Enzyme Activity Research Articles

Proteolytic and Biofilm-forming Capacity of Bacteria Isolated from a UHT Milk Processing Plant

The destabilization of milk during processing, caused by bacteria, represents a significant challenge for the dairy industry. This study aimed to determine the spoilage potential of 31 psychrotrophic, mesophilic, or thermophilic strains isolated from the UHT-milk production chain. This encompassed the biofilm-forming ability on polystyrene and stainless-steel surfaces, along with the strains' caseinolytic activity and heat resistance. The effect of 5 mM MgCl2 on the biofilm-forming capacity was also determined. The results indicated that the spoilage potential is highly strain-dependent. On polystyrene Pseudomonas brenneri C10.3.4, Staphylococcus pasteuri RE1.9, and B. licheniformis SDP.15 were the strongest biofilm-formers of each group, whereas on stainless-steel, Pseudomonas lactis D1.11, Lacticaseibacillus paracasei P2.20 and Bacillus sonorensis C4.13 exhibited the highest capacity. Staphylococcus pasteuri RE1.9 and Staphylococcus epidermidis E3.6 biofilm cells showed the highest heat resistance. Moreover, biofilm-born cells of the spore-forming B. licheniformis SDP.15 and B. sonorensis C4.13 were significantly more heat-resistant than their free-cell equivalents. Furthermore, 22 of the assessed strains showed proteolytic activity, although only the proteases produced by P. lactis E6.10 maintained their enzymatic activity after being treated at 92°C. These findings may contribute to developing strategies to enhance the dairy industry's long-term economic sustainability. Keywords: UHT milk; spoilage potential; caseinolytic activity; biofilm-forming ability; thermal resistance

Antioxidant and anti-inflammatory potential of vanillic acid improves nephrotoxicity induced by sodium arsenite in mice

ABSTRACT This study examined the potential of vanillic acid (VA) to protect against renal oxidative stress and inflammation caused by sodium arsenite (SA) in mice. Mice were assigned to five groups: control, VA (100 mg/kg), SA (50 ppm in drinking water for 8 weeks), and SA + VA (50 and 100 mg/kg orally in the 7th and 8th weeks). After the experiment was ended, the Mice were sacrificed and serum and renal tissue samples were collected for additional assessments. Treatment with VA suppressed SA-induced increase in blood urea nitrogen and creatinine in the serum. Furthermore, renal histological damage induced by SA administration was ameliorated with VA treatment. Also, the increase in the level of lipid peroxidation marker (thiobarbituric acid reactive substances) along with the reduction in total thiol levels and the diminished activities of antioxidant enzymes (catalase, superoxide dismutase, and glutathione peroxidase) in the renal tissue of SA-treated mice were effectively reversed following treatment with VA. The results exhibited that the VA-treated groups (50 and 100 mg/kg) mitigated the elevation of inflammatory markers in kidney tissue (tumor necrosis factor-α and nitric oxide) in SA-exposed mice. Our research findings indicate that VA could be a potential therapeutic agent for the management of SA-associated nephrotoxicity.

Analysis of kallikrein-related peptidase 7 (KLK7) autolysis reveals novel protease and cytokine substrates.

Kallikrein-related peptidase 7 (KLK7) is one of 15 members of the tissue kallikrein family and is primarily expressed in the skin epidermis. The activity of KLK7 is tightly regulated by multiple stages of maturation and reversible inhibition, similar to several other extracellular proteases. In this work, we used protease-specific inhibitors and active sitevariants to show that KLK7 undergoes autolysis at two separate sites in the 170 and 99 loops (chymotrypsinogen numbering), resulting in a loss of enzymatic activity. A protein BLAST search using the autolyzed KLK7 loop sequences identified mast cell chymase as a potential KLK7 substrate. Indeed, KLK7 cleaves chymase resulting in a concomitant loss of activity. We further demonstrate that KLK7 can hydrolyze other mast cell proteases as well as several cytokines. These cytokines belong mainly to the interferon and IL-10 families including IFN-α, IFN-β, IFN-γ, IL-28A/IFN-λ2, IL-20, IL-22, and IL-27. This is the first study to identify a possible molecular interaction link between KLK7 and mast cell proteases and cytokines. Although the precise biological implications of these findings are unclear, this study extends our understanding of the delicate balance of proteolytic regulation of enzyme activity that maintains physiological homeostasis, and facilitates further biological investigations.

Increasing the dual-enzyme cascade biocatalysis efficiency and stability of metal-organic frameworks via one-step coimmobilization for visual detection of glucose.

In biosensing analysis, the activity of enzyme systems is limited by their fragility, and substrates catalyzed by monoenzymes tend to undergo spontaneous decomposition during ineffective mass transfer processes. In this study, we propose a novel strategy to encapsulate the glucose oxidase and horseradish peroxidase (GOx&HRP) cascade catalytic system within the hydrophilic zeolite imidazole framework ZIF-90. By leveraging the specific pore structure of ZIF-90, we effectively immobilized GOx and HRP molecules in their three-dimensional conformations, which improved the catalytic activity of the encapsulated enzymes compared with that of free GOx and HRP in various harsh environments. Additionally, our strategy reduced the occurrence of ineffective mass transfer and enhanced the sensitivity of the biosensor through an enzyme cascade system. When this biosensor was applied to serum samples containing complex biological matrices, the degradation of GOx&HRP by various proteases and the surface adsorption of diverse biomolecules were effectively prevented, thereby generating stable and reliable signals of glucose levels. The sensor shows remarkable sensitivity and selectivity for determining glucose concentrations ranging from 0 to 2.5 μg ml-1, with a detection limit as low as 0.034 μg ml-1. Furthermore, we developed a paper-based colorimetric sensor utilizing GOx&HRP@ZIF-90 integrated with a smartphone platform for the visual detection of blood glucose.

Microhabitat accessibility determines peptide substrate degradation by soil microbial community.

Soil pore space, considered the most complex biomaterial that exists, generates a complex environment, that gives rise to a wide variety of properties, such as microbial diversity and carbon storage. Soils contain, at the same time, the largest carbon reservoir on earth and an immense amount of nutrient-limited microbial biomass. The reason why this carbon is not consumed by soil microbes is attributed to the complex nature of soil, which forms a labyrinth where carbon and microbes cannot be in direct contact. In the present study, by using microfluidics, we tested the effect of labyrinth-like structures of decreasing accessibility on the decomposing activity of soil microbial communities from a soil inoculum. The two parameters used to study the effect of microhabitat accessibility were either the turning angle in an array of channel-like pore structures or the fractal order in an array of maze-like pore structures. We found that in both cases, channels and mazes, decreasing accessibility produced a higher peptide substrate degradation. When we analyzed the degradation within the structures, we found that most of the activity is concentrated in the regions of intermediate accessibility. We think that the increased degradation activity in low accessibility mazes might be due to the reduced interactions within the microbial communities which leads to a reduction in competition. Lowered competition allows different communities with a wide range of metabolic strategies to cohabit in the structures, which resulted in a bulk increase of the peptide substrate degradation.IMPORTANCEThe role microbes have in the environment is highly influenced by the characteristics of their habitat. Here, we show that a complex habitat enhances the enzymatic activity of a soil microbial inoculum. This might occur due to a reduced competition in complex habitats, which allows a more diverse community to coexist and explore a wider variety of metabolic strategies. The different rates of enzymatic activity in different levels of complexity suggest emergent properties of microbial communities in complex microhabitats which could have important implication for microbial processes, such as soil carbon storage and nutrient cycling.

Spatially Quantitative Imaging of Enzyme Activity in a Living Cell.

Enzyme activity plays a key role in cell heterogeneity. Its spatially quantitative imaging in a living cell not only directly displays but also helps people to understand cell heterogeneity. Current methods are hard to achieve due to the short intracellular retention or lack of internal reference of the imaging probes. Herein, we rationally designed a self-referenced Raman probe Val-Cit-Cys(StBu)-Pra-Gly-CBT (Yne-CBT) which takes an intracellular cathepsin B (CTSB)-initiated CBT-Cys click reaction to yield a long-retained cyclic dimer in cell. In the meantime, Raman signal changes of its two chemical bonds (C≡C and C≡N) after the reaction are used for self-referencing and quantitative Raman imaging of CTSB activity. In vitro experiments demonstrated that, with shell-isolated nanoparticle-enhanced Raman spectroscopy technique, 20 μM Yne-CBT was able to quantitatively detect CTSB activity with a limit of detection of 61.4 U L-1. Under a homemade microfluidic channel, Yne-CBT was successfully applied for spatially quantitative imaging CTSB activity in a living cell. Our strategy provides people with a facile method to directly and quantitatively display cell heterogeneity.

Investigating the mechanism of auxin-mediated fulvic acid-regulated root growth in Oryza sativa through physiological and transcriptomic analyses.

As rice is one of the most crucial staple food sources worldwide, enhancing rice yield is paramount for ensuring global food security. Fulvic acid (FA), serving as a plant growth promoter and organic fertilizer, holds significant practical importance in studying its impact on rice root growth for improving rice yield and quality. This study investigated the effects of different concentrations of FA on the growth of rice seedlings. The results indicated that 0.05 g/L FA could promote the growth of rice seedlings, while 0.5 g/L FA inhibited root growth, reduced cell activity and enzyme activity in the root tips, and accumulated reactive oxygen species in root cells. To further elucidate the molecular mechanisms underlying these effects, we performed transcriptomic analysis and found that auxin (Aux) may be involved in the growth process mediated by FA. Furthermore, transcriptome heatmap analysis revealed a significant upregulation of the Aux/indoleacetic acid (Aux/IAA) gene family after FA treatment, suggesting that this gene family plays a crucial role in the impact of FA on root growth. Additionally, by detecting endogenous Aux content and adding exogenous Aux inhibitors, we confirmed the involvement of FA in rice seedling root growth as well as in the synthesis and transduction pathway of Aux.

Biological mechanism and functional verification of key genes related to major depressive disorder and type 2 diabetes mellitus.

Major depressive disorder (MDD) and type 2 diabetes (T2D) have been shown to be linked, but a comprehensive understanding of the underlying molecular mechanisms remains elusive. The purpose of this study was to explore the biological relationship between MDD and T2D and verify the functional roles of key genes. We used the Gene Expression Omnibus database to investigate the targets associated with MDD and T2D. Using linear models for microarray data, differentially expressed genes associated with MDD and T2D were identified in GSE76826 and GSE95849, respectively, and 126 shared genes were significantly upregulated. Weighted gene coexpression network analysis identified modules associated with MDD and T2D in the GSE38206 and GSE20966 datasets and identified 8 common genes. Functional enrichment analysis revealed that these genes were enriched in cell signaling, enzyme activity, cell structure and amino acid biosynthesis and involved in cell death pathways. Finally, combined with the CTD and GeneCards databases, lysophosphatidylglycerol acyltransferase 1 (LPGAT1) was identified as a key gene. LPGAT1 was validated in GSE201332 and GSE182117, and the subject operating characteristic curve showed good diagnostic potential for MDD and T2D. Additionally, we used an in vitro model of MDD related to T2D to verify the expression of LPGAT1. A subsequent gene knockdown assay revealed that the downregulation of LPGAT1 improved mitochondrial function and reduced apoptosis in damaged neurons. Taken together, our results highlight the role of LPGAT1 in the connection between MDD and T2D, and these findings provide new insights into potential therapeutic targets for depression associated with diabetes.

Intake of Condensed Tannins (Acacia mearnsii) by Lambs in Confinement and Its Impact on Growth Performance, Rumen Environment, and Meat

This study determined whether adding condensed tannins to the diet of confined lamb improves performance, metabolism, health, and meat composition and quality. We used 24 Lacaune lambs with an average initial weight of 24.5 ± 0.24 kg. The animals were divided into 12 pens with two animals each. In the treatment group, a black wattle extract was added to the lamb concentrate (2.5 g/kg dry matter), while the control group received only the basal diet (without extract). Black wattle contained 98.6 g/kg of condensed tannin. There was no difference between the performance variables, which included weight gain, feed intake, and feed efficiency. However, the group fed on condensed tannins showed higher carcass yield and a higher percentage of linked intramuscular fat. In meat, a lower proportion of saturated fatty acids combined with higher concentrations of unsaturated fatty acids was observed in lambs of the condensed tannin group. The polyunsaturated fatty acids (PUFA) were no different; however, a higher PUFA/SFA ratio was observed in animals with condensed tannin intake, and a higher proportion of ω6 and ω3 was observed in the meat of these animals. The meat’s protein and ash content did not differ between treatments, as did the meat’s water retention capacity, color, and luminosity. Furthermore, animals that fed on condensed tannins had lower cholesterol levels and higher globulin content. The values of erythrogram variables were lower in lambs that consumed condensed tannins. More significant ruminal bacterial activity was also observed in the group receiving condensed tannins. The antioxidant effect was verified with lower thiobarbituric acid reactive species (TBARS) levels and more significant antioxidant enzyme activity. We conclude that adding condensed tannins improves carcass yield and increases the percentage of fat in the carcass, improving the fatty acid profile, which may be linked to the antioxidant effect, in addition to the health benefits of the consumer of this product.

Preparation and Properties of the Sodium Hyaluronate Composite Hydrogel for Medical Cosmetology.

As society advances, an increasing number of people are focusing on the antiaging process of the body and seeking ways to maintain youthful facial features. Intradermal injection has been used to effectively improve the rough and wrinkled skin, playing a role in skin rejuvenation. However, the main component of intradermal injection products is cross-linked sodium hyaluronate (SHA), which has biological toxicity and potential carcinogenicity. In this study, amino acids were used as hyaluronidase inhibitors and combined with non-cross-linked SHA to prepare a synergically stable SHA composite hydrogel. The effects of amino acids on the viscosity and enzyme activity of the hydrogel were investigated. To determine the stability and antioxidant properties of the composite hydrogel, the effects of the introduction of stabilizer and antioxidant on the hydrogel properties were systematically studied. The results of the in vitro study showed that the introduction of amino acids effectively reduced the activity of hyaluronidase, addressing the problem of rapid hydrolysis and the short half-life of SHA hydrogel invivo. In addition, the results revealed that NaCl stabilizer, niacinamide, and vitamin B12 antioxidants effectively maintained the stability and antioxidant properties of the hydrogels. In vivo results showed that SHA composite hydrogels had no irritating effect on the skin, and the subcutaneous experiments of mice showed that SHA composite hydrogel still retained a high content after 4 weeks. Therefore, the SHA composite hydrogels have promising applications in the field of medical cosmetology.

Impact of two arbuscular mycorrhizal fungi species on arsenic tolerance and accumulation in safflower (Carthamus tinctorius L.)

BackgroundArbuscular mycorrhizal fungi (AMF) can regulate metal(loid) tolerance in plants and their capacity for phytoremediation. These effects can vary depending on the host plant and the AMF species. The impact of different AMF species on the ability of safflower (Carthamus tinctorius L.) for arsenic (As) phytoremediation is still largely unknown. Therefore, this study aimed to assess the effect of two AMF species, Rhizophagus irregularis, and Funneliformis mosseae, on the tolerance and accumulation of As in safflower in soils spiked with varying arsenate concentrations (0, 25, 50, and 100 mg kg−1).ResultsThe results indicated that both AMF species established effective symbiotic relationships with safflower. However, plants inoculated with R. irregularis exhibited higher mycorrhizal dependency and root colonization, especially under 100 mg kg−1 As. Both AMF species significantly improved plant growth parameters, chlorophyll content, and phosphorus (P) nutrition, which resulted in increased P/As ratio and enhanced tolerance index in safflower plants. In addition, AMF inoculation reduced As-induced lipid peroxidation by enhancing catalase and peroxidase activity in leaves and roots. While the mycorrhizal symbiosis didn’t affect As availability in soils, it significantly reduced shoot As concentration and the translocation factor under all As levels. Furthermore, mycorrhizal inoculation, especially with R. irregularis, increased As concentration and modified-bioconcentration factor in the roots and enhanced total As uptake per plant.ConclusionsBased on the results and multivariate analyses, both AMF species, particularly R. irregularis, enhanced safflower's As tolerance by retaining As in roots, improving phosphorus nutrition, and increasing antioxidant enzyme activity, showcasing their potential to enhance phytostabilization in safflower plants.

Enhancing Soil Health and Tea Plant Quality Through Integrated Organic and Chemical Fertilization Strategies

As the global demand for high-quality tea increases, adopting sustainable agricultural practices is crucial to maintaining environmental health and improving crop productivity. Employing organic fertilizers has the potential to boost agricultural output and improve soil health, as well as curb the spread of pests and diseases. The purpose of this survey was to determine the impact of a range of organic fertilizer mixtures on both tea plants and rhizosphere soil characteristics in tea plantations. This study investigated the response of Jin Guanyin tea (Camellia sinensis L.) plants to various organic fertilizer ratios: 2/3 chemical fertilizer + 1/3 organic fertilizer (JTC), 1/2 chemical fertilizer + 1/2 organic fertilizer (JHOC), 1/3 chemical fertilizer + 2/3 organic fertilizer (JTO), and organic fertilizer only (JOF), with chemical fertilizer alone (JCF) as the control. The experiment was conducted in Xingcun Town, Wuyishan, Fujian Province, China, on 13 October 2021. Key metrics measured included tea plant growth indicators, soil physicochemical properties, enzyme activities, and microbial functional diversity. Results show that JTC and JTO produce the largest leaf area and bud weight, significantly surpassing those in JCF. JCF demonstrated the longest new tip length and highest bud density, while JHOC achieved the highest chlorophyll content, significantly exceeding JCF. Soil analysis revealed that total nitrogen, available nitrogen, organic matter, and pH were highest in JOF, significantly overtaking JCF. Conversely, total phosphorus, available potassium, and available phosphorus levels were highest in JCF. JHOC also had the highest total potassium content compared to JCF. Soil enzyme activity assessments showed that polyphenol oxidase and urease activities peaked in JTC, significantly exceeding those in JCF. JHOC exhibited the highest acid phosphatase activity, while JTO exhibited the highest protease activity. Catalase activity was highest in JOF, both significantly surpassing JCF. Microbial functional diversity analysis indicated that combined organic fertilization improved soil microorganisms’ utilization of carbon sources, significantly enhancing the Shannon diversity index and evenness. Key carbon sources identified included α-cyclodextrin, D-galacturonic acid, and 4-hydroxy benzoic acid. Overall, JHOC emerged as the optimal fertilization strategy, yielding superior growth indicators, enhanced soil physicochemical properties, increased enzyme activity, and improved microbial functional diversity compared to JCF. This study has important value for guiding the rational application of fertilizers in tea gardens, improving the soil environment of tea gardens, enhancing the quality of tea leaves, and achieving sustainable tea production.

Hybrid Soybean as Green Manure for Improving Soil Properties and Subsequent Crop Growth

The rapid increase in fertilizer use has led to the degradation of soil quality, nutrient imbalances, reduced biodiversity, and soil compaction. To address these challenges, hybrid soybeans with efficient biological nitrogen fixation capabilities and broad environmental adaptability were selected as green manure to reduce fertilizer application, thereby improving soil fertility and structure. This study utilized the varieties “Forage Soybean S001” (S001), “Neinong S002 Forage Soybean” (S002), “Mengnong S003 Forage Soybean” (S003), “Mengnong S004 Forage Soybean” (S004), “Mengnong S005 Forage Soybean” (S005), and “Mengnong S006 Forage Soybean” (S006) as green manure materials. The clean tillage (CK) treatment served as the control, ensuring a residue-free soil surface while maintaining consistent practices in soil preparation, irrigation, and field management across all treatments. Field planting of green manure and subsequent crops was conducted at the M-Grass Ecology and Environment (Group) Company’s experimental site in Hohhot in early May of 2023 and 2024. The plots each measured 20 m2, with three replications arranged in a randomized block design. A combination of field experiments and laboratory analyses was utilized to investigate the effects of incorporating various hybrid soybean varieties as green manure on soil nutrient levels, soil enzyme activity, soil microbial communities, and the subsequent growth of oats. The results indicated that incorporating various hybrid soybean varieties as green manure into the soil significantly improved soil nutrient levels and enzyme activity. The diversity and richness of soil bacterial communities increased significantly, accompanied by alterations in community structure and composition. These changes enhanced soil fertility and optimized the microbial community structure, promoting the growth of subsequent crops. Among all the treatments, S001 and S004 were particularly effective in enhancing the soil environment, indicating their potential as superior green manure resources for broader application.

Enhancing soil quality in intensive rice cultivation through short-term growth of green manure and its incorporation combined with rice husk or its ash: a laboratory incubation study

ABSTRACT A novel approach, i.e. mung bean was grown in paddy soil for 1 month as a pre-rice crop, which is a short but a feasible period applicable to the current intensive rice monoculture cropping system in the Vietnamese Mekong Delta. This study aimed to assess how short-term growth of green manure and its incorporation combined with rice husk or its ash impact the soil quality of sandy loam soil and silty clay soil. Four treatments, viz. soil without mung bean (control), soil plus mung bean incorporation, soil plus mung bean and rice husk of 10 Mg ha−1, and soil plus mung bean and rice husk ash of 5 Mg ha−1, were established. Different soil parameters were determined to evaluate their initial effects after incubating for 60 days. In both soils, the incorporation of mung bean significantly increased β-glucosidase, acid phosphatase, and urease activities, as well as C mineralization compared with control. Soil labile C was increased by 15–50% by incorporation of mung bean, irrespective of the application of rice husk or its ash, compared to that in control. The highest total C and available N were found in mung bean combined with rice husk followed by mung bean with rice husk ash, only mung bean, and control. Sandy loam soil with a lower exchangeable K level showed significant improvements in the exchangeable K content with rice husk and its ash amendments. Therefore, these practices, short-term green manure planting, could offer benefits to farmers for enhancing soil quality such as enzyme activities in the intensive paddy cultivation.

Short‐term effects of a heavy dairy manure application on soil chemical and biological indicators in an irrigated semiarid cropping system

AbstractIntensive dairy production in southern Idaho is associated with the annual application of manure to croplands. However, a one‐time heavy application of manure could alternatively be used as a means to improve soil fertility and health for years or even decades, circumventing the need for frequent applications. To determine if this practice would negatively affect soil properties in the short term, we analyzed chemical and biological indicators of soil health for 2 years after dairy manure incorporation. Soil indicators measured were pH, electrical conductivity, extractable nitrogen (N) and phosphorus, total carbon (C) and N, enzyme activities, net N mineralization, soil organic C, soil protein, active C, ammonia oxidation potential, and particulate organic matter. Manure (with and without synthetic fertilizer) was found to significantly affect chemical and biological indicators in both topsoil (0–15 cm) and subsoil (15–30 cm), but the responses were greater in the subsoil. This can be attributed to the fact that manure was incorporated to approximately 30 cm via moldboard plow. All indicators responded positively to manure, except pH, which decreased slightly in the subsoil in the first year after application. Principal component analysis of chemical and biological indicators, across all years and depths, showed that the first two components explained 62% and 8.5% of the variance. While soil indicators were not adversely affected by manure, silage corn (Zea mays L.) yields in year 1 were significantly lower in manured plots, though in year 2, barley grain (Hordeum vulgare L.) yields were statistically similar among manure and fertilizer.

Weed management modifies functional properties of both weeds and microbial nitrogen‐cycling communities in Mediterranean vineyards

Abstract Nitrogen (N) availability is crucial to maintaining crop productivity in agroecosystems, driven primarily by soil microbial processes such as nitrification and denitrification. Weeds are an integral part of agroecosystems and are involved in many processes related to the N cycle, but how weed management could shift plant–microbe interactions, and thus, N‐cycling is yet to be determined. Using a network of 15 Mediterranean vineyards, we quantified the effect of 5 years of different weed management practices (chemical weeding, tillage, mowing) on the above‐ground and below‐ground functional properties of weed communities and soil microbial N‐cycling. Specific root length (SRL) of the tilled and mowed weed communities were 30% and 44% lower than in the herbicide‐treated weed communities. Soil pH and texture were the main drivers of soil microbial activity as quantified by substrate‐induced respiration (SIR), potential denitrifying enzyme activities to SIR ratio (PDEA:SIR) and potential nitrifying and denitrifying enzyme activity ratio (PNEA:PDEA). SIR was also impacted by the management: Mowed weed communities had 58% higher SIR compared to herbicide‐treated communities. Weed communities with high SRL were associated with soils with a higher nitrifying enzyme efficiency per unit of respired carbon. Synthesis and applications. Overall, our findings indicate that vineyard weed management influences the potential nitrifying enzyme activities by modifying the root strategies of weed communities. This study highlights that the design of sustainable weed management strategies should incorporate unintended effects on soil microbial communities and N‐cycling.

Selective Lipophilization of Natural Phenolic Alcohols Induced by In Situ Choline Chloride-Based Natural Deep Eutectic Solvents.

In this scientific work, a novel and green method for selective lipophilization of EVOO's bioactive phenolic alcohols (PAs), namely, tyrosol, hydroxytyrosol, and its metabolite homovanillyl alcohol as fatty acid esters, is elucidated. The PAs have been employed as hydrogen bond donors in the formation of natural deep eutectic solvents (NADES) with choline chloride (ChCl). The fast and cheap esterification method by in situ formation of choline chloride-based deep eutectic solvents promotes the derivatization of PAs with various fatty acids as acylating agents in the absence of organic solvents and catalysts. Furthermore, given the growing interest in the application of NADES formed by bioactive molecules in the pharmacological and cosmetic fields, we analyzed the activity of antioxidant enzymes, superoxide dismutase, and glutathione S-transferase of three chemical formulations obtained after the formation of PA-oleate in the H2O2-treated HaCat human keratinocytes cell line, assessing also their toxicity via the MTT assay.

Biocontrol Potential of Endophytic Bacillus velezensis LSR7 Against Rubber Red Root Rot Disease

To obtain an effective bacterial biocontrol strain against the fungal pathogen Ganoderma pseudoferreum, causing rubber tree red root rot disease, healthy rubber tree tissue from Baisha County, Hainan Province, was selected as the isolation source, and bacterial strains with strong antifungal effects against G. pseudoferreum were screened. The strain was identified by molecular biology, in vitro root segment tests, pot growth promotion tests, and genome detection. The strain was further evaluated by biological function tests, genome annotation analysis, and plant defense-related enzyme activity detection. The results show that strain LSR7 had good antagonistic effects against G. pseudoferreum, and the inhibition rate reached 88.49%. The strain LSR7 was identified as Bacillus velezensis by genome sequencing. In a greenhouse environment, LSR7 prevents and treats red root rot disease in rubber trees and promotes the growth of rubber tree seedlings. LSR7 secreted cell wall hydrolases (protease, glucanase, and cellulase), amylases, and siderophores. LSR7 also formed biofilms, facilitating plant colonization. Genome prediction showed that LSR7 secreted multiple antifungal lipopeptides. LSR7 enhanced rubber tree resistance to G. pseudoferreum by increasing the activity of defense enzymes. Bacillus velezensis LSR7 has biocontrol potential and is a candidate strain for controlling red root rot disease in rubber trees.

Caffeic acid improves biocontrol effect of Pantoea jilinensis D25 against tomato gray mold.

Gray mold in tomato caused by Botrytis cinerea is a destructive disease, which can be treated using biocontrol agents. Pretreatment of biocontrol strains with oxidative-stress-ameliorating compounds can enhance their tolerance to oxidative microenvironment in infected fruit wounds. In this study, we aimed to determine the effect of caffeic acid (CA) on the biocontrol efficacy of Pantoea jilinensis D25 in gray mold in cherry tomato. D25 strain pretreated with CA exhibited enhanced oxidative stress response in cherry tomato wounds. CA-treated D25 cells recovered from cherry tomato wounds had lower ROS level and cellular oxidative damage than D25 cells not treated with CA. The antioxidation-related genes (CAT and GPX) were upregulated and colonization ability of D25 strain was improved in cherry tomato wounds after CA application. Furthermore, the biocontrol effects of CA-treated D25 strain were improved. CA pretreatment to D25 strain could significantly improve the expression of defense-related genes (SlMYC-2, SlLoxD, SlEIN2, and SlEIN3) and activity of defense-related enzymes in cherry tomato wounds. Application of CA to D25 strain could improve its ability to combat antioxidant stress and biocontrol efficacy against postharvest tomato gray mold. © 2024 Society of Chemical Industry.

Co-Application of Nitric Oxide and Melatonin Alleviated Chromium-Induced Oxidative Stress and Improved Edible Flower Quality of Calendula officinalis L.

Plant small molecules, such as nitric oxide (NO) and melatonin (MN) as natural and human health-friendly compounds, play important roles in the mitigation of abiotic stresses in plants. Heavy metals such as chromium (Cr) are hazardous for the survival of ornamentals, especially edible flowers. This study evaluated the effects of NO (50 µM; sourced as sodium nitroprusside) and MN (50 µM) applied two times through foliar spraying at 1-week intervals on alleviating Cr (120 µM; K2Cr2O7)-induced oxidative stress in edible flowers of Calendula officinalis cv. Orange King. Cr stress decreased plant dry mass, leaf SPAD values, net photosynthetic rates, and the maximum photochemical quantum yield (Fv/Fm), and increased the oxidative stress markers. The individual application of NO or MN significantly mitigated the adverse effects, and the combined application of NO and MN synergistically enhanced plant tolerance to Cr stress, including increased activities of antioxidant enzymes in plants and concentrations of carbohydrate, ascorbic acid, sugar, total protein, as well as ash contents of edible flowers. The co-application also significantly elevated the concentrations of total phenolics, flavonoids, free reducing power, antioxidant capacity DPPH, and total carotenoids in Cr-treated plants compared with those in Cr-stressed plants. Additionally, the essential oil contents in flowers increased in response to the signaling molecule treatment under Cr stress. Compared with individual applications, the co-application of NO and MN had more significant effects. Our results indicate that the combination of signaling molecules, such as MN and NO, can not only increase the biomass of edible calendula plants but also improve flower quality for use as a novel food.