Search

The use of organochlorine and organophosphorus pesticides has been prohibited due to their highly toxicity. In recent years, pyrethroids (PYRs) have been widely used in agricultural production and the environment due to their high efficiency and stability, but the residual hazards caused by their frequent use have become increasingly prominent. 3-Phenoxybenzoic acid (3-PBA) is one of the major metabolites of PYRs, which is an environmental estrogen with great potential harms. Pesticide residues have seriously affected people’s production and life, which has attracted extensive attention from researchers. PYRs and 3-PBA degrading bacteria have been widely reported, and microbial and enzymatic degradation is recognized as an effective method for reducing or removing pesticide residues from agricultural products and the environment. The continuous development of genetic engineering and molecular biology technology provides a new way to explore methods for reducing pesticide residues. In this article, we summarize the basic properties and residual hazards of PYRs and 3-PBA, and we review the current status of PYRs residues in agricultural products and the environment as well as recent progress in research on the modes of microbial metabolism and the mechanisms of microbial adsorption and degradation of PYRs. Moreover, we give an outlook on enzymes degrading PYRs and their genetic engineering in order to provide a reference for solving the problem of pesticide residues in agricultural products and the environment.

ObjectiveTo establish a culture-dependent rapid detection method for gas-producing spoilage bacteria in vinegar.MethodsOne kind of medium was screened out from six candidate media and modified. Then its specificity， accuracy， and sensitivity were determined， on which a detection method was proposed. This method was subsequently applied to assess heat sterilization conditions and preservative concentrations for vinegar products and to verify the detection effectiveness of vinegar products.ResultsA modified MRS medium that could specifically detect gas-producing spoilage bacteria in vinegar samples was proposed， with which negative results were obtained targeting at other 12 spoilage bacteria isolated from vinegar. The established method was adopted to examine 75 unknown vinegar samples and plastic bottle incubation method was used as control. Consistent results were obtained using both methods， however the detection rate of established method was 3-5 times faster than control， with a detection limit （initial bacterial count） ranging from 1 CFU to 10 CFU. The larger bacterial load is， the shorter detection time would be. And it will take only 1-2 d for high-contamination vinegar samples. Results also showed that sterilization at 75-85 ℃ for 5-15 min could effectively kill the gas-producing spoilage bacteria that is recalcitrant to common preservatives within their maximum allowable concentrations. The verification was in agreement with the actual situation.ConclusionThe constructed method features fast， specific， accurate， and sensitive. This study sheds light on detection and comprehensive control of gas-producing spoilage bacteria for vinegar enterprises.

Phenolic acid decarboxylase (PAD) (lyase, EC 4.1.1.102) catalyzes the conversion of phenolic acids such as coumaric acid, ferulic acid, caffeic acid, and glucosic acid that are widely distributed in plants into 4-vinyl derivatives. 4-Vinyl derivatives are not only high-grade fragrances, but also key precursors for the synthesis of other spices such as vanillin. Food spices are mainly chemically synthesized in the current market. By contrast, the biosynthesis method, which is characterized by single precursor substances, mild conditions and environmental friendliness, has broad application prospects, and biosynthesized spices are regarded as being equivalent to natural products. Therefore, using PAD for the biosynthesis of 4-vinyl derivatives is of great significance to supplementing the production pathway of this type of fragrance. In this article, PAD derived from microorganisms are summarized from five aspects: origins, molecular structure, catalytic mechanism and structure-function correlation, catalytic properties, and techniques to improve the catalytic efficiency.

To select high-efficiency strains suitable for semi-dry black douchi fermentation, this study compared and analyzed the koji-making effects of six Aspergillus oryzae strains and one Lichtheimia corymbifera strain with large differences in enzyme-producing capacity. The results showed that A. oryzae HN3.042, DM1 and DM2 had a strong ability to metabolize amylase, and the fermented douchi had a lower L* value. A. oryzae 24M-1, 30M-1, and PNM003 had a strong ability to produce protease, aminopeptidase, and carboxypeptidase, resulting in greater utilization of protein substrates and higher contents of total acid and amino nitrogen in the fermented douchi. In terms of volatile flavor substances, the douchi fermented with stains HN3.042, DM1, and DM2 had a relatively higher content of 1-octen-3-ol, isovaleric acid, and 4-methylpentanoic acid. The douchi fermented with strains 24M-1, 30M-1, and PNM003 had a relatively higher content of trans-2-nonenal, 3-octanone, and isophorone, resulting in richer and better flavor quality. L. corymbifera QM3 had lower enzymatic activity when compared with A. oryzae, resulting in poorer physicochemical indicators, lower contents of free amino acids and volatile flavor substances and poorer quality in douchi. The study suggests that the quality of douchi is related to the enzyme-producing capacity of the koji mold. The predominance of amylase in the koji enzyme system is conducive to the formation of color and acidic flavor substances in douchi, while with the predominance of proteolytic enzymes is conducive to the formation of amino nitrogen and good flavor quality in douchi.

Pyrethroids (PYRs) are widely used as pesticides due to low toxicity and high efficacy; however, PYRs residues have caused increasingly serious environmental and food safety problems. 3-Phenoxybenzoic acid (3-PBA), one of the major intermediate degradation products of PYRs, is more stable and toxic than the parent pesticides, and its residue can further aggravate environmental and agricultural product pollution. In recent years, filamentous fungal degradation of PYRs and 3-PBA has been reported, and research on this topic mainly focuses on strain screening, degradation characteristics, degradation pathways and localization of degradation enzymes. Unfortunately, key enzymes and their encoding genes involved in the degradation process are rarely reported. With the development of sequencing technology, molecular biology technology has provided a new strategy to mine PYR-degrading enzymes and their encoding genes in filamentous fungi. In this article, the basic properties, residues status and hazards of PYRs and 3-PBA are described. The filamentous fungi capable of degrading PYRs and 3-PBA, and their degradation pathways and degrading enzymes are reviewed. In addition, future prospects for the development of methods for screening and verification of degrading enzymes and their encoding genes are discussed. We expect that this review will provide a theoretical basis for understanding the degradation pathways and mechanisms of PYRs and 3-PBA by filamentous fungi and provide a reference for reducing residual pesticides in the environment and agricultural products.

China is a big producer and consumer of grains and oils. The development of high-yield grains is closely related to chemicals such as pesticides. With the improvement of people’s living standards, residents’ requirements for foods have changed from ‘security of output’ to ‘equal emphasis on quality and output’. In order to strengthen the management of grain quality and safety, it is urgent to comprehensively understand the status of pesticide pollution in grains and develop more efficient, convenient and rapid detection technologies. This paper briefly summarizes the characteristics of pesticides and pesticide residues, analyzes the current status of the use and residues of pesticides in raw materials for grains and oils in China, reviews the existing rapid detection methods and technologies for pesticide residues in grains, and compares the advantages and disadvantages of various rapid detection methods and products. This review is expected to provide a reference for quality inspection during grain purchase.

π-Stacking is common in materials, but different π–π stacking modes remarkably affect the properties and performances of materials. In particular, weak interactions, π-stacking and hydrogen bonding often have a significant impact on the stability and sensitivity of high-energetic compounds. A fused [5,7,5]-tricyclic energetic compound with a conjugated structure has been designed and synthesized. 4 H -[1,2,5]Oxadiazolo[3,4- e ][1,2,4]triazolo[3,4- g ][1,2,4]triazepin-8-amine is obtained in 48% yield from 3-amino-4-carboxy-1,2,5-oxadiazole through an efficient two-step reaction. Owing to its layered planar structure and weak π interactions between layers, 4 H -[1,2,5]oxadiazolo[3,4- e ][1,2,4]triazolo[3,4- g ][1,2,4]triazepin-8-amine exhibits high thermal stability (Td = 318 °C), low sensitivity (IS = 40 J, FS = 360 N), and relatively excellent detonation performance (D = 7059 ms–1 , P = 20.2 GPa). This detonation performance is superior to that of the conventional explosive TNT. The developed procedure provides a new method for the synthesis of fused ring compounds. [ABSTRACT FROM AUTHOR]

Tunnel disease detection and maintenance are critical tasks in urban engineering, and are essential for the safety and stability of urban transportation systems. Water stain detection presents unique challenges due to its variable morphology and scale, which leads to insufficient multiscale contextual information extraction and boundary information loss in complex environments. To address these challenges, this paper proposes a method called Deep Aggregation Network with Edge Information Supplement (DAEiS-Net) for detecting tunnel water stains. The proposed method employs a classic encoder–decoder architecture. Specifically, in the encoder part, a Deep Aggregation Module (DAM) is introduced to enhance feature representation capabilities. Additionally, a Multiscale Cross-Attention Module (MCAM) is proposed to suppress noise in the shallow features and enhance the texture information of the high-level features. Moreover, an Edge Information Supplement Module (EISM) is designed to mitigate semantic gaps across different stages of feature extraction, improving the extraction of water stain edge information. Furthermore, a Sub-Pixel Module (SPM) is proposed to fuse features at various scales, enhancing edge feature representation. Finally, we introduce the Tunnel Water Stain Dataset (TWS), specifically designed for tunnel water stain segmentation. Experimental results on the TWS dataset demonstrate that DAEiS-Net achieves state-of-the-art performance in tunnel water stain segmentation. [ABSTRACT FROM AUTHOR]

Ten SSR markers based on transcriptome sequencing were employed to genotype 231 samples of G. littoralis subsp. littoralis (Apiaceae) from nine cultivated populations and seven wild populations, aiming to assess the genetic diversity and genetic structure, and elucidate the origin of the cultivated populations. Cultivated populations exhibited relatively high genetic diversity (h = 0.441, I = 0.877), slightly lower than that of their wild counterparts (h = 0.491, I = 0.930), likely due to recent domestication and ongoing gene flow between wild and cultivated germplasm. The primary cultivated population in Shandong have the crucial genetic status. A single origin of domestication was inferred through multiple analysis, and wild populations from Liaoning and Shandong are inferred to be potentially the ancestor source for the present cultivated populations. Phenotypic analysis revealed a relatively high heritability of root length across three growth periods (0.683, 0.284, 0.402), with significant correlations observed between root length and petiole length (Pearson correlation coefficient = 0.30, P<0.05), as well as between root diameter and leaf area (Pearson correlation coefficient = 0.36, P<0.01). These parameters can serve as valuable indicators for monitoring the developmental progress of medicinal plants during field management. In summary, this study can shed light on the intricate genetic landscape of G. littoralis subsp. littoralis, providing foundational insights crucial for conservation strategies, targeted breeding initiatives, and sustainable management practices in both agricultural and natural habitats. [ABSTRACT FROM AUTHOR]