Search

This research investigated a synthetic amendment to improve composting and resource recycling of pig manure and biogas residue. We further examined whether adding a synthetic amendment impacts the microbial ecosystem in the composted materials. Three mixing ratios were used to investigate composting performance: no synthetic amendment (T0), 5% synthetic amendment (T1), and 10% synthetic amendment (T2) (T1 and T2 were measured as a wet weight ratio). There were no significant differences in the fundamental characteristics between composting products in T0 and T1. The moisture content of composting material in T0, T1, and T2 significantly decreased from a baseline of approximately 65% to 35.5%, 37.3%, and 55.9%, respectively. Meanwhile, the germination index significantly increased to 111.6%, 155.6%, and 62.3%, respectively. When an optimal proportion of synthetic amendment was added, T1 showed high degree of humification, lignocellulase activities, and effective biodegradation. Firmicutes, Actinobacteria, Proteobacteria, and Bacteroidetes were the dominant bacteria, while Ascomycota and Basidiomycota were the dominant fungi in all treatment groups. Amino sugar and nucleotide sugar metabolism, glycolysis, starch, and sucrose metabolism were among the primary pathways in predicted functions. The synthetic amendment can generate a mature composting product and can be reused or recycled to conserve resources.

Chinese jujube (Zizyphus jujuba Mill.), a member of the Rhamnaceae family with favorable nutritional and flavor quality, exhibited characteristic climacteric changes during its fruit growth stage. Therefore, fruit samples were harvested at four developmental stages on days 55 (young fruits), 76 (white-mature fruits), 96 (half-red fruits), and 116 (full-red fruits) after flowering (DAF). This study then investigated those four growth stage changes of the jujube proteome using label-free quantification proteomics. The results identified 4762 proteins in the samples, of which 3757 proteins were quantified. Compared with former stages, the stages examined were designated as “76 vs. 55 DAF” group, “96 vs. 76 DAF” group, and “116 vs. 96 DAF” group. Gene Ontology (GO) and KEGG annotation and enrichment analysis of the differentially expressed proteins (DEPs) showed that 76 vs. 55 DAF group pathways represented amino sugar, nucleotide sugar, ascorbate, and aldarate metabolic pathways. These pathways were associated with cell division and resistance. In the study, the jujube fruit puffing slowed down and attained a stable growth stage in the 76 vs. 55 DAF group. However, fatty acid biosynthesis and phenylalanine metabolism was mainly enriched in the 96 vs. 76 DAF group. Fatty acids are precursors of aromatic substances and fat-soluble pigments in fruit. The upregulation of differential proteins at this stage indicates that aromatic compounds were synthesized in large quantities at this stage and that fruit would enter the ripening stage. During the ripening stage, 55 DEPs were identified to be involved in photosynthesis and flavonoid biosynthesis in the 116 vs. 96 DAF group. Also, the fruit entered the mature stage, which showed that flavonoids were produced in large quantities. Furthermore, the color of jujube turned red, and photosynthesis was significantly reduced. Hence, a link was established between protein profiles and growth phenotypes, which will help improve our understanding of jujube fruit growth at the proteomic level.

N-acetyl-d-neuraminic acid (NeuAc) has attracted considerable attention because of its wide-ranging applications. The use of cheap carbon sources such as glucose without the addition of any precursor in microbial NeuAc production has many advantages. In this study, improved NeuAc production was attained through the optimization of amino sugar metabolism pathway kinetics and reservation of a phosphoenolpyruvate (PEP) pool in Escherichia coli. N-acylglucosamine 2-epimerase and N-acetylneuraminate synthase from different sources and their best combinations were used to obtain optimized enzyme kinetics and expression intensity, which resulted in a significant increase in NeuAc production. Next, after a design was engineered for enabling the PEP metabolic pathway to retain the PEP pool, the production of NeuAc reached 16.7 g/L, which is the highest NeuAc production rate that has been reported from using glucose as the sole carbon source.

The broth of sea cucumber was decolorized with mineral sorbents, as perlite and bentonite, and with chitosans of crab carapace and shrimp shell. The chitosans were the most effective in sorption and subsequent removal of the protein-pigment complex, providing the decolorization degree of 35–55 %. Besides, the content of glycosides in the broth was twice decreased. The amino sugars content changed in dependence on the chitosan origin: the chitosan of crab carapace did not influence on this parameter, but the chitosan of shrimp shell caused its halving. For the optimal combination of chemical compounds in the broth, the chitosan with high molecular weight (1300 kDa) extracted from crab carapace should be used for decolorizing. Preliminary fermentation of the broth with Protamex increased concentration of biologically active peptides with low molecular weight in the solution. The fermented and decolorized broth of sea cucumber has good organoleptic properties and high content of biologically active components, as glycosides, amino sugars and low molecular weight peptides, so could be used as the basis for nonalcoholic tonic drinks.

Understanding the processes controlling amino sugar accumulation in soil is essential for predicting the contribution of microbial residues to soil organic matter (SOM). The accumulation of amino sugars in soil is affected by multiple factors. Seldom are those factors examined together. We measured amino sugar concentration, extracellular enzyme activity, microbial respiration rate, and soil aggregate composition in an agricultural soil under 33-years of conservation management. The accumulation patterns of different amino sugars under the effects of no-tillage farming and cover cropping were compared and contrasted. The relative importance of physical, biochemical, and microbial controls of amino sugar accumulation was quantified using structural equation modelling. Our results show that although different types of amino sugars exhibited similar accumulation patterns in soil, their stabilization mechanisms might vary as demonstrated by structural equation models. The structural equation models indicate that macroaggregates had the largest total effect (0.59, P

Subtropical ecosystems are generally characterized by phosphorus (P)-deficient soils; however, extreme P-rich soils develop on phosphate rocks. We aimed to integrate metabolomic and ionomic analyses to survey how in situ trees adaptively respond to such contrasting P soils. Gas (GC-MS) or liquid (LC-MS) chromatography-mass spectrometry and inductively coupled plasma-optical emission spectrometer (ICP-OES) were used to analyze leaf metabolome and ionome of Quercus variabilis, which grew at two geologic P-rich and P-deficient sites in subtropical China. Two Q. variabilis populations were significantly discriminated in terms of metabolome and ionome, with major contributions from 25 identified metabolites (e.g. sugars and P-containing compounds) and P and four other chemical elements. And of these 25 metabolites, orthophosphate was predominant in influencing the variation in the metabolomes of Q. variabilis between the two P-type sites. Moreover, orthophosphate was correlated with leaf P (r = 0.85, p

Mussel wastes include byproducts such as seed, barnacles fouling, broken shells, byssus threads, which are associated with serious environmental impacts on aquatic ecosystems. The objective of reducing wastes and to avoid environmental problems can be achieved by establishing alternative methods to valorize mussel wastes converting them into high value-added products. The present study aims to obtain by chemical methods the extraction of chitin and glucosamine from shells ofMytilus galloprovincialis. Chitin, which chemically is a linear polysaccharide of β (1→4) linkedN-acetylglucosamine monomers, possesses multifunctional properties and is suitable for various applications mainly in pharmaceutical, biomedical food and packaging fields. Glucosamine (C6H13NO5) is an amino sugar (2-amino-2-deoxy-β-D-glucopyranose) and is a part of the structure of twopolysaccharides,chitosanandchitin. Due to its high aqueous solubility and physical stability is used as a potential solid-dispersion carrier to improve the biopharmaceutical properties of drugs. The influence of temperature, solid/liquid ratio (g/ml), molarity of solutions and agitation on chitin production and acid hydrolysis of chitin was studied to achieve optimum output of chitin and glucosamine. Our results demonstrates that the production of glucosamine and chitin is greatly influenced by the experimental conditions. The best yield for glucosamine was obtained at a solid/liquid ratio of 1:15 at 60°C for 1 hour.

The objective of this experiment was to study the effect of cotton residues incorporation on soil properties, soil organic nitrogen (N) fractions, and N-mineralizing enzyme (protease, and urease) activity in the 0–40 cm soil layer in the long-term continuous cotton field. In this experiment, seven treatments, including cotton residues incorporation for 5, 10, 15 and 20 years (marked as 5a, 10a, 15a, and 20a) and continuous cropping for 5, 10 and 20 years (marked as CK5, CK10 and CK20) were conducted. The results showed that the soil organic carbon (C) and N increased gradually with the increase in the duration of continuous cropping with cotton residues incorporation. Compared with CK20, the 20a treatments reduced the content of amino acid N (AAN), ammonium N (AN), amino sugar N (ASN), hydrolysable unidentified N (HUN), and acid insoluble N (AIN) significantly by 48.6, 32.2, 96.9, 48.3, and 38.7%, respectively (p p

Pearl oyster Pinctada fucata martensii is widely recognized for biomineralization and has been cultured for high-quality marine pearl production. To ascertain how dietary vitamin D3 (VD3) levels affect the features of pearl production by P. f. martensii and discover the mechanisms regulating this occurrence, five experimental diets with variable levels of VD3 were used with inclusion levels of 0, 500, 1,000, 3,000, and 10,000 IU/kg. The distinct inclusion levels were distributed into five experimental groups (EG1, EG2, EG3, EG4, and EG5). All the experimental groups were reared indoors except the control group (CG) reared at the sea. Pearl oysters, one year and a half old, were used in the grafting operation to culture pearls. During the growing period that lasted 137 days, EG3 had the highest survival rate, retention rate, and high-quality pearl rate. A similar trend was found for EG3 and CG with significantly higher pearl thickness and nacre deposition rates than other groups, but no significant differences were observed between them. A metabolomics profiling using GC–MS and LC–MS of pearl oysters fed with low quantities of dietary VD3 and optimal levels of dietary VD3 revealed 135 statistically differential metabolites (SDMs) (VIP > 1 and p < 0.05). Pathway analysis indicated that SDMs were involved in 32 pathways, such as phenylalanine metabolism, histidine metabolism, glycerophospholipid metabolism, alanine aspartate and glutamate metabolism, arginine and proline metabolism, glycerolipid metabolism, amino sugar and nucleotide sugar metabolism, and tyrosine metabolism. These results provide a theoretical foundation for understanding the impacts of VD3 on pearl production traits in pearl oyster and reinforce forthcoming prospects and application of VD3 in pearl oyster in aquaculture rearing conditions.

N-acetylglucosamine 6-phosphate deacetylase (NagA) catalyzes the conversion of N-acetylglucosamine-6-phosphate to glucosamine-6-phosphate in amino sugar catabolism. This conversion is an essential step in the catabolism of sialic acid in several pathogenic bacteria, including Pasteurella multocida, and thus NagA is identified as a potential drug target. Here, we report the unique structural features of NagA from P. multocida (PmNagA) resolved to 1.95 A. PmNagA displays an altered quaternary architecture with unique interface interactions compared to its close homolog, the Escherichia coli NagA (EcNagA). We confirmed that the altered quaternary structure is not a crystallographic artifact using single particle electron cryo-microscopy. Analysis of the determined crystal structure reveals a set of hot-spot residues involved in novel interactions at the dimer-dimer interface. PmNagA binds to one Zn2+ ion in the active site and demonstrates kinetic parameters comparable to other bacterial homologs. Kinetic studies reveal that at high substrate concentrations (~10-fold the KM ), the tetrameric PmNagA displays hysteresis similar to its distant neighbor, the dimeric Staphylococcus aureus NagA (SaNagA). Our findings provide key information on structural and functional properties of NagA in P. multocida that could be utilized to design novel antibacterials.

Global warming may have a great impact on soil organic carbon (SOC) turnover in permafrost peatlands. The response of microbial residues, as precursors of SOC, to climate warming remains unknown. A 6-year in situ warming experiment was conducted in the permafrost peatlands of Great Hing'an Mountains. Three commonly used amino sugars (glucosamine, GluN; galactosamine, GalN; muramic acid, MurA), for the quantification of microbial residues, were determined in two depths (0–15 cm, shallow soil; 15–30 cm, deep soil) of the bulk and rhizosphere soil of the shrub and Eriophorum vaginatum L. The amount of GluN, GalN, and MurA in deep shrub rhizosphere soil in the warming treatment decreased by 12.65%, 26.11%, and 14.78%, respectively, as compared to that in the control treatment. Yet, warming did not alter the amount of amino sugars in shallow and deep bulk soil. Warming decreased the concentrations of GluN, MurA, and total amino sugars in the deep rhizosphere soil of Eriophorum vaginatum L. by 22.04%, 26.14%, and 18.71%, respectively. Amino sugars in the deep rhizosphere soil of Eriophorum vaginatum L. had a higher temperature sensitivity than those in the deep bulk soil, while total amino sugars in the shallow rhizosphere soil of Eriophorum vaginatum L. had a lower temperature sensitivity than those in the deep rhizosphere soil.

Amino sugars are important indices for the contribution of soil microorganisms to soil organic matter. Consequently, the past decade has seen a great increase in the number of studies measuring amino sugars. However, some uncertainties remain in the interpretation of amino sugar data. The objective of the current opinion paper is to summarize current knowledge on amino sugars in soils, to give some advice for future research objectives, and to make a plea for the correct use of information. The study gives an overview on the origin of muramic acid (MurN), glucosamine (GlcN), galactosamine (GalN), and mannosamine (ManN). Information is also provided on measuring total amino sugars in soil but also on compound-specific δ13C and δ15N determination. Special attention is given to the turnover of microbial cell-wall residues, to the interpretation of the GlcN/GalN ratio, and to the reasons for converting fungal GlcN and MurN to microbial residue C. There is no evidence to suggest that the turnover of fungal residues generally differs from that of bacterial residues. On average, MurN contributes 7% to total amino sugars in soil, GlcN 60%, GalN 30%, and ManN 4%. MurN is highly specific for bacteria, GlcN for fungi if corrected for the contribution of bacterial GlcN, whereas GalN and ManN are unspecific microbial markers.

Hass avocado postharvest ripening heterogeneity creates several logistics problems at destination markets. Although several approaches mainly based on targeted analysis have been undertaken to broaden our understanding of the potential causes of this postharvest ripening heterogeneity, still the secret is not yet unveiled. In this study biopsies from individual fruit displaying contrasting ripening behavior (slow vs fast) and subjected to different storage conditions (immediately after harvest, 30 d regular air at 5 °C and 30 d at 5 °C and 4 kPa O 2 and 6 kPa CO 2 ) were analyzed for targeted fatty acid analysis and cell wall enzyme activity combined with a more integrative approach based on gel free proteomics LC–MS/MS. The high throughput proteomics was capable of discriminating between slow and fast ripening avocado fruit. Proteins that were mainly less abundant in the slow ripening phenotype were annotated to correct protein folding, translation and de novo synthesis and higher abundant proteins were annotated to amino sugar and nucleotide metabolism, detoxification and stress response and proteolysis. Our study opens new insights into the causes of heterogeneous ripening and may provide new markers for avocado ripening at harvest and after prolonged storage.

Microbial residues are a significant component of soil organic carbon (C), yet their distribution and function remain understudied. We evaluated changes in microbial residues and their contribution to organic C along a soil development sequence on three contrasting parent materials (granite, basalt and andesite) and three conifer biomes (ponderosa pine (Pinus ponderosa Laws.), PP; white fir (Abies concolor Lindl.), WF; and red fir (Abies magnifica A. Murr.), RF) at different elevations in the Sierra Nevada of California. Soil samples were taken from both A and B horizons and microbial residues were determined by amino sugar analysis. The effect of conifer biome on amino sugars was complex and dependent on parent material and horizon. We found parent material significantly influenced soil amino sugars which exhibited a pattern of andesite > basalt > granite in both A and B horizons. Both correlation and redundancy analyses indicated a significant correlation of amino sugars with the amount of short-range-order materials. This suggests soil mineralogy plays an important role in influencing amino sugar accumulation. This is further supported by larger differences among parent materials than between conifer biomes in ratios of fungal-to bacterial-derived amino sugars. The proportion of amino sugars to soil organic C was significantly influenced by parent material in the B horizon following the pattern of basalt > andesite > granite, but not affected by conifer biome. Our results suggest that mineralogy strongly influences the degree to which soil microbial residues persist in temperate forest soils.

Theory and experiments suggest that rhizodeposition can accelerate N-cycling by stimulating microbial decomposition of soil organic matter (SOM). However, there are remarkably few experimental demonstrations on the degree to which variations in root exudation alter rhizosphere N dynamics in the field. We conducted a series of in situ substrate addition experiments and a modeling exercise to investigate how exudate mimics and enzyme solutions (at varying concentrations) influence rhizosphere SOM and N dynamics in a loblolly pine ( Pinus taeda ) plantation (Duke Forest). Exudates were added semi-continuously to unfertilized and fertilized soils in summer and fall; enzymes were added during the following summer. Exudate additions enhanced the microbial biomass specific activities of enzymes that degrade fast-cycling N pools (i.e., amino acids and amino sugars), and increased microbial allocation to N-degrading compounds. More, such effects occurred at low exudate concentrations in unfertilized soil and at higher concentrations in fertilized soil. Direct additions of a subset of enzymes (amino sugar- and cellulose-degrading) to soils increased net N mineralization rates, but additions of enzymes that cleave slow-cycling SOM did not. We conclude that exudates can stimulate microbes to decompose labile SOM and release N without concomitant changes in microbial biomass, yet the investment of plants to trigger this effect may be greater in N-rich soils.

Differences in the concentration of metabolites in the biofluids of animals closely reflect their physiological diversities. In order to set the basis for a metabolomic atlas for giant panda (Ailuropoda melanoleuca), we characterized the metabolome of healthy giant panda feces (23), urine (16), serum (6), and saliva (4) samples by means of 1H NMR. A total of 107 metabolites and a core metabolome of 12 metabolites was quantified across the four biological matrices. Through univariate analysis followed by robust principal component analysis, we were able to describe how the molecular profile observed in giant panda urine and feces was affected by gender and age. Among the molecules modified by age in feces, fucose plays a peculiar role because it is related to the digestion of bamboo's hemicellulose, which is considered as the main source of energy for giant panda. A metagenomic investigation directed toward this molecule showed that its concentration was indeed positively related to the two-component system pathway and negatively related to the amino sugar and nucleotide sugar metabolism pathway. Such work is meant to provide a robust framework for further -omics research studies on giant panda to accelerate our understanding of the interaction of giant panda with its natural environment.

Withering is an important biological process accompanied by dehydration and cell wall metabolism in postharvest plant organs during curing/processing and storage. However, dynamics involved in cell wall metabolism and resultant water loss during withering in postharvest tobacco leaves is not well-documented. Here, tandem mass tag (TMT)-based quantitative proteomic analysis in postharvest tobacco leaves (cultivar K326) under different withering conditions was performed. In total, 11,556 proteins were detected, among which 496 differentially abundant proteins (DAPs) were identified. To elucidate the withering mechanism of tobacco leaves, 27 DAPs associated with cell wall metabolism were screened. In particular, pectin acetylesterases, glucan endo-1,3-beta-glucosidases, xyloglucan endotransglucosylase/hydrolase, alpha-xylosidase 1-like, probable galactinol-sucrose galactosyltransferases, endochitinase A, chitotriosidase-1-like and expansin were the key proteins responsible for the withering of postharvest tobacco leaves. These DAPs were mainly involved in pectin metabolism, cellulose, hemicellulose and galactose metabolism, amino sugar and nucleotide sugar metabolism as well as cell wall expansion. Furthermore, relative water content and softness values were significantly and positively correlated. Thus, dehydration and cell wall metabolism were crucial for tobacco leaf withering under different conditions. Nine candidate DAPs were confirmed by parallel reaction monitoring (PRM) technique. These results provide new insights into the withering mechanism underlying postharvest physiological regulatory networks in plants/crops.

Altered metabolism and deregulated cellular energetics are now considered a hallmark of all cancers. Glucose, glutamine, fatty acids, and amino acids are the primary drivers of tumor growth and act as substrates for the hexosamine biosynthetic pathway (HBP). The HBP culminates in the production of an amino sugar uridine diphosphate N-acetylglucosamine (UDP-GlcNAc) that, along with other charged nucleotide sugars, serves as the basis for biosynthesis of glycoproteins and other glycoconjugates. These nutrient-driven post-translational modifications are highly altered in cancer and regulate protein functions in various cancer-associated processes. In this review, we discuss recent progress in understanding the mechanistic relationship between the HBP and cancer.

It has been recognized that land use change affects soil organic carbon (SOC) dynamics and the associated microbial turnover. However, the contribution of microbial residue to SOC storage remains largely unknown in land use change processes. To this end, we adopted a &ldquo, space for time&rdquo, approach to examine the dynamics of SOC and amino sugars, which was a biomarker of microbial residue C, in different natural forest conversions. Three typical converted forests were selected: an assisted natural regeneration (ANR) and two coniferous plantations of Cunninghamia lanceolata (Lamb.) Hook (Chinese fir) and Pinus massoniana Lamb. (pine) each. All of these were developed at the same time after the harvest of an old natural forest and they were used to evaluate the effects of forest conversions with contrasting anthropogenic disturbance on SOC and microbial residue C, along with the natural forest. Natural forest conversion led to an approximately 42% decrease in SOC for ANR with low anthropogenic disturbance, 60% for the Chinese fir plantation, and 64% for the pine plantation. In contrast, the natural forest conversion led to a 32% decrease in the total amino sugars (TAS) for ANR, 43% for the Chinese fir plantation, and 54% for the pine plantation at a soil depth of 0&ndash, 10 cm. The ratios of TAS to SOC were significantly increased following natural forest conversion, with the highest ratio being observed in the Chinese fir plantation, whereas the ratios of glucosamine to muramic acid (GluN/MurA) were significantly decreased in the two plantations, but not in ANR. The contents of SOC, individual amino sugar, or TAS, and GluN/MurA ratios were consistently higher at a soil depth of 0&ndash, 10 cm than at 10&ndash, 20 cm for all of the experimental forests. Redundancy analysis showed that microbial residue C was significantly correlated with SOC, and both were positively correlated with fine root biomass, annual litterfall, and soil available phosphorus. Taken together, our findings demonstrated that microbial residue C accumulation varied with SOC and litter input, and played a more important role in SOC storage following forest conversion to plantations with higher anthropogenic disturbance.

Soil nitrogen (N) cycling can be affected by no-tillage and crop residue application. However, it remains unclear how crop residue application rates affect soil organic N (SON) fractions, N-hydrolyzing enzymes and their relationships. A field experiment was conducted in northeastern China to investigate the effects of no-tillage (NT) and residue application at either 0 (NTR0%), 33 (NTR33%), 67 (NTR67%) or 100% (NTR100%) on SON fractions, soil N-hydrolyzing enzyme activities, and their relationships at depths of 0−10 and 10−20 cm. The results showed that in the 0−10 cm soil layer, compared with the NTR0% treatment, concentrations of hydrolysable NH4+-N, amino sugar-N and active-SON and N-acetyl-β- d -glucosaminidase (NAG) activity were significantly increased in the NTR33% treatment. Amidase showed a significantly higher activity under the NTR100% treatment. Urease activity was significantly increased in residue application treatments. In the 10−20 cm soil layer, compared to the NTR0% treatment, the NTR33% treatment showed a significantly higher concentration of active-SON. Concentrations of hydrolysable unknown-N and stable-SON were significantly increased in both NTR67% and NTR100% treatments. NTR33% and NTR67% treatments significantly increased protease and amidase activities, respectively, and urease showed a significantly higher activity under the two treatments. The results of redundancy analysis indicated a relationship of SON fractions with soil microbial biomass carbon and pH in the 0−10 cm soil layer, and with protease and NAG activities in the 10−20 cm soil layer. These results suggested that crop residue application at a low rate (33 %) had a greater potential for enhancing active SON supplies, whereas moderate and high rates (67 % and 100 %) of crop residue application were more effective in maintaining a stable SON pool in the Phaeozem area of northeastern China.

WOS: 000403692800006, Four new chiral Schiff base ligands (3a-4a, 3b-4b) have been prepared using aminoisopropylidene derivatives of glucose and aminochloralose derivatives of mannose. The synthesized compounds 1 and 2 were characterized by nuclear magnetic resonance (H-1 and C-13 NMR), Fourier transform infrared spectroscopy (FTIR), UV/visible spectroscopy, and elemental analysis. A total of eight Schiff base compounds (3a-6a, 3b-6b) were tested for antimicrobial activity against Escherichia coli ATCC 12228, Staphylococcus aureus ATCC 6538, Klebsiella pneumoniae CCM 2318, Pseudomonas aeruginosa ATCC 27853, Salmonella typhimurium CCM 5445, Enterococcus faecalis ATCC 29212, Bacillus subtilis ATCC 6633, and Candida albicans ATCC 10239 and exhibited a range of activities.

Enzymes belonging to the GNAT superfamily are widely distributed in nature where they play key roles in the transfer of acyl groups from acyl-CoAs to primary amine acceptors. The amine acceptors run the gamut from histones to aminoglycoside antibiotics to small molecules such as serotonin. Whereas those family members that function on histones have been extensively studied, the GNAT enzymes that employ nucleotide-linked sugars as their substrates have not been well characterized. Indeed, though the structures of two of these “amino sugar” GNAT enzymes have been determined within the past 10 years, details concerning their active site architectures have been limited because of a lack of bound nucleotide-linked sugar substrates. Here we describe a combined structural and biochemical analysis of FdhC from Acinetobacter nosocomialis O2. On the basis of bioinformatics, it was postulated that FdhC catalyzes the transfer of a 3-hydroxybutanoyl group from 3-hydroxylbutanoyl-CoA to dTDP-3-amino-3,6-dideoxy-d-galactose, to yield an unusual sugar that is ultimately incorporated into the surface polysaccharides of the bacterium. We present data confirming this activity. In addition, the structures of two ternary complexes of FdhC, in the presence of CoA and either 3-hydroxybutanoylamino-3,6-dideoxy-d-galactose or 3-hydroxybutanoylamino-3,6-dideoxy-d-glucose, were solved by X-ray crystallographic analyses to high resolution. Kinetic parameters were determined, and activity assays demonstrated that FdhC can also utilize acetyl-CoA, 3-methylcrotonyl-CoA, or hexanoyl-CoA as acyl donors, albeit at reduced rates. Site-directed mutagenesis experiments were conducted to probe the catalytic mechanism of FdhC. Taken together, the data presented herein provide significantly new molecular insight into those GNAT superfamily members that function on nucleotide-linked amino sugars.

Rhizosphere microbial communities play an essential role in determining plant productivity, particularly in agriculturally marginal environments. Perennial plants like switchgrass (Panicum virgatum) are thought to particularly influence microbial community composition and function within their rhizosphere. We compared microbial communities in switchgrass rhizospheres and their associated bulk soils in two regions of the U.S. upper Midwest (Michigan and Wisconsin) with contrasting soil types, and at two site types with differing switchgrass establishment ages and management intensities. We characterized microbial communities with a range of culture-independent methods, including amplicon sequencing of 16S/18S rRNA and nifH genes, and membrane lipid profiling. In addition, we quantified abundances of soil amino sugars, a time-integrative indicator of microbial necromass. We found that amino sugar contents and microbial lipid profiles differed between rhizosphere and bulk soils, while DNA-based assays did not provide this discriminatory power. Differences between rhizosphere and bulk soils were not significantly affected by region or site type. Rhizosphere soils had higher microbial lipid abundances, particularly those associated with arbuscular mycorrhizal fungi and Gram-negative bacteria, while amino sugar abundances decreased in the rhizosphere. Our findings suggest switchgrass rhizospheres systematically stimulate microbial growth and microbial residue turnover.

The majority of oligosaccharides used as prebiotics typically consist of a combination of 3 kinds of neutral monosaccharides, d-glucose, d-galactose, and d-fructose. In this context, we aimed to generate new types of prebiotic oligosaccharides containing other monosaccharides, and to date have synthesized various oligosaccharides containing an amino sugar, uronic acid, and their derivatives. In this study, we investigated the effects of 4 kinds of sucrose (Suc) analog disaccharides containing d-glucosamine, N-acetyl-d-glucosamine, d-glucuronic acid, or d-glucuronamide as constituent monosaccharides, on the growth of 8 species of bifidobacteria and 3 species of lactobacilli isolated from the human intestine. The results of these experiments were compared with those obtained from identical experiments using Suc. We confirmed that all bacterial strains could utilize Suc as a nutrient source for growth; in contrast, only specific species of bifidobacteria showed growth with Suc analog disaccharides. When oligosaccharides are utilized as a nutrient source by bacteria, they are often broken down into monosaccharides or their derivatives by cellular enzymes before entering the intracellular glycolytic pathway. Therefore, to clarify the above phenomenon involved in the growth of bifidobacteria using Suc analog disaccharides, we investigated the cellular glycosidases of 3 strains of bifidobacteria shown to be capable or incapable of growth in the presence of these disaccharides. As the result, it was confirmed that the strains capable of growth using Suc analog disaccharides show greater productivity of glycosidases that degrade these disaccharides than strains not capable of growth; however, we have not identified the enzymes here.

The dynamics of microbial necromass of municipal solid waste over long-term landfill remain unknown. This study presents the first investigation on the dynamics of bacterial and fungal necromass of municipal sludge in non-aeration versus alternating aeration landfill bioreactors by using amino sugar biomarkers. Results showed that under non-aeration treatment, the decomposition rate of muramic acid derived from bacteria is higher than that of fungal-derived glucosamine. The relative change in glucosamine and muramic acid in the early period of landfills under the alternating aeration treatment is consistent with that under non-aeration treatment. However, with the increase in alternating aeration cycles, bacterial necromass muramic acid exerts a lower decomposition rate than fungal necromass glucosamine. Throughout the entire landfill period, galactosamine is the amino sugar with the slowest decomposition rate under non-aeration mode but the amino sugar with the fastest decomposition rate under alternating aeration mode. The present work fills the knowledge gap of microbial necromass dynamics of municipal solid waste in landfills.

Plant residue incorporation improves soil microbial nitrate immobilization, which in turn alleviates nitrate accumulation, thereby improving N retention capacity and reducing N losses. However, how and why the respective nitrate immobilization by fungi and bacteria, which are dominant microorganisms in soil, responds to residue addition remains unknown. By adopting a novel amino sugar-based stable isotope probing approach, we show that both fungal and bacterial nitrate immobilization increased after Paspalum notatum residue addition. The increased proportion of the former was higher than that of the latter, and their difference became much larger with the increased residue addition rate. Furthermore, 70% and 32% of the variations in fungal and bacterial nitrate immobilization activities were explained by their respective biomass. The relative importance of fungal and bacterial nitrate immobilization shifted in a consistent manner with the relative abundance of fungi and bacteria, and the magnitude of these shifts was related to the residue addition rate. Our work demonstrates strong links between increased residue inputs, alterations in microbial community composition, and enhanced ecosystem functioning of nitrate immobilization and retention in soil.

N-acetylglucosamine (GlcNAc) and glucosamine (GlcN) enhance the competitiveness of the laboratory strain DL1 ofStreptococcus gordoniiagainst the caries pathogenStreptococcus mutans. Here we examine how amino sugars affect the interaction of five low-passage clinical isolates of abundant commensal streptococci withS. mutansutilizing a dual-species biofilm model. Compared to glucose, growth on GlcN or GlcNAc significantly reduced the viability ofS. mutansin co-cultures with most commensals, shifting the proportions of species. Consistent with these results, production of H2O2was increased in most commensals when growing on amino sugars, and inhibition ofS. mutansbyStreptococcus cristatus, Streptococcus oralis,orS. gordoniiwas enhanced by amino sugars on agar plates. All commensals exceptS. oralishad higher arginine deiminase activities when grown on GlcN, and in some cases GlcNAc. Inex vivobiofilms formed using pooled cell-containing saliva (CCS), the proportions ofS. mutanswere drastically diminished when GlcNAc was the primary carbohydrate. Increased production of H2O2could account in large part for the inhibitory effects of CCS biofilms. Surprisingly, amino sugars appeared to improve mutacin production byS. mutanson agar plates, suggesting that the commensals have mechanisms to actively subvert antagonism byS. mutansin co-cultures. Collectively, these findings demonstrate that amino sugars can enhance the beneficial properties of low-passage commensal oral streptococci and highlight their potential for moderating the cariogenicity of oral biofilms.SIGNIFICANCEDental caries is driven by dysbiosis of oral biofilms in which dominance by acid-producing and acid-tolerant bacteria results in loss of tooth mineral. Our previous work demonstrated the beneficial effects of amino sugars, GlcNAc and GlcN, in promoting the antagonistic properties of a health-associated oral bacterium,Streptococcus gordonii,in competition with the major caries pathogenStreptococcus mutans.Here we investigated 5 low-passage clinical isolates of the most common streptococcal species to establish how amino sugars may influence the ecology and virulence of oral biofilms. Using multiplein vitromodels, including a human saliva-derived microcosm biofilm, experiments showed significant enhancement by at least one amino sugar in the ability of most of these bacteria to suppress the caries pathogen. Therefore, our findings demonstrated the mechanism of action by which amino sugars may affect human oral biofilms to promote health.

Aluminum (Al) at high concentrations inhibits root growth, damage root systems, and causes significant reductions in rice yields. Indica and Japonica rice have been cultivated in distinctly different ecological environments with different soil acidity levels, thus, they might have different mechanisms of Al-tolerance. In the present study, transcriptomic analysis in the root apex for Al-tolerance in the seedling stage was carried out within Al-tolerant and -sensitive varieties belonging to different subpopulations (i.e., Indica, Japonica, and mixed). We found that there were significant differences between the gene expression patterns of Indica Al-tolerant and Japonica Al-tolerant varieties, while the gene expression patterns of the Al-tolerant varieties in the mixed subgroup, which was inclined to Japonica, were similar to the Al-tolerant varieties in Japonica. Moreover, after further GO (gene ontology) and KEGG (Kyoto Encyclopedia of Genes and Genomes) analyses of the transcriptomic data, we found that eight pathways, i.e., &ldquo, Terpenoid backbone biosynthesis&rdquo, &ldquo, Ribosome&rdquo, Amino sugar and nucleotide sugar metabolism&rdquo, Plant hormone signal transduction&rdquo, TCA cycle&rdquo, Synthesis and degradation of ketone bodies&rdquo, and &ldquo, Butanoate metabolism&rdquo, were found uniquely for Indica Al-tolerant varieties, while only one pathway (i.e., &ldquo, Sulfur metabolism&rdquo, ) was found uniquely for Japonica Al-tolerant varieties. For Al-sensitive varieties, one identical pathway was found, both in Indica and Japonica. Three pathways were found uniquely in &ldquo, Starch and sucrose metabolism&rdquo, Metabolic pathway&rdquo

Glycosaminoglycan (GAGs) are linear chain glycans consisting of repeating uronic sugar and amino sugar copolymers and play major roles in fundamental biological processes. Despite being ubiquitous in cells, the structure of GAGs remains relatively elusive and is challenging to characterize with mass spectrometry. This chapter discusses how Fourier transform mass spectrometry (FTMS) plays a vital role in developing methods for high throughput structural elucidation of GAGs. High mass accuracy measurements of the mass spectrum allow for composition assignment of the intact glycan; tandem mass spectrometry with various ion activation techniques have been used to determine the location of structural microheterogeneities with high specificity. Software analysis packages for GAGs have also been developed recently, allowing for the option of high-throughput analysis without the need for any user supervision. New and promising developments in FTMS have significantly improved structural characterization possibilities in the field of glycomics.

Lipopolysaccharides (LPSs) play key roles in humoral immunity. Recently, the LPS structure of the Psychrobacter cryohalolentis K5T strain was reported. Due to the presence of unnatural amino sugars and branched linkages, its structure is unique. Herein we report the total synthesis of an LPS analogue of P. cryohalolentis K5T. After overcoming the issues like ring conformation changes and elimination of triflate, we were able to develop a strategy for the synthesis of the newly reported 2,3,4-triacetamido-2,3,4-trideoxy-l-arabinose derivative. Coupling of different donors with suitable acceptors from the nonreducing end to the reducing end and further functional group modifications delivered the protected LPS hexasaccharide repeating unit. After functional group modifications, we were unable to oxidize the hindered primary hydroxyl group to synthesize the target molecule. Alternatively, removal of the permanent protecting groups afforded the LPS hexasaccharide repeating unit analogue of Psychrobacter cryoh...

Malolactic fermentation (MLF), usually induced by Oenococcus oeni (O. oeni), is an important process to improve wine quality. Acid acclimation has been proven to be useful for enhancing the viability of lyophilized O. oeni. To explain the involved mechanisms, cell integrity, morphology and protein patterns of lyophilized O. oeni SD-2a were investigated with acid acclimation. After lyophilization, improvement of cell integrity and more extracellular polymeric substances (EPS) were observed in acid acclimated cells. Combined with GO and KEGG analysis, different abundant proteins were noticeably enriched in the carbohydrate metabolism process, especially amino sugar and nucleotide sugar metabolism. The most significant result was the over-expression of proteins participating in cell wall biosynthesis, EPS production, ATP binding and the bacterial secretion system. This result indicated the important role of acid acclimation on cell envelope properties. In addition, protein response to stress and arginine deiminase pathway were also proven to be over-expressed.

Growth and division by most bacteria requires remodelling and cleavage of their cell wall. A byproduct of this process is the generation of free peptidoglycan (PG) fragments known as muropeptides, which are recycled in many model organisms. Bacteria and hosts can harness the unique nature of muropeptides as a signal for cell wall damage and infection, respectively. Despite this critical role for muropeptides, it has long been thought that pathogenic mycobacteria such as Mycobacterium tuberculosis do not recycle their PG. Herein we show that M. tuberculosis and Mycobacterium bovis BCG are able to recycle components of their PG. We demonstrate that the core mycobacterial gene lpqI, encodes an authentic NagZ β-N-acetylglucosaminidase and that it is essential for PG-derived amino sugar recycling via an unusual pathway. Together these data provide a critical first step in understanding how mycobacteria recycle their peptidoglycan., Bacterial growth and division require remodelling of the cell wall, which generates free peptidoglycan fragments. Here, Moynihan et al. show that Mycobacterium tuberculosis can recycle components of their peptidoglycan, and characterise a crucial enzyme required for this process.

A modified GC-MS analytical procedure based on trimethylsilyl-dithioacetal (TMSD) derivatization has been established for a simultaneous determination of thirteen carbohydrates. Different from previous approaches, the current GC-MS method was featured by a powerful practicability for simultaneous detection of aldoses, uronic acids, ketoses, and amino sugars; simplifying GC-MS chromatograms and producing a single peak for each derivatized sugar, as well as high resolution, sensitivity, and repeatability. An additional liquid-liquid extraction from derivatization mixtures was performed not only to increase the detection sensitivity of amino sugars but also to decrease the by-products of derivatization. Contrarily, three amino sugars were detected at a very low intensity or not detected at all. The effect of time on monosaccharide- mercaptalated reaction was systematically investigated. The effect of trimethylsilylation on the formation of TMSD was also optimized. The established GC-MS based on TMSD derivatization was suitable for complex carbohydrate analysis and has been successfully applied for the detection of free carbohydrates in water extracts of Anemarrhena asphodeloides roots and determination of monosaccharides in Glossy ganoderma polysaccharides.

We investigated presence and distribution of glycosaminoglycans (GAGs) in Meretrix meretrix soft tissue by determining GAG composition in the different parts, namely, mantle edge, foot, gill, adductor muscle, and viscera. The occurrence of glycan ingredients was examined by histochemistry, whereas GAG and general polysaccharide contents in clam tissue were qualified through extraction and determination. Tissue sections stained with alcian blue or periodic acid–Schiff demonstrated the general existence of saccharides and trifling generation of GAGs in clam tissues. GAGs coexisting with glycogens appeared to be primarily produced in the mantle and foot tissues in mucus form by visualization. The GAG content of the polysaccharide extract ranged from 16.8 to 75.8 mg in 10 g of 5 dried tissue materials in comparison with total carbohydrate level in the range of 500–1760 mg, thereby indicating that GAGs were not the major components of polysaccharide extracts. GAG composition only accounted for approximately 4% of total glycan components, which consist of the determinations of amino sugar and uronic acid. The soft tissues of clam contained abundant saccharide compounds but sparse amounts of GAGs. The results will benefit the subsequent development of products made from the polysaccharide components of M. meretrix.

Spr1654 from Streptococcus pneumoniae plays a key role in the production of unusual sugars, presumably functioning as a pyridoxal-5′-phosphate (PLP)-dependent aminotransferase. Spr1654 was predicted to catalyse the transferring of amino group to form the amino sugar 2-acetamido-4-amino-2, 4, 6-trideoxygalactose moiety (AATGal), representing a crucial step in biosynthesis of teichoic acids in S. pneumoniae . We have determined the crystal structures of the apo-, PLP- and PMP-bound forms of Spr1654. Spr1654 forms a homodimer, in which each monomer contains one active site. Using spectrophotometry and based on absorbance profiles of PLP- and PMP-formed enzymes, our results indicate that l -glutamate is most likely the preferred amino donor. Structural superposition of the crystal structures of Spr1654 on previously determined structures of other sugar aminotransferases in complex with glutamate and/or UDP-activated sugar allowed us to identify key Spr1654 residues for ligand binding and catalysis. The crystal structures of Spr1654 and in complex with PLP and PMP can direct the future rational design of novel therapeutic compounds against S. pneumoniae .

Milk contains nutrients needed by the body, and the main components of different animal milk vary. Accordingly, we evaluated cow and goat milk's nutrition and their effects on the gut microbiota in mice models using a high-throughput 16S rRNA sequencing technology. The intestinal microbiota of mice changed significantly after the intake of cow and goat milk, and the goat milk had a greater effect on the intestinal microbial community than the cow milk. Bifidobacterium, Allobaculum, Olsenella and Akkermansia grew significantly in both cow and goat milk groups compared with the control group, indicating that milk positively affected their growth. We also found that the citrate cycle (TCA cycle), pyruvate metabolism, and amino sugar and nucleotide sugar metabolism, as well as lipoic acid metabolism, were higher in the goat milk group than in the cow milk group. Association analysis of milk components and their representative intestinal microbiota showed that casein, αs1-casein, and β + κ-casein were positively correlated with Enterococcus and Allobaculum, and negatively correlated with Roseburia. Protein and αs2-casein were positively associated with Akkermansia, Bifidobacterium and Eubacterium.

A bacterium isolated from wastewater sludge, identified as Bacillus subtilis F9, was confirmed to produce bioflocculant with excellent flocculation activity. The effects of culture conditions such as initial pH, temperature, carbon source, nitrogen source, and inoculum size on bioflocculant production were studied here. The results indicated that 2.32g/L of purified bioflocculant could be extracted with the following optimized conditions: 20gL(-1) sucrose as the carbon source, 3.5gL(-1) peptone as the nitrogen source, an initial pH of 7.0, and a temperature of 40°C. The purified bioflocculant consisted of 10.1% protein and 88.3% sugar, including 38.4% neutral sugar, 2.86% uronic acid, and 2.1% amino sugar. The neutral sugar consisted of sucrose, glucose, lactose, galactose, and mannose at a molar ratio of 2.7:4.7:3.2:9.1:0.8. Elemental analysis of the purified bioflocculant revealed that the weight fractions of carbon, hydrogen, oxygen, nitrogen, and sulfur were 30.8%, 5.3%, 54.7%, 6.4%, and 2.9%, respectively. Furthermore, the purified bioflocculant was pH tolerant within the range of 2-8 and thermotolerant from 10°C to 100°C, with optimal activity at pH 7.0 and at a temperature of 40°C. The purified bioflocculant showed industrial potential for the treatment of drinking water. Considering these properties, especially its low molecular weight (5.3×10(4)Da), this bioflocculant with excellent solubility and favorable flocculation activity is particularly suited for flocculating small particles.

Methods for the absolute quantification of glycans are needed in glycoproteomics, during development and production of biopharmaceuticals and for the clinical analysis of glycan disease markers. Here we present a strategy for the chemo-enzymatic synthesis of (13)C labeled N-glycan libraries and provide an example for their use as internal standards in the profiling and absolute quantification of mAb glycans by matrix-assisted laser desorption ionization-time-of-flight (MALDI-TOF) mass spectrometry. A synthetic biantennary glycan precursor was (13)C-labeled on all four amino sugar residues and enzymatically derivatized to produce a library of 15 glycan isotopologues with a mass increment of 8 Da over the natural products. Asymmetrically elongated glycans were accessible by performing enzymatic reactions on partially protected UV-absorbing intermediates, subsequent fractionation by preparative HPLC, and final hydrogenation. Using a preformulated mixture of eight internal standards, we quantified the glycans in a monoclonal therapeutic antibody with excellent precision and speed.

Kedarcidin, produced by Streptoalloteichus sp. ATCC 53650, is a fascinating chromoprotein of 114 amino acid residues that displays both antibiotic and anticancer activity. The chromophore responsible for its chemotherapeutic activity is an ansa-bridged enediyne with two attached sugars, l-mycarose, and l-kedarosamine. The biosynthesis of l-kedarosamine, a highly unusual trideoxysugar, is beginning to be revealed through bioinformatics approaches. One of the enzymes putatively involved in the production of this carbohydrate is referred to as KedS8. It has been proposed that KedS8 is an N-methyltransferase that utilizes S-adenosylmethionine as the methyl donor and a dTDP-linked C-4' amino sugar as the substrate. Here we describe the three-dimensional architecture of KedS8 in complex with S-adenosylhomocysteine. The structure was solved to 2.0 A resolution and refined to an overall R-factor of 17.1%. Unlike that observed for other sugar N-methyltransferases, KedS8 adopts a novel tetrameric quaternary structure due to the swapping of β-strands at the N-termini of its subunits. The structure presented here represents the first example of an N-methyltransferase that functions on C-4' rather than C-3' amino sugars.

Tannerella forsythia is a Gram-negative oral pathogen strongly associated with periodontitis. This bacterium has an absolute requirement for exogenous Nacetylmuramic acid (MurNAc), an amino sugar which forms the repeating disaccharide unit with amino sugar N-acetylglucosamine (GlcNAc) of the peptidoglycan backbone. In silico genome analysis indicates that T. forsythia lacks the key biosynthetic enzymes needed for the de novo synthesis of MurNAc, and thus relies on alternative ways to meet its requirement for peptidoglycan biosynthesis. In the subgingival niche, the bacterium can acquire MurNAc and peptidoglycan fragments (muropeptides) released by the cohabiting bacteria during their cell wall breakdown associated with cell division.T. forsythia is able to also utilize host sialic acid (Neu5Ac) in lieu of MurNAc or muropeptides for its survival during the biofilm growth. The evidence suggests that the bacterium might be able to shunt sialic acid into a metabolic pathway leading to peptidoglycan synthesis. In this review, we explore the mechanisms by which T. forsythia is able to scavenge MurNAc, muropeptide, and sialic acid for its peptidoglycan synthesis, and the impact of these scavenging activities on pathogenesis.

The structures of capsular polysaccharides (CPSs) produced by different Acinetobacter baumannii strains have proven to be invaluable in confirming the role of specific genes in the synthesis of rare sugars through the correlation of genetic content at the CPS biosynthesis locus with sugars found in corresponding CPS structures. A module of four genes (rmlA, rmlB, vioA and vioB) was identified in the KL57 capsule biosynthesis gene cluster of A. baumannii isolate BAL_212 from Vietnam. These genes were predicted to direct the synthesis of 4-acetamido-4,6-dideoxy-d-glucose (N-acetylviosamine, d-Qui4NAc) and the K57 CPS was found to contain this monosaccharide. The K57 structure was determined and, in addition to d-Qui4NAc, included three N-acetylgalactosamine residues in the main chain, with a single glucose side branch. The KL57 gene cluster has not been found in any other A. baumannii genomes, but the rmlA-rmlB-vioA-vioB module is present in the KL119 gene cluster that would likely produce a d-Qui4NAc-containing CPS.

Saccharomyces cerevisiae can transport and phosphorylate glucosamine, but cannot grow on this amino sugar. While an enzyme catalyzing the reaction from glucosamine-6-phosphate to fructose-6-phosphate, necessary for glucosamine catabolism, is present in yeasts using N-acetylglucosamine as carbon source, a sequence homology search suggested that such an enzyme is absent from Saccharomyces cerevisiae. The gene YlNAG1 encoding glucosamine-6-phosphate deaminase from Yarrowia lipolytica was introduced into S. cerevisiae and growth in glucosamine tested. The constructed strain grew in glucosamine as only carbon and nitrogen source. Growth on the amino sugar required respiration and caused an important ammonium excretion. Strains overexpressing YlNAG1 and one of the S. cerevisiae glucose transporters HXT1, 2, 3, 4, 6 or 7 grew in glucosamine. The amino sugar caused catabolite repression of different enzymes to a lower extent than that produced by glucose. The availability of a strain of S. cerevisiae able to grow on glucosamine opens new possibilities to investigate or manipulate pathways related with glucosamine metabolism in a well-studied organism., Te fnancial support by grant CIVP18A3896 of the Fundación Ramón Areces (Madrid, Spain) is gratefully acknowledged.

High-performance liquid chromatography (HPLC) is routinely used to analyze monosaccharide composition. This is the first report describing the simultaneous determination of uronic acid, amino sugar, and neutral sugar in the polysaccharide from Angelica sinensis using pre-column derivatization. We were able to analyze the monosaccharide composition of acidic Angelica polysaccharides (AAPS) using this method. Ten different monosaccharides, namely d-mannose, d-glucosamine, l-rhamnose, d-galactosamine, d-glucuronic acid, d-galacturonic acid, d-glucose, d-galactose, l-arabinose, and l-fucose were made into pre-column derivatives to serve as the standard for AAPS analysis. Samples were separated on a Hypersil BDS C18 column (4.6 mm × 250 mm, i.d.) and detected by UV detection at 250 nm wavelength. The mobile phase was composed of aqueous ammonium acetate buffer (100 mM, pH 5.0), acetonitrile, and tetrahydrofuran in the ratio of 81:17:2. Analytes were performed at 25 °C with a flow rate of 1.0 ml/min. Our study found that AAPS is composed of d-mannose, d-glucosamine, l-rhamnose, d-galactosamine, d-glucuronic acid, d-galacturonic acid, and d-glucose in a molar ratio of 1.5:14.1:1.7:1.6:2.0:2.3:1.

The ST0452 protein from the thermophilic archaean Sulfolobus tokodaii has been identified as an enzyme with multiple sugar-1-phosphate nucleotidylyltransferase and amino-sugar-1-phosphate acetyltransferase (amino-sugar-1-P AcTase) activities. Analysis of the protein showed that in addition to glucosamine-1-phosphate (GlcN-1-P) AcTase activity, it possesses unique galactosamine-1-phosphate (GalN-1-P) AcTase activity not detected in any other proteins. Comparison of the crystal structures of the ST0452 protein and GlmU from Escherichia coli (EcGlmU), which possesses only GlcN-1-P AcTase activity, showed that the overall sequence identity between these two proteins is less than 25 %, but the amino acid residues predicted to comprise the catalytic center of EcGlmU are conserved in the ST0452 protein. To understand the molecular mechanism by which the ST0452 amino-sugar-1-P AcTase activity recognizes two independent substrates, several ST0452 substitution and truncation mutant proteins were constructed and analyzed. We found that His308 is essential for both GalN-1-P and GlcN-1-P AcTase activities, whereas Tyr311 and Asn331 are important only for the GalN-1-P AcTase activity. In addition, deletion of the C-terminal 5 or 11 residues showed that the 11-residue C-terminal region exerts a modest stimulatory effect on GalN-1-P AcTase activity but dramatically suppresses GlcN-1-P AcTase activity. This region also appears to make an important contribution to the thermostability of the entire ST0452 protein. Systematic deletions from the C-terminus also demonstrated that the C-terminal region with the β-helix structure has an important role mediating the trimerization of the ST0452 protein. This is the first report of an analysis of a thermostable archaeal enzyme exhibiting multiple amino-sugar-1-P AcTase activities.

Amino sugars are dual-purpose compounds in bacteria: they are essential components of the outer wall peptidoglycan (PG) and the outer membrane of Gram-negative bacteria and, in addition, when supplied exogenously their catabolism contributes valuable supplies of energy, carbon and nitrogen to the cell. The enzymes for both the synthesis and degradation of glucosamine (GlcN) and N-acetylglucosamine (GlcNAc) are highly conserved but during evolution have become subject to different regulatory regimes. Escherichia coli grows more rapidly using GlcNAc as a carbon source than with GlcN. On the other hand, Bacillus subtilis, but not other Bacilli tested, grows more efficiently on GlcN than GlcNAc. The more rapid growth on this sugar is associated with the presence of a second, GlcN-specific operon, which is unique to this species. A single locus is associated with the genes for catabolism of GlcNAc and GlcN in E. coli, although they enter the cell via different transporters. In E. coli the amino sugar transport and catabolic genes have also been requisitioned as part of the PG recycling process. Although PG recycling likely occurs in B. subtilis, it appears to have different characteristics.

The molecular mechanisms that underlie drought stress responses in kenaf, an important crop for the production of natural fibers, are poorly understood. To address this issue, we describe here the first iTRAQ-based comparative proteomic analysis of kenaf seedlings. Plants were divided into the following three treatment groups: Group A, watered normally (control); Group B, not watered for 6 days (drought treatment); and Group C, not watered for 5 days and then rewatered for 1 day (recovery treatment). A total of 5014 proteins were detected, including 4932 (i.e., 98.36%) that were matched to known proteins in a BLAST search. We detected 218, 107, and 348 proteins that were upregulated in Group B compared with Group A, Group C compared with Group A, and Group B compared with Group C, respectively. Additionally, 306, 145, and 231 downregulated proteins were detected during the same comparisons. Seventy differentially expressed proteins were analyzed and classified into 10 categories: photosynthesis, sulfur metabolism, amino sugar and nucleotide sugar metabolism, oxidative phosphorylation, ribosome, fatty acid elongation, thiamine metabolism, tryptophan metabolism, plant-pathogen interaction, and propanoate. Kenaf adapted to stress mainly by improving the metabolism of ATP, regulating photosynthesis according to light intensity, promoting the synthesis of osmoregulators, strengthening ion transport signal transmission, and promoting metabolism and cell stability. This is the first study to examine changes in protein expression in kenaf plants exposed to drought stress. Our results identified key drought-responsive genes and proteins and may provide useful genetic information for improving kenaf stress resistance.

The ability of anammox bacteria to utilize organic matter has drawn extensive attention. However, the metabolic discrepancies between autotrophic and mixotrophic anammox consortia need to be further explored. Here, microbial transcript and metabolomic analysis were conducted for the samples harvested in the reactors and batch assays to investigate the phenotype discrepancies and intrinsic causes in autotrophic and mixotrophic anammox consortia. Results showed that metabolically active community structures did not show significant difference between autotrophic and mixotrophic anammox consortia (C/N = 0.3). Changes in the metabolic state were the main cause for those discrepancies in virtue of the added acetate oxidized via the acetyl-CoA pathway by mixotrophic anammox bacteria. At C/N ratio of 0.3, anammox activity was obviously promoted compared to that in the autotrophic condition, due to higher levels of NADH and NAD+, as well as ATP consumption. Mixotrophic anammox consortia were found to yield more biomass, resulting from enhanced purine, pyrimidine, and putrescine synthetic pathways for regulating bacterial growth. Up-regulated amino sugar and nucleotide sugar metabolism pathways participating in regulating more extracellular polysaccharides secreted by mixotrophic anammox consortia. In adverse environment with higher COD concentration, more extracellular proteins were produced by anammox consortia to protect themselves and amino acids also accumulated in the cell. This study provides useful information to catch the optimal metabolism way of anammox consortia and accelerate anammox bacterial cultivation or reactor startup for wastewater treatment.

The chemical structures of the unusual hopanoid-containing lipid A samples of the lipopolysaccharides (LPS) from three strains of Bradyrhizobium (slow-growing rhizobia) have been established. They differed considerably from other Gram-negative bacteria in regards to the backbone structure, the number of ester-linked long chain hydroxylated fatty acids, as well as the presence of a tertiary residue that consisted of at least one molecule of carboxyl-bacteriohopanediol or its 2-methyl derivative. The structural details of this type of lipid A were established using one- and two-dimensional NMR spectroscopy, chemical composition analyses, and mass spectrometry techniques (electrospray ionization Fourier-transform ion cyclotron resonance mass spectrometry and MALDI-TOF-MS). In these lipid A samples the glucosamine disaccharide characteristic for enterobacterial lipid A was replaced by a 2,3-diamino-2,3-dideoxy-d-glucopyranosyl-(GlcpN3N) disaccharide, deprived of phosphate residues, and substituted by an α-d-Manp-(1→6)-α-d-Manp disaccharide substituting C-4' of the non-reducing (distal) GlcpN3N, and one residue of galacturonic acid (d-GalpA) α-(1→1)-linked to the reducing (proximal) amino sugar residue. Amide-linked 12:0(3-OH) and 14:0(3-OH) were identified. Some hydroxy groups of these fatty acids were further esterified by long (ω-1)-hydroxylated fatty acids comprising 26-34 carbon atoms. As confirmed by mass spectrometry techniques, these long chain fatty acids could form two or three acyloxyacyl residues. The triterpenoid derivatives were identified as 34-carboxyl-bacteriohopane-32,33-diol and 34-carboxyl-2β-methyl-bacteriohopane-32,33-diol and were covalently linked to the (ω-1)-hydroxy group of very long chain fatty acid in bradyrhizobial lipid A. Bradyrhizobium japonicum possessed lipid A species with two hopanoid residues.

The main objective of this study was to further investigate whether the occurrence of Strecker degradation in krill-based products is due to the presence of N-Acetylglucosamine (amino sugar derived from krill exoskeleton) or lipid-derived carbonyls. A simple model system comprising amino acids was incubated at 60°C for 0, 3, 9, and 24 h with five selected lipid-derived carbonyls or five Strecker-derived volatiles or an amino sugar. The presence of both amino sugar and lipid-derived carbonyls (especially α,β-unsaturated aldehydes) caused non-enzymatic browning reactions: (i) pyrrole formation; (ii) browning development; and (iii) Strecker degradation of amino acids, with a faster reaction rate by amino sugar. In addition, the presence of a high level of Strecker degradation products might enhance pyrrole formation. Practical applications: This work provides information about the Strecker degradation of amino acids induced by amino sugar (N-Acetylglucosamine) and lipid-derived carbonyl compounds, and the increase of pyrrole formation is ascribed to the presence of a high level of Strecker degradation products. The obtained knowledge from this fundamental study explains the occurrence of Strecker degradation in krill products especially after enzymatic treatment due to the increased level of amino acids, lipid oxidation products and amino sugar derived from krill shell. This information is not only applicable to krill matrix but also to similar matrices from other food systems. Non-enzymatic browning reactions, especially Strecker degradation of amino acids in krill-based products during their thermal treatment, are induced either through Maillard reaction due to the presence of amino sugar derived from krill exoskeleton or through the lipid peroxidation pathway due to the presence of unsaturated aldehydes derived from lipid oxidation.

Acidobacteria constitute an abundant fraction of the soil microbial community and are currently divided into 26 subdivisions. Most cultivated members of the Acidobacteria are affiliated with subdivision 1, while only a few representatives of subdivisions 3, 4, 8, 10 and 23 have been isolated and described so far. Two novel isolates of subdivision 4 of the Acidobacteria were isolated from subtropical savannah soils and are characterized in the present work. Cells of strains A22_HD_4HT and Ac_23_E3T were immotile rods that divided by binary fission. Colonies were pink and white, respectively. The novel strains A22_HD_4HT and Ac_23_E3T were aerobic mesophiles with a broad range of tolerance towards pH (4.0–9.5 and 3.5–10.0, respectively) and temperature (15–44 and 12–47 °C, respectively). Both showed chemo-organoheterotrophic growth on some sugars, the amino sugar N-acetylgalactosamine, a few amino acids, organic acids and various complex protein substrates. Major fatty acids of A22_HD_4HT and Ac_23_E3T were iso-C15 : 0, summed feature 1 (C13 : 0 3-OH/iso-C15 : 1 H), summed feature 3 (C16 : 1ω7c/C16 : 1ω6c) and anteiso-C17 : 0. The major quinone was MK-8; in addition, MK-7 occurred in small amounts. The DNA G+C contents of A22_HD_4HT and Ac_23_E3T were 53.2 and 52.6 mol%, respectively. The closest described relative was Blastocatella fastidiosa A2-16T, with 16S rRNA gene sequence identity of 93.2 and 93.3 %, respectively. Strains A22_HD_4HT and Ac_23_E3T displayed 16S rRNA gene sequence similarity of 97.4 % to each other. On the basis of the low DNA–DNA hybridization value, the two isolates represent different species. Based on morphological, physiological and molecular characteristics, the new genus Aridibacter gen. nov. is proposed, with two novel species, the type species Aridibacter famidurans sp. nov. (type strain A22_HD_4HT = DSM 26555T = LMG 27985T) and a second species, Aridibacter kavangonensis sp. nov. (type strain Ac_23_E3T = DSM 26558T = LMG 27597T).