Advances in biochemical engineering/biotechnology最新文献

Biomass pretreatment plays a crucial role in the conversion of lignocellulosic biowaste materials into valuable biofuels and biochemicals. Enzymatic pretreatment, in particular, has gained significant attention due to its eco-friendly nature and efficiency in breaking down complex biomass structures. This comprehensive review aims to provide an overview of enzymes used in biomass pretreatment, including cellulases, hemicellulases, ligninases, and their applications in enhancing the efficiency of biomass conversion processes. The review also discusses recent advancements, challenges, and future prospects in the field of enzymatic biomass pretreatment.

Bacterial cellulose (BC) is a polymer produced by specific species of bacteria, most often by the species Komagataeibacter xylinus and Gluconacetobacter xylinus. BC may be distinguished from other types of cellulose by its origin. It is a kind of cellulose that is highly pure and robust, which is made up of long chains of glucose units that create a 3D network. The production of BC takes place via fermentation. During this process, the bacteria utilize sugar and produce cellulose as a byproduct. BC has been extensively researched for its potential use in the medical industry, food industry, and many other fields. Application includes development of an artificial skin for wound dressing because of its remarkable inter- and intramolecular hydrogen bonding and thermal and mechanical strength. BC has a large potential to be used in the food industry, where it can be combined with other polysaccharides to be used in food products as additives, edible film/coating, or active food packaging material to prolong the shelf life of the product and reduce the rate of chemical reactions and microbial growth in food products.

Cyanobacteria as phototrophic microorganisms bear great potential for biotechnological application and a truly sustainable bioeconomy. Besides production of biomass and natural compounds, CO₂-based production of diverse value-added compounds with engineered strains enjoys ever-growing interest. Representatives of the genera Synechocystis and Synechococcus are the most used cyanobacterial model organisms for this purpose, with studies ranging from basic research to their utilization as cell factories. For both genera, genetic tools become more and more established, being, however, still far less advanced compared to those available for heterotrophic workhorse strains. Production of CO₂-based compounds, typically established on a proof-of-concept basis, ranges from highly complex products such as pigments, proteins, and hormones to more simple bulk products such as biofuels and commodity chemicals. For some small molecules, e.g., isobutyraldehyde, 2,3-butanediol, L-lactic acid, sucrose, and ethanol, the gram per liter scale has been achieved. The general benefits of cyanobacterial photobiotechnology are the use of light as energy source and the capacity to use CO₂ via photosynthetic carbon fixation. Additionally, the photosynthetic apparatus offers the opportunity to directly utilize electrons derived from photosynthetic water oxidation for redox biotransformations. In this respect, several enzymes have successfully been implemented in cyanobacterial strains, and high specific rates comparable to those achieved with heterotrophs have been reached. Moreover, oxygenic photosynthesis provides an ideal framework to implement oxyfunctionalization reactions also benefitting from the intracellular in situ supply of O₂. This chapter summarizes the recent advances in cyanobacterial biotechnology with a focus on Synechocystis and Synechococcus strains, encompassing both biotransformation reactions and CO₂-based product formation. Additionally, we discuss advantages and limitations of cyanobacterial chassis strains and give perspectives for future research and required measures to establish this unique group of bacteria in industrial biotechnology.

In this chapter, we discuss the necessity of novel chassis organisms for the production of natural products to steer away from petrochemical approaches and the usage of common model organisms. We present the social amoeba Dictyostelium discoideum as a novel host for the production of complex organic substances and exploration of cryptic biosynthetic routes of secondary metabolites. We shed light on the genetic repertoire of the amoeba in terms of natural product biosyntheses and give an overview of growth characteristics, genetic engineering tools, and cultivation methodologies from shake flasks to stirred-tank bioreactors. Finally, an outlook is made on the perspective of D. discoideum as the chassis for biotechnological production and discovery of novel active substances.

The circular bioeconomy connects waste recycling with utilizing organic biomass waste for bioenergy, bio-based materials, and biochemical production. This integration promotes efficient resource utilization, reduced greenhouse gas emissions, and sustainable economic growth. Several technologies such as composting, anaerobic digestion, biochar production, gasification, pyrolysis, pelletization, and advanced thermal conversion technologies are utilized to manage agricultural waste efficiently. Waste-to-energy systems and food waste valorization techniques are employed to convert agro-waste into renewable energy sources such as bioethanol, biodiesel, and biogas through fermentation, transesterification, and anaerobic digestion. These biofuels offer renewable alternatives to fossil fuels, reducing greenhouse gas emissions and dependence on non-renewable resources. Rice husk, a globally abundant agricultural waste, can be utilized for energy production through technologies like direct combustion and fast pyrolysis. Biobutanol, synthesized from acetone-butanol-ethanol fermentation of agricultural residues like orange peel, presents a promising fuel option. Agricultural waste can also serve as feedstock for bio-based chemicals like organic acids, solvents, and polymers, reducing reliance on petroleum-based chemicals. Agro-waste materials like grass, garlic peel, and rice bran have shown potential for dye adsorption in wastewater treatment applications. Moreover, agricultural waste can be repurposed as animal feed, contributing to waste reduction and providing sustainable nutrition for livestock. Plant seeds and green biomass offer sustainable protein sources, while residues like straw and sawdust can be used for mushroom cultivation. Agro-waste biopolymers like starch and cellulose can be transformed into biodegradable plastics and biocomposites, offering eco-friendly alternatives. Additionally, agro-waste materials like straw, rice husks, and bamboo can be processed into construction materials, reducing environmental impact in building projects. Extracts from plant residues and fruit pomace can be utilized in pharmaceuticals, nutraceuticals, and cosmetics. Valorizing agro-waste for food, feed, fibers, and fuel offers opportunities to minimize waste and maximize resource efficiency, resulting in high-value products.

Electro-bioremediation of wastewater is a novel, nature-based solution towards clean water, based on microbial electrochemical technologies (METs). Electro-bioremediation technologies for wastewater treatment, except enhanced bioremediation results and renewable energy generation, offer an unlocked opportunity for harvesting by-products and using them in other applications. This concept contributes to circularity, sustainability, and environmental compatibility, mitigating the impact of climate change. In addition, wastewater valorization and, thus, water resilience are possible thereby leading to protection of water resources. Compounds and metabolites naturally synthesized by the microorganisms involved in the wastewater electro-assisted biodegradation, can result in the enhancement of both extracellular electron transfer (EET) and bioremediation. Such microbial products are added-value, natural, non-toxic and biodegradable such as biosurfactants (BSFs) and polyhydroxyalkanoates (PHAs). In this chapter, the effect of the presence of BSFs and PHAs in MET during electro-bioremediation, as well as when fed with conventional substrates, are exhaustively evaluated. The significance of BSFs even when they are added exogenously is also examined. The major categories of by-products biosynthesis including organic acids, biopolymers, recovered heavy metals and phenazines such as pyocyanin during electro-bioremediation processes are also discussed. Consequently, a future direction in wastewater electro-bioremediation is proposed.

Cable bacteria grow as multicellular filaments several centimetres deep into the sediment of freshwaters and oceans. Hereby, cable bacteria show unique characteristics such as electrogenic sulphur oxidation, extremely high conductivity and ability for CO₂ fixation. This offers several possibilities of future applications in biotechnology with an outlook to sustainable processes. So far, research on cable bacteria is mostly concerning metabolism, electron transfer and effect on the surrounding sediment. Cultures are always performed on sediment from the natural habitat and in simple, small-scale reaction tubes, requiring further development for reproducible cultivation with scale-up capabilities. However, based on the known properties of cable bacteria, possible areas of application can already be derived. The use of cable bacteria in bioremediation is a promising approach, as the degradation of hydrocarbons has already been proven. Co-cultivation with plants could open up a further field of application, such as the described reduction of methane emissions from rice fields. Due to the extremely high conductivity of the filaments, cable bacteria are also very promising for incorporation into biodegradable microelectronics. By integrating electrodes into a suitable reactor system, bioelectrochemical processes could be implemented, either with the goal of electron uptake and product formation or for electricity generation.

Intensive agricultural production generates a lot of residues yearly, exhausting and depleting the soils and accumulating pesticides and mineral fertilizers. Although introducing the no-till technologies is related to the reduction of tillage, leaving most of the plant residues on the field and decreasing fertigation, the global crop residues are estimated to be 2800 million tons per year. They could be successfully utilized via several approaches integrated into the circular bioeconomy concept. Thus, stopping the existing vicious circle of digging most of the primary materials such as fossil fuels, the vast application of chemical fertilizers, gaining increased or restored biodiversity, capturing CO₂ into the soils and enhancing the organic content, having cleaner underground waters, soils and crop production, and finally improved quality of life. The transformation of these residues into value-added products faces various technological and commercialization difficulties that limit their fuller utilization. In the present chapter, we aim to describe the production of agricultural residues in the EU and present their properties and technologies for biological valorization. In addition, the potential risks associated with the micro- and nano-plastics content of agricultural residues are discussed.

Today, organic chemical products are predominantly produced based on fossil raw materials. The demand for climate-friendly products, legal requirements and the EU emissions trading scheme (EU-ETS) are forcing the chemical industry to focus on increased recycling and production based on CO₂ and biomass in the future. To avoid competition with the food sector associated with the industrial use of biomass, organic waste, residual materials and CO₂ are to be tapped as carbon sources. This chapter describes the volume potential of these alternative raw materials in the EU and technologies for their utilisation in basic, speciality and fine chemical products for various applications and markets. The question of the availability of sustainable carbon sources arises for the large-volume products of basic chemistry. A detailed techno-economic analysis (TEA) to produce methanol based on CO₂ is therefore presented as an example. Finally, the requirements for achieving the raw material transition by 2050 are discussed.

The wine industry is very important, the European wine production representing over 60% of the global production. According to the European Commission, the total annual wine production (2013-2020) in European countries reached a volume of 165 million hL. Europe is also the most important wine exporter occupying around 70% of the global market. In parallel, the wine industry produces a large quantity of biowaste that, in the context of a sustainable economy, needs to be valorized. In order to protect the environment, the landfilling of such biowaste has to be avoided due to its acidity and the possible generation of hazardous products by decomposition. On the other hand, vinification residues contain valuable compounds like: oils, polyphenols, tocopherols, and organic elements (carbon and nitrogen) making the valorization of these by-products compulsory. Ecological solutions for the valorization of grape seeds, grape skins, stems, as well as wine lees resulting from grape vinification have to be found. Different solutions for the processing of these biowastes to generate added value products are described and the economic aspects underlined.