Reviews in Environmental Science and Bio/Technology最新文献

Renewable resources have gained significant attention and are being evaluated as a base material for developing biodegradable packaging materials. A massive quantity of agricultural/food processing waste has been employed alone or in combination to make biodegradable packaging material with good barriers and functional capabilities. Onion is extensively used in dishes and condiments preparation. To meet consumer demand, the onion processing industry focuses on onion-based value-added products such as peeled onion, onion paste, onion powder, etc., that generate a considerable amount of solid waste (OSW). This OSW cannot be fit for animal fodder, landfill, and incineration due to their high carbon content and phytopathogens. OSW was found to be explored in the packaging sector because of high cellulose, lignin, and polyphenols. The biopolymers and pigments in OSW can be effectively used in active/smart packaging, which will aid in monitoring packaged food quality. The pigments and bioactive components in OSW can serve as indicators, maintaining the freshness of packaged foods in real-time by visual examination and reducing food loss and waste. The present review provides an approach of OSW for packaging material development and their potential application for food quality monitoring.

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Wastewater generated from distillery industries is a matter of great concern due to its dark brown color, high organic load and resistance to natural biodegradation. Therefore, enormous effort is needed to avoid the discharge of this highly polluted effluent into natural water bodies and their consequent contamination. However, the treatment of the ever-increasing quantities of distillery wastewater in a cost-effective and eco-friendly manner is very challenging. The current physicochemical techniques available are either costly, energy-intensive or involve toxic chemicals. Thus, there is an urgent need to complement the existing knowledge on the biodegradation of distillery effluent with valuable resource recovery to find an appropriate solution for its sustainable management. This review incorporates a summary of the problems associated with distillery wastewater with special attention towards major color-causing components present in it and the challenges they pose. Detailed examination of various bioremediation approaches used by researchers for the treatment of distillery effluent is also provided. Moreover, the review scrutinizes the utilization of distillery wastewater for valuable product recovery to reduce its environmental burden and ascribe value to it. The study might help researchers and policy makers to develop suitable strategies for the microbiological treatment of high organic load and color-containing wastewater generated from various industries along with resource recovery, a beneficial step in the direction of sustainable development and circular economy.

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As the demand for metal resources increases and the quality and availability of rich ore resources decline, the focus is shifting to low-cost, eco-friendly bioleaching technologies that can effectively utilize low-grade minerals. The stress on bioleaching microorganisms due to high concentrations of metal ions in the bioleaching system is one of the most important factors limiting the effectiveness of bioleaching. Using the common copper-bearing ore bioleaching process as an example, the copper ion concentration reached 6 g/L. An in-depth examination of the copper defensive mechanism of bioleaching microorganisms will help elucidate the physiological mechanism of such extremophiles and pave the way for future genetically engineered highly efficient strains. We elaborate on the copper tolerance mechanism of extremophiles through the lens of biofilms, cell membranes, metal transport mechanisms, intracellular buffer mechanisms, and energy metabolism.

The transition of the mineral processing sectors, which depend mainly on various petroleum-origin chemicals, to the green industry based on the production of greener materials and the reduction of carbon footprints, is mandatory due to the growing concerns regarding the extensive environmental impact of the mining industry. In this context, biological ore beneficiation is spurring increasing interest from scientists and industrials. The latest scientific developments in bio-metallurgy have allowed it to exploit biotechnologies in the flotation process as a novel/cleaner approach for separating gangue materials from valuables minerals. Current fundamental research projects have focused on the progress of biotechnology and the employment of biopolymers, microorganisms, and their metabolites, as well as plant-derived biosurfactants in the emerging field of bioprocessing, particularly bioflotation. Almost all studies on flotation have focused on chemical and physical parameters, and the role of natural biosurfactants remains little explored. This review presents a thorough understanding of the bioflotation concept by assessing previous research on several elements of bioflotation, including the impacts of biotechnology and operating factors (pH, biomass, and biosurfactants concentration), probable mechanisms, and unexplored areas, but from various pragmatic viewpoints. Recent studies are summarized by categorizing microorganisms, plants, and biopolymers based on their bioflotation performances. Furthermore, the most recent research investigations on biological flotation of specific minerals (salt-type sulphide and oxide) are reviewed. Finally, critical challenges of bioflotation are discussed, and novel perspectives are provided to contribute to solving the difficulties faced in its implementation.

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Aerobic hydrogen-oxidizing bacteria (HOB) is a group of active, abundant, and diverse microorganisms with representatives in nearly all phyla, distributed in soil exposed to atmospheric or elevated hydrogen. In this review, first, we discuss the fundamental physiology, isolation, and identification techniques for HOB. On this basis, the hydrogenase genetic organization and metabolic strategy of Cupriavidus necator, Mycobacterium smegmatis as representative HOB are summarized. Availability of hydrogen, oxygen, nutrients, and environmental variables such as temperature and moisture are key ecological factors influencing H₂ oxidation activity, hydrogenase groups, and microbial composition. Finally, we systematically illustrate the ecological roles of HOB and the interactions between HOB and other soil microbiota, particularly rhizobia in agricultural soils and Cyanobacteria in deserts. Intensive studies should focus on the cell functioning regulated by hydrogenases and on the full play of ecological roles by competitive HOB consortiums in soil niches, which is expected to facilitate the biogeochemical process of carbon dioxide fixation and energy utilization.

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The use of chemicals by society has resulted in calls for more effective control of their emissions. Many of these chemicals are poorly characterized because of lacking data on their use, environmental fate and toxicity, as well as lacking detection techniques. These compounds are sometimes referred to as contaminants of emerging concern (CECs). Urban areas are an important source of CECs, where these are typically first collected in sewer systems and then discharged into the environment after being treated in a wastewater treatment plant. A combination of emission estimation techniques and environmental fate models can support the early identification and management of CEC-related environmental problems. However, scientific insight in the processes driving the fate of CECs in sewer systems is limited and scattered. Biotransformation, sorption and ion-trapping can decrease CEC loads, whereas enzymatic deconjugation of conjugated metabolites can increase CEC loads as metabolites are back-transformed into their parent respective compounds. These fate processes need to be considered when estimating CEC emissions. This literature review collates the fragmented knowledge and data on in-sewer fate of CECs to develop practical guidelines for water managers on how to deal with in-sewer fate of CECs and highlights future research needs. It was assessed to what extent empirical data is in-line with text-book knowledge and integrated sewer modelling approaches. Experimental half-lives (n = 277) of 96 organic CECs were collected from literature. The findings of this literature review can be used to support environmental modelling efforts and to optimize monitoring campaigns, including field studies in the context of wastewater-based epidemiology.

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Pesticides can impact the agriculture and environmental sector both positively and negatively. An over-reliance on their application to crops to control pests can disturb ecosystems. Therefore, the scientific community and policymakers must be aware of the commitment and active stance they need to take up to effectively elaborate on solutions toward mitigating environmental contamination over the coming few years. We, therefore, reviewed the academic literature on bioremediation from 2018 to 2021 (the latest year of complete publication) to provide a meta-analysis of microbial systems capable of dissipating pesticides from agricultural soils. Natural attenuation can control lindane; however, it is time-consuming and unconvincing to scale. By introducing a suite of microorganisms into the system for substrate-specific biodegradation, we can boost the bioprocess and ultimately level up its cost-effectiveness. Options of microorganisms for bioaugmentation include the fungus Trametes versicolor and the bacteria Pigmentiphaga spp. and Paenanthrobacter spp. Bioaugmentation and biostimulation are enablers of environmental reclamation in agroecosystems. However, those biocatalytic strategies can be costly while manifesting as degraders to ecological sustainability. For instance, allochthonous and recombinant microorganisms can reduce genetic diversity by promoting antagonistic relationships. In addition, some stimulant minerals can be more toxic and harmful to beneficial non-target organisms than the target pesticide. Prudence and safety are significant aspects of ensuring environmentally safer applications for pesticide-degrading approaches. Therefore, our analytical insights can provide knowledge to progress the field’s prominence in developing high-throughput microbiological removal of hazardous active compounds from agricultural soils.

Large-scale production of single-cell protein (SCP) has the potential not only to solve some of the food insecurity and water scarcity crises that plague a significant portion of our world today but also holds the promise to reduce the cost associated with the treatment of industrial and agricultural wastewater. Resource recovery of SCP from organic waste by microbes like yeast and microalgae is commonly documented. However, recently, a class of phototrophic bacteria, purple non-sulphur bacteria (PNSB), has emerged as a favourable option in terms of both wastewater treatment and resource recovery. PNSB are metabolically versatile and tolerant to a wide range of conditions, hence their ability to thrive in diverse waste streams. Besides its rich protein content, PNSB contains other nutritionally valuable bioproducts like carotenoids, coenzyme Q10, 5-aminolevulinic acid, and pantothenic acid. Recent evidence also indicates that PNSB-based aquafeed enhances growth and boosts immunity in certain aquaculture trials. It does not possess the same toxicity as most gram-negative bacteria due to its comparatively less potent lipopolysaccharide composition. With diverse promising prospects of PNSB-based SCP, it is critical to extensively examine the landscape from a holistic standpoint, highlighting the potential challenges large-scale SCP production may pose. Thus, this review explores the comparative advantages of utilizing PNSB for SCP production, essential components of PNSB-based SCP processing, and possible environmental and economic gains associated with the process. Current challenges with PNSB-based SCP production and future outlooks are also examined.

Nitrification is an intermediary reaction common to various processes applied to treat nitrogen-containing wastewaters. The genus Nitrospira is the most diverse among nitrifying microorganisms and of significant importance in nitrification in natural and engineered environments. These microorganisms are versatile, and niche differentiation has been observed even at the same lineage level. In general, bacteria of the genus Nitrospira can adapt to a wide range of conditions such as substrate concentrations, dissolved oxygen, and temperature. However, environmental and operating factors governing the presence and abundance of these organisms in different habitats are still not completely understood. Nitrite-oxidizing bacteria and complete ammonia oxidizers (comammox) of the genus Nitrospira are the nitrifying organisms frequently predominant in wastewater treatment plants. Nitrospira may also be associated with opportunities for wastewater treatment such as bioprocesses that consume less energy for aeration and produce a smaller volume of pollutant gases during nitrification. Nevertheless, the genus Nitrospira has not yet been completely characterized, and very few isolates have been obtained, making it difficult to investigate their unique metabolism for wastewater treatment. Therefore, to fill knowledge gaps and improve the understanding of the ecophysiology and importance of Nitrospira, it is crucial to develop an integrated strategy for the cultivation, identification, and characterization of these microorganisms. Thus, this review aims to identify some research gaps on Nitrospira and highlight the importance of this genus in the treatment of nitrogen-containing wastewater, as well as the interfering factors associated with niche differentiation and methods currently used to investigate these microorganisms.

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