolerance in crop plants. This review throws light on major droughts stress-induced molecular/physiological mechanisms in response to severe and prolonged drought stress and addresses the molecular response of chloroplasts in common vegetable crops. It further highlights research gaps, identifying unexplored domains and suggesting recommendations for future investigations.

Aluminum toxicity and aluminum stress-induced physiological tolerance responses in higher plants.

Abstract: Aluminum (Al) precipitates in acidic soils having a pH < 5.5, in the form of conjugated organic and inorganic ions. Al-containing minerals solubilized in the soil solution cause several negative impacts in plants when taken up along with other nutrients. Moreover, a micromolar concentration of Al present in the soil is enough to induce several irreversible toxicity symptoms such as the rapid and transient over-generation of reactive oxygen species (ROS) such as superoxide anion (O2•-), hydrogen peroxide (H2O2), and hydroxyl radical (•OH), resulting in oxidative bursts. In addition, significant reductions in water and nutrient uptake occur which imposes severe stress in the plants. However, some plants have developed Al-tolerance by stimulating the secretion of organic acids like citrate, malate, and oxalate, from plant roots. Genes responsible for encoding such organic acids, play a critical role in Al tolerance. Several transporters involved in Al resistance mechanisms are members of the Aluminum-activated Malate Transporter (ALMT), Multidrug and Toxic compound Extrusion (MATE), ATP-Binding Cassette (ABC), Natural resistance-associated macrophage protein (Nramp), and aquaporin gene families. Therefore, in the present review, the discussion of the global extension and probable cause of Al in the environment and mechanisms of Al toxicity in plants are followed by detailed emphasis on tolerance mechanisms. We have also identified and categorized the important transporters that secrete organic acids and outlined their role in Al stress tolerance mechanisms in crop plants. The information provided here will be helpful for efficient exploration of the available knowledge to develop Al tolerant crop varieties.

Plant response to silver nanoparticles: a critical review.

Abstract: Although several metal ions/metal nanoparticles (NPs) are toxic to both plants and animals, some of them are used as nutrients and growth promoters. Plants exposed to silver nanoparticles (Ag-NPs) ...

Insights into phenolic compounds from microalgae: structural variety and complex beneficial activities from health to nutraceutics

Abstract: Phenolic compounds (PCs) are a family of secondary metabolites with recognized biological activities making them attractive for the biomedical "red" biotechnology The development of the eco-sustainable production of natural bioactive metabolites requires using easy cultivable organisms, such as microalgae, which represents one of the most promising sources for biotechnological applications Microalgae are photosynthetic organisms inhabiting aquatic systems, displaying high levels of biological and functional diversities, and are well-known producers of fatty acids and carotenoids They are also rich in other families of bioactive molecules eg phenolic compounds Microalgal PCs however are less investigated than other molecular components This study aims to provide a state-of-art picture of the actual knowledge on microalgal phenolic compounds, reviewing information on the PC content variety and chemodiversity in microalgae, their environmental modulation, and we aim to report discuss data on PC biosynthetic pathways We report the challenges of promoting microalgae as a relevant source of natural PCs, further enhancing the interests of microalgal "biofactories" for biotechnological applications (ie nutraceutical, pharmacological, or cosmeceutical products)

Scaffolds for the manufacture of cultured meat.

Abstract: The cultured meat market has been growing at an accelerated space since the first creation of cultured meat burger back in 2013. Substantial efforts have been made to reduce costs by eliminating serum in growth media and improving process efficiency by employing bioreactors. In parallel, efforts are also being made on scaffolding innovations to offer better cells proliferation, differentiation and tissue development. So far, scaffolds used in cultured meat research are predominantly collagen and gelatin, which are animal-derived. To align with cell-based meat vision i.e. environment conservation and animal welfare, plant-derived biomaterials for scaffolding are being intensively explored. This paper reviews and discusses the advantages and disadvantages of scaffold materials and potential scaffolding related to scale-up solution for the production of cultured meat.

Biotechnological applications of Bacillus licheniformis

Abstract: Bacillus licheniformis is a Gram positive spore-forming bacterial species of high biotechnological interest with numerous present and potential uses, including the production of bioactive compounds that are applied in a wide range of fields, such as aquaculture, agriculture, food, biomedicine, and pharmaceutical industries. Its use as an expression vector for the production of enzymes and other bioproducts is also gaining interest due to the availability of novel genetic manipulation tools. Furthermore, besides its widespread use as a probiotic, other biotechnological applications of B. licheniformis strains include: bioflocculation, biomineralization, biofuel production, bioremediation, and anti-biofilm activity. Although authorities have approved the use of B. licheniformis as a feed additive worldwide due to the absence of toxigenic potential, some probiotics containing this bacterium are considered unsafe due to the possible transference of antibiotic resistance genes. The wide variability in biological activities and genetic characteristics of this species makes it necessary to establish an exact protocol for describing the novel strains, in order to evaluate its biotechnological potential.

Advances in laccase-triggered anabolism for biotechnology applications

Abstract: This is the first comprehensive overview of laccase-triggered anabolism from fundamental theory to biotechnology applications. Laccase is a typical biological oxidordeuctase that induces the one-el...

Microbial production of gamma-aminobutyric acid: applications, state-of-the-art achievements, and future perspectives.

Abstract: Gamma-aminobutyric acid (GABA) is an important non-protein amino acid with wide-ranging applications. Currently, GABA can be produced by a variety of methods, including chemical synthesis, plant enrichment, enzymatic methods, and microbial production. Among these methods, microbial production has gained increasing attention to meet the strict requirements of an additive in the fields of food, pharmaceutical, and livestock. In addition, renewable and abundant resources, such as glucose and lignocellulosic biomass can also be used for GABA microbial production under mild and environmentally friendly processing conditions. In this review, the applications, metabolic pathways and physiological functions of GABA in different microorganisms were firstly discussed. A comprehensive overview of the current status of process engineering strategies for enhanced GABA production, including fermentation optimization and whole-cell conversion from different feedstocks by various host strains is also provided. We also presented the state-of-the-art achievements in strain development strategies for industrial lactic acid bacteria (LAB), Corynebacterium glutamicum and Escherichia coli to enhance the performance of GABA bioproduction. In order to use bio-based GABA in the fields of food and pharmaceutical, some Generally Recognized as Safe (GRAS) strains such as LAB and C. glutamicum will be the promising chassis hosts. Toward the end of this review, current challenges and valuable research directions/strategies on the improvements of process and strain engineering for economic microbial production of GABA are also suggested.

Enzymatic regeneration and conservation of ATP: challenges and opportunities.

Abstract: Adenosine triphosphate (ATP), the universal energy currency of life, has a central role in numerous biochemical reactions with potential for the synthesis of numerous high-value products. ATP can b...

Dissolution and processing of silk fibroin for materials science.

Abstract: In recent decades, silk fibroin (SF) from silkworm Bombyx mori has been extensively researched and applied in several fields, including: cosmetics, biomedicine and biomaterials. The dissolution and regeneration of SF fibers is the key and prerequisite step for the application of silk protein-based materials. Various solvents and dissolving systems have been reported to dissolve SF fibers. However, the dissolution process directly affects the characteristics of SF and particularly impacts the mechanical properties of the resulting silk biomaterials in subsequent processing. The purpose of this review is to summarize the common solvents, the dissolution methods for silk protein, the properties of the resulting SF protein. The suitable use of SF dissolved in the corresponding solvent was also briefly introduced. Recent applications of SF in various biomaterials are also discussed.

Nitrilase: a promising biocatalyst in industrial applications for green chemistry.

Abstract: Nitrilases are widely distributed in nature and are able to hydrolyze nitriles into their corresponding carboxylic acids and ammonia. In industry, nitrilases have been used as green biocatalysts for the production of high value-added products. To date, biocatalysts are considered to be important alternatives to chemical catalysts due to increasing environmental problems and resource scarcity. This review provides an overview of recent advances of nitrilases in aspects of distribution, enzyme screening, molecular structure and catalytic mechanism, protein engineering, and their potential applications in industry.

Characterization of glycosylation in monoclonal antibodies and its importance in therapeutic antibody development.

Abstract: Glycosylation is one of the structurally diverse and complex forms of post translational modifications observed in proteins which influence the effector functions of IgG-Fc. Although the glycosylation constitutes 2-3% of the total mass of the IgG antibody, a thorough assessment of glycoform distribution present on the antibody is a critical quality attribute (cQA) for the majority of novel and biosimilar monoclonal antibody (mAb) development. This review paper will highlight the impact of different glycoforms such as galactose, fucose, high mannose, NANA (N-acetylneuraminic acid), and NGNA (N-glycoylneuraminic acid) on the safety/immunogeneicity, efficacy/biological activity and clearance (pharmacodynamics/pharmacokinetic property (PD/PK)) of biological molecules. In addition, this paper will summarize routinely employed reliable analytical techniques such as hydrophilic interaction chromatography (HILIC), high performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) and mass spectrometry (MS) for characterizing and monitoring glycosylation in monoclonal antibodies (mAbs). The advantages and disadvantages of each of the methods are addressed. The scope of this review paper is limited to only N-linked and O-linked glycosylation.

DNA barcoding: a modern age tool for detection of adulteration in food

Abstract: Globalization of the food trade requires precise and exact information about the origin, methods of production, transformation technologies, authentication, and the traceability of foodstuffs. New ...

Colors of life: a review on fungal pigments.

Abstract: Colorants find social and commercial applications in cosmetics, food, pharmaceuticals, textiles, and other industrial sectors. Among the available options, chemically synthesized colorants are popular due to their low-cost and flexible production modes, but health and environmental concerns have encouraged the valorization of biopigments that are natural and ecofriendly. Among natural biopigment producers, microorganisms are noteworthy for their all-seasonal production of stable and low-cost pigments with high-yield titers. Fungi are paramount sources of natural pigments. They occupy diverse ecological niches with adaptive metabolisms and biocatalytic pathways, making them entities with an industrial interest. Industrially important biopigments like carotenoids, melanins, riboflavins, azaphilones, and quinones produced by filamentous fungi are described within the context of this review. Most recent information about fungal pigment characteristics, biochemical production routes and pathways, potential applications, limitations, and future research perspectives are described.

Degradation of organic pollutants by intimately coupling photocatalytic materials with microbes: a review.

Abstract: With the rapid development of industry and agriculture, large amounts of organic pollutants have been released into the environment Consequently, the degradation of refractory organic pollutants has become one of the toughest challenges in remediation To solve this problem, intimate coupling of photocatalysis and biodegradation (ICPB) technology, which allows the simultaneous action of photocatalysis and biodegradation and thus integrates the advantages of photocatalytic reactions and biological treatments, was developed recently ICPB consists mainly of porous carriers, photocatalysts, biofilms, and an illuminated reactor Under illumination, photocatalysts on the surface of the carriers convert refractory pollutants into biodegradable products through photocatalytic reactions, after which these products are completely degraded by the biofilms cultivated in the carriers Additionally, the biofilms are protected by the carriers from the harmful light and free radicals generated by the photocatalyst Compared with traditional technologies, ICPB remarkably improves the degradation efficiency and reduces the cost of bioremediation In this review, we introduce the origin and mechanisms of ICPB, discuss the development of reactors, carriers, photocatalysts, and biofilms used in ICPB, and summarize the applications of ICPB to treat organic pollutants Finally, gaps in this research as well as future perspectives are discussed

Metabolic engineering of Yarrowia lipolytica for terpenoids production: advances and perspectives

Abstract: Terpenoids are a large family of natural products with diversified structures and functions that are widely used in the food, pharmaceutical, cosmetic, and agricultural fields. However, the traditional methods of terpenoids production such as plant extraction and chemical synthesis are inefficient due to the complex processes, high energy consumption, and low yields. With progress in metabolic engineering and synthetic biology, microbial cell factories provide an interesting alternative for the sustainable production of terpenoids. The non-conventional yeast, Yarrowia lipolytica, is a promising host for terpenoid biosynthesis due to its inherent mevalonate pathway, high fluxes of acetyl-CoA and NADPH, and the naturally hydrophobic microenvironment. In this review, we highlight progress in the engineering of Y. lipolytica as terpenoid biomanufacturing factories, describing the different terpenoid biosynthetic pathways and summarizing various metabolic engineering strategies, including progress in genetic manipulation, dynamic regulation, organelle engineering, and terpene synthase variants.

Bioactive components from Moringa oleifera seeds: production, functionalities and applications - a critical review.

Abstract: A readily distinguishable and indigenous member of the plant kingdom in the Indian subcontinent is the 'drumstick tree', i.e. Moringa oleifera Lam. In addition to India, this drought-tolerant and rapidly evolving tree is currently extensively disseminated across the globe, including subtropical and tropical areas. The plant boasts a high nutritional, nutraceutical and therapeutic profile, mainly attributing to its significant repertoire of the biologically active components in different parts: protein, flavonoids, saponins, phenolic acids, tannin, isothiocyanate, lipids, minerals, vitamins, amongst others. M. oleifera seeds have been shown to elicit a myriad of pharmacological potential and health benefits, including: antimicrobial, anticancer, antidiabetic, antioxidant, antihypertensive, anti-inflammatory and cardioprotective properties. Additionally, the seed cakes obtained from post-extraction process are utilized for: coagulation, flocculation and sedimentation purposes, benefiting effluent management and the purification of water, mainly because of their capability in eliminating microbes and organic matter. Despite the extraordinary focus on other parts of the plant, especially the foliage, the beneficial aspects of the seeds have not been sufficiently highlighted. The health benefits of bioactive components in the seeds are promising and demonstrate enough potential to facilitate the development of functional foods. In this review, we present a critical account of the types, characteristics, production and isolation of bioactive components from M. oleifera seeds. Furthermore, we appraise the: pharmacological activities, cosmetic, biodiesel, lubricative, modern farming, nutritive and wastewater treatment applications of these functional ingredients. We infer that there is a need for further human/clinical studies and evaluation, despite their health benefits. Additionally, the safety issues need to be adequately clarified and assessed, in order to establish a conventional therapeutic profile.

Advances in production of high-value lipids by oleaginous yeasts.

Abstract: The global market for high-value fatty acids production, mainly omega-3/6, hydroxy fatty-acids, waxes and their derivatives, has seen strong development in the last decade. The reason for this growth was the increasing utilization of these lipids as significant ingredients for cosmetics, food and the oleochemical industries. The large demand for these compounds resulted in a greater scientific interest in research focused on alternative sources of oil production - among which microorganisms attracted the most attention. Microbial oil production offers the possibility to engineer the pathways and store lipids enriched with the desired fatty acids. Moreover, costly chemical steps are avoided and direct commercial use of these fatty acids is available. Among all microorganisms, the oleaginous yeasts have become the most promising hosts for lipid production - their efficient lipogenesis, ability to use various (often highly affordable) carbon sources, feasible large-scale cultivations and wide range of available genetic engineering tools turns them into powerful micro-factories. This review is an in-depth description of the recent developments in the engineering of the lipid biosynthetic pathway with oleaginous yeasts. The different classes of valuable lipid compounds with their derivatives are described and their importance for human health and industry is presented. The emphasis is also placed on the optimization of culture conditions in order to improve the yield and titer of these valuable compounds. Furthermore, the important economic aspects of the current microbial oil production are discussed.

Yarrowia lipolytica as a biorefinery platform for effluents and solid wastes valorization - challenges and opportunities.

Abstract: Due to its physiological and enzymatic features, Yarrowia lipolytica produces several valuable compounds from a wide range of substrates. Appointed by some authors as an industrial workhorse, Y. lipolytica has an extraordinary ability to use unrefined and complex low-cost substrates as carbon and nitrogen sources, aiding to reduce the waste surplus and to produce added-value compounds in a cost-effective way. Dozens of review papers regarding Y. lipolytica have been published till now, proving the interest that this yeast arouses in the scientific community. However, most of them are focused on metabolic pathways involved in substrates assimilation and product formation, or the development of synthetic biology tools in order to obtain engineered strains for biotechnological applications. This paper provides an exhaustive and up-to-date revision on the application of Y. lipolytica to valorize liquid effluents and solid wastes and its role in developing cleaner biotechnological approaches, aiming to boost the circular economy. Firstly, a general overview about Y. lipolytica is introduced, describing its intrinsic features and biotechnological applications. Then, an extensive survey of the literature regarding the assimilation of oily wastes (waste cooking oils, oil cakes and olive mill wastewaters), animal fat wastes, hydrocarbons-rich effluents, crude glycerol and agro-food wastes by Y. lipolytica strains will be discussed. This is the first article that brings together the environmental issue of all such residues and their valorization as feedstock for valuable compounds production by Y. lipolytica. Finally, it will demonstrate the potential of this non-conventional yeast to be used as a biorefinery platform.

Microalgae culture quality indicators: a review.

Abstract: Microalgae are photosynthetic microorganisms that have generated increasing interest in recent years due to their potential applications. Their biological capacity to grow faster than higher plants...

Rhizosphere assisted bioengineering approaches for the mitigation of petroleum hydrocarbons contamination in soil.

Abstract: The high demand for petroleum oil has led to hydrocarbon contamination in soil, including agricultural lands, and many other ecosystems across the globe. Physical and chemical treatments are effect...

Co-culturing microbial consortia: approaches for applications in biomanufacturing and bioprocessing.

Abstract: The application of microbial co-cultures is now recognized in the fields of biotechnology, ecology, and medicine. Understanding the biological interactions that govern the association of microorganisms would shape the way in which artificial/synthetic co-cultures or consortia are developed. The ability to accurately predict and control cell-to-cell interactions fully would be a significant enabler in synthetic biology. Co-culturing method development holds the key to strategically engineer environments in which the co-cultured microorganism can be monitored. Various approaches have been employed which aim to emulate the natural environment and gain access to the untapped natural resources emerging from cross-talk between partners. Amongst these methods are the use of a communal liquid medium for growth, use of a solid-liquid interface, membrane separation, spatial separation, and use of microfluidics systems. Maximizing the information content of interactions monitored is one of the major challenges that needs to be addressed by these designs. This review critically evaluates the significance and drawbacks of the co-culturing approaches used to this day in biotechnological applications, relevant to biomanufacturing. It is recommended that experimental results for a co-cultured species should be validated with different co-culture approaches due to variations in interactions that could exist as a result of the culturing method selected.

Potential use of fungal-bacterial co-cultures for the removal of organic pollutants.

Abstract: Fungi and bacteria coexist in a wide variety of natural and artificial environments which can lead to their association and interaction - ranging from antagonism to cooperation - that can affect the survival, colonization, spatial distribution and stress resistance of the interacting partners. The use of polymicrobial cultivation approaches has facilitated a more thorough understanding of microbial dynamics in mixed microbial communities, such as those composed of fungi and bacteria, and their influence on ecosystem functions. Mixed (multi-domain) microbial communities exhibit unique associations and interactions that could result in more efficient systems for the degradation and removal of organic pollutants. Several previous studies have reported enhanced biodegradation of certain pollutants when using combined fungal-bacterial treatments compared to pure cultures or communities of either fungi or bacteria (single domain systems). This article reviews: (i) the mechanisms of pollutant degradation that can occur in fungal-bacterial systems (e.g.: co-degradation, production of secondary metabolites, enhancement of degradative enzyme production, and transport of bacteria by fungal mycelia); (ii) case studies using fungal-bacterial co-cultures for the removal of various organic pollutants (synthetic dyes, polycyclic aromatic hydrocarbons, pesticides, and other trace or volatile organic compounds) in different environmental matrices (e.g. water, gas/vapors, soil); (iii) the key aspects of engineering artificial fungal-bacterial co-cultures, and (iv) the current challenges and future perspectives of using fungal-bacterial co-cultures for environmental remediation.

Pigments from Antarctic bacteria and their biotechnological applications.

Abstract: Pigments from microorganisms have triggered great interest in the market, mostly by their “natural” appeal, their favorable production conditions, in addition to the potential new chemical structur...

Regulation of carotenoid degradation and production of apocarotenoids in natural and engineered organisms.

Abstract: Carotenoids are important precursors of a wide range of apocarotenoids with their functions including: hormones, pigments, retinoids, volatiles, and signals, which can be used in the food, flavors, fragrances, cosmetics, and pharmaceutical industries. This article focuses on the formation of these multifaceted apocarotenoids and their diverse biological roles in all living systems. Carotenoid degradation pathways include: enzymatic oxidation by specific carotenoid cleavage oxygenases (CCOs) or nonspecific enzymes such as lipoxygenases and peroxidases and non-enzymatic oxidation by reactive oxygen species. Recent advances in the regulation of carotenoid cleavage genes and the biotechnological production of multiple apocarotenoids are also covered. It is suggested that different developmental stages and environmental stresses can influence both the expression of carotenoid cleavage genes and the formation of apocarotenoids at multiple levels of regulation including: transcriptional, transcription factors, posttranscriptional, posttranslational, and epigenetic modification. Regarding the biotechnological production of apocarotenoids especially: crocins, retinoids, and ionones, enzymatic biocatalysis and metabolically engineered microorganisms have been a promising alternative route. New substrates, carotenoid cleavage enzymes, biosynthetic pathways for apocarotenoids, and new biological functions of apocarotenoids will be discussed with the improvement of our understanding of apocarotenoid biology, biochemistry, function, and formation from different organisms.