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Bioprocessing technologies in biorefinery for sustainable production of fuels, chemicals, and polymers
Sets the stage for large-scale production of biofuels and bio-based chemicals In response to diminishing supplies as well as the environmental hazards posed by fossil fuels and petrochemicals, interest and demand for green, sustainable biofuels and bio-based chemicals are soaring. Biomass may be the solution. It is an abundant carbon-neutral renewable feedstock that can be used for the production of fuels and chemicals. Currently, biorefineries use corn, soybeans, and sugarcane for bioethanol and biodiesel production; however, there are many challenges facing biorefineries, preventing biomass from reaching its full potential. This book provides a comprehensive review of bioprocessing technologies that use lignocellulosic biomass for the production of biofuels, biochemicals, and biopolymers. It begins with an overview of integrated biorefineries. Next, it covers: - Biomass feedstocks, including sugar, starch, oil, and energy crops as well as microalgae - Pretreatment technologies for lignocellulosic biomass - Hydrolytic enzymes used in biorefineries for the hydrolysis of starch and lignocelluloses - Bioconversion technologies for current and future biofuels such as ethanol, biodiesel, butanol, hydrogen, and biogas - Specialty chemicals, building block chemicals, and biopolymers produced via fermentation - Phytochemicals and functional food ingredients extracted from plant materials All the chapters have been written and edited by leading experts in bioprocessing and biorefining technologies. Contributions are based on a thorough review of the literature as well as the authors' firsthand experience developing and working with bioprocessing technologies. By setting forth the current state of the technology and pointing to promising new directions in research, Bioprocessing Technologies in Biorefinery for Sustainable Production of Fuels, Chemicals, and Polymers will enable readers to move towards large-scale, sustainable, and economical production of biofuels and bio-based chemicals.
eBook
Microbial Electrosynthesis Using 3D Bioprinting of ISporomusa ovata/I on Copper, Stainless-Steel, and Titanium Cathodes for COsub.2 Reduction
Acetate can be produced from carbon dioxide (CO[sub.2] ) and electricity using bacteria at the cathode of microbial electrosynthesis (MES). This process relies on electrolytically-produced hydrogen (H[sub.2] ). However, the low solubility of H[sub.2] can limit the process. Using metal cathodes to generate H[sub.2] at a high rate can improve MES. Immobilizing bacteria on the metal cathode can further proliferate the H[sub.2] availability to the bacteria. In this study, we investigated the performances of 3D bioprinting of Sporomusa ovata on three metal meshes—copper (Cu), stainless steel (SS), and titanium (Ti), when used individually as a cathode in MES. Bacterial cells were immobilized on the metal using a 3D bioprinter with alginate hydrogel ink. The bioprinted Ti mesh exhibited higher acetate production (53 ± 19 g/m[sup.2] /d) at −0.8 V vs. Ag/AgCl as compared to other metal cathodes. More than 9 g/L of acetate was achieved with bioprinted Ti, and the least amount was obtained with bioprinted Cu. Although all three metals are known for catalyzing H[sub.2] evolution, the lower biocompatibility and chemical stability of Cu hampered its performance. Stable and biocompatible Ti supported the bioprinted S. ovata effectively. Bioprinting of synthetic biofilm on H[sub.2] -evolving metal cathodes can provide high-performing and robust biocathodes for further application of MES.
Journal Article
Microbial Synthesis of Heme Ib/I: Biosynthetic Pathways, Current Strategies, Detection, and Future Prospects
Heme b, which is characterized by a ferrous ion and a porphyrin macrocycle, acts as a prosthetic group for many enzymes and contributes to various physiological processes. Consequently, it has wide applications in medicine, food, chemical production, and other burgeoning fields. Due to the shortcomings of chemical syntheses and bio-extraction techniques, alternative biotechnological methods have drawn increasing attention. In this review, we provide the first systematic summary of the progress in the microbial synthesis of heme b. Three different pathways are described in detail, and the metabolic engineering strategies for the biosynthesis of heme b via the protoporphyrin-dependent and coproporphyrin-dependent pathways are highlighted. The UV spectrophotometric detection of heme b is gradually being replaced by newly developed detection methods, such as HPLC and biosensors, and for the first time, this review summarizes the methods used in recent years. Finally, we discuss the future prospects, with an emphasis on the potential strategies for improving the biosynthesis of heme b and understanding the regulatory mechanisms for building efficient microbial cell factories.
Journal Article
The microbiome-shaping roles of bacteriocins
The microbiomes on human body surfaces affect health in multiple ways. They include not only commensal or mutualistic bacteria but also potentially pathogenic bacteria, which can enter sterile tissues to cause invasive infection. Many commensal bacteria produce small antibacterial molecules termed bacteriocins that have the capacity to eliminate specific colonizing pathogens; as such, bacteriocins have attracted increased attention as potential microbiome-editing tools. Metagenome-based and activity-based screening approaches have strongly expanded our knowledge of the abundance and diversity of bacteriocin biosynthetic gene clusters and the properties of a continuously growing list of bacteriocin classes. The dynamic acquisition, diversification or loss of bacteriocin genes can shape the fitness of a bacterial strain that is in competition with bacteriocin-susceptible bacteria. However, a bacteriocin can only provide a competitive advantage if its fitness benefit exceeds the metabolic cost of production, if it spares crucial mutualistic partner strains and if major competitors cannot develop resistance. In contrast to most currently available antibiotics, many bacteriocins have only narrow activity ranges and could be attractive agents for precision therapy and prevention of infections. A common scientific strategy involving multiple disciplines is needed to uncover the immense potential of microbiome-shaping bacteriocins.Small antibacterial molecules termed bacteriocins can influence microbiome composition by providing an advantage to bacteriocin producers over bacteriocin-sensitive strains. In this Review, Peschel and colleagues provide an overview of the types of bacteriocins, their costs and benefits, and how they may provide new avenues for antibacterial drug development.
Journal Article
Bacterial biopolymers: from pathogenesis to advanced materials
Bacteria are prime cell factories that can efficiently convert carbon and nitrogen sources into a large diversity of intracellular and extracellular biopolymers, such as polysaccharides, polyamides, polyesters, polyphosphates, extracellular DNA and proteinaceous components. Bacterial polymers have important roles in pathogenicity, and their varied chemical and material properties make them suitable for medical and industrial applications. The same biopolymers when produced by pathogenic bacteria function as major virulence factors, whereas when they are produced by non-pathogenic bacteria, they become food ingredients or biomaterials. Interdisciplinary research has shed light on the molecular mechanisms of bacterial polymer synthesis, identified new targets for antibacterial drugs and informed synthetic biology approaches to design and manufacture innovative materials. This Review summarizes the role of bacterial polymers in pathogenesis, their synthesis and their material properties as well as approaches to design cell factories for production of tailor-made bio-based materials suitable for high-value applications.Bacteria produce diverse polymers, such as polysaccharides, polyesters, polyphosphates and extracellular DNA. In this Review, Moradali and Rehm discuss the types of bacterial polymers and their role in bacterial physiology and pathogenesis as well as their production and use as novel biomaterials.
Journal Article
Microbial production of advanced biofuels
Concerns over climate change have necessitated a rethinking of our transportation infrastructure. One possible alternative to carbon-polluting fossil fuels is biofuels produced by engineered microorganisms that use a renewable carbon source. Two biofuels, ethanol and biodiesel, have made inroads in displacing petroleum-based fuels, but their uptake has been limited by the amounts that can be used in conventional engines and by their cost. Advanced biofuels that mimic petroleum-based fuels are not limited by the amounts that can be used in existing transportation infrastructure but have had limited uptake due to costs. In this Review, we discuss engineering metabolic pathways to produce advanced biofuels, challenges with substrate and product toxicity with regard to host microorganisms and methods to engineer tolerance, and the use of functional genomics and machine learning approaches to produce advanced biofuels and prospects for reducing their costs.Biofuels produced by conversion of biomass by engineered microorganisms have the potential to replace fossil fuels and reduce carbon emissions. In this Review, Keasling and colleagues discuss engineering of metabolic pathways to produce advanced biofuels and approaches to reduce metabolite toxicity and cost and increase titre, rate and yield.
Journal Article
Pseudomonas aeruginosa’s greenish-blue pigment pyocyanin: its production and biological activities
A subject of great interest is the bioprospecting of microorganisms and their bioactive byproducts, such as pigments. Microbial pigments have various benefits, including being safe to use due to their natural makeup, having therapeutic effects, and being produced all year round, regardless of the weather or location.
Pseudomonas aeruginosa
produces phenazine pigments that are crucial for interactions between
Pseudomonas
species and other living things. Pyocyanin pigment, which is synthesized by 90–95% of
P. aeruginosa
, has potent antibacterial, antioxidant, and anticancer properties. Herein, we will concentrate on the production and extraction of pyocyanin pigment and its biological use in different areas of biotechnology, engineering, and biology.
Journal Article
Challenging microalgal vitamins for human health
Background
Vitamins’ deficiency in humans is an important threat worldwide and requires solutions. In the concept of natural biofactory for bioactive compounds production, microalgae represent one of the most promising targets filling many biotechnological applications, and allowing the development of an eco-sustainable production of natural bioactive metabolites. Vitamins are probably one of the cutting edges of microalgal diversity compounds.
Main text
Microalgae can usefully provide many of the required vitamins in humans, more than terrestrial plants, for instance. Indeed, vitamins D and K, little present in many plants or fruits, are instead available from microalgae. The same occurs for some vitamins B (B
12
, B
9
, B
6
), while the other vitamins (A, C, D, E) are also provided by microalgae. This large panel of vitamins diversity in microalgal cells represents an exploitable platform in order to use them as natural vitamins’ producers for human consumption. This study aims to provide an integrative overview on vitamins content in the microalgal realm, and discuss on the great potential of microalgae as sources of different forms of vitamins to be included as functional ingredients in food or nutraceuticals for the human health. We report on the biological roles of vitamins in microalgae, the current knowledge on their modulation by environmental or biological forcing and on the biological activity of the different vitamins in human metabolism and health protection.
Conclusion
Finally, we critically discuss the challenges for promoting microalgae as a relevant source of vitamins, further enhancing the interests of microalgal “biofactory” for biotechnological applications, such as in nutraceuticals or cosmeceuticals.
Journal Article
Effects of light intensity on growth and lipid production in microalgae grown in wastewater
Background Cultivation of microalgae in wastewater could significantly contribute to wastewater treatment, biodiesel production, and thus the transition to renewable energy. However, more information on effects of environmental factors, including light intensity, on their growth and composition (particularly fatty acid contents) is required. Therefore, we investigated the biomass and fatty acid production of four microalgal species, isolated in the Northern hemisphere and grown at three light intensities (50, 150 and 300 μE m−2 s−1). Results Increases in light intensities resulted in higher biomass of all four species and, importantly, raised fatty acid contents of both Desmodesmus sp. and Scenedesmus obliquus. Fourier-transform IR spectrometry analysis showed that the increases in fatty acid content were associated with reductions in protein, but not carbohydrate, contents. Assessment of fatty acid composition revealed that increasing light intensity led to higher and lower contents of oleic (18:1) and linolenic (18:3) acids, respectively. The microalgae consumed more than 75% of the nitrogen and phosphorus present in the wastewater used as growth medium. Conclusion The results show the importance of optimizing light intensities to improve fatty acid production by microalgae and their quality as sources of biodiesel. In addition, increase in fatty acid content is associated with decrease in protein content.
Journal Article