Advances in biochemical engineering/biotechnology最新文献

The fast growth accompanied with high substrate consumption rates and a versatile metabolism paved the way to exploit Vibrio natriegens as unconventional host for biotechnological applications. Meanwhile, a wealth of knowledge on the physiology, the metabolism, and the regulation in this halophilic marine bacterium has been gathered. Sophisticated genetic engineering tools and metabolic models are available and have been applied to engineer production strains and first chassis variants of V. natriegens. In this review, we update the current knowledge on the physiology and the progress in the development of synthetic biology tools and provide an overview of recent advances in metabolic engineering of this promising host. We further discuss future challenges to enhance the application range of V. natriegens.

The expanding field of synthetic biology requires diversification of microbial chassis to expedite the transition from a fossil fuel-dependent economy to a sustainable bioeconomy. Relying exclusively on established model organisms such as Escherichia coli and Saccharomyces cerevisiae may not suffice to drive the profound advancements needed in biotechnology. In this context, Cupriavidus necator, an extraordinarily versatile microorganism, has emerged as a potential catalyst for transformative breakthroughs in industrial biomanufacturing. This comprehensive book chapter offers an in-depth review of the remarkable technological progress achieved by C. necator in the past decade, with a specific focus on the fields of molecular biology tools, metabolic engineering, and innovative fermentation strategies. Through this exploration, we aim to shed light on the pivotal role of C. necator in shaping the future of sustainable bioprocessing and bioproduct development.

Methanogenic archaea convert bacterial fermentation intermediates from the decomposition of organic material into methane. This process has relevance in the global carbon cycle and finds application in anthropogenic processes, such as wastewater treatment and anaerobic digestion. Furthermore, methanogenic archaea that utilize hydrogen and carbon dioxide as substrates are being employed as biocatalysts for the biomethanation step of power-to-gas technology. This technology converts hydrogen from water electrolysis and carbon dioxide into renewable natural gas (i.e., methane). The application of methanogenic archaea in bioproduction beyond methane has been demonstrated in only a few instances and is limited to mesophilic species for which genetic engineering tools are available. In this chapter, we discuss recent developments for those existing genetically tractable systems and the inclusion of novel genetic tools for thermophilic methanogenic species. We then give an overview of recombinant bioproduction with mesophilic methanogenic archaea and thermophilic non-methanogenic microbes. This is the basis for discussing putative products with thermophilic methanogenic archaea, specifically the species Methanothermobacter thermautotrophicus. We give estimates of potential conversion efficiencies for those putative products based on a genome-scale metabolic model for M. thermautotrophicus.

Wastewaters often contain an array of economically valuable elements, including elements considered critical raw materials and elements for fertilizer production. Plant-based treatment approaches in constructed wetlands, open ponds, or hydroponic systems represent an eco-friendly and economical way to remove potentially toxic metal(loid)s from wastewater (phytoextraction). Concomitantly, the element-enriched biomass represents an important secondary raw material for bioenergy generation and the recovery of raw materials from the harvested plant biomass (phytomining). At present, phytoextraction in constructed wetlands is still considered a nascent technology that still requires more fundamental and applied research before it can be commercially applied. This chapter discusses the different roles of plants in constructed wetlands during the phytoextraction of economically valuable elements. It sheds light on the utilization of plant biomass in the recovery of raw materials from wastewater streams. Here, we consider phytoextraction of the commonly studied water pollutants (N, P, Zn, Cd, Pb, Cr) and expand this concept to a group of rather exotic metal(loid)s (Ge, REE, PGM) highlighting the role of phytoextraction in the face of climate change and finite resources of high-tech metals.

Human communities need water and mineral resources, the supply of which requires the implementation of recycling and saving strategies. Both closed and active mining sites could beneficiate of the implementation of nature-based solutions, including bioreactors involving sulphate-reducing prokaryotes (SRP), in order to separate and recover arsenic (As) and metals from aqueous stream while producing clean water. Selective precipitation strategies can be designed based on the selection of microbial communities adapted to the pH conditions, generally acidic, and to available low-cost electron donors. Laboratory batch and continuous experiments must be implemented for each type of mine water in order to determine the optimal flow-sheet in which As could be precipitated as sulphides (orpiment or realgar), inside the bioreactor or offline, through stripping of biologically produced hydrogen sulphides (H₂S). The respective concentrations and proportions of As and metals and the initial acid mine drainage pH are key parameters that will influence the feasibility of efficient selective precipitation. SRP-based bioreactors could be combined with complementary treatment steps in optimised mine water management solutions that will minimise the production of As-contaminated end-solid waste.

Potentially toxic elements (PTE) pollution in water bodies is an emerging problem in recent decades due to uncontrolled discharges from human activities. Copper, zinc, arsenic, cadmium, lead, mercury, and uranium are considered potentially toxic and carcinogenic elements that threaten human health. Microalgae-based technologies for the wastewater treatment have gained importance in recent years due to their biomass high growth rates and effectiveness. Also, these microalgae-bacteria systems are cost-effective and environmentally friendly, utilize sunlight and CO₂, and simultaneously address multiple environmental challenges, such as carbon mitigation, bioremediation, and generation of valuable biomass useful for biofuel production. Additionally, microalgae possess a diverse array of extracellular and intracellular mechanisms that enable them to remove and mitigate the toxicity of PTE present in wastewater. Therefore, photobioreactors are promising candidates for practical applications in bioremediation of wastewater containing toxic elements. Despite the increasing amount of research in this field in recent years, most studies are conducted in laboratory scale and there is a scarcity of large-scale studies under real and variable environmental conditions. Besides, the limited understanding of the multiple mechanisms controlling PTE biosorption in wastewater containing high organic matter loads and potentially toxic elements requires further studies. This chapter provides a schematic representation of the mechanisms and factors involved in the remediation of potentially toxic elements by microalgae, as well as the main results obtained in recent years.

Iron is a common contaminant in source water and wastewater. The mining and metallurgical industries in particular can produce and discharge large quantities of wastewater with high iron concentrations. Due to the harmful effects of iron on organisms and infrastructure, efficient technologies for iron removal from water and wastewater are needed. On the other hand, iron is a valuable commodity for a wide range of applications. Microorganisms can facilitate iron removal and recovery through aerobic and anaerobic processes. The most commonly utilized microbes include iron oxidizers that facilitate iron precipitation as jarosites, schwertmannite, ferrihydrite, goethite, and scorodite, and sulfate reducers which produce hydrogen sulfide that precipitates iron as sulfides. Biological iron removal has been explored in various suspended cell and biofilm-based bioreactors that can be configured in parallel or series and integrated with precipitation and settling units for an effective flow sheet. This chapter reviews principles for biological iron removal and recovery, the microorganisms involved, reactor types, patents and examples of laboratory- and pilot-scale studies, and full-scale implementations of the technology.

Aluminum biorecovery is still at an early stage. However, a significant number of studies showing promising results already exist, although they have revealed problems that need to be solved so aluminum biorecovery can have a wider application and industrial upscaling. In this chapter, we revise the existing knowledge on the biorecovery of aluminum from different sources. We discuss the design, overall performance, advantages, technical problems, limitations, and possible future directions of the different biotechnological methods that have been reported so far. Aluminum biorecovery from different sources has been studied (i.e., solid wastes and primary sources of variable origin, wastewater with low concentrations of dissolved aluminum at pH-neutral or weakly acidic conditions, and acidic mine waters with high concentrations of dissolved aluminum and other metal(loid)s) and has shown that the process efficiency strongly depends on factors such as (1) the physicochemical properties of the source materials, (2) the physiological features of the used (micro)organisms, or (3) the biochemical process used. Bioleaching of aluminum from low-grade bauxite or red mud can much be achieved by a diverse range of organisms (e.g., fungi, bacteria) with different metabolic rates. Biorecovery of aluminum from wastewaters, e.g., domestic wastewater, acidic mine water, has also been accomplished by the use of microalgae, cyanobacteria (for domestic wastewater) or by sulfate-reducing bacteria (acidic mine water). In most of the cases, the drawback of the process is the requirement of controlled conditions which involves a continuous supply of oxygen or maintenance of anoxic conditions which make aluminum biorecovery challenging in terms of process design and economical value. Further studies should focus on studying these processes in comparison or in combination to existing economical processes to assess their feasibility.

The recovery of metals from waste material has been on the increase in the past few years due to a number of reasons such as supporting the diversification of metal supply resources. In addition, the alternative use of the waste material for metal recovery can add to the main production line, boosting production throughput and profitability thus, allowing companies to sustain their activities during times of low commodity prices. While there has been a lot of research and interest in the recovery of precious metals such as platinum group metals (PGMs), Au, and Ag from solid waste material, there has been limited focus on the recovery of these value metals from wastewater. This is mostly related to challenges associated with finding cost-effective technologies that can recover these metals from solutions of low metal concentrations. In recent years, bio-based technologies have, however, become established as potential alternatives to traditional techniques in the treatment of wastewater due to their ability to recover metals from solutions of low concentrations. While wastewater might be characterized by some significant value metal content, it also contains other components that have potential economic value if recovered or converted to by-products. Such an approach may not only provide an opportunity for extraction of metal resources from wastewater but also contributes toward the circular economy. This chapter presents insights into precious metal recovery from wastewater using bio-based technologies, compares such an approach to the traditional techniques, explores the recovery of other value-added products and finally considers some of the challenges associated with the large-scale application of the bio-based technologies.