N-acetylglucosaminidase Research Articles

Response of soil nitrogen mineralization, nitrification and denitrification to milk vetch (Astragalus sinicus L.) application in a paddy field

We conducted incubation experiments with a paddy soil collected from a long-term field experiment to explore the effect of Chinese milk vetch (Astragalus sinicus L., CMV) application on potential nitrogen (N) denitrification (PDA), nitrification (PNA), mineralization (PNM), soil chemical properties, microbial communities, enzyme activities, yields and nutrient uptake of rice under different fertilization treatments. Five treatments were included: no chemical fertilizers (C0), chemical fertilizers (C100), Chinese milk vetch (M), CMV combined with 100% chemical fertilizers (MC100) and with 80% chemical fertilizers (MC80). Results showed that the M, MC100, and MC80 treatments significantly increased PNM and PNA compared with the C100 treatment (P < 0.05). Meanwhile, the CMV application significantly increased total N, microbial biomass N, and carbon (C) concentrations, the abundances of the bacterial phylum Actinobacteria, and the genera Bradyrhizobium, Mycobacterium, Streptomyces and Reyranella, N-acetyl-glucosaminidase (NAG) activity, yields and N nutrient uptake of rice grain compared with the C100 treatment (P < 0.05). Correlation analyses indicated that grain yield and N uptake of rice, soil total N, microbial biomass C and N, the bacterial phylum Actinobacteria, the genera Bradyrhizobium, Mycobacterium, Streptomyces, Reyranella, and NAG were significantly correlated with PNM under different fertilization regimes, while microbial biomass C and N, Actinobacteria, Bradyrhizobium, and Reyranella were positively related to PNA (P < 0.05). Together, the application of CMV alone or in combination with chemical fertilizers can improve soil properties and rice growth, which may accelerate N mineralization and nitrification in this soil.

Effects of inoculation with Bacillus arenosi on physical and biochemical properties of soil, surface runoff and erosion in degraded forestlands of Northern Iran

A viable practice to improve key properties of soil, and reduce runoff generation and erosion may be inoculation with selected bacteria. However, no previous studies have evaluated whether the direct inoculation of Bacillus arenosi K64 (hereafter simply indicated as B. arenosi) to soil impacts the main physical and biochemical properties of soil as well as the runoff and erosion rates. This study has measured the infiltration rate (IR), tensile strength (TS), mean weight diameter (MWD), polysaccharides (PS) and important enzymes of soil (β-glucosidase, N-acetyl glucosaminidase, phosphatase and arylsulphatase) in degraded forest soils (Northern Iran) inoculated with B. arenosi in comparison to untreated soils (control). Moreover, the runoff coefficient and soil loss have been measured in plots with soil sampled in those sites under natural rainfalls. IR, TS and MWD increased by 65 % to 160 % in treated soils compared to the control. PS and enzymes were significantly higher (by 20 % to 200 %) after soil inoculation. A noticeable decrease in both surface runoff and soil loss (both by 45 %) in the inoculated soils resulted from those changes. High correlations between the hydrological response of soil on one side, and the measured physical and biochemical variables on the other side were observed. A derivative variable calculated by the Principal Component Analysis can be considered as a meaningful parameter to estimate the changes in soil properties and response due to inoculation with bacteria. Agglomerative Hierarchical Cluster Analysis clearly discriminated the treated from the untreated soils. This study has demonstrated that soil inoculation with B. arenosi plays a significant role in reducing runoff generation and soil erosion under the experimental conditions, thanks to the general improvement in physical and biochemical properties of soil.

Abstract MP32: Megalin and lysosomal disruption in the kidney epithelial cells of high salt diet fed rats: protective role of angiotensin II type 2 receptor

Earlier we have reported that 2-days high salt diet (HSD) feeding caused proteinuria in obese rats and the AT 2 R agonist treatment prevented proteinuria. Since HSD feeding for 2 days and the AT 2 R activation did not affect blood pressure, GFR, glomerular structure, and inflammation, the mechanism responsible for proteinuria remains unknown. Megalin is a proximal tubule epithelial cells endocytic receptor responsible for filtered protein reabsorption. The absorbed proteins are directed to lysosomes for degradation. Lysosomes is a nutrient sensing subcellular compartment and a critical part of the endocytic machinery and cellular trafficking. We hypothesized that high salt intake caused lysosomal stress, which negatively impacted megalin-protein cellular trafficking and thus caused proteinuria. Therefore, we evaluated the markers of lysosomal stress and megalin expression in the proximal tubules of HSD fed obese Zucker rats. Urinary excretion of N-acetyl-glucosaminidase (NAG), which is a marker of lysosomal injury and oxidative stress, was significantly increased in HSD fed rats compared with normal salt diet (NSD: 16.6 vs HSD: 40.5 RFU/hr/µg Cr). This increase was associated with an increase in another oxidative stress marker H 2 O 2 in the urine (NSD: 0.37 vs HSD: 1.72 ΔRFU/min). Confocal analysis revealed that megalin was localized in the lysosomes in HSD fed rats, as megalin was co-localized with the lysosomal marker LAMP-1 in the proximal tubules. Moreover, in HSD fed rats there was a remarkable increase (2-fold) in the lysosomal size (fig) and number per tubule (NSD: 18 vs HSD: 48). The AT 2 R agonist C21 (0.3 mg/Kg/day, i.p.) treatment of HSD-fed rats restored surface megalin expression, reduced urinary NAG and H 2 O 2 and the lysosomal number and size. Our in vitro studies performed in OK cells (proximal tubule epithelial cells) treated with high NaCl (100 mM) without/with the AT 2 R agonist C21 (1µM) also revealed that compared to NSD, high NaCl reduced megalin surface expression and C21 treatment prevented it. We conclude that high salt intake causes lysosomal stress. Particularly, large lysosomal size potentially is affecting endocytic machinery, including impairing megalin-protein dissociation and megalin recycling, thus causing proteinuria.

Effects of climate warming on soil nitrogen cycles and bamboo growth in core giant panda habitat

Climate change can pose a significant threat to terrestrial ecosystems by disrupting the circulation of soil nitrogen. However, experimental analyses on the effect of climate change on soil nitrogen cycles and the implications for the conservation of key wildlife species (i.e., the giant panda, Ailuropoda melanoleuca) remain understudied. We investigated the effects of a 1.5 °C, 3 °C, and 4.5 °C temperature increase on nitrogen distribution in different soil layers of bamboo forest via an in-situ experiment and assessed the implications for the growth and survival of arrow bamboo (Bashania faberi), a critical food resource for giant pandas. Our results showed that warming treatments generally increased soil N content, while effects differed between surface soil and subsurface soil and at different warming treatments. Particularly an increase of 1.5 °C raised the subsurface soil NO3-N content, as well as the content of N in bamboo leaves. We found a significant positive correlation between the subsurface soil NO3-N content and the N content of arrow bamboo. An increase of 3–4.5 °C raised the content of total N and NO3-N in the surface soil and led to a reduction in the total aboveground biomass and survival rate of arrow bamboo. Limited warming (e.g., the increase of 0–1.5 °C) may promote the soil N cycle, raise the N-acetylglucosaminidase (NAG) enzyme activity, increase NO3-N in subsurface soil, increase the N content of bamboo, and boost the biomass of bamboo – all of which could be beneficial to giant panda survival. However, higher warming (e.g., an increase of 3–4.5 °C) resulted in mass death of bamboo and a large reduction in aboveground biomass. Our findings provide a cautiously optimistic scenario for bamboo forest ecosystems under low levels of warming over a short period of time, but risks from higher levels of warming may be serious, especially considering the unpredictability of global climatic change.

#412 Influence of SGLT2I on tubulointerstitium in DKD patients with moderate renal dysfunction

Abstract Background and Aims In the FAGOTTO study (jRCTs041200069) to evaluate changes of renal hemodynamics on initial glomerular filtration rate (GFR) dip induced by Sodium-glucose cotransporter 2 inhibitors (SGLT2i) in patients (pts) with type 2 diabetic kidney disease (DKD) and moderate renal dysfunction, we reported that SGLT2 inhibition maintained the levels of glomerular filtration fraction (FF) and renal vascular resistance (RVR) during decrease in GFR as well as renal plasma and blood flow. In this sub analysis, we evaluated if GFR dip by SGLT2i might induce tubulointerstitial disorder by measuring urinary biomarkers. Method The FAGOTTO study was a 12-week multicenter, open-label, randomized (1:1), parallel-group study treated with Canagliflozin (Group CA) or control groups (Group CO) in DKD pts with 30 ≤ estimated GFR (eGFR) ≤ 60 mL/min/1.73 m2. Urinary biomarkers including liver-type fatty-acid binding protein (L-FABP), N-acetyl-glucosaminidase (NAG), β2-microglobulin (β2MG) and monocyte chemoattractant protein-1 (MCP-1) were measured at baseline, 4 weeks and 12 weeks after start of the trial. The adjusted mean and SE for changes were calculated at each time point by a linear mixed model with baseline values, time point, and interaction of the treatment group as the fixed effects. We compared these changes between treatment the groups the Tukey-Kramer method to correct for multiplicity. Results The adjusted mean changes in L-FABP at the 4-week and 12-week time point after trial start were estimated −0.35 and −0.17 μg/gCr in Group CA and 0.06 and 1.23 μg/gCr in Group CO in a linear mixed model, respectively. Similarly, the changes were estimated 2.63 and 3.71 U/gCr in Group CA and 1.38 and −1.21 U/gCr in Group CO in NAG, 317.7 and 291.4 μg/gCr in Group CA and 416.6 and 375.1 μg/gCr in Group CO in β2MG and 19.6 and 64.6 pg/gCr in Group CA and −7.7 and −2.7 pg/gCr in Group CO in MCP-1, respectively. When compared the changes in L-FABP, NAG, β2MG and MCP-1 between Group Ca and Group Co by Tukey-Kramer multiple-comparison test, there were no significant differences in any biomarkers. (Figure). Conclusion In this analysis, no significant difference in any of these biomarkers was detected in Group CA compared to those in Group CO at 4 weeks and 12 weeks after administration of SGLT2i. Although further studies should be needed to conclude, transient decrease in GFR after administration of SGLT2i might not be involved with tubulointerstitial damage and our study gives one evidence as a safety information in use of SGLT2i to DKD pts with moderate renal dysfunction.

Short rotation willow to restore degraded marginal land and enhance climate resiliency within the Prairie Pothole Region: A potential nature-based solution

Short rotation willow (SRW) is a land management strategy involving the cultivation of rapidly growing, biomass-rich herbaceous-woody plants. This practice holds promise for renewable energy production, water quality preservation, carbon sequestration, greenhouse gas (GHG) mitigation, enhancement of soil extracellular enzyme activities (EEAs), and promotion of overall soil health. The rapid growth of SRW demands substantial water and nutrient resources, posing concerns when cultivated in marginal riparian lands within the Prairie Pothole Region (PPR), potentially leading to alterations in groundwater table (GWT) depth fluctuations, elevated soil salinity levels, and disruptions to biogeochemical cycles. Hence, this study comprehensively evaluated the effects of establishing SRW as a degraded marginal riparian land use practice in the PPR and attempted to answer several vital questions in the field and microcosm scale on soil hydrology, salinity, nutrients, soil organic carbon (SOC), GHG emissions, and EEAs involved in biogeochemical cycling. In a field experiment, the effects of SRW were evaluated by measuring the depth to GWT, groundwater and soil electrical conductivity (EC), macronutrients (N, P, K, and S), and SOC content in different fractions and chemical compositions during the first rotation (3-year cycle) compared with adjacent annual crop and pasture in two semi-arid PPR sites. In a microcosm experiment, GHG (CO2, CH4, and N2O) emissions and EEAs [β-glucosidase (BG), N-acetyl glucosaminidase (NAG), and alkaline phosphatase (AP)] were measured in intact soil cores treated with declining water tables and different groundwater salinity levels. No consistent land use impacts on GWT or soil EC were observed between sites. Land use in site B significantly impacted GWT depth, implying site-specific factors, such as topography and soil characteristics, may be dominant over land use effects. Under SRW, the levels of macronutrients in the soil varied but did not significantly reduce the overall nutrient content of the soil. Total SOC was highest in pasture; light fraction organic carbon and particulate organic carbon followed a similar land use pattern, i.e., pasture > SRW = annual crop. Land uses affected GHG emissions significantly in the order of pasture > annual crop = SRW. GHG emission varied with salinity and GWT but there was no interaction with land use practices. Soil EEAs were significantly impacted by different land uses, i.e., pasture > annual crop = SRW, suggesting that the effects resulted from associated SOC. Our microcosm experiment suggests that the SRW land use practice holds promise as a sustainable Nature-Based Solution for enhancing climate resiliency in PPR. It exhibits a lower global warming potential compared to annual crop and pasture. Therefore, widespread implementation of the SRW land use practice in degraded marginal land could help mitigate the effects of climate change in the region.

Effectiveness of a tissue conditioner containing antifungals in a rat model of denture stomatitis.

This study investigated the effectiveness of a drug-modified tissue conditioner in an animal model of denture stomatitis. Wistar rats wore a Candida albicans-contaminated palatal device for 4 days. Next, nystatin (Nys) or chlorhexidine (Chx) were added to a tissue conditioner in their raw or β-cyclodextrin-complexed (βCD) forms at their minimum inhibitory concentrations. As controls, one group was not subjected to any procedure (NC), one group used sterile devices, one group had denture stomatitis but was not treated (DS), and another had the devices relined with the tissue conditioner without the addition of any drug (Soft). After 4 days of treatment, treatment effectiveness was assessed visually, histologically, and through CFU count, and myeloperoxidase (MPO) and N-acetylglucosaminidase (NAG) assays. Rats from the Soft, Nys, Nys:βCD, and Chx groups presented a significant decrease in the microbial load compared with the untreated group. Treatment groups showed lower MPO and NAG activity compared to the non-treated group. The addition of antifungals to a soft tissue conditioner can be a promising approach for denture stomatitis treatment.

Substitution of Inorganic Fertilizer with Organic Fertilizer Influences Soil Carbon and Nitrogen Content and Enzyme Activity under Rubber Plantation

Conventional fertilization practices can lead to many ecological problems, such as nutrient imbalance, soil acidity, and reduced soil fertility, in natural rubber plantations. To address these challenges, a field investigation was strategically carried out to substitute inorganic fertilizer with organic fertilizer, consisting of six treatments: no fertilization (CK), inorganic fertilizer (NPK), 25% replacement of inorganic through organic (25% manure (M)), 50% replacement of inorganic through organic (50% manure (M)), 75% replacement of inorganic through organic (75% manure (M)), and 100% organic fertilizer (100% manure). The soil physicochemical properties (soil organic carbon (SOC), total nitrogen (TN), mineral nitrogen (N), ammonium nitrogen (NH4+-N), and nitrate nitrogen (NO3−-N)), C:N, pH, and the carbon- and nitrogen-converting enzymes β-1,4-glucosidase (BG), N-acetylglucosaminidase (NAG) and L-leucine aminopeptidase (LAP) were all determined. The partial substitution of inorganic fertilizer with organic fertilizer (i.e., 75% M at surface soil layer) showed higher SOC (14.52 g·kg−1), TN (1.06 g·kg−1), N (20.07 mg·kg−1), C:N (14.63), NH4+-N (10.63 mg·kg−1), and NO3−-N (11.06 mg·kg−1) than NPK and CK. This increase in physicochemical properties after partial replacement of inorganic with organic fertilizer resulted from higher carbon and nitrogen enzyme activities (BG (143.17·nmol·g−1·h−1), NAG (153.96 nmol·g−1·h−1), and LAP (153.48 nmol·g−1·h−1)) compared to NPK and CK. Further, the Pearson correlation and redundancy analysis (RDA) analyses confirmed a significant positive correlation between SOC, N, and soil enzymes. This study presents a new strategy for assessing the impact of partially replacing inorganic fertilizer with organic fertilizer in rubber plantations in tropical regions, mainly by modifying the soil nutrient composition.

Nutrient Uptake Potential of Nonleguminous Species and Its Interaction with Soil Characteristics and Enzyme Activities in the Agro-ecosystem.

The potential nutrient uptake abilities of a plant are essential for improving the yield and quality. Green manures can take up a huge amount of macronutrients from the soil. The mechanisms underlying the differences in nutrient uptake capacity among different nonlegume species remain unclear. The plot experiments were conducted to investigate the performance of nonlegume species including forage radish (Raphanus raphanistrum subsp. sativus), oil radish (Raphanus sativus var. Longipinnatus), February orchid (Orychophragmus violaceus L), and rapeseed (Baricca napus), while a ryegrass (Lolium perenne L.) species was used as a control. The study results showed that forage radish had the highest nutrient uptake (N and P), i.e., 322 and 101% in Hunan and 277 and 469% in the Sichuan site, respectively, compared with the control. While the greatest K uptake was found in forage radish, i.e., 123%, and February orchid, 243%, in the Hunan and Sichuan sites. Forage radish also presented higher phosphorus use efficiency in both experimental areas: Hunan by 301% and Sichuan by 633% compared to the control. Significant modifications were found in nutrient availability and enzyme activities after the cultivation of various species. The oil radish enhanced the β-glucosidase (BG) and leucine-aminopeptidase enzyme activities by 324 and 367%, respectively, while forage radish developed the highest phosphatase (Phase) and N-acetyl-glucosaminidase (NAG) activities compared to the ryegrass in Hunan. In the Sichuan site, the oil radish promotes enzyme activities such as Phase (126%), BG (19%), and NAG (17%), compared to the control. It is concluded that forage radish, oil radish, and February orchid can easily improve soil nutrient quality in green manuring practices and provide valuable nutrient management systems.

Effect of biochar on soil microbial community, dissipation and uptake of chlorpyrifos and atrazine

For the application of biochar in restoring pesticide-contaminated soils and minimizing the risk associated with their uptake in plants, it is crucial to understand the biochar impact on soil biological activities and dissipation and accumulation of pesticides in plant and soil systems. In this study, the effect of Mentha-distilled waste-derived biochar was investigated on chlorpyrifos and atrazine contaminated sandy loam soil. The four application rates of atrazine (2, 4, 6, and 8 mg kg−1) and chlorpyrifos (2, 4, 6, and 12 mg kg−1) and a single application rate of biochar (4%) were used in this study. The degradation of pesticides, the diversity of the bacterial community, and enzymatic activities (alkaline phosphatase, dehydrogenase, arylsulfatase, phenol oxidase, urease activity and N-acetyl glucosaminidase) were examined in soil. The uptake of two pesticides and their effect on growth and stress parameters were also investigated in plants (A. paniculata). The dissipation of chlorpyrifos and atrazine followed simple first-order kinetics with a half-life of 6.6–74.6 and 21–145 days, respectively. The presence of deisopropyl atrazine desethyl atrazine (metabolites of atrazine) and 3,5,6-trichloro-2-pyridinol (a metabolite of chlorpyrifos) was observed in soil and plant tissues. Biochar application significantly (p = 0.001) enhanced the degradation rate of chlorpyrifos and atrazine leading to the lower half-life of chlorpyrifos and atrazine in soil. A significant reduction (p = 0.001) in the uptake of chlorpyrifos and atrazine and alteration in their binding affinity and uptake rate in plant tissues was observed in biochar treatments. The incorporation of biochar improved chlorpyrifos/atrazine degrader and plant growth-promoting bacterial genera such as Balneimonas, Kaistobacter, Rubrobacter, Ammoniphilus, and Bacillus. The upregulation of functional genes associated with nucleotide, energy, carbohydrate, amino acid metabolism, xenobiotic biodegradation, and metabolism: atrazine degradation was observed in biochar treatments. The biochar amendments significantly (p = 0.001) reduced the plant’s uptake velocity (Vmax) and affinity (Km) of chlorpyrifos and atrazine. These results delineated that Mentha-distilled waste-derived biochar can potentially remediate chlorpyrifos and atrazine contaminated soils and ensure the safety of plants for consumption.Graphical

Understory vegetation had important impact on soil microbial characteristics than canopy tree under N addition in a Pinus tabuliformis plantation

Forest ecosystem is a complex community, and its soil microbes play a vital role in global matter cycling. However, the patterns of rhizosphere soil microbial characteristics among tree-shrub-grass and their responses to nitrogen (N) deposition are still unclear. This study evaluated the microbial biomasses, processes (gas fluxes), and enzyme activities in the rhizosphere soils of tree (Pinus tabuliformis), shrub (Rosa xanthina), and grass (Carex lanceolata) and their responses to N addition (0, 3, 6, 9 g N m−2 y−1 corresponding to N0, N3, N6, N9) in a P. tabuliformis plantation. (1) Microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), microbial biomass phosphorus (MBP) contents, as well as CO2, CH4 flux rates in the rhizosphere soil of C. lanceolata were significantly higher than those in the rhizosphere soils of P. tabuliformis and R. xanthina (P < 0.05). The activities of alkaline phosphatase (ALT), leucine aminopeptidase (LAP), β-glucosidase (BG), D-cellulosidase (CBH), N-acetyl-glucosaminidase (NAG), and xylosidase (XYL) in the rhizosphere soils of C. lanceolata and R. xanthina were significantly higher than those in the rhizosphere soil of P. tabuliformis. (2) Soil MBC content, N2O, and CH4 flux rates increased after N addition, while the CO2 flux rate decreased. MBP content initially increased and then reduced with N additions, and the maximum values observed in N3 or N9 treatments. (3) In the rhizosphere soil of P. tabuliformis, N addition enhanced the NAG, BG, CBH, and XYL activities. While low N increased and high N decreased these enzyme activities in the rhizosphere soils of C. lanceolata and R. xanthina, with the maximum values obtained in N3 treatment. (4) N addition directly reduced the CO2 flux rate and indirectly enhanced the gas flux rate by increasing soil MBC and MBP contents. Species change indirectly affected the microbial biomass and enzyme activity by altering soil chemical properties, which eventually affected gas flux rates. Our study emphasizes the effects of tree-shrub-grass on soil microbial characteristics, which can improve the evaluation of soil ecological processes and responses to N deposition in forest ecosystems.

Changes in the activity of soil enzymes after fire

Fire can have widespread impacts on biogeochemical processes of carbon (C) and nutrient cycling. Soil extracellular enzyme activity (EEA) plays crucial roles in biogeochemical processes, while the general response pattern of EEAs to fire remains elusive. Here, we synthesized 1064 paired observations of fire effects on eight soil EEAs of β-D-Cellobiosidase (CB), β-1,4-Glucosidase (BG), β-1,4-Xylosidase (XYL), N-acetyl-glucosaminidase (NAG), urease (URE), phosphatase (PHO), peroxidase (PER), and phenol oxidase (POX) from 51 publications on a global scale. Results showed that fire significantly decreased hydrolases of C acquisition (sum of CB, BG, and XYL), N acquisition (sum of URE and NAG), and P acquisition (PHO) EEAs by 21.0%, 25.5%, and 29.9%, respectively. In contrast, fire significantly enhanced oxidative enzyme (sum of PER and POX) activities by 12.4%. Among all experimental, environmental, and soil variables, ecosystem type and soil C and N had greater effects on the various responses of EEAs to fire across studies. In addition, changes in soil C and N pools and microbial biomass were positively correlated with changes in hydrolytic EEAs but negatively correlated with changes in oxidative EEAs. These results suggest that the differential fire effects on soil hydrolytic and oxidative EEAs may be a crucial mechanism regulating soil C and nutrient cycling following fire events.

Comparison of microbial colonization between natural and plastic substrata in a polluted watershed.

Plastic pollution represents a threat for biological communities and the ecological functions they provide in river ecosystems. In this study, we compared the microbial colonization of two plastics (biodegradable and non-biodegradable) and three natural substrata (leaves, sediment and rocks) in two study sites of an urbanized watershed differing in their plastic-contamination degree (upstream and downstream). The density and diversity of bacterial, fungal and algal communities, as well as the extracellular enzymatic activities β-glucosidase (GLU), N-acetyl-glucosaminidase (NAG) and phosphatase (PHO), were analyzed in each substrata and site over a four-week colonization experiment. Results showed higher microbial densities and enzymatic activities in leaves and sediment compared to plastics and rocks, probably due to the greater availability of organic carbon and nutrients in the former substrata. However, the microbial colonization of the two plastics was only different in the downstream site where bacterial density and enzymatic activities were higher in the biodegradable compared to the non-biodegradable plastic. Accordingly, the presence of biodegradable plastics would enhance the heterotrophic metabolism in plastic-polluted rivers.

Potential impacts of seasonal and altitudinal changes on enzymatic peat decomposition in the High Andean Paramo region of Ecuador

The Andean Paramo is a vast ecosystem, characterized by distinct vegetational zones at several altitudinal levels with huge water storage and carbon fixation capacity within its peat-like andosols, due to a slow decomposition rate of organic matter. These characteristics become mutually related as enzymatic activities increase with temperature and are associated with oxygen penetration, restricting the activity of many hydrolytic enzymes according to the enzyme Latch Theory. This study describes the changing activity of sulfatase (Sulf), phosphatase (Phos), n-acetyl-glucosaminidase (N-Ac), cellobiohydrolase (Cellobio), β-glucosidase (β-Glu), and peroxidase (POX) on an altitudinal scale from 3600 to 4200 m, in rainy and dry seasons at 10 and 30 cm sampling depth, related to physical and chemical soil characteristics, like metals and organic elements. Linear fixed-effect models were established to analyze these environmental factors to determine distinct decomposition patterns. The data suggests a strong tendency towards decreasing enzyme activities at higher altitudes and in the dry season up to two-fold stronger activation for Sulf, Phos, Cellobio, and β-Glu. Especially the lowest altitude showed considerably stronger activity of N-Ac, β-Glu, and POX. Although sampling depth revealed significant differences for all hydrolases but Cellobio, it had minor effects on model outcomes. Further organic rather than physical or metal components of the soil explain the enzyme activity variations. Although the levels of phenols coincided mostly with the soil organic carbon content, there was no direct relation between hydrolases, POX activity, and phenolic substances. The outcome suggests that slight environmental changes with global warming might cause important changes in enzyme activities leading to increased organic matter decomposition at the borderline between the paramo region and downslope ecosystems. Expected extremer dry seasons could cause critical changes as aeration increases peat decomposition leading to a constant liberation of carbon stocks, which puts the paramo region and its ecosystem services in great danger.

Short-term prescribed fire-induced changes in soil microbial communities and nutrients in native rangelands of Florida

Prescribed burning is widely used land management strategy to reduce the risks of wildfire and to achieve a wide range of ecological, economic, and societal benefits. However, it can also affect carbon (C), nitrogen (N), and phosphorus (P) cycling with potential subsequent effects on soil microbial communities. This study examined the short-term effects of prescribed burning on soil chemical properties, potential enzyme activities, and bacterial and fungal community composition in native rangelands of Florida. Fire-induced responses were assessed immediately (2 days) and 2 to 3 months after a prescribed fire event. Soil pH, total C, and extractable NH4+ and P concentration declined after fire. Total N concentration increased 2 days after fire but returned to initial level 2 to 3 months after fire. Prescribed fire elicited no observable effects on soil total P and extractable Ca, K, Mg, Mn, Fe, and Al concentration. Reductions in potential beta glucosidase and N-acetyl glucosaminidase activity were observed 2 days after fire but returned at pre-fire levels after 2–3 months. Bacterial and fungal diversity and community composition at the phylum level showed no short-term changes. At the Order level, bacterial Desulfurellales increased while fungal Eurotiales and Pleosporales decreased 2 days after fire. Prescribed burning had minimal effect on soil microbial community composition in the short-term, probably due to limited effects of fire on soil heating and rapid post-fire vegetative recovery. Although the impacts of prescribed fire on soil properties have been widely acknowledged, this study is the first to document short-term fire-induced soil microbial responses in subtropical native rangelands of Florida. This work contributes to a wealth of evidence indicating limited impacts of prescribed fire on soil microbial community composition.

Functional characterization of N-acetyl glucosaminidase from Myrothecium verrucaria for bio-control of plant pathogenic fungi and bio-production of N-acetyl glucosamine

As a common structural element of invertebrates and fungi, chitin offers an ideal target for bio-control of agricultural pests as well as production of N-acetyl glucosamine (NAG). Therefore, chitin degrading enzymes have several biotechnological applications. In the present investigation, the bio-control and NAG production potential of Myrothecium verrucaria N-acetyl glucosaminidase (MvNAGase) were studied. Cloning and biochemical characterization of MvNAGase (1743 bp) suggest that it belongs to the glycosyl hydrolase-20 family. Chitooligosaccharides hydrolysis revealed the exo-acting nature of the enzyme with NAG as an end product. rMvNAGase displayed significant antifungal potential towards plant pathogenic fungi: Ustilago maydis, Bipolaris sorokiniana and Fusarium oxysporum. The bioprocess was optimized using an enzymic cocktail of earlier identified and characterized endo-chitinase and rMvNAGase to maximize NAG production from the chitin. Under specific experimental conditions, the chitin conversion was achieved up to 87%. The study propose the possible application of rMvNAGase in bio-control of agricultural pests and biochemical production of NAG from the crude chitin.

Potential implications of biochar and compost on the stoichiometry-based assessments of soil enzyme activity in heavy metal-polluted soils

Biochar and compost application in soil has been proved as an environmental management and soil remediation strategy for upgrading soil quality and growth-promoting soil microorganisms. A detailed examination of the fluctuations and stoichiometric interactions between β-glucosidase (BG), N-acetylglucosaminidase (NAG), leucine aminopeptidase (LAP), and acid phosphatase (AP) after applying biochar and compost to the heavy metal soils was conducted in the paper. However, biochar stimulated the activity of AP and inhibited BG, NAG, and LAP. Compost and biochar-compost might strengthen BG, NAG, LAP, and AP activities. Redundancy analysis discovered that the crucial parameters that affected soil enzyme activity were TN, NO3−-N, and TP. However, the stoichiometric ratio of C/N, C/P, and N/P with the application of the biochar, compost, and biochar-compost could be changed. While alleviating the P-limitation in soils under Cu stress, biochar may also alleviate the C-limitation in soils under As, Cd, and Zn stress. Compost and biochar-compost application alleviated C-limitation in heavy-metal (Cu, As, Cd, and Zn) polluted soil. This work will help us further understand the stoichiometry and energy restrictions of biochar and compost on ecological functional enzymes.

A novel rat model of denture stomatitis and the role of antibiotics in the development of the disease.

This study compared different conditions to establish a rat model of denture stomatitis. Immunocompetent Wistar rats were divided into two groups (n=35): Tetracycline=administration of 0.83mg/ml of tetracycline hydrochloride 7 days before induction of denture stomatitis and amoxicillin=administration of 0.156mg/ml of amoxicillin with clavulanic acid 4 days before induction of denture stomatitis. A suspension of Candida albicans was inoculated on the palate followed by the use of a palatal device contaminated with C. albicans inoculum for 4 days to induce denture stomatitis. As controls, some rats were not submitted to any procedure or used a sterile palatal device for 4 days. The development of denture stomatitis was confirmed by visual analysis, colony-forming units per milliliter (CFU/ml) count, histopathological and immunohistochemical analyses, and through myeloperoxidase (MPO) and N-acetylglucosaminidase (NAG) assays. Rats were euthanized right after device removal (T0), 4 (T4), or 6 (T6) days after device removal. Tetracycline improved the development of the disease, with more severe clinical signs at T0. Similar results were observed in the CFU/ml count and in the histometric and immunohistochemical analyses. Higher MPO expression was detected in the palates of the tetracycline group (P=.006). Despite the subtle differences between antibiotics, tetracycline showed better results in inducing and maintaining denture stomatitis for at least 4 days after device removal.

Greenhouse gas emission responses to different soil amendments on the Loess Plateau, China

Soil amendments are commonly used to reduce greenhouse gas (GHG) emissions by altering the physical, biological, and chemical qualities of soil, but the mechanism by which this is achieved still vague. This two-year study surveyed the influences of biochar (BC), Bacillus mucilaginosus (BM), and Bacillus subtilis (BS) on the physical, enzyme activities, soil microbial and GHG emissions. Results indicated that soil amendment addition decreased the activities of β-glucosidase (BG), cellobiohydrolase (CBH), β-xylosidase (BX), sucrase, cellulase by 8.81%, 8.99%, 22.08%, 59.46%, 74.61%, respectively, and increased N-acetylglucosaminidase (NAG) activity by 155.00%. Soil amendments had little effect on soil microbes, apart from those related to the C and N cycles, such as Proteobacteria, Mortierellomycota and Acidobacteriota. In addition, BC, BM, and BS amendments decreased mean cumulative CO2 emissions by 38.43%, 11.83%, and 38.54%, respectively. Cumulative N2O emissions from the BC treatment increased by 28.17% in 2019 and decreased by 37.22% in 2020. For the BM and BS treatments, cumulative N2O emissions did not significantly change in 2019 but decreased by 4.93% and 57.85% in 2020, respectively. Generally, soil amendments decreased the greenhouse emission intensity (GHGI) and global warming potential (GWP). Moreover, a structural equation model (SEM) revealed factors that directly or indirectly controlled GHG emissions, including NAG, BX, CBH, Proteobacteria, Mortierellomycota and Acidobacteriota. These factors were limited mainly by soil C and N substrates, such as ammonium-nitrogen (NH4+-N), available phosphorus (AP), and soil organic matter (SOM). Overall, soil amendments can reduce GHG emissions in the long term, but they are affected by many factors.However, soil amendments alone have limited effects on reducing GHG emissions on the Loess Plateau. Suggesting combining and applying biochar and plant growth-promoting rhizobacteria (PGPR) may enhance soil quality and alleviate GHG emissions.

Assessment of soil enzymatic resilience in chlorpyrifos contaminated soils by biochar aided Pelargonium graveolens L. plantation.

Chlorpyrifos (CP), a broad-spectrum organophosphorus insecticide, is known for deleterious effects on soil enzymatic activities. Hence, the present study aims to examine the resilience effect of biochar (BC) aided Pelargonium graveolens L. plantation on enzymatic activities of chlorpyrifos contaminated soil. The two chlorpyrifos contaminated agriculture soils (with concentrations: S1: 46.1 and S2: 95.5mgkg-1) were taken for the pot experiment. The plant biomass, plant growth parameters, soil microbial biomass, and enzymatic activities such as alkaline phosphatase, N-acetyl glucosaminidase, aryl sulphatase, cellulase, β-glucosidase, dehydrogenase, phenoloxidase, and peroxidase enzymes were examined. Ecoenzyme activities and their stoichiometry were used to enumerate the different indices including geometric mean, weighted mean, biochemical activity indices, integrated biological response, treated-soil quality index, and vector analysis in all treatments. The results of the study demonstrated that the biochar incorporation enhanced the tolerance of P. graveolens (from 42-45% to 55-67%) in chlorpyrifos contaminated soil and reduced the CP accumulation in plants. A reduction in the inhibitory effect of chlorpyrifos on soil enzymatic activities and plant growth by BC incorporation was observed along with an increase in the activities of ecoenzymes (16.7-18.6%) in soil. The investigation indicated more microbial investments in C and P than that in N acquisition under CP stress. The BC amendment catalyzed the activities of lignin and cellulose-degrading enzymes and enhanced nutrition acquisition. The CP contamination and BC amendment have no significant effect on the oil quality of P. graveolens. The study demonstrated that BC-aided P. graveolens plantation offers sustainable phytotechnology for CP contaminated soil with an economic return.