Quorum-quenching enzyme Est816 assisted antibiotics against periodontitis induced by Aggregatibacter actinomycetemcomitans in rats.

Introduction: Quorum-quenching enzyme Est816 hydrolyzes the lactone rings of N-acyl homoserine lactones, effectively blocking the biofilm formation and development of Gram-negative bacteria. However, its applications in the oral field is limited. This study aimed to evaluate the efficacy of enzyme Est816 in combination with antibiotics against periodontitis induced by Aggregatibacter actinomycetemcomitans in vitro and in vivo. Methods: The antimicrobial efficacy of enzyme Est816 in combination with minocycline, metronidazole, and amoxicillin was determined using the minimum inhibitory concentration test. The anti-biofilm effect of enzyme Est816 was assessed using scanning electron microscopy, live/dead bacterial staining, crystal violet staining, and real-time quantitative PCR. Biocompatibility of enzyme Est816 was assessed in human gingival fibroblasts (HGF) by staining. A rat model of periodontitis was established to evaluate the effect of enzyme Est816 combined with minocycline using micro-computed tomography and histological staining. Results: Compared to minocycline, metronidazole, and amoxicillin treatment alone, simultaneous treatment with enzyme Est816 increased the sensitivity of biofilm bacteria to antibiotics. Enzyme Est816 with minocycline exhibited the highest rate of biofilm clearance and high biocompatibility. Moreover, the combination of enzyme Est816 with antibiotics improved the antibiofilm effects of the antibiotics synergistically, reducing the expression of the virulence factor leukotoxin gene (ltxA) and fimbria-associated gene (rcpA). Likewise, the combination of enzyme Est816 with minocycline exhibited a remarkable inhibitory effect on bone resorption and inflammation damage in a rat model of periodontitis. Discussion: The combination of enzyme Est816 with antibiotics represents a prospective anti-biofilm strategy with the potential to treat periodontitis.

Strain engineering of Bacillus coagulans with high osmotic pressure tolerance for effective L-lactic acid production from sweet sorghum juice under unsterile conditions.

Open unsterile fermentation of the low-cost non-food crop, sweet sorghum, is an economically feasible lactic acid biosynthesis process. However, hyperosmotic stress inhibits microbial metabolism and lactic acid biosynthesis, and engineering strains with high osmotic tolerance is challenging. Herein, heavy ion mutagenesis combined with osmotic pressure enrichment was used to engineer a hyperosmotic-tolerant Bacillus coagulans for L-lactic acid production. The engineered strain had higher osmotic pressure tolerance, when compared with the parental strain, primarily owing to its improved properties such as cell viability, cellular antioxidant capacity, and NADH supply. In a pilot-scale open unsterile fermentation using sweet sorghum juice as a feedstock, the engineered strain produced 94 g/L L-lactic acid with a yield of 91 % and productivity of 6.7 g/L/h, and optical purity of L-lactic acid at the end of fermentation was 99.8 %. In short, this study provided effective and low-cost approach to produce polymer-grade L-lactic acid.

Microbial tolerance engineering for boosting lactic acid production from lignocellulose.

Lignocellulosic biomass is an attractive non-food feedstock for lactic acid production via microbial conversion due to its abundance and low-price, which can alleviate the conflict with food supplies. However, a variety of inhibitors derived from the biomass pretreatment processes repress microbial growth, decrease feedstock conversion efficiency and increase lactic acid production costs. Microbial tolerance engineering strategies accelerate the conversion of carbohydrates by improving microbial tolerance to toxic inhibitors using pretreated lignocellulose hydrolysate as a feedstock. This review presents the recent significant progress in microbial tolerance engineering to develop robust microbial cell factories with inhibitor tolerance and their application for cellulosic lactic acid production. Moreover, microbial tolerance engineering crosslinking other efficient breeding tools and novel approaches are also deeply discussed, aiming to providing a practical guide for economically viable production of cellulosic lactic acid.

From single atoms to self-assembled quantum single-atomic nanowires: noble metal atoms on black phosphorene monolayers.

Transition metal (TM) nanostructures, such as one dimensional (1D) nanowires with/without substrates, usually possess drastically different properties from their bulk counterparts, due to their distinct stacking and electronic confinement. Correspondingly, it is of great importance to establish the dominant driving force in forming 1D single-metal-atom-wires (SMAWs). Here, with first-principles calculations, taking the black phosphorene (BP) monolayer as a prototype 2D substrate, we investigate the energetic and kinetic properties of all the 5d-TM atoms on the 2D substrate to reveal the mechanism of formation of SMAWs. In contrast to other 5d- and 4d-TMs, noble metal elements Pd and Pt are found to prefer to grow along the trough in an atom-by-atom manner, self-assembling into SMAWs with a significant magic growth behavior. This is due to distinct binding energies and diffusion barriers along the trough, i.e., zig-zag direction, as compared to other directions of the BP. The present findings are valuable in the fabrication and modulation of 1D nanostructures which can be anticipated to possess desirable functionalities for potential applications such as in nanocatalysis, nanosensors, and related areas.

Synthesis and luminescence properties of ZnO:Eu3+ nano crystalline via a facile solution method.

Different ZnO:Eu3+ nanocrystalline were obtained from a facile solution method with two different precipitators. The comparison of photoluminescence property of two different ZnO:Eu3+ nanocrystalline was performed. The XRD patterns and the PL spectra indirectly indicate that the dopant Eu3+ ions had entered into the crystal lattices of ZnO. The study on the PL spectra of the as-prepared ZnO:Eu3+ nanocrystalline shows that with the change of dopant concentration, the ratio of relative emission intensity of electric dipole transition to magnetic dipole transition changes, which fully expresses that the presence of the inversion centers is associated with the dopant concentration of Eu3+.

Poly[bis-[µ-1,4-bis-(imidazol-1-ylmeth-yl)benzene]-dichloridomanganese(II)].

In the crystal structure of the title compound, [MnCl(2)(C(14)H(14)N(4))(2)](n), the Mn(II) atom, lying on an inversion center, is coordinated by four N atoms from four 1,4-bis-(imidazol-1-ylmeth-yl)benzene (bimb) ligands and two Cl(-) anions in a distorted octa-hedral geometry. The bimb ligands bridge the Mn(II) atoms, forming a two-dimensional polymeric complex, which is composed of a 52-membered [Mn(4)(bimb)(4)] ring with distances of 7.7812 (2) and 27.4731 (9) Šbetween opposite metal atoms. Weak C-H⋯π inter-actions are present in the crystal structure.

Diaqua-(5-carb-oxy-benzene-1,3-dicarboxyl-ato-κO,O)(6,6'-dimethyl-2,2'-bipyridine-κN,N')nickel(II) hepta-hydrate.

In the title compound, [Ni(C(9)H(4)O(6))(C(12)H(12)N(2))(H(2)O)(2)]·7H(2)O, the Ni(II) atom is six-coordinated by two O atoms from a chelating carboxyl-ate group of a 5-carb-oxy-benzene-1,3-dicarboxyl-ate ligand, two O atoms of two water mol-ecules and two N atoms from a 6,6'-dimethyl-2,2'-bipyridine ligand in a distorted octa-hedral geometry. The compound exhibits a three-dimensional supra-molecular structure composed of the complex mol-ecules and lattice water mol-ecules, which are linked together by inter-molecular O-H⋯O hydrogen bonds and partly overlapping π-π inter-actions between the pyridine and benzene rings [centroid-centroid distances = 3.922 (2) and 3.921 (2) Å]. One of the lattice water mol-ecules is disordered over two positions in an occupancy ratio of 0.521 (6):0.479 (6).

Poly[bis[µ-1,3-bis-(imidazol-1-ylmeth-yl)benzene-κN:N]bis-(nitrato-κO)cadmium].

A novel metal-organic framework based on 1,3-bis-(imidazol-1-ylmeth-yl)benzene (1,3-bimb), [Cd(NO(3))(2)(C(14)H(14)N(4))(2)](n), has been synthesized hydro-thermally. The structure exhibits a two-dimensional metal-organic (4,4)-net composed of Cd(II) atoms and bimb ligands, and such layers are further joined through inter-layer C-H⋯O hydrogen bonds to generate a three-dimensional supra-molecular structure.

Poly[[hexa-aqua-bis-(µ(3)-benzene-1,3,5-tricarboxyl-ato-κO:O:O)bis-(5,5'-dimethyl-2,2'-bipyridine-κN,N')trizinc] hexa-hydrate].

In the title compound, {[Zn(3)(C(9)H(3)O(6))(2)(C(12)H(12)N(2))(2)(H(2)O)(6)]·6H(2)O}(n), one Zn(II) atom, lying on an inversion center, is six-coordinated by two O atoms from two benzene-1,3,5-tricarboxyl-ate (btc) ligands and four water mol-ecules in a distorted octa-hedral geometry. The other Zn(II) atom is five-coordinated by two N atoms from a 5,5'-dimethyl-2,2'-bipyridine (dmbpy) ligand, two O atoms from two btc ligands and one water mol-ecule in a distorted trigonal-bipyramidal geometry. The compound features a one-dimensional ladder structure, with windows of ca 10.245 (1) × 15.446 (2) Å. The ladders are linked together by inter-molecular O-H⋯O hydrogen bonds and π-π inter-actions between the benzene rings and between the pyridine rings [centroid-to-centroid distances 3.858 (2) and 3.911 (3) Å, respectively] to form a three-dimensional supra-molecular structure. One of the lattice water molecules is disordered over two positions in a 0.592:0.408 ratio.

Synthesis, crystal structure and luminescent properties of one 3D Cd(II) coordination polymer [Cd(H3BPTC)2(bpy)]n (H4BPTC = 1,1'-biphenyl-2,2',6,6'-tetracarboxylic acid, bpy = 4,4'-bipyridine).

A new 3D metal-organic coordination polymer [Cd(H(3)BPTC)(2)(bpy)](n) (1) (H(4)BPTC = 1,1'-biphenyl-2,2',6,6'-tetracarboxylic acid, bpy =4,4'-bipyridine) has been synthesized and characterized by single X-ray diffraction and IR spectroscopy. The one-dimensional metal-organic chains of the title complex, namely [Cd(H(3)BPTC)(2)](n), are held together through hydrogen bonding and bridging "second" ligand 4,4'-bpy to give a three-dimensional metal-organic network. The thermal stability of complex 1 was studied by thermal gravimetric (TG) and differential thermal analysis (DTA). Compound 1 exhibits photoluminescence with an emission maximum at ca. 380 nm upon excitation at ca. 251 nm.

1-(2-Fluoro-benz-yl)quinolinium bis-(2-sulfanylidene-1,3-dithiole-4,5-dithiol-ato-κS,S')nickelate(III).

The crystal structure of the title compound, (C(16)H(13)FN)[Ni(C(3)S(5))(2)], consists of Ni(III) complex anions and 1-(2-fluoro-benz-yl)quinolinium (fbq) cations. In the complex anion, the Ni(III) cation is chelated by two 2-sulfanylidene-1,3-dithiole-4,5-dithiol-ate (dmit) dianions in a distorted square-planar geometry; the two dmit mean planes are twisted with respect to each other at a dihedral angle of 8.44 (3)°. In the fbq cation, the dihedral angle between the benzene ring and the quinoline ring system is 80.57 (14)°. The centroid-centroid distance of 3.860 (5) Šbetween benzene rings indicates π-π stacking between adjacent fbq cations. The distance of 3.4958 (18) Šbetween the S atom and the centroid of the pyridine ring suggests the existence of a lone-pair-aromatic inter-action between the anion and the cation. A short S⋯S contact [3.387 (2) Å] is also observed in the crystal structure.

Diaqua-(5-carb-oxy-benzene-1,3-di-carboxyl-ato-κO)(4,4'-dimethyl-2,2'-bipyridine-κN,N')zinc.

In the title compound, [Zn(C(9)H(4)O(6))(C(12)H(12)N(2))(H(2)O)(2)], the Zn(II) atom is five-coordinated by two N atoms from a 4,4'-dimethyl-2,2'-bipyridine ligand, one O atom from a 5-carb-oxy-benzene-1,3-dicarboxyl-ate ligand and two water mol-ecules in a distorted trigonal-bipyramidal geometry. The complex mol-ecules are linked by inter-molecular O-H⋯O hydrogen bonds and partly overlapping π-π inter-actions [centroid-centroid distance = 4.017 (2) Å] into a three-dimensional supra-molecular network.