Amination of Diazocarbonyl Compounds: N–H Insertion under Metal-Free Conditions

Transition-metal-free intermolecular N–H insertion of α-diazocarbonyl compounds is reported. Among the series of nitrogen sources examined, dibenzenesulfonimide was found to be the choice in terms of the yields and the reaction time. Primary mechanistic experiments suggest that a pathway involving a sequence of protonation and nucleophilic substitution was preferred

Polysubstituted 2‑Aminopyrrole Synthesis via Gold-Catalyzed Intermolecular Nitrene Transfer from Vinyl Azide to Ynamide: Reaction Scope and Mechanistic Insights

A gold-catalyzed intermolecular reaction of vinyl azides and ynamides is described. This process presents an efficient and mild approach to multisubstituted 2-aminopyrroles in good-to-excellent yields. Control experiments were carried out to distinguish the reactivity between vinyl azides and the corresponding 2<i>H</i>-azirines. A plausible reaction mechanism was also proposed according to previous reports and our preliminary mechanistic studies

Polysubstituted 2‑Aminopyrrole Synthesis via Gold-Catalyzed Intermolecular Nitrene Transfer from Vinyl Azide to Ynamide: Reaction Scope and Mechanistic Insights

A gold-catalyzed intermolecular reaction of vinyl azides and ynamides is described. This process presents an efficient and mild approach to multisubstituted 2-aminopyrroles in good-to-excellent yields. Control experiments were carried out to distinguish the reactivity between vinyl azides and the corresponding 2<i>H</i>-azirines. A plausible reaction mechanism was also proposed according to previous reports and our preliminary mechanistic studies

Soil Aggregate Stratification of Ureolytic Microbiota Affects Urease Activity in an Inceptisol

Ureolytic microbes play a pivotal role in the maintenance of soil fertility. Soil aggregates are supposed to provide heterogeneous habitats for microorganisms, which may result in distinct metabolic functions. However, limited information is available regarding the distribution patterns, driving factors, and activity of ureolytic microbiota at the aggregate scale. In this study, we characterized the ureolytic microbiota and urease activity of three soil aggregate fractions from an Inceptisol subjected to 5 years of different fertilization regimes. Correlations between soil chemical characteristics and ureolytic microbial communities were analyzed. The results showed that the total abundance as well as the relative abundance of copiotrophic ureolytic microbes generally increased with the increasing soil aggregate size. This trend was in line with the nutrient distribution patterns, including labile carbon, NH4+, total carbon, nitrogen, and phosphorus. Soil urease activity also increased significantly with the increasing soil aggregate size and was positively correlated with copiotrophic ureolyric microbes, such as Betaproteobacteria, Alphaproteobacteria, and Gammaproteobacteria. Thus, we speculated that larger size soil aggregates with greater availability of labile carbon support more copiotrophic ureolyric microbes with a high growth rate, leading to a high density of total ureolytic microbes and higher urease activity. Smaller aggregates with less available carbon were associated with more oligotrophs, higher abundances of total ureolytic microbes, and higher urease activity. Our results suggest that larger soil aggregates and associated ureolyric microbes play a more important role in nutrient cycling for crop growth in this Inceptisol ecosystem

Data_Sheet_1_Nitrite-Oxidizing Bacteria Community Composition and Diversity Are Influenced by Fertilizer Regimes, but Are Independent of the Soil Aggregate in Acidic Subtropical Red Soil.PDF

<p>Nitrification is the two-step aerobic oxidation of ammonia to nitrate via nitrite in the nitrogen-cycle on earth. However, very limited information is available on how fertilizer regimes affect the distribution of nitrite oxidizers, which are involved in the second step of nitrification, across aggregate size classes in soil. In this study, the community compositions of nitrite oxidizers (Nitrobacter and Nitrospira) were characterized from a red soil amended with four types of fertilizer regimes over a 26-year fertilization experiment, including control without fertilizer (CK), swine manure (M), chemical fertilization (NPK), and chemical/organic combined fertilization (MNPK). Our results showed that the addition of M and NPK significantly decreased Nitrobacter Shannon and Chao1 index, while M and MNPK remarkably increased Nitrospira Shannon and Chao1 index, and NPK considerably decreased Nitrospira Shannon and Chao1 index, with the greatest diversity achieved in soils amended with MNPK. However, the soil aggregate fractions had no impact on that alpha-diversity of Nitrobacter and Nitrospira under the fertilizer treatment. Soil carbon, nitrogen and phosphorus in the soil had a significant correlation with Nitrospira Shannon and Chao1 diversity index, while total potassium only had a significant correlation with Nitrospira Shannon diversity index. However, all of them had no significant correlation with Nitrobacter Shannon and Chao1 diversity index. The resistance indices for alpha-diversity indexes (Shannon and Chao1) of Nitrobacter were higher than those of Nitrospira in response to the fertilization regimes. Manure fertilizer is important in enhancing the Nitrospira Shannon and Chao1 index resistance. Principal co-ordinate analysis revealed that Nitrobacter- and Nitrospira-like NOB communities under four fertilizer regimes were differentiated from each other, but soil aggregate fractions had less effect on the nitrite oxidizers community. Redundancy analysis and Mantel test indicated that soil nitrogen, carbon, phosphorus, and available potassium content were important environmental attributes that control the Nitrobacter- and Nitrospira-like NOB community structure across different fertilization treatments under aggregate levels in the red soil. In general, nitrite-oxidizing bacteria community composition and alpha-diversity are depending on fertilizer regimes, but independent of the soil aggregate.</p

Fatty acid profiles (%) of the strain H4X^T and related type strains of the genus <i>Pontibacter</i>.

<p>Strains: 1, H4X^T; 2, <i>Pontibacter korlensis</i> X14-1^T; 3, <i>Pontibacter actiniarum</i> KMM 6156^T; 4, <i>Pontibacter xinjiangensis</i> 311-10^T; 5, <i>Pontibacter saemangeumensis</i> GCM0142^T. All data were taken from this study, otherwise it was indicated by asterisks. tr, trace (<1%).</p><p>Summed feature 1: C_15∶1 iso H/C_13∶0 3OH.</p><p>Summed feature 3: C_16∶1 ω6c/C_16∶1ω7c.</p><p>Summed feature 4: C_17∶1 anteiso B/iso I.</p><p>Summed feature 5: C_18∶2ω6, 9c/C_18∶0 ante.</p><p>Summed feature 8: C_18∶1ω7c/C_18∶1ω6c.</p><p>Summed feature 9: iso-C_17∶1ω9c/C_16∶0 10 methyl.</p

Core Species Derived from Multispecies Interactions Facilitate the Immobilization of Cadmium

Microbial consortia have opened new avenues for heavy-metal remediation. However, the limited understanding of the overall effect of interspecific interactions on remediation efficacy hinders its application. Here, the effects of multispecies growth and biofilm formation on Cd immobilization were explored from direct and multiple interactions through random combinations of two or three rhizosphere bacteria. In monocultures, Cd stress resulted in an average decrease in planktonic biomass of 26%, but through cooperation, the decrease was attenuated in dual (21%) and triple cultures (13%), possibly involving an increase in surface polysaccharides. More than 65% of the co-cultures exhibited induction of biofilm formation under Cd stress, which further enhanced the role of biofilms in Cd immobilization. Notably, excellent biofilm-forming ability or extensive social induction makes Pseudomonas putida and Brevundimonas diminuta stand out in multispecies biofilm formation and Cd immobilization. These two core species significantly increase the colonization of soil microorganisms on rice roots compared to the control, resulting in a 40% decrease in Cd uptake by rice. Our study enhances the understanding of bacterial interactions under Cd stress and provides a novel strategy for adjusting beneficial soil consortia for heavy-metal remediation

Maximum-likelihood phylogenetic tree based on multiple sequence alignment of 16S rRNA genes of the isolate <i>Pontibacter diazotrophicus</i> sp. nov. H4X^T and other closely related type strains.

<p>Bootstrap values (expressed as percentages of 1000 replicates) that are >75% are shown at branch points. Asterisks indicate that the corresponding nodes were also recovered in the Bayesian tree. Bar, 0.01 substitutions per nucleotide position.</p

Differential properties of the strain H4X^T and related type strains of the genus <i>Pontibacter.</i>

<p>Strains: 1, H4X^T; 2, <i>P</i>. <i>korlensis</i> X14-1^T; 3, <i>P</i>. <i>actiniarum</i> KMM 6156^T; 4, <i>P</i>. <i>xinjiangensis</i> 311-10^T; 5, <i>P</i>. <i>saemangeumensis</i> GCM0142^T. All data were obtained from this study unless otherwise indicated by asterisks. All strains produce N-acetyl-β-glucosaminidase, naphthol-AS-BI-phosphohydrolase, acid phosphatase, leucinearylamidase, valine arylamidase, esterase lipase (C8), alkaline phosphatase and esterase(C4); all strains are negative for hydrolysis of tyrosine, chitin and cellulose, production of indole and H₂S, V-P test, glucose fermentation, and activities of arginine dihydrolase, urease, lysine decarboxilase, ornithine decarboxilase, tryptophane deaminase and α-fucosidase. The strains H4X^T, <i>P</i>. <i>korlensis</i> X14-1^T, <i>P</i>. <i>actiniarum</i> KMM 6156^T and <i>P</i>. <i>xinjiangensis</i> 311-10^T are not able to assimilate itaconic acid, acetate, L-serine, salicin, L-fucose, D-sorbitol, propionate, valeric acid, 3-hydroxybenzoic acid, 4-hydroxybenzoic acid and L-proline.</p><p>+: positive; -: negative; w: weakly positive; nd: not determined.</p

Polar lipids of the strain <i>Pontibacter diazotrophicus</i> sp. nov. H4X^T.

<p>PE, phosphatidylethanolamine; APL, aminophospholipid; PL1-4, unknown phospholipids.</p