Microbial necromass in soil profiles increases less efficiently than root biomass in long-term fenced grassland: Effects of microbial nitrogen limitation and soil depth.

Grassland fencing is acknowledged as a crucial initiative to enhance biodiversity and to increase soil organic carbon (SOC) content in ecologically fragile regions or barren systems. Theoretical perspectives propose that fencing induced an increase in root biomass, and its penetration into the soil profile introduced organic matter that facilitated SOC formation through microbial necromass and root residues. It is hypothesized that long-term grassland fencing increases root biomass, thereby enhancing SOC formation within the soil profile through microbial residues in badland ecosystems. To test this hypothesis, we selected grasslands subjected to varying durations of fencing post-grazing (i.e., 10, 15, 20, 30, and 40 y). Our investigation aimed to clarify microbial necromass dynamics in 0-100 cm soil profiles after fencing and to identify the influencing factors. Long-term grassland fencing (i.e., >30 y) increased root biomass by 160 %, SOC by 69 %, and necromass by 41 % compared to grazed grassland within the 0-40 cm horizon; in contrast, increased root biomass by 870 %, SOC by 111 %, and necromass by 46 % in the 40-100 cm horizon. Necromass in deep soil (40-100 cm) accounted for about 50 % of total residues in the 0-100 cm profile. Increased root and living microbial biomass stimulated the necromass accumulation, with a more pronounced increase in fungal residues compared with bacterial residues. Nonetheless, microbial nutrient limitation increases C or N-acquisition enzyme coefficients, which subsequently reduced fungal and bacterial residues and stimulated their recycling. Despite substantial increases in root biomass within the soil profile after fencing, limitation of microbial N and depth reduced the effectiveness of enhancing SOC and necromass. In conclusion, although microbial residues were the important source of SOC in grasslands of the Loess Plateau, microbial N limitation impeded necromass accumulation, and the interplay of root biomass, soil depth, and nutrient limitation regulated the dynamics of necromass following grassland fencing.

A Synthetic Oligosaccharide Resembling Francisella tularensis Strain 15 O-Antigen Capsular Polysaccharide as a Lead for Tularemia Diagnostics and Therapeutics.

Francisella tularensis, a category A bioterrorism agent, causes tularemia in many animal species. F. tularensis subspecies tularensis (type A) and holarctica (type B) are mainly responsible for human tularemia. The high mortality rate of 30-60 % caused by F. tularensis subspecies tularensis if left untreated and the aerosol dispersal renders this pathogen a dangerous bioagent. While a live attenuated vaccine strain (LVS) of F. tularensis type B does not provide sufficient protection against all forms of tularemia infections, a significant level of protection against F. tularensis has been observed for both passive and active immunization of mice with isolated O-antigen capsular polysaccharide. Well-defined, synthetic oligosaccharides offer an alternative approach towards the development of glycoconjugate vaccines. To identify diagnostics and therapeutics leads against tularemia, a collection of F. tularensis strain 15 O-antigen capsular polysaccharide epitopes were chemically synthesized. Glycan microarrays containing synthetic glycans were used to analyze the sera of tularemia-infected and non-infected animals and revealed the presence of IgG antibodies against the glycans. Two disaccharide (13 and 18), both bearing a unique formamido moiety, were identified as minimal glycan epitopes for antibody binding. These epitopes are the starting point for the development of diagnostics and therapeutics against tularemia.

Divergent contributions of microbes and plants to soil organic carbon in the drawdown area of a large reservoir: Impacts of periodic flooding and drying.

The distribution patterns and accumulation mechanisms of plant and microbial residues, along with their potential contributions to soil organic carbon (SOC), remain subjects of considerable debate, particularly within drawdown areas affected by reservoir operation. In this study, surface soil samples (0-10 cm) were collected from three different elevations within the drawdown area of the Three Gorges Reservoir. Amino sugars and lignin phenols served as biomarkers for microbial residues and plant-derived materials, respectively. The results revealed that with increasing duration of flooding, the content of amino sugars increased from 0.26 mg g-1 to 0.64 mg g-1, whereas the content of lignin phenols decreased from 204.09 mg kg-1 to 37.93 mg kg-1. Moreover, as the duration of flooding increased, the contribution of microbial necromass carbon (MNC) to SOC rose from 29% to 47%, while the contribution of plant-derived carbon to SOC gradually declined. Plants biomass and iron minerals influenced the accumulation of lignin phenols, whereas amino sugars were affected by plants biomass, microbial biomass carbon and nitrogen, and clay minerals. The periodic flooding and drying events induced alterations in carbon inputs and environmental characteristics within the drawdown area, resulting in fluctuations in the contributions of plants and MNC to SOC in this region. The findings of this study highlight the critical role played by both plant- and microbial-derived carbon in the retention and turnover of SOC within the terrestrial-aquatic transition zone.

Grassland degraded patchiness reduces microbial necromass content but increases contribution to soil organic carbon accumulation.

Plant and microbially derived carbon (C) are the two major sources of soil organic carbon (SOC), and their ratio impacts SOC composition, accumulation, stability, and turnover. The contributions of and the key factors defining the plant and microbial C in SOC with grassland patches are not well known. Here, we aim to address this issue by analyzing lignin phenols, amino sugars, glomalin-related soil proteins (GRSP), enzyme activities, particulate organic carbon (POC), and mineral-associated organic carbon (MAOC). Shrubby patches showed increased SOC and POC due to higher plant inputs, thereby stimulating plant-derived C (e.g., lignin phenol) accumulation. While degraded and exposed patches exhibited higher microbially derived C due to reduced plant input. After grassland degradation, POC content decreased faster than MAOC, and plant biomarkers (lignin phenols) declined faster than microbial biomarkers (amino sugars). As grassland degradation intensified, microbial necromass C and GRSP (gelling agents) increased their contribution to SOC formation. Grassland degradation stimulated the stabilization of microbially derived C in the form of MAOC. Further analyses revealed that microorganisms have a C and P co-limitation, stimulating the recycling of necromass, resulting in the proportion of microbial necromass C in the SOC remaining essentially stable with grassland degradation. Overall, with the grassland degradation, the relative proportion of the plant component decreases while than of the microbial component increases and existed in the form of MAOC. This is attributed to the physical protection of SOC by GRSP cementation. Therefore, different sources of SOC should be considered in evaluating SOC responses to grassland degradation, which has important implications for predicting dynamics in SOC under climate change and anthropogenic factors.

Canopy and understory nitrogen additions differently affect soil microbial residual carbon in a temperate forest.

Atmospheric nitrogen (N) deposition in forests can affect soil microbial growth and turnover directly through increasing N availability and indirectly through altering plant-derived carbon (C) availability for microbes. This impacts microbial residues (i.e., amino sugars), a major component of soil organic carbon (SOC). Previous studies in forests have so far focused on the impact of understory N addition on microbes and microbial residues, but the effect of N deposition through plant canopy, the major pathway of N deposition in nature, has not been explicitly explored. In this study, we investigated whether and how the quantities (25 and 50 kg N ha-1 year-1) and modes (canopy and understory) of N addition affect soil microbial residues in a temperate broadleaf forest under 10-year N additions. Our results showed that N addition enhanced the concentrations of soil amino sugars and microbial residual C (MRC) but not their relative contributions to SOC, and this effect on amino sugars and MRC was closely related to the quantities and modes of N addition. In the topsoil, high-N addition significantly increased the concentrations of amino sugars and MRC, regardless of the N addition mode. In the subsoil, only canopy N addition positively affected amino sugars and MRC, implying that the indirect pathway via plants plays a more important role. Neither canopy nor understory N addition significantly affected soil microbial biomass (as represented by phospholipid fatty acids), community composition and activity, suggesting that enhanced microbial residues under N deposition likely stem from increased microbial turnover. These findings indicate that understory N addition may underestimate the impact of N deposition on microbial residues and SOC, highlighting that the processes of canopy N uptake and plant-derived C availability to microbes should be taken into consideration when predicting the impact of N deposition on the C sequestration in temperate forests.

Microbial necromass facilitated the humification process through amino sugar reactions during the co-composting of cow manure plus sawdust.

Humus (HS) reservoirs can embed microbial necromass (including cell wall components that are intact or with varying degrees of fragmentation) in small pores, raising widespread concerns about the potential for C/N interception and stability in composting systems. In this study, fresh cow manure and sawdust were used for microbial solid fermentation, and the significance of microbial residues in promoting humification was elucidated by measuring their physicochemical properties and analyzing their microbial informatics. These results showed that the stimulation of external carbon sources (NaHCO3) led to an increase in the accumulation of bacterial necromass C/N from 6.19 and 0.91 µg/mg to 21.57 and 3.20 µg/mg, respectively. Additionally, fungal necromass C/N values were about 3 times higher than the initial values. This contributed to the increase in HS content and the increased condensation of polysaccharides and nitrogen-containing compounds during maturation. The formation of cellular debris mainly depends on the enrichment of Actinobacteria, Proteobacteria, Ascomycota, and Chytridiomycota. Furthermore, Euryarchaeota was the core functional microorganism secreting cell wall lytic enzymes (including AA3, AA7, GH23, and GH15). In conclusion, this study comprehensively analyzed the transformation mechanisms of cellular residuals at different profile scales, providing new insights into C/N cycles and sequestration.

Responses of Soil Carbon and Microbial Residues to Degradation in Moso Bamboo Forest.

Moso bamboo (Phyllostachys heterocycla cv. Pubescens) is known for its high capacity to sequester atmospheric carbon (C), which has a unique role to play in the fight against global warming. However, due to rising labor costs and falling bamboo prices, many Moso bamboo forests are shifting to an extensive management model without fertilization, resulting in gradual degradation of Moso bamboo forests. However, many Moso bamboo forests are being degraded due to rising labor costs and declining bamboo timber prices. To delineate the effect of degradation on soil microbial carbon sequestration, we instituted a rigorous analysis of Moso bamboo forests subjected to different degradation durations, namely: continuous management (CK), 5 years of degradation (D-5), and 10 years of degradation (D-10). Our inquiry encompassed soil strata at 0-20 cm and 20-40 cm, scrutinizing alterations in soil organic carbon(SOC), water-soluble carbon(WSOC), microbial carbon(MBC)and microbial residues. We discerned a positive correlation between degradation and augmented levels of SOC, WSOC, and MBC across both strata. Furthermore, degradation escalated concentrations of specific soil amino sugars and microbial residues. Intriguingly, extended degradation diminished the proportional contribution of microbial residuals to SOC, implying a possible decline in microbial activity longitudinally. These findings offer a detailed insight into microbial C processes within degraded bamboo ecosystems.

Stereoselective and controllable C3-Amination or C1,C3-di-amination of 2-nitroglycals.

Precise and selective modification of carbohydrates is a critical strategy in producing diverse carbohydrate derivatives for exploiting their functions. We disclosed a simple, efficient, and highly regioselective and stereoselective protocol to controllable amination of 2-nitroglycals under mild conditions in 5 min. A range of 3-amino-carbohydrates including 3-arylamino-2-nitro-glycals and 1,3-di-amino-carbohydrate derivatives were obtained in good to excellent yield with excellent stereoselectivity. The produced 3-amino-2-nitro-glycals can be used as a precursor for further transformation.

High stocking rates effects in continuous season long grazing reduces the contribution of microbial necromass to soil organic carbon in a semi-arid grassland in Inner Mongolia.

Livestock grazing strongly influences the accumulation of soil organic carbon (SOC) in grasslands. However, whether the changes occurring in SOC content under different intensities of continuous summer long grazing are associated with the changes in microbially-derived necromass C remains unclear. Here, we established a sheep grazing experiment in northern China in 2004 with four different stocking rates. Soil samples were collected after 17 years of grazing and analyzed for physical, chemical, and microbial characteristics. Grazing decreased SOC and microbial necromass carbon (MNC). Notably, grazing also diminished contributions of MNC to SOC. MNC declined with decreasing plant carbon inputs with degradation of the soil environment. Direct reductions in microbial necromass C, which indirectly reduced SOC, resulted from reduced in plant C inputs and microbial abundance and diversity. Our study highlights the key role of stocking rate in governing microbial necromass C and SOC and the complex relationships these variables.

Amino Sugar-Enriched Fraction of Korean Red Ginseng Extract Induces the Priming Step of NLRP3 Inflammasome.

Intracellular protein complexes, known as inflammasomes, activate caspase-1 and induce the secretion of pro-inflammatory cytokines, namely interleukin (IL)-1ß and -18. Korean Red Ginseng extract (RGE) is a known immunomodulator and a potential candidate for the regulation of inflammasomes. The saponins, such as ginsenosides, of RGE inhibit inflammasome signaling, while non-saponin substances containing amino sugars promote the priming step, up-regulating inflammasome components (pro-IL-1ß, NLRP3, caspase-1, and Asc). In this study, the amino sugar-enriched fraction (ASEF), which increases only non-saponin components, including amino sugars, without changing the concentration of saponin substances, was used to investigate whether saponin or non-saponin components of RGE would have a greater impact on the priming step. When murine macrophages were treated with ASEF, the gene expression of inflammatory cytokines (IL-1α, TNFα, IL-6, and IL-10) increased. Additionally, ASEF induced the priming step but did not affect the inflammasome activation step, such as the secretion of IL-1ß, cleavage of caspase-1, and formation of Asc pyroptosome. Furthermore, the upregulation of gene expression of inflammasome components by ASEF was blocked by inhibitors of Toll-like receptor 4 signaling. Maltol, the main constituent of ASEF, promoted the priming step but inhibited the activation step of the inflammasome, while arginine, sugars, arginine-fructose-glucose, and fructose-arginine, the other main constituents of ASEF, had no effect on either step. Thus, certain amino sugars in RGE, excluding maltol, are believed to be the components that induce the priming step. The priming step that prepares the NLRP3 inflammasome for activation appears to be induced by amino sugars in RGE, thereby contributing to the immune-boosting effects of RGE.

Galactosamine and mannosamine are integral parts of bacterial and fungal extracellular polymeric substances.

Extracellular polymeric substances (EPS) are produced by microorganisms and interact to form a complex matrix called biofilm. In soils, EPS are important contributors to the microbial necromass and, thus, to soil organic carbon (SOC). Amino sugars (AS) are used as indicators for microbial necromass in soil, although the origin of galactosamine and mannosamine is largely unknown. However, indications exist that they are part of EPS. In this study, two bacteria and two fungi were grown in starch medium either with or without a quartz matrix to induce EPS production. Each culture was separated in two fractions: one that directly underwent AS extraction (containing AS from both biomass and EPS), and another that first had EPS extracted, followed then by AS determination (exclusively containing AS from EPS). We did not observe a general effect of the quartz matrix neither of microbial type on AS production. The quantified amounts of galactosamine and mannosamine in the EPS fraction represented on average 100% of the total amounts of these two AS quantified in cell cultures, revealing they are integral parts of the biofilm. In contrast, muramic acid and glucosamine were also quantified in the EPS, but with much lower contribution rates to total AS production, of 18% and 33%, respectively, indicating they are not necessarily part of EPS. Our results allow a meaningful ecological interpretation of mannosamine and galactosamine data in the future as indicators of microbial EPS, and also attract interest of future studies to investigate the role of EPS to SOC and its dynamics.

[Effects of thinning on accumulation of soil microbial residue carbon of Picea asperata plantations in sub-alpine region of western Sichuan, China]. / 间伐对川西亚高山云杉人工林土壤微生物残体碳积累的影响.

Microbial residues are an important component of soil organic carbon (SOC). It is unclear how long-term thinning affects the accumulation characteristics of microbial residue carbon (C). We analyzed the differences in soil physicochemical properties, microbial communities, extracellular enzyme activities, and microbial residue C in topsoil (0-10 cm) and subsoil (20-30 cm) in Picea asperata plantation of non-thinned (control, 4950 trees·hm-2) and thinned for 14 years (1160 trees·hm-2) stands, aiming to reveal the regulatory mechanism of thinning on microbial residue C accumulation. The results showed that thinning significantly increased SOC content, total nitrogen content, available phosphorus content, the proportion of particulate organic C, soil water content, C-cycle hydrolase, and acid phosphatase activities, but significantly reduced the proportion of mineral-associated organic C. Thinning significantly affected the content of fungal and microbial residue C, and the contribution of microbial residue C to SOC, and these effects were independent of soil layer. The content of fungal and microbial residue C was 25.0% and 24.5% higher under thinning treatments. However, thinning significantly decreased the contribution of microbial residue C to SOC by 12.3%, indicating an increase in the proportion of plant-derived C in SOC. Stepwise regression analysis showed that total nitrogen and soil water content were key factors influencing fungal and micro-bial residue C accumulation. In summary, thinning promoted microbial residue C sequestration by altering soil pro-perties and changed the composition of SOC sources.

Spatial variation and controls of soil microbial necromass carbon in a tropical montane rainforest.

Soil microbial necromass carbon is an important component of the soil organic carbon (SOC) pool which helps to improve soil fertility and texture. However, the spatial pattern and variation mechanisms of fungal- and bacterial-derived necromass carbon at local scales in tropical rainforests are uncertain. This study showed that microbial necromass carbon and its proportion in SOC in tropical montane rainforest exhibited large spatial variation and significant autocorrelation, with significant high-high and low-low clustering patterns. Microbial necromass carbon accounted for approximately one-third of SOC, and the fungal-derived microbial necromass carbon and its proportion in SOC were, on average, approximately five times greater than those of bacterial-derived necromass. Structural equation models indicated that soil properties (SOC, total nitrogen, total phosphorus) and topographic features (elevation, convexity, and aspect) had significant positive effects on microbial necromass carbon concentrations, but negative effects on its proportions in SOC (especially the carbon:nitrogen ratio). Plant biomass also had significant negative effects on the proportion of microbial necromass carbon in SOC, but was not correlated with its concentration. The different spatial variation mechanisms of microbial necromass carbon and their proportions in SOC are possibly related to a slower accumulation rate of microbial necromass carbon than of plant-derived organic carbon. Geographic spatial correlations can significantly improve the microbial necromass carbon model fit, and low sampling resolution may lead to large uncertainties in estimating soil carbon dynamics at specific sites. Our work will be valuable for understanding microbial necromass carbon variation in tropical forests and soil carbon prediction model construction with microbial participation.

Microbial Necromass, Lignin, and Glycoproteins for Determining and Optimizing Blue Carbon Formation.

Coastal wetlands contribute to the mitigation of climate change through the sequestration of "blue carbon". Microbial necromass, lignin, and glycoproteins (i.e., glomalin-related soil proteins (GRSP)), as important components of soil organic carbon (SOC), are sensitive to environmental change. However, their contributions to blue carbon formation and the underlying factors remain largely unresolved. To address this paucity of knowledge, we investigated their contributions to blue carbon formation along a salinity gradient in coastal marshes. Our results revealed decreasing contributions of microbial necromass and lignin to blue carbon as the salinity increased, while GRSP showed an opposite trend. Using random forest models, we showed that their contributions to SOC were dependent on microbial biomass and resource stoichiometry. In N-limited saline soils, contributions of microbial necromass to SOC decreased due to increased N-acquisition enzyme activity. Decreases in lignin contributions were linked to reduced mineral protection offered by short-range-ordered Fe (FeSRO). Partial least-squares path modeling (PLS-PM) further indicated that GRSP could increase microbial necromass and lignin formation by enhancing mineral protection. Our findings have implications for improving the accumulation of refractory and mineral-bound organic matter in coastal wetlands, considering the current scenario of heightened nutrient discharge and sea-level rise.

Unveiling the Occurrence and Non-Negligible Role of Amino Sugars in Waste Activated Sludge Fermentation by an Enriched Chitin-Degradation Consortium.

Polysaccharides in extracellular polymeric substances (EPS) can form a hybrid matrix network with proteins, impeding waste-activated sludge (WAS) fermentation. Amino sugars, such as N-acetyl-d-glucosamine (GlcNAc) polymers and sialic acid, are the non-negligible components in the EPS of aerobic granules or biofilm. However, the occurrence of amino sugars in WAS and their degradation remains unclear. Thus, amino sugars (∼6.0%) in WAS were revealed, and the genera of Lactococcus and Zoogloea were identified for the first time. Chitin was used as the substrate to enrich a chitin-degrading consortium (CDC). The COD balances for methane production ranged from 83.3 and 95.1%. Chitin was gradually converted to oligosaccharides and GlcNAc after dosing with the extracellular enzyme. After doing enriched CDC in WAS, the final methane production markedly increased to 60.4 ± 0.6 mL, reflecting an increase of ∼62%. Four model substrates of amino sugars (GlcNAc and sialic acid) and polysaccharides (cellulose and dextran) could be used by CDC. Treponema (34.3%) was identified as the core bacterium via excreting chitinases (EC 3.2.1.14) and N-acetyl-glucosaminidases (EC 3.2.1.52), especially the genetic abundance of chitinases in CDC was 2.5 times higher than that of WAS. Thus, this study provides an elegant method for the utilization of amino sugar-enriched organics.

1-Amino-1-deoxy-d-fructose ("fructosamine") and its derivatives.

Fructosamine has long been considered as a key intermediate of the Maillard reaction, which to a large extent is responsible for specific aroma, taste, and color formation in thermally processed or dehydrated foods. Since the 1980s, however, as a product of the Amadori rearrangement reaction between glucose and biologically significant amines such as proteins, fructosamine has experienced a boom in biomedical research, mainly due to its relevance to pathologies in diabetes and aging. In this chapter, we assess the scope of the knowledge on and applications of fructosamine-related molecules in chemistry, food, and health sciences, as reflected mostly in publications within the past decade. Methods of fructosamine synthesis and analysis, its chemical, and biological properties, and degradation reactions, together with fructosamine-modifying and -recognizing proteins are surveyed.

[Impacts of Land Use Intensification Level on Fluvo-aquic Cropland Soil Microbial Community Abundance and Necromass Accumulation in North China].

Despite the essential role of soil microorganisms in nutrient turnover in soil ecological systems and the recognized paramount significance of microbial necromass to soil organic carbon accumulation, how microbial community abundance and necromass respond to land use intensification level regulation remains poorly understood. To address this knowledge gap, based on the land use intensification level, three treatments were set up[annual wheat-maize rotation (CC), alternating temporary grassland with wheat planting (TG), and perennial grassland (PG)], and a long-term fixed filed experiment was established to investigate the influences of the regulation of land use intensification level on bacterial and fungal community abundances; the accumulation of bacterial, fungal, and total microbial necromass; and their contributions to SOC sequestration using droplet digital PCR and amino sugar detection technologies. We further sought to determine the key factors driving the bacterial, fungal, and total microbial necromass C accumulation. Our results demonstrated that fungal community abundance was strongly affected by land use intensification level regulation compared to that of the bacterial community, which increased with decreasing land use intensification level. The total microbial necromass C predominated the SOC accumulation across all three land use intensification levels, which contributed 52.78%, 58.36%, and 68.87% to SOC, respectively, exhibiting an increasing trend with the decline in land use intensification level. Fungal necromass C accounted for more than 80% of the total microbial necromass C, indicating its predominance in the accumulation of the total microbial necromass C and active variation via the reduction in land use intensification level. There was no significant difference in bacterial necromass C (MurA) content, with the trend of CC

Microbial pathways driving stable soil organic carbon change in abandoned Moso bamboo forests in southeast China.

Mineral-associated organic carbon (MOC) is a stable component of the soil carbon (C) pool, critical to realize carbon sequestration and coping with climate change. Many Moso bamboo (Phyllostachys edulis) forests in subtropical and tropical areas that used to be intensively managed have been left unmanaged. Still, studies on MOC changes occurring during the transition from intensive management to unmanagement are lacking. Besides, the understanding of the role of microorganisms in MOC accumulation is far from satisfactory. Based on the combination of field investigation and laboratory analysis of 40 Moso bamboo forest sampling plots with different unmanaged chronosequence's in southeast China, we observed the MOC content in Moso bamboo forests left unmanaged for 2-5 years had decreased, whereas that in forests left unmanaged for 11-14 years had increased compared with that in intensively managed forests. Specifically, the MOC contents in forests left unmanaged for 11-14 years were significantly higher than in those under intensive management or unmanaged for 2-5 years. Moreover, we found that microorganisms drove MOC change through two different pathways: (i) more microorganisms led to more soil nutrients, which led to more amino sugars, ultimately resulting in the accumulation of MOC, and (ii) microorganisms promoted the accumulation of MOC by influencing the content of metal oxides (poorly crystalline aluminum oxides and free aluminum oxides). We believe that ignoring the interaction between microorganisms and metal oxides may lead to uncertainty in evaluating the relative contribution of microbial residues to MOC.

Recent Advances in Chemical Synthesis of Amino Sugars.

Amino sugars are a kind of carbohydrates with one or more hydroxyl groups replaced by an amino group. They play crucial roles in a broad range of biological activities. Over the past few decades, there have been continuing efforts on the stereoselective glycosylation of amino sugars. However, the introduction of glycoside bearing basic nitrogen is challenging using conventional Lewis acid-promoted pathways owing to competitive coordination of the amine to the Lewis acid promoter. Additionally, diastereomeric mixtures of O-glycoside are often produced if aminoglycoside lack a C2 substituent. This review focuses on the updated overview of the way to stereoselective synthesis of 1,2-cis-aminoglycoside. The scope, mechanism, and the applications in the synthesis of complex glycoconjugates for the representative methodologies were also included.

Plant influences on soil microbial carbon pump efficiency.

Microbe-mediated carbon transformation plays an important role in soil carbon sequestration, which is considered to be one of the key strategies to achieve carbon neutrality in the long term. Assessing the efficiency of microbial necromass accumulation relative to plant carbon input or microbial respiration will help to identify ways to promote soil carbon sequestration from an ecosystem perspective.