Research on spatial and temporal differences of carbon emissions and influencing factors in eight economic regions of China based on LMDI model.

With the gradual increase of international willingness to reach the carbon peak and carbon neutrality, this paper decomposes the influencing factors of China's carbon emission changes from 2008 to 2019 using the Logarithmic Mean Divisia Index model (LMDI), and analyzes the contribution amount and rate of each influencing factor. The results found that: for the whole country, the cumulative growth of carbon emissions during the study period is about 416,484.47 (104 tons), among which the economic growth effect plays a major role in promoting, with a cumulative contribution rate of 284.16%; The increase in regulation intensity and the optimization of industrial structure, however, suppress carbon emissions well, with a cumulative contribution rate of about - 199.21% and - 64.75%, respectively, during the study period. For economic regions, the cumulative influence direction of each driver is the same as that of the whole country, while the population size effect in the northeast economic region and the regulation input effect in the eastern coastal economic region act in the opposite direction from other economic regions, and the carbon emission reduction direction of the energy intensity effect varies from one economic region to another. Accordingly, this paper proposes policy recommendations to enhance regulatory intensity, optimize industrial and energy consumption structure, implement localized emission reduction strategies, and promote synergistic emission reduction in economic zones.

The impact of Water Ecological Civilization City Pilot on urban green innovation: the case of China.

As an essential part of ecological civilization, water ecological civilization has significant influence on the green and sustainable development of cities. Under the background of China's Water Ecological Civilization City Pilot (WECCP), based on data from 275 cities in China from 2007 to 2019 by using the difference-in-differences (DID) model, we empirically analyzed the influence of the WECCP establishment on urban green innovation and explored the impact mechanism in depth using a mediating effect model, which aimed to verify whether the "Porter hypothesis" holds true in China. The result indicated that the WECCP had made a remarkable contribution to enhancing urban green innovation in the pilot cities. Further research found that the input mechanism played an important mediating role. In addition, the heterogeneity test indicated that cities in the central region, at low administrative levels, and in the first batch of pilots gained more from the policy establishment. This paper has theoretical implications for understanding the derived innovation benefits of the environmental policy, practical implications for identifying new drivers of urban innovation, and provides related experience for the country to further promote and expand water ecological civilization construction and useful policy inspiration for other developing countries to formulate ecological and environmental policies.

Study on the measurement of industrial eco-efficiency, spatial distribution and influencing factors in Yangtze River Economic Belt.

Nowadays, China insists on the strategy of ecological priority and green development, and the Yangtze River Economic Belt is a pioneering demonstration belt for the construction of ecological civilization in China. Promoting industrial ecological efficiency is of great significance to Chinese sustainable development and high-quality economic development. Based on the provincial panel data of 11 provinces and cities in the Yangtze River Economic Belt region from 2011 to 2020, we use the super-efficient slacks-based measure of efficiency SBM model to measure the industrial eco-efficiency of the Yangtze River Economic Belt, reveal the spatial differences in industrial eco-efficiency of different provincial units, and explore the industrial eco-efficiency. The results show that: (1) from the perspective of the Yangtze River Economic Belt as a whole, industrial eco-efficiency is on a stable upward trend, but the efficiency level is not high, and there is more room for improvement; (2) in terms of the spatial distribution of industrial eco-efficiency in the Yangtze River Economic Belt, there are significant differences, with industrial eco-efficiency in the downstream region being higher than that in the midstream region and the upstream region, and the lowest in the midstream region, while in terms of the spatial distribution pattern, the industrial eco-efficiency of 11 provinces and cities in the Yangtze River Economic Belt eco-efficiency has a significant positive spatial autocorrelation; (3) in terms of influencing factors, economic development level, factor endowment, and foreign investment can significantly influence industrial eco-efficiency in the Yangtze River Economic Belt. The study's result helps provide theoretical guidance and practical reference for promoting the green and ecological development of industries in the Yangtze River Economic Belt.

Threshold Effect of Environmental Regulation and Green Innovation Efficiency: From the Perspective of Chinese Fiscal Decentralization and Environmental Protection Inputs.

In the context of China's 14th Five-Year Plan and 2035 visionary goals of national economic and social development, to achieve the national dual carbon goals, an innovation-driven green development strategy must be implemented, and the relationship between environmental regulation and green innovation efficiency must be clarified. Based on the DEA-SBM model, in this study, we measured the green innovation efficiency of 30 provinces and cities in China from 2011 to 2020 by introducing environmental regulation as the core explanatory variable, and two threshold variables, environmental protection input and fiscal decentralization, to empirically analyze the threshold effect of environmental regulation on green innovation efficiency. We found that: (1) The green innovation efficiency of 30 provinces and municipalities in China is spatially distributed as strong in the east and weak in the west. (2) A double-threshold effect exists with environmental protection input as the threshold variable. Environmental regulation showed an inverted N-shaped relationship of first inhibiting, then promoting, and finally inhibiting green innovation efficiency. (3) A double-threshold effect exists with fiscal decentralization as the threshold variable. Environmental regulation showed an inverted N-shaped relationship of inhibiting, promoting, and then inhibiting green innovation efficiency. The study results provide theoretical guidance and practical reference for China to achieve the dual carbon goal.

Transcriptome analysis of genes and metabolic pathways associated with nicotine degradation in Aspergillus oryzae 112822.

BACKGROUND: Nicotine-degrading microorganisms (NDMs) have recently received much attention since they can consume nicotine as carbon and nitrogen source for growth. In our previous work, we isolated an efficient nicotine-degrading fungus Aspergillus oryzae 112822 and first proposed a novel demethylation pathway of nicotine degradation in fungi. However, the underlying mechanisms of the demethylation pathway remain unresolved. In the present study, we performed a comparative transcriptome analysis to elucidate the molecular mechanisms of nicotine tolerance and degradation in A. oryzae 112822. RESULTS: We acquired a global view of the transcriptional regulation of A. oryzae 112822 exposed to nicotine and identified 4381 differentially expressed genes (DEGs) by nicotine treatment. Candidate genes encoding cytochrome P450 monooxygenases (CYPs), FAD-containing amine oxidase, molybdenum cofactor (Moco)-containing hydroxylase, and NADH-dependent and FAD-containing hydroxylase were proposed to participate in the demethylation pathway of nicotine degradation. Analysis of these data also revealed that increased energy was invested to drive nicotine detoxification. Nicotine treatment led to overproduction of reactive oxygen species (ROS), which formed intracellular oxidative stress that could induce the expression of several antioxidant enzymes, such as superoxide dismutase (SOD), catalase (CAT), and peroxiredoxin (Prx). Thioredoxin system was induced to restore the intracellular redox homeostasis. Several glutathione S-transferases (GSTs) were induced, most likely to participate in phase II detoxification of nicotine by catalyzing the conjugation of glutathione (GSH) to active metabolites. The toxin efflux pumps, such as the ATP-Binding Cassette (ABC) transporters and the major facilitator superfamily (MFS) transporters, were overexpressed to overcome the intracellular toxin accumulation. By contrast, the metabolic pathways related to cellular growth and reproduction, such as ribosome biogenesis and DNA replication, were inhibited by nicotine treatment. CONCLUSION: These results revealed that complex regulation networks, involving detoxification, transport, and oxidative stress response accompanied by increased energy investment, were developed for nicotine tolerance and degradation in A. oryzae 112822. This work provided the first insight into the metabolic regulation of nicotine degradation and laid the foundation for further revealing the molecular mechanisms of the nicotine demethylation pathway in filamentous fungi.

Rational designed mutagenesis of levansucrase from Bacillus licheniformis 8-37-0-1 for product specificity study.

Levansucrases, which belong to the glycoside hydrolase family 68 (GH68), synthesize ß (2-6)-linked fructan levan with sucrose as substrate. We described the use of a levansucrase (Bl_SacB) from Bacillus licheniformis 8-37-0-1 for catalysis of fructosyl transfer to obtain high levan yield previously. In the present study, six variants (Y246A, N251A, K372A, R369A, R369S, and R369K) were constructed through sequence alignment and structural analysis to explore the synthesis mechanism of Bl_SacB. The selected residues were predicted to localize to the substrate-entering channel of the active cavity and close to or remote from the catalytic triad. The products of these variants ranged from homopolymers levan to fructo-oligosaccharides (FOSs). The primary FOSs were identified through MS and NMR analyses as neolevan-type neokestose [ß-D-Fru-(2-6)-α-D-Glc-(1-2)-ß-D-Fru], levan-type 6-kestose [ß-D-Fru-(2-6)-ß-D-Fru-(2-1)-α-D-Glc], and inulin-type 1-kestose [ß-D-Fru-(2-1)-ß-D-Fru-(2-1)-α-D-Glc]. The mutation at Tyr246 located remote from the catalytic triad led to the production of short-chain oligosaccharides with degree of polymerization (DP) of up to 25. The replaced Arg369 located close to the catalytic triad resulted in either elimination of polysaccharide synthesis or complete change in the dominant linkage of the products. The Michaelis constants (Km) of Y246A, N251A, K372A, and R369K were found to be similar to that of the wild type (WT). However, the turnover number (kcat) and the value of transfructosylation versus hydrolysis activity of the six variants decreased compared with those of the WT. Hence, the residues located on the surface of the substrate-entering channel of Bl_SacB can be critical in product linkage type and/or elongation mechanism.

Molecular cloning and functional analysis of squalene synthase (SS) in Panax notoginseng.

Panax notoginseng (Burk.) F. H. Chen, which is a used traditional Chinese medicine known as Sanqi or Tianqi in China, is widely studied for its ability to accumulate the triterpene saponins. Squalene synthase (SS: EC 2.5.1.21) catalyzes the first enzymatic step from the central isoprenoid pathway toward sterol and triterpenoid biosynthesis. In this study, SS from P. notoginseng was cloned and investigated followed by its recombinant expression and preliminary enzyme activity. The nucleotide sequence of the ORF contains 1 248 nucleotides and encodes 415 amino acid residues with molecular weight of 47.16kDa and pI of 6.50. Bioinformatics analysis revealed that the deduced PnSS protein had a high similarity with other plant squalene synthases. To obtain soluble recombinant enzymes, 29 hydrophobic amino acids were deleted from the carboxy terminus and expressed as GST-Tag fusion protein in Escherichia coli BL21 (DE3). Approximately 66.46kDa recombinant protein was checked on SDS-PAGE and Western Blot analysis. Preliminary activity of the resultant bacterial crude extract was analyzed by gas chromatograph-mass spectrometer (GC-MS). The identification and function of PnSS is important for further studies of the triterpene saponins biosynthesis in P. notoginseng.