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Abstract Terrestrial hydrological and nutrient cycles are subjected to major disturbances by agricultural operations and urbanization that profoundly influence freshwater resources. Non‐point source pollution is one of the primary causes for water quality deterioration, and thus an emerging imperative in limnology is establishing empirical models that connect watershed attributes and hydrological drivers with lake nutrient dynamics. Here, we compiled three nation‐wide nutrient, meteorological, and watershed‐landscape data sets, to develop Generalized Linear Models that predict lake phosphorus and nitrogen concentrations as a function of the surrounding watershed characteristics within various hydrological distances across 104 Chinese lakes and reservoirs. Our national‐scale investigation revealed that lake nutrient concentrations can be satisfactorily predicted by proxies of natural drivers and anthropogenic activities, reflecting the properties of the surrounding watershed. Counter to previous studies, we found that China's lake nutrient concentrations strongly depend on watershed characteristics within a hydrological distance of less than 45 km rather than the entire watershed. Furthermore, extensive human activities in watersheds not only compromise our predictive capacity, but also increase the hydrological distance that is relevant to predict lake nutrients. This national‐scale characterization can inform one of the most contentious issues in the context of China's lake management, that is, the determination of the extent of the nearshore area, where nutrient control should be prioritized. As far as we know, our study represents the first attempt to apply the concept of hydrological distance and establish statistical models that can delineate the critical spatial domain primarily responsible for the nutrient conditions along the watershed‐lake continuum.

Childhood obesity presents a serious health concern associated with gut microbiota alterations. Dietary interventions targeting the gut microbiota have emerged as promising strategies for managing obesity in children. This study aimed to elucidate the impact of stachyose (STS) supplementation on the gut microbiota composition and metabolic processes in obese children. Fecal samples were collected from 40 obese children (20 boys and 20 girls) aged between 6 and 15 and in vitro fermentation was conducted with or without the addition of STS, respectively, followed by 16S rRNA amplicon sequencing and analysis of short-chain fatty acids (SCFAs) and gases. Notably, our results revealed that STS supplementation led to significant alterations in gut microbiota composition, including an increase in the abundance of beneficial bacteria such as Bifidobacterium and Faecalibacterium, and a decrease in harmful bacteria including Escherichia-Shigella, Parabacteroides, Eggerthella, and Flavonifractor. Moreover, STS supplementation resulted in changes in SCFAs production, with significant increases in acetate levels and reductions in propionate and propionate, while simultaneously reducing the generation of gases such as H2S, H2, and NH3. The Area Under the Curve (AUC)-Random Forest algorithm and PICRUSt 2 were employed to identify valuable biomarkers and predict associations between the gut microbiota, metabolites, and metabolic pathways. The results not only contribute to the elucidation of STS’s modulatory effects on gut microbiota but also underscore its potential in shaping metabolic activities within the gastrointestinal environment. Furthermore, our study underscores the significance of personalized nutrition interventions, particularly utilizing STS supplementation, in the management of childhood obesity through targeted modulation of gut microbial ecology and metabolic function.

Drinking water is closely related to human health, disease and mortality, and contaminated drinking water causes 485,000 deaths from diarrhea each year worldwide. China has been facing increasingly severe water scarcity due to both water shortages and poor water quality. Ensuring safe and clean drinking water is a great challenge and top priority, especially for China with 1.4 billion people. In China, more than 4000 centralized drinking water sources including rivers, lakes and reservoirs, and groundwater have been established to serve urban residents. However, there is little knowledge on the percentage, serving population and water quality of three centralized drinking water source types. We collected nationwide centralized drinking water sources data and serving population data covering 395 prefecture-level and county-level cities and water quality data in the two most populous provinces (Guangdong and Shandong) to examine their contribution and importance. Geographically, the drinking water source types can be classified into three clear regions exhibiting apparent differences in the respective contributions of rivers, lakes and reservoirs, and groundwater. We further found that overall, lakes and reservoirs account for 40.6% of the centralized drinking water sources vs. river (30.8%) and groundwater (28.6%) in China. Lakes and reservoirs are particularly important in the densely populated eastern region, where they are used as drinking water sources by 51.0% of the population (318 million). Moreover, the contribution to the drinking water supply from lakes and reservoirs is increasing due to their better water quality and many cross-regional water transfer projects. These results will be useful for the government to improve and optimize the establishment of centralized drinking water sources, which provide safe and clean drinking water in China to safeguard people's lives and health and realize sustainable development goals.

IntroductionFlavonoids have antiviral, antitumor, anti-inflammatory, and other biological activities. They have high market value and are widely used in food and medicine fields. They also can regulate gut microbiota and promote human health. However, only a few flavonoids have been reported for their regulatory effects on human gut microbiota.MethodsThe effects of hesperidin, hesperetin-7-O-glucoside, hesperetin, naringin, prunin, naringenin, rutin, isoquercitrin, and quercetin on gut microbiota structural and metabolic differences in healthy subjects were studied by means of in vitro simulated fermentation technology.ResultsResults showed that the nine kinds of flavonoids mentioned above, especially hesperetin-7-O-glucoside, prunin, and isoquercitrin, were found to have more effect on the structure of human gut microbiota, and they could significantly enhance Bifidobacterium (p

d-pantolactone is an intermediate in the synthesis of d-pantothenic acid, which is known as vitamin B5. The commercial synthesis of d-pantolactone is carried out through the selective resolution of dl-pantolactone catalyzed by lactone hydrolase. In contrast to a kinetic resolution approach, the deracemization of dl-pantolactone is a simpler, greener, and more sustainable way to obtain d-pantolactone with high optical purity. Herein, an efficient three-enzyme cascade was developed for the deracemization of dl-pantolactone, using l-pantolactone dehydrogenase from Amycolatopsis methanolica (AmeLPLDH), conjugated polyketone reductase from Zygosaccharomyces parabailii (ZpaCPR), and glucose dehydrogenase from Bacillus subtilis (BsGDH). The AmeLPLDH was used to catalyze the dehydrogenated l-pantolactone into ketopantolactone; the ZpaCPR was used to further catalyze the ketopantolactone into d-pantolactone; and glucose dehydrogenase together with glucose fulfilled the function of coenzyme regeneration. All three enzymes were co-expressed in E. coli strain BL21(DE3), which served as the whole-cell biocatalyst. Under optimized conditions, 36 h deracemization of 1.25 M dl-pantolactone d-pantolactone led to an e.e.p value of 98.6%, corresponding to productivity of 107.7 g/(l·d).

Glycolate oxidase is a peroxisomal flavoprotein catalyzing the oxidation of glycolate to glyoxylate and plays crucial metabolic roles in green algae, plants, and animals. It could serve as a biocatalyst for enzymatic production of glyoxylate, a fine chemical with a wide variety of applications in perfumery, flavor, and the pharmaceutical and agrochemical industries. However, the low catalytic activity of native glycolate oxidase and low levels of active enzyme in heterologous expression limit its practical use in industrial biocatalysis. Herein, the glycolate oxidase from Chlamydomonas reinhardtii (CreGO) was selected through phylogenetic tree analysis, and its low level of soluble expression in E. coli BL21(DE3) was improved through the use of the glutathione thioltransferase (GST), the choice of the vector pET22b and the optimization of induction conditions. The semi-rational design of the fusion enzyme GST-Gly-Ser-Gly-CreGO led to the superior variant GST-Gly-Ser-Gly-CreGO-Y27S/V111G/V212R with the kcat/Km value of 29.2 s−1·mM−1, which was six times higher than that of the wild type. In contrast to GST-Gly-Ser-Gly-CreGO, 5 mg/mL of crude enzyme GST-Gly-Ser-Gly-CreGO-Y27S/V111G/V212R together with 25 μg/mL of catalase catalyzed the oxidation of 300 mM of methyl glycolate for 8 h, increasing the yield from 50.4 to 93.5%.

Pyruvic acid has numerous applications in the food, chemical, and pharmaceutical industries. The high costs of chemical synthesis have prevented the extensive use of pyruvate for many applications. Metabolic engineering and traditional strategies for mutation and selection have been applied to microorganisms to enhance their ability to produce pyruvate. In the past decades, different microbial strains were generated to enhance their pyruvate production capability. In addition to the development of genetic engineering and metabolic engineering in recent years, the metabolic transformation of wild-type yeast, E. coli, and so on to produce high-yielding pyruvate strains has become a hot spot. The strategy and the understanding of the central metabolism directly related to pyruvate production could provide valuable information for improvements in fermentation products. One of the goals of this review was to collect information regarding metabolically engineered strains and the microbial fermentation processes used to produce pyruvate in high yield and productivity.

When a train enters a tunnel, the passengers in the train will feel tinnitus. The main reason is that the pressure in the tunnel enters the vehicle through the adjusting system of the train, which will cause discomfort to the passengers. In this paper, according to the quasi-periodicity and repeatability of mass data in the process of train running in tunnels, a control method based on the IOTs big data is proposed, and an adaptive iterative learning control algorithm based on the IOTs big data is established. The fan operation frequency of ventilation system is regulated by adaptive iterative learning control algorithm, and can adjust the new air and exhaust gas of the ventilation system in real time to restrain the pressure fluctuation in the train. Finally, the simulation results show that the adaptive iterative learning control algorithm based on the Internet of Things can significantly reduce the amplitude of pressure fluctuation in the tunnel and the change rate of the ventilator, and improve the passenger comfort program. Moreover, the real-time measured data also show that the proposed closed-loop adaptive iterative learning control algorithm based on the Internet of Things is obviously superior to active control.

China has made considerable efforts to mitigate the pollution of lakes over the past decade, but the success rate of these restoration actions at a national scale remains unclear. The present study compiled a 13-year (2005–2017) comprehensive dataset consisting of 24,319 records from China's 142 lakes and reservoirs. We developed a novel Water Quality Index (WQI-DET), customized to China's water quality classification scheme, to investigate the spatio-temporal pollution patterns. The likelihood of regime shifts during our study period is examined with a sequential algorithm. Our analysis suggests that China's lake water quality has improved and is also characterized by two WQI-DET abrupt shifts in 2007 and 2010. However, we also found that the eutrophication problems have not been eradicated and heavy metal (HM) pollution displayed an increasing trend. Our study suggests that the control of Cr, Cd and As should receive particular attention in an effort to alleviate the severity of HM pollution. Priority strategies to control HM pollution include the reduction of the contribution from mining activities and implementation of soil remediation in highly polluted areas. The mitigation efforts of lake eutrophication are more complicated due to the increasing importance of internal nutrient loading that can profoundly modulate the magnitude and timing of system response to external nutrient loading reduction strategies. We also contend that the development of a rigorous framework to quantify the socioeconomic benefits from well-functioning lake and reservoir ecosystems is critically important to gain leeway and keep the investments to the environment going, especially if the water quality improvements in many Chinese lakes and reservoirs are not realized in a timely manner. Keywords: Lakes, Restoration, Pollution, Eutrophication, Heavy metals

Chitin, the second richest polymer in nature, is composed of the monomer N-acetylglucosamine (GlcNAc), which has numerous functions and is widely applied in the medical, food, and chemical industries. However, due to the highly crystalline configuration and low accessibility in water of the chitin resources, such as shrimp and crab shells, the chitin is difficult utilize, and the traditional chemical method causes serious environment pollution and a waste of resources. In the present study, three genes encoding chitinolytic enzymes, including the N-acetylglucosaminidase from Ostrinia furnacalis (OfHex1), endo-chitinase from Trichoderma viride (TvChi1), and multifunctional chitinase from Chitinolyticbacter meiyuanensis (CmChi1), were expressed in the Pichia pastoris system, and the positive transformants with multiple copies were isolated by the PTVA (post-transformational vector amplification) method, respectively. The three recombinants OfHex1, TvChi1, and CmChi1 were induced by methanol and purified by the chitin affinity adsorption method. The purified recombinants OfHex1 and TvChi1 were characterized, and they were further used together for degrading chitin from shrimp and crab shells to produce GlcNAc through liquid-assisted grinding (LAG) under a water-less condition. The substrate chitin concentration reached up to 300 g/L, and the highest yield of the product GlcNAc reached up to 61.3 g/L using the mechano-enzymatic method. A yield rate of up to 102.2 g GlcNAc per 1 g enzyme was obtained.

Abstract In this paper, a novel method of image extraction is proposed. Firstly, the image information is embedded into the parameters of the chaotic system, and then the image is overlapped and embedded to complete the image hiding. This process is equivalent to a dynamic system with unknown time-varying parameters. Secondly, the D-type iterative learning control algorithm is used to extract the information hidden in the image, because iterative learning can be used to estimate the time-varying parameter system completely in the time interval. Finally, the numerical simulation shows that the algorithm can effectively extract the hidden information under various attacks.

China is facing severe acid deposition. Acid deposition can cause economic loss, corrosion, and damage to materials, and the reduction of material life span. In this study, the administrative areas (including municipalities, prefecture-level cities, regions, autonomous prefectures, and leagues--hereinafter referred to the cities) at and above the prefecture level were selected as research areas. Monitoring results of acid precipitation and ambient air sulfur dioxide (SO2) from the China National Environmental Monitoring Network were used, research findings available domestically and abroad were summarized, and a set of material exposure inventory per capita was established, based on urban and rural areas in Eastern, Central, and Western China regions. Losses of construction materials caused by acid deposition in the cities were assessed by using the said materials' acid rain exposure response functions available. The results showed that, material loss caused by acid deposition in China was 32.165 billion yuan (RMB, similarly hereinafter) in 2013, accounting for 0.057% of GDP (Gross Domestic Product) and 3.4% of the total investment for environmental pollution governance this year. [ABSTRACT FROM AUTHOR]

Abstract  An amine:hydroxyacetone aminotransferase from an isolated soil bacterium, Moraxella lacunata WZ34, was employed to synthesize alaninol in the presence of hydroxyacetone and isopropylamine in this study. The optimal carbon and nitrogen sources were glycerol and beef extract, respectively. A wide range of amino donor specificity was detected with the aminotransferase, which exhibited a relative high activity (9.83 U mL−1) in the presence of isopropylamine. The enzyme was the most active at pH 8.5, and showed relatively higher activity at alkaline than acidic pH. Maximum activity was achieved at 30 °C, and the enzyme had good thermal stability below 60 °C. Metal ions such as Mg2+ had positive effect (132.6%) on the enzyme, and (aminooxy)acetic acid, a typical aminotransferase inhibitor, significantly inhibited its activity. The enzyme activity was enhanced by the addition of 0.05 mM pyridoxal-5′-phosphate (PLP). [ABSTRACT FROM AUTHOR]