Activity Of Degrading Enzymes Research Articles

Mechanism of abscisic acid in promoting softening of postharvest 'Docteur Jules Guyot' pear (Pyrus communis L.).

Abscisic acid (ABA) is a key hormone in plant growth and development, playing a central role in responses to various biotic and abiotic stresses as well as in fruit ripening. The present study examined the impact of ABA and nordihydroguaiaretic acid (NDGA) on various postharvest 'Docteur Jules Guyot' pear fruit characteristics, including firmness, pectinase activity, pectin content, volatile aromatic substances, and the expression of correlated genes. The results showed that ABA quickly reduced fruit firmness, increasing the activity of pectin degradation-related enzymes. The contents of water-soluble pectin (WSP) and ionic-soluble pectin (ISP) increased, and covalent binding pectin (CBP) decreased under ABA treatment. Among the detected volatile aromatic substances, the highest-level substance of the fruit was ester, and the ABA treatment significantly promoted the amount of ester substances. The cell wall disassembly-related genes PcPME3, PcPG1, PcPG2, PcPL, PcARF2, and PcGAL1, as well as ABA biosynthesis-related genes PcNCED1 and PcNCED2, were also significantly induced by ABA. Conversely, all these genes were repressed in the NDGA treatment group. Therefore, it was speculated that ABA may promote the softening of postharvest European pear fruit by affecting the activity of pectin degradation enzymes in fruit cell walls.

Conjugation Strategies for Low Solubility Proteins to Single‐Walled Carbon Nanotubes as a Sensitive Fluorescent Assay to Protease Activity

AbstractSingle‐walled carbon nanotube (SWCNT)‐based optical biosensors are shown to detect hydrolase activity directly on target substrates. This study presents a metastable protein conjugation approach to immobilize hydrophobic proteins and enhance sensitivity of protease detection. The method combines covalent conjugation of substrate proteins via carbodiimide chemistry with non‐covalent polymer wrapping of SWCNT, carboxymethyl cellulose (CMC). The formation of protein‐SWCNT complexes as a result of multi‐site conjugation between the proteins and carboxyl groups, enabled iterative pelleting, washing, and resuspension steps to be applied to the probes which allowed for the removal of unbound proteins and residual materials, enhancing the sensor's sensitivity by approximately threefold, reaching a limit of detection (LOD) of 6.4 ng ml−1 in a 5 minute reaction. This immobilization approach is applied to extracellular matrix (ECM) proteins such as gelatin and collagen to detect ECM degrading enzyme activity. ECM degrading enzymes caused a fluorescent intensity decrease of the SWCNT probes, enabling quantification of enzyme concentration between the range 160 ng ml−1 to 100 µg ml−1 within 5 minutes of reaction. This hybrid approach provides a rapid and sensitive platform for detecting extracellular degrading enzymes with potential applications in cancer diagnosis and prognosis, wound healing, high‐throughput screening for enzyme inhibitors, and drug discovery.

AaSlt2 Is Required for Vegetative Growth, Stress Adaption, Infection Structure Formation, and Virulence in Alternaria alternata.

Slt2 is an important component of the Slt2-MAPK pathway and plays critical regulatory roles in growth, cell wall integrity, melanin biosynthesis, and pathogenicity of plant fungi. AaSlt2, an ortholog of the Saccharomyces cerevisiae Slt2 gene, was identified from A. alternata in this study, and its function was clarified by knockout of the gene. The ΔAaSlt2 strain of A. alternata was found to be defective in spore morphology, vegetative growth, and sporulation. Analysis of gene expression showed that expression of the AaSlt2 gene was significantly up-regulated during infection structure formation of A. alternata on hydrophobic and pear wax extract-coated surfaces. Further tests on onion epidermis confirmed that spore germination was reduced in the ΔAaSlt2 strain, together with decreased formation of appressorium and infection hyphae. Moreover, the ΔAaSlt2 strain was sensitive to cell wall inhibitors, and showed significantly reduced virulence on pear fruit. Furthermore, cell wall degradation enzyme (CWDE) activities, melanin accumulation, and toxin biosynthesis were significantly lower in the ΔAaSlt2 strain. Overall, the findings demonstrate the critical involvement of AaSlt2 in growth regulation, stress adaptation, infection structure formation, and virulence in A. alternata.

Metaproteomics identifies key cell wall degrading enzymes and proteins potentially related to inter-field variability in fiber quality during flax dew retting

In this study, metaproteomics and biochemical analyses were used to identify for the first time specific proteins and associated micro-organisms responsible for cell wall degrading enzyme activity during dew retting of flax in two adjacent fields in northern France. This approach identified 6032 non-redundant proteins present at 4 key retting stages (R0/day 1, R2/day 6, R4/day 13, and R7/day 25), of which 75 contained CAZy (Carbohydrate Active Enzyme) motifs belonging to 31 different families from all 5 CAZy classes. 19 families were putatively related to the degradation of different plant cell wall polymers including lignin (AA1), pectins (CE13, CE8, PL1, PL3, GH28, GH35), hemicellulose (GH2, GH10, GH26, GH35, GH55, GH3, GH5, GH17) and cellulose (GH5, GH7, GH3, GH94, AA3). Taxonomy of identified proteins indicated that 85 % come from bacteria, 13 % from fungi, and 2 % from plants; however, ∼60 % of CAZymes involved in the degradation of plant wall polymers are of fungal origin. Although 88 % of total proteins and almost 65 % of cell wall degrading CAZymes were similar between the two investigated fields, certain differences in the abundance and dynamics of certain CAZymes might be related to observed inter-field variability in cell wall degrading enzyme activities, stem/fiber yield and industrial qualities of fibers harvested from the two fields. Overall, these results highlight the interest of using metaproteomics for improving our biological understanding of how retting impacts fiber quality. In addition, the identification of several new bacterial and fungal species in this study demonstrates that such an approach is also extremely powerful for generating novel taxonomic data.

Analysis of Straw Degradation and Whole Genome of Acrophialophora multiforma.

Lignin is one of the main components in plants, which can transform value-added bioenergy and chemicals. At the same time, due to the close combination of lignin and hemicellulose in the structure, it becomes a barrier for cellulose utilization. Therefore, the effective degradation of lignin is of great significance for the utilization of these resources. In this study, the lignin degrading ability of Acrophialophora multiforma strain GZUIFR 22.397 was preliminarily investigated through straw degradation experiments and enzyme activity determination. Then, the whole genome of strain A. multiforma GZUIFR 22.397 was sequentially analyzed and annotated through multiple gene function annotation databases to comprehensively evaluate its lignin degrading potential. The results showed that the weight loss of straw reached 5.98 ± 3.95%. Laccase activity was 77.49 ± 2.65 U/L, lignin peroxidase activity was 160.57 ± 29.07 U/L, and manganese peroxidase activity was 294.83 ± 3.77 U/L. The genome of A. multiforma strain GZUIFR 22.397 spans 33.81 megabases and encompasses 9,370 genes. Among these, 6,122 genes have been annotated in the Gene Ontology (GO), 2,286 in the Cluster of Orthologous Groups of proteins (KOG), 2,283 in the Kyoto Encyclopedia of Genes and Genomes (KEGG), and 603 in the Carbohydrate Active enZYmes Database (CAZy). Concurrently, the genome analysis predicted the presence of 9 genes for laccase, 2 genes for lignin peroxidase, and 2 genes for manganese peroxidase. In summary, these results indicated that A. multiforma GZUIFR 22.397 has lignin degrading ability, and laid the foundation for deciphering the molecular mechanism of A. multiforma GZUIFR 22.397 to degrade lignin.

Remediation of PBDE-contaminated soil using biochar-based bacterial consortium QY2Y

Biochar-immobilized microbial technologies hold substantial promise for the remediation of environmental contaminants. However, the understanding of remediation efficiency and the operation of microbial consortia in complex soil environments using biochar as a carrier remains limited. In this study, we explored the impacts of biochar combined with bacterial consortium QY2Y (consisting of Chitinophaga sp. MH-1, Achromobacter sp. YH-1, Methylobacterium sp. ZY-1, and Sphingomonas sp. GY-1) on BDE-47 dissipation in contaminated soil, as well as its effects on soil-plant systems. The findings indicated that the immobilization of biochar and QY2Y not only stimulated the biodegradation of BDE-47 (61.50%) but also decreased the bioavailability of BDE-47, subsequently reducing the concentration of BDE-47 in the edible portion of rapeseed (Brassica napus L.) by 82.00%. In addition, the combined treatment notably increased soil pH, enhanced the physicochemical properties and nutrient conditions of the soil, and amplified soil dehydrogenase, catalase, urease, and acid phosphatase activities by 58.72%, 69.25%, 54.24%, and 74.74%, respectively. The application of biochar-based QY2Y improved the soil microbial community structure, bolstered the interspecific symbiotic and cooperative relationships, and restructured the keystone taxa. The key species microbes had direct and significant positive effects on BDE-47 degradation, soil nutrients, and soil enzyme activity. This study deepens our understanding of the potential applications of immobilized microbial consortia in treating PBDE-contaminated soils and offers guidance for the management and remediation of contaminated soils.

Foliar spraying of boron prolongs preservation period of strawberry fruits by altering boron form and boron distribution in cell.

Boron (B), an essential micronutrient for fruit development, also plays a crucial role in maintaining the shelf life of strawberries (Fragaria ananassa Duch.) by affecting cell wall structure and components. We investigated the distribution pattern of B within cells and cell walls in strawberry fruits under different B levels and revealed the relationship between the B distribution in cell walls and fruit firmness after harvesting. Foliar spraying of 0.1% H3BO3 promoted the growth of strawberry seedlings and improved fruit yield and flesh firmness by 45.7% and 25.6%. During the fruit softening and decay process, the content of bound B and cell wall-B decreased while more B was allocated to the protoplast and apoplast. The changes in B distribution in cells were attributed to cell damage during fruit decay, and B extended the freshness period of the fruits by alleviating the decrease of B distribution in cell walls. After leaving the fruits at room temperature for 10 h, the B content in different cell wall components significantly decreased, while foliar spraying of B alleviated the reduction of B content in covalently bound pectin (CBP), cellulose, and hemicellulose. Meanwhile, B spraying on fruit decreased the activity of cell wall degradation enzymes, including polygalacturonase (PG) and pectin lyase (PL), by 20.2% and 38.1%, while enhancing the demethylation of pectin by increasing pectin methylesterase (PME) activity from 21.6 U/g to 25.7 U/g. Thus, foliar spraying of 0.1% H3BO3 enhances the cross-linking of B with cell wall components and maintains cell wall structure, thereby prolonging the shelf life of strawberry fruits.

Continuous flow high-pressure homogenization for preserving the nutritional quality and stability of watermelon juice under simulated market storage conditions

This study examined the efficacy of continuous flow high-pressure homogenization (CFHPH) under varying pressures, inlet temperatures, and flow rates, in preserving the nutritional quality and stability of watermelon juice during simulated market conditions and compared it with traditional high-temperature short-time (HTST) processing. The retention of ascorbic acid, carotenoids, and amino acids was analyzed using liquid chromatography, while PPO (polyphenol oxidase) and POD (peroxidase) enzyme activity was assessed using a UV–vis spectrophotometer.We observed a significant decrease (p ≤ 0.05) in ascorbic acid levels after 15 days of storage. For carotenoids, the impact was influenced by the interaction of pressure, flow rate, and inlet temperature within CFHPH, with no clear trend emerging regarding their preservation over 45 days of storage at 4 °C. However, overall retention of carotenoids surpassed that of HTST samples. Both methods enhanced free amino acid contents significantly and decreased PPO and POD activity, with HTST being slightly more effective. Ornithine and histidine concentrations significantly increased, with up to a fourfold rise in samples treated with 300 MPa pressure and up to a tenfold rise for HTST at 95 °C after 45 days of storage. This study suggests optimizing the CFHPH process to enhance the shelf-life and nutritional value of watermelon juice, offering consumers a healthier and longer-lasting choice. Industrial relevanceOur findings highlight CFHPH's higher retention of bioactive compounds, reduction in degradative enzyme activity, and enhancement of the amino acid profile, making it a compelling choice for the fruit juice processing industry. Despite the energy-intensive nature of CFHPH, its ability to preserve vital bioactive compounds like carotenoids and ascorbic acid addresses the growing consumer demand for nutritious and stable juice options. The benefits of CFHPH in maintaining juice quality and nutritional value may outweigh the associated energy costs, making it a promising technology for fruit juice processing.

Effect of Nitrogen Fertilizer on Capsaicinoids and Related Metabolic Substances of Dried Chili Pepper Fruit

Reducing fertilizer pollution is an important direction for modern ecological agriculture. Commonly, excessive nitrogen is applied to pepper. Capsaicin is one of the most important economic qualities of spicy peppers, but the effect of nitrogen on capsaicin is still inconsistent. This study aims to elucidate the impact of nitrogen fertilizer on capsaicin accumulation and to provide guidance on fertilizer application on highly spicy chili peppers. The experiment was conducted with five nitrogen fertilizer concentrations: N1 (urea 750 kg ha−1), N2 (urea 562.5 kg ha−1), N3 (urea 375 kg ha−1), N4 (urea 187.5 kg ha−1), and N0 (no nitrogen fertilizer). Nitrogen treatment was applied to two varieties with different spiciness levels from the seedling stage. The fruits in different layers of pepper plants were sampled on the 20th, 35th, and 50th day after anthesis, and the fruits’ size, content of capsaicin, capsaicin precursors, capsaicin competitors, as well as capsaicin-related enzyme activities and gene expression level were analyzed. The results indicate that, when applying N2 and N3, both chili pepper varieties exhibited higher fruit length, diameter, weight, and yield values. There were increased contents of total phenol, flavonoids, and tannins in both fruit varieties with N2 application. Moreover, the placenta weights of the bottom, middle, and top layers of the fruits on the 35th day were improved by 40.14%, 26.80%, and 55.91% for ‘Honglong 23’ and 55.10%, 37.04%, and 75.56% for ‘Hongxi’ compared with N0. At the same time, under N2 treatment, the phenylalanine ammonia-lyase (PAL) enzyme activity of capsaicin synthase significantly increased. In contrast, the capsaicin-degrading enzyme activities of peroxidase (POD) and polyphenol oxidase (PPO) decreased notably. The expression levels of capsaicin-synthetic genes such as phenylalanine cleavage enzyme gene (PAL), acyltransferase gene (AT3), 4-Coumaroyl coenzyme A ligase gene (4CL), cinnamate 4-hydroxylase gene (C4H), caffeoyl coenzyme A-3-oxo-methyltransferase gene (COMT), paminotransferase gene (PAMT), and hydroxycinnamyltransferase gene (HCT) were up-regulated in N2 fruits, which led to a significant increase in capsaicin content compared with the other four nitrogen amounts. A further reduction in nitrogen application to N3 and N4 resulted in a decrease in the precursor substance’s total phenol content and PAL activity and an increase in the competitive substance’s flavonoid, lignin, POD, and PPO enzyme activities. At the same time, the expression levels of capsaicinoid synthetic genes were downregulated in the N3 and N4 treatments, leading to a low content of total capsaicinoids. The capsaicinoid content showed a trend of 35th day > 50th day > 20th day for both varieties. Additionally, the contents of total capsaicinoids, total phenols, flavonoids, and lignins, as well as PAL enzyme activity, and the expression levels of PAL, AT3, 4CL, C4H, COMT, PAMT, and HCT exhibited characteristics of bottom layers > middle layers > top layers. The activities of POD and PPO gradually increased from the bottom to the top layers. The N2 (562.5 kg ha−1) treatment resulted in increases in placenta mass, maximum capsaicinoid precursor substance of total phenol content, and synthase enzyme activity, as well as decreases in capsaicinoid competing substances and degradative enzyme activity, so there were more substances available for capsaicin synthesis. Combined with the higher fruit weight and capsaicinoid content in the N2 treatment, N2 was considered a suitable nitrogen fertilizer dosage for highly spicy chili pepper cultivation.

Phenanthrene-Degrading and Nickel-Resistant Neorhizobium Strain Isolated from Hydrocarbon-Contaminated Rhizosphere of Medicago sativa L.

Pollutant degradation and heavy-metal resistance may be important features of the rhizobia, making them promising agents for environment cleanup biotechnology. The degradation of phenanthrene, a three-ring polycyclic aromatic hydrocarbon (PAH), by the rhizobial strain Rsf11 isolated from the oil-polluted rhizosphere of alfalfa and the influence of nickel ions on this process were studied. On the basis of whole-genome and polyphasic taxonomy, the bacterium Rsf11 represent a novel species of the genus Neorhizobium, so the name Neorhizobium phenanthreniclasticum sp. nov. was proposed. Analysis of phenanthrene degradation by the Rsf1 strain revealed 1-hydroxy-2-naphthoic acid as the key intermediate and the activity of two enzymes apparently involved in PAH degradation. It was also shown that the nickel resistance of Rsf11 was connected with the extracellular adsorption of metal by EPS. The joint presence of phenanthrene and nickel in the medium reduced the degradation of PAH by the microorganism, apparently due to the inhibition of microbial growth but not due to the inhibition of the activity of the PAH degradation enzymes. Genes potentially involved in PAH catabolism and nickel resistance were discovered in the microorganism studied. N. phenanthreniclasticum strain Rsf11 can be considered as a promising candidate for use in the bioremediation of mixed PAH-heavy-metal contamination.

Evolution of glucuronoxylan side chain variability in vascular plants and the compensatory adaptations of cell wall-degrading hydrolases.

Polysaccharide structural complexity not only influences cell wall strength and extensibility but also hinders pathogenic and biotechnological attempts to saccharify the wall. In certain species and tissues, glucuronic acid side groups on xylan exhibit arabinopyranose or galactose decorations whose genetic and evolutionary basis is completely unknown, impeding efforts to understand their function and engineer wall digestibility. Genetics and polysaccharide profiling were used to identify the responsible loci in Arabidopsis and Eucalyptus from proposed candidates, while phylogenies uncovered a shared evolutionary origin. GH30-family endo-glucuronoxylanase activities were analysed by electrophoresis, and their differing specificities were rationalised by phylogeny and structural analysis. The newly identified xylan arabinopyranosyltransferases comprise an overlooked subfamily in the GT47-A family of Golgi glycosyltransferases, previously assumed to comprise mainly xyloglucan galactosyltransferases, highlighting an unanticipated adaptation of both donor and acceptor specificities. Further neofunctionalisation has produced a Myrtaceae-specific xylan galactosyltransferase. Simultaneously, GH30 endo-glucuronoxylanases have convergently adapted to overcome these decorations, suggesting a role for these structures in defence. The differential expression of glucuronoxylan-modifying genes across Eucalyptus tissues, however, hints at further functions. Our results demonstrate the rapid adaptability of biosynthetic and degradative carbohydrate-active enzyme activities, providing insight into plant-pathogen interactions and facilitating plant cell wall biotechnological utilisation.

Cinnamic acid derivatives played a major role in the resistance of peach leaves to Xanthomonas arboricola pv. pruni infection

AbstractPeach bacterial shot hole is a common global disease of peach trees caused by the pathogen Xanthomonas arboricola pv. pruni (Xap). To preliminarily explore the resistance mechanism of peach bacterial shot hole, leaves of the resistant variety ‘Yanbao’ and the susceptible variety ‘Frederic’ were used as test materials. The contents of total phenols, total flavonoids and lignin were analysed after 1 day of inoculation treatment, and the activities of defence enzymes and cell wall degradation enzymes in the leaves were determined. Furthermore, the resistant substances were screened by combining broad‐target metabolomics technology and in vitro antibacterial activity. The results showed that the contents of total phenols, total flavonoids and lignin in peach leaves were related to resistance. The resistant varieties resisted infection by inhibiting the activities of polygalacturonase (PG) and pectin methyl trans‐eliminase (PMTE) produced by Xap in peach leaves and increasing the activities of 4‐coumarate:coenzyme A ligase (4CL), cinnamic acid‐4‐hydroxylase (C4H), phenylalanine ammonia lyase (PAL) and peroxidase (POD). A total of six resistant compounds were screened from 85 differential metabolites. The minimum inhibitory concentrations of methyl ferulate (MF), p‐coumaric acid (p‐CA) and methyl caffeate (MC) on Xap were 0.0625, 00625 and 0.125 mg/mL, respectively, while that of the positive control drug oxytetracycline (OTC) was 0.125 mg/mL. The antibacterial activities of MF and p‐CA were better than that of OTC, and MF was equivalent to OTC. In addition, homoeriodictyol, hesperetin and fraxin have certain antibacterial effects. Before inoculation treatment, the contents of MF, p‐CA and MC in ‘Yanbao’ were 1.13, 1.24 and 1.96 times higher than those in ‘Frederic’, respectively, while they were 1.29, 1.80 and 1.94 times after inoculation treatment, respectively. During the process of pathogen infection, MF and p‐CA in the leaves of resistant peach varieties played a role in inducing resistance, while MC was a component of resistance. The above three cinnamic acid derivatives play an important roles in the resistance of peach bacterial shot hole and are potential control drugs.

Nonlinear responses of ericaceous and ectomycorrhizal Arctic shrubs across a long‐term experimental nutrient gradient

AbstractIn the Arctic tundra, warming is anticipated to stimulate nutrient release and potentially alleviate plant nutrient limitations. Typically simulated by fertilization experiments that saturate plant nutrient demand, future increases in soil fertility are thought to favor ectomycorrhizal (EcM) over ericaceous shrubs and have often been identified as a key driver of Arctic shrub expansion. However, the projected increases in fertility will likely vary in their alleviation of nutrient limitations. The resulting responses of shrubs and their mycorrhizae across the gradient of nutrient limitation may be nonlinear and could contradict the current predictions of tundra vegetation shifts. We compared the functional responses of two dominant shrubs, EcM dwarf birch (Betula nana) and ericaceous Labrador tea (Rhododendron tomentosum), across a long‐term nitrogen and phosphorus fertilization gradient experiment in Arctic Alaska. Using linear mixed‐effects modeling, we tested the responses of shrub cover, height, and root enzyme activities to soil fertility. We found that B. nana cover and height linearly increased with soil fertility. In contrast, R. tomentosum cover initially increased, but decreased after surpassing the intermediate levels of increased soil fertility. Its height did not change. Enzyme activity did not respond to soil fertility on EcM‐colonized B. nana roots, but sharply declined on R. tomentosum roots. Overall, the nonlinear responses of shrubs to our fertility gradient demonstrate the importance of experiments grounded in replicated regression design. Our results indicate that under moderate increases in soil fertility, Arctic shrub expansion may not only include deciduous EcM shrubs but also ericaceous shrubs. Regardless of shifts aboveground, changes in root enzyme activity belowground point to some EcM shrub species playing a more influential role in tundra soils; as EcM roots remained steady in their liberation of soil organic nutrients with heightened soil fertility, degradative root enzyme activity on the dominant ericaceous shrub dropped—in some instances with even the slightest increase in fertility.

A transition from arbuscular to ectomycorrhizal forests halts soil carbon sequestration during subtropical forest rewilding

Ecological succession and restoration rapidly promote multiple dimensions of ecosystem functions and mitigate global climate change. However, the factors governing the limited capacity to sequester soil organic carbon (SOC) in old forests are poorly understood. Ecological theory predicts that plants and microorganisms jointly evolve into a more mutualistic relationship to accelerate detritus decomposition and nutrient regeneration in old than young forests, likely explaining the changes in C sinks across forest succession or rewilding. To test this hypothesis, we conducted a field experiment of root-mycorrhizal exclusion in successional subtropical forests to investigate plant-decomposer interactions and their effects on SOC sequestration. Our results showed that SOC accrual rate at the 0–10 cm soil layer was 1.26 mg g−1 yr−1 in early-successional arbuscular mycorrhizal (AM) forests, which was higher than that in the late-successional ectomycorrhizal (EcM) forests with non-significant change. A transition from early-successional AM to late-successional EcM forests increase fungal diversity, especially EcM fungi. In the late-successional forests, the presence of ectomycorrhizal hyphae promotes SOC decomposition and nutrient cycle by increasing soil nitrogen and phosphorus degrading enzyme activity as well as saprotrophic microbial richness. Across early- to late-successional forests, mycorrhizal priming effects on SOC decomposition explain a slow-down in the capacity of older forests to sequester soil C. Our findings suggest that a transition from AM to EcM forests supporting greater C decomposition can halt the capacity of forests to provide nature-based global climate change solutions.

Effects of different proportions of fruit tree branches on nicotine content and microbial diversity during composting of tobacco waste

Adding fruit tree branches to the compost pile in appropriate proportions is one of the methods used to address the challenge of tobacco waste recycling. However, the effects of different proportions of fruit tree branches on nicotine concentration and microbial diversity during tobacco waste composting have not been reported. In this study, a composting system with tobacco waste, cow dung, and fruit tree branches was established in a laboratory fermenter to assess the impact of adding 10%, 20%, and 30% fruit tree branches on quantity changes. In addition, the relationships between nicotine degradation, compost properties, enzyme activities, and microbial diversities were determined using biochemical assay methods and high-throughput sequencing. The results showed that adding appropriate proportions of fruit branch segments affected changes in physical and chemical properties during composting and promoted tobacco waste compost maturity. Aerobic composting effectively degraded nicotine in tobacco waste. Increased proportions of fruit branch segments led to elevations in nicotine degradation rates and enzyme activities related to lignocellulose degradation. The addition of fruit branches influenced the relative abundance and species of dominant bacteria and fungi at the phylum and genus levels. However, it did not significantly affect the relative abundance of the main bacterial genera involved in nicotine degradation. Nevertheless, it reduced the sensitivity of enzyme activity to nicotine content within heaps, increasing reliance on total nitrogen changes. The results of this study provide a theoretical basis for the utilization of tobacco waste in composting systems and indicate that fruit tree branches can enhance nicotine degradation efficiency during tobacco waste composting.

The Alzheimer's disease gene SORL1 regulates lysosome function in human microglia.

The SORL1 gene encodes the sortilin related receptor protein SORLA, a sorting receptor that regulates endo-lysosomal trafficking of various substrates. Loss of function variants in SORL1 are causative for Alzheimer's disease (AD) and decreased expression of SORLA has been repeatedly observed in human AD brains. SORL1 is highly expressed by microglia, the tissue resident immune cells of the brain. Loss of SORLA leads to enlarged lysosomes in hiPSC-derived microglia like cells (hMGLs). However, whether SORLA deficiency contributes to microglia dysfunction and how this is relevant to AD is not known. In this study, we show that loss of SORLA results in decreased lysosomal degradation and lysosomal enzyme activity due to altered trafficking of lysosomal enzymes in hMGLs. Furthermore, lysosomal exocytosis, an important process involved in immune responses and cellular signaling, is also impaired in SORL1 deficient microglia. Phagocytic uptake of fibrillar amyloid beta 1-42 and synaptosomes is increased in SORLA deficient hMGLs, but due to reduced lysosomal degradation, these substrates aberrantly accumulate in lysosomes. Overall, these data highlight the microglial endo-lysosomal network as a potential novel pathway through which SORL1 may increase AD risk and contribute to development of AD. Additionally, our findings may inform development of novel lysosome and microglia associated drug targets for AD.

Responsive mechanism of Hemerocallis citrina Baroni to complex saline-alkali stress revealed by photosynthetic characteristics and antioxidant regulation.

Saline-alkali stress induces oxidative damage and photosynthesis inhibition in H. citrina, with a significant downregulation of the expression of photosynthesis- and antioxidant-related genes at high concentration. Soil salinization is a severe abiotic stress that impacts the growth and development of plants. In this study, Hemerocallis citrina Baroni was used to investigate its responsive mechanism to complex saline-alkali stress (NaCl:Na2SO4:NaHCO3:Na2CO3 = 1:9:9:1) for the first time. The growth phenotype, photoprotective mechanism, and antioxidant system of H. citrina were studied combining physiological and transcriptomic techniques. KEGG enrichment and GO analyses revealed significant enrichments of genes related to photosynthesis, chlorophyll degradation and antioxidant enzyme activities, respectively. Moreover, weighted gene co-expression network analysis (WGCNA) found that saline-alkali stress remarkably affected the photosynthetic characteristics and antioxidant system. A total of 29 key genes related to photosynthesis and 29 key genes related to antioxidant enzymes were discovered. High-concentration (250mmolL-1) stress notably inhibited the expression levels of genes related to light-harvesting complex proteins, photosystem reaction center activity, electron transfer, chlorophyll synthesis, and Calvin cycle in H. citrina leaves. However, most of them were insignificantly changed under low-concentration (100mmolL-1) stress. In addition, H. citrina leaves under saline-alkali stress exhibited yellow-brown necrotic spots, increased cell membrane permeability and accumulation of reactive oxygen species (ROS) as well as osmolytes. Under 100mmolL-1 stress, ROS was eliminate by enhancing the activities of antioxidant enzymes. Nevertheless, 250mmolL-1 stress down-regulated the expression levels of genes encoding antioxidant enzymes, and key enzymes in ascorbate-glutathione (AsA-GSH) cycle as well as thioredoxin-peroxiredoxin (Trx-Prx) pathway, thus inhibiting the activities of these enzymes. In conclusion, 250mmolL-1 saline-alkali stress caused severe damage to H. citrina mainly by inhibiting photosynthesis and ROS scavenging capacity.

Antifungal activity of heat-treated wood extract against wood decay fungi

Using heat treatment for wood protection has been driven to maturity, but the role of heat-treated wood extracts in decay resistance has lacked attention. To assess the potential of heat-treated wood extract for wood preservation, the antifungal activity of the extract against wood decay fungi and the effects of the extract on fungal wood degrading enzyme activity and cell membrane integrity were tested. Small shavings generated during the processing of larch (Larix gmelinii (Rupr.) Kuzen) were heat-treated and extracted. The antifungal activity of extract against wood decay fungi and decay resistance of extract impregnated wood were tested to assess their potential. The effect of extracts on the enzyme activity of the white-rot fungus, Trametes versicolor (L.) Lloyd and the brown-rot fungus, Gloeophyllum trabeum (Pers.: Fr.) Murr. for wood degradation was assessed by detecting the activity of cellulose, hemicellulose, and ligninase of fungi incubated with extract. The effect of extracts on the integrity of cell membranes of fungi was assessed by staining with propidium iodide (PI) and the leakage detection of nucleic acid and protein in fungi after exposure to extract. The toxicity to freshwater luminescent bacteria (Vibrio qinghaiensis sp. -Q67) and mouse macrophages (RAW264.7) of the extract impregnated wood leachate was tested and compared with the leachate of the raw wood. The results denoted that the decay resistance of poplar (Populus tomentosa Carr.) wood could be improved by heat-treated larch wood extract, and the effect of the extract impregnated wood leachate on Q67 and RAW264.7 was the same as that of raw wood leachate. The extract inhibited ligninase activity (only for T. versicolor), cellulase activity, and respiratory metabolism of tested fungi, and impaired the membrane integrity. The study identified a potential wood preservative.

Quantitative assessment, molecular docking and novel metabolic pathways reveal the interaction mechanisms between norfloxacin biodegradation and environmental implications

Norfloxacin (NOR) is widely used in medicine and animal husbandry, but its accumulation in the environment poses a substantial threat to ecological and human health. Traditional physical, chemical, and rudimentary biological methods often fall short in mitigating NOR contamination, necessitating innovative biological approaches. This study proposes an engineered bacterial consortium found in marine sediment as a strategy to enhance NOR degradation through inter-strain co-metabolism of diverse substrates. Strategically supplementing the engineered bacterial consortium with exogenous carbon sources and metal ions boosted the activity of key degradation enzymes like laccase, manganese peroxidase, and dehydrogenase. Iron and amino acids demonstrated synergistic effects, resulting in a remarkable 70.8% reduction in NOR levels. The innovative application of molecular docking elucidated enzyme interactions with NOR, uncovering potential biodegradation mechanisms. Quantitative assessment reinforced the efficiency of NOR degradation within the engineered bacterial consortium. Four metabolic routes are herein proposed: acetylation, defluorination, ring scission, and hydroxylation. Notably, this study discloses distinctive, co-operative metabolic pathways for NOR degradation within the specific microbial community. These findings provide new ways of understanding and investigating the bioremediation potential of NOR contaminants, which may lead to the development of more sustainable and effective environmental management strategies.

Blue light treatment delays postharvest ripening of kiwifruit by suppressing ethylene biosynthesis, starch degradation, and cell wall metabolism

The study aimed to investigate the effects of blue light (BL) on the postharvest ripening and softening of kiwifruit. The postharvest ripening of kiwifruit were significantly inhibited by BL; 100 μmol m−2 s−1 light intensity exhibited the best effect. The delay of postharvest ripening of kiwifruit by BL was associated with the inhibition of total soluble solids accumulation, reduction in respiratory rate and ethylene production as well as 1-aminocyclopropane-1-carboxylate synthase and 1-aminocyclopropane-1-carboxylic acid oxidase activities. Moreover, it also inhibited starch degradation and related enzyme activities (α-amylase and β-amylase), prevented the degradation of protopectin, cellulose and hemicellulose while promoting the accumulation of water soluble pectin. Additionally, it suppressed the activities of polygalacturonase, pectinlyase, pectin methylesterase, and cellulase. Transcriptome and gene expression analyses showed that BL-treated kiwifruit had lower expression levels of genes involved in ethylene biosynthesis, starch degradation, and cell wall metabolism, compared with the dark controls. BL also altered transcription factor responses to light, such as v-myb avian myeloblastosis viral oncogene homolog (MYB) and basic helix-loop-helix (bHLH) families. In summary, this study analyzed the physiological and molecular mechanisms by which BL delays the postharvest ripening of kiwifruit and provides a new preservation method for the postharvest quality maintenance of kiwifruit.