Strain J2 Research Articles

Efficient pyridine biodegradation by Stenotrophomonas maltophilia J2: Degradation performance, mechanism, and immobilized application for wastewater

Stenotrophomonas maltophilia J2, a highly efficient pyridine-degrading bacterium, was isolated from the aerobic tank of a pesticide-contaminated wastewater treatment plant. The strain J2 demonstrated an impressive pyridine degradation rate of 98.34% ± 0.49% within 72 h, at a pyridine concentration of 1100 mg·L-1, a temperature of 30 °C, a pH of 8.0, and a NaCl concentration of 0.5%. Notably, two new pyridine metabolic intermediates, 1,3-dihydroxyacetone and butyric acid, were discovered, indicating that J2 may degrade pyridine through two distinct metabolic pathways. Furthermore, the immobilized strain J2 was obtained by immobilizing J2 with biochar derived from the stem of Solidago canadensis L. In the pyridine-contaminated wastewater bioremediation experiment, the immobilized strain J2 was able to remove 2000 mg·L-1 pyridine with a 98.66% ± 0.47% degradation rate in 24 h, which was significantly higher than that of the control group (3.17% ± 1.24%), and remained above 90% in subsequent cycles until the 27th cycle. High-throughput sequencing analysis indicated that the J2 +B group had an elevated relative abundance of bacteria and functional genes that could be associated with the degradation of pyridine. The results offer a foundation for the effective use of immobilized strain in the treatment of recalcitrant pyridine-contaminated wastewater.

Surfactin for enhanced removal of aromatic hydrocarbons during biodegradation of crude oil

Oil biodegradation studies using the powerful surfactant have mainly focused on saturated hydrocarbons or parent aromatic hydrocarbons, but not specifically on the position or degree of alkyl substitution of aromatic hydrocarbons. Removal of substituted aromatic hydrocarbons remains a controversial topic in biodegradation. In this study, the effect of surfactin addition on specific alkylated aromatic isomers and saturated hydrocarbons was observed in aerobic biodegradation experiments with four species of bacteria. The relative susceptibility of the individual alkylphenanthrene, alkyldibenzothiophene and methyltriaromatic steroid isomers to biodegradation was determined by their depletion rates. The results show that different bacteria induce removal of alkylated aromatic hydrocarbons and alteration of other petroleum hydrocarbons in various ways. Bacillus amyloliquefaciens strain BC is the best for biodegradation of general petroleum hydrocarbons, because it can convert n-alkanes, n-alkylcyclohexanes, isoprenoids, and aromatic hydrocarbons. Achromobacter strain J3 can degrade methylphenanthrenes, methyltriaromatic steroids, triaromatic steroids, and steranes better than other bacteria. Citrobacter sp strain J1 induces the highest degradation rate for dimethylphenanthrenes, trimethylphenanthrenes, and dimethyldibenzothiophenes, and Brucella melitensis strain J2 selectively degrades methyldibenzothiophenes. Surfactin addition increases the biodegradation rate of alkylaromatic hydrocarbons by 1.5–87.2%, and can significantly enhance the biodegradation of alkylphenanthrenes, alkyldibenzothiophenes and methyltriaromatic steroids. Alkyldibenzothiophenes can be used as markers for determining the levels of biodegradation of crude oils, and when used in conjunction with triaromatic steroids are a powerful indicator of the biodegradation of petroleum. The use of surfactin for enhancing the removal of aromatic hydrocarbons provides a wide range of applications in the environmental remediation and petroleum industry.

Production of biosurfactant from agro-industrial waste by Bacillus safensis J2 and exploring its oil recovery efficiency and role in restoration of diesel contaminated soil

Abstract In this study, biosurfactant production by Bacillus safensis J2 in submerged fermentation employing agro-industrial waste (bagasse) as a sole carbon source was examined. Biosurfactant produced was characterized to predict its properties and stability to various environmental stresses. Further, the strain and its extracted biosurfactant was used in oil recovery operation and in restoration of diesel contaminated soil. Findings suggest that bagasse of sugarcane may serve as an efficient substrate for cost-effective production of biosurfactant as 0.92 ± 0.06 g/L of biosurfactant by the strain was produced in 15 g bagasse. Stability studies indicate that properties of the biosurfactant were stable at various temperature and pH and have the efficiency to persist its emulsification activity at varying salt concentration. Oil recovery operation demonstrated that the biosurfactant is effective in recovering up to 46.5 % of the trapped oil from the sand pack column and acute earth worm toxicity test reveal that the soil treatment E5 (100 g soil + 10 g Bagasse + 250 ml distilled H 2 O + 10 ml diesel oil+ Strain J2+ 25 ml crude Biosurfactant) is effective in restoration and detoxification of diesel contaminated soil.

Cytotoxic and antibacterial activities of biologically synthesized gold nanoparticles assisted by Micrococcus yunnanensis strain J2

Abstract In the present study the capability of Micrococcus yunnanensis J2 (isolated from Sarcheshme mine soil samples and identified by 16S rDNA sequencing) for biosynthesis of gold nanoparticles (Au NPs) was evaluated. The produced biogenic Au NPs were characterized using UV–visible spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction spectroscopy (XRD), thermal gravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR) methods. The related TEM and SEM images of biogenic Au NPs indicated spherical shaped and well dispersed nanostructures with the average particle size of 53.8 nm. Zeta potential analysis of as-synthesized Au NPs showed a peak at − 17.6 ± 1.8 mV. The XRD profile of the biogenic Au NPs contained five peaks positioned at 2θ of 38.2°, 45.8°, 63.7°, 77.6°, and 82.1° due to (111), (200), (220), (311), and (222) lattice planes, respectively, which clearly indicated the crystalline structure of the obtained Au NPs. Cytotoxic activity of biologically synthesized Au NPs (assisted by MTT-based colorimetric assay) revealed IC50 (µg/mL) of 73.6 ± 1.9, 85.6 ± 2.9, 63.5 ± 2.1, 65.2 ± 1.9, 105.3 ± 1.7, and 88.4 ± 2.1 against six cancer cell lines of U87, HT1080, PC12, Caco2, MCF7, and A549, respectively. However, two normal cells of 3T3 and Vero inhibited by 85% in the presence of 500 µg/mL of the biogenic Au NPs. Evaluation of antibacterial effect of the produced Au NPs and Au3+ ions against three Gram-positive and four Gram-negative bacterial strains exhibited lower inhibitory activity of Au NPs compared to that of Au3+ ions.

P‐version finite elements and finite cells for finite strain elastoplastic problems

AbstractIn this paper, the p‐version finite element method and its fictitious domain extension, the finite cell method, are extended to the finite strain J2 plasticity. High‐order shape functions are used for the finite element approximation of volume‐preserving plastic dominated deformations. The accuracy and efficiency of p‐version elements and cells in the finite plastic strain range are evaluated by the computation of two benchmark problems. It is shown that they provide locking free behavior and simplified meshing. These results are verified in comparison with the results of h‐version elements in F‐bar formulation. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Ethanol production by a Paenibacillus species isolated from an Icelandic hot spring – Production yields from complex biomass

Ethanol production using Paenibacillus strain J2 was studied on carbohydrates and lignocellulosic biomass hydrolysates including grass (Phleum pratense) and barley straw (Hordeum vulgare). The strain has a broad substrate spectrum; fermentation of glucose yielded ethanol (major product), acetate, butyrate (minor), hydrogen, and carbon dioxide. At glucose concentrations below 30 mM fermentation was not inhibited. Higher substrate loadings resulted in decreased glucose utilization and a shift of end products towards butyrate. The maximum yields of ethanol were 1.45 mol ethanol mol glucose -1 . The end products from lignocellulosic (4.5 g L -1 dw) biomass hydrolysates pretreated with 0.5% HCl or NaOH (control was unpretreated) prior to cellulase treatment were investigated. Ethanol production from cellulose hydrolysates without chemical pre-treatment yielded 5.5 mM ethanol g -1 with lower yields from paper and lignocellulosic biomasses (1.2-1.7 mM g -1 ). Ethanol production was enhanced by dilute acid or base pre-treatment combined with enzymatic treatment with the highest yields from grass (3.2 mM ethanol g -1

PhlF− mutant of Pseudomonas fluorescens J2 improved 2,4-DAPG biosynthesis and biocontrol efficacy against tomato bacterial wilt

Pseudomonas fluorescens J2 can produce 2,4-diacetylphloroglucinol (2,4-DAPG) as the main antibiotic compound and effectively inhibits the wilt pathogens Ralstonia solanacearum and Fusarium oxysporum. The phlF which negatively regulates the 2,4-DAPG synthesis in strain J2 was disrupted by homologous recombination to construct a mutant strain J2-phlF−. The mutant J2-phlF− produced much more 2,4-DAPG and showed higher inhibitory effect on R. solanacearum than the wild type strain J2 in vitro. The mutant J2-phlF− also showed more colonization of tomato roots and higher inhibition to R. solanacearum in soil than wild type strain J2. The biocontrol efficiency of mutant J2-phlF− was higher against tomato bacterial wilt than wild type strain J2, but the differences were not significant. However, the application of both strains with organic fertilizer improved the colonization and biocontrol efficiency against tomato bacterial wilt and mutant strain J2-phlF− showed higher biocontrol efficiency against tomato bacterial wilt than wild type strain J2. Both strains, J2 and J2-phlF−, could also promote the growth of tomato plants.

Characterizations of Bacterial Cellulose Producing Strain Gluconoacetobacter hansenii CGMCC3917

Gluconoacetobacter hansenii CGMCC3917 (M438), isolated from inoculums of strain J2 treated by high hydrostatic pressure, has strong ability of producing cellulose as more than three times as that of its initial strain J2. In this paper, in order to further study the effects of high hydrostatic pressure treatment on characterizations of strain J2 on the basis of previous study, properties of these two strains were examined and compared. The results indicated that the mutant strain M438 and its initial strain J2 had different Phenotypic Characterizations in liquid seed medium. The fermentation parameters showed that cell growth rate of strain M438 was relatively higher than that of strain J2, namely, residual sugar, residual nitrogen and acidity of strain M438 were less than that of strain J2. Furthermore, water holding capacity (WHC) and water release rate (WRR) of bacterial cellulose (BC) membranes produced by M438 were both better than those of BC membranes produced by J2. However, SEM imagines suggested that there was no evidence difference in microstructure of BC membranes. Additionally, FT-IR also showed no difference between BC membranes produced by strain M438 and its initial strain J2.

Gracilibacillus xinjiangensis sp. nov., a new member of the genus Gracilibacillus isolated from Xinjiang region, China

A Gram-positive, endospore-forming, rod-shaped bacterium, designated isolate J2(T) was isolated from a soil sample from Xinjiang Uyghur Autonomous Region, China. The isolate was observed to grow at 16-46°C and pH 6.5-8.0. Chemotaxonomic analysis showed menaquinone-7 (MK-7) to be the major isoprenoid quinone; diphosphatidylglycerol, phosphatidylglycerol, one aminophospholipid, two phosphoglycolipids and one glycolipid as the major cellular polar lipids; and anteiso-C15:0, iso-C15:0, anteiso-C17:0 and C16:0 as the major fatty acids. Comparative analyses of the 16S rRNA gene sequence showed that strain J2(T) is most closely related to Gracilibacillus ureilyticus (with 98.8% similarity), Gracilibacillus dipsosauri (97.2%), Gracilibacillus quinghaiensis (97.1%) and Gracilibacillus thailandensis (97.0%). The DNA-DNA reassociation values between strain J2(T) and G. ureilyticus MF38(T), G. dipsosauri DD1(T), G. quinghaiensis YIM-C229(T) and G. thailandensis TP2-8(T) were 29.8±3.7, 23.0±3.5, 15.8±4.9 and 15.9±5.0%, respectively. The genomic DNA G+C content of strain J2(T) was determined to be 36.5mol%. Based on these data, strain J2(T) is considered as a novel species of the genus Gracilibacillus, for which the name Gracilibacillus xinjiangensis sp. nov. is proposed. The type species is J2(T) (=CGMCC 1.12449(T)=JCM 18859(T)).

Asymptotic Analysis for the Singular Stress Behaviour around an Interface Edge of Dissimilar Power-Law Hardening Materials Joint

An asymptotic analysis for singular stress fields around an interface-edge of dissimilar power-law hardening materials joint has been presented under plane strain condition and J2 deformation plasticity theory. Both the balance of force and the continuity of displacement are satisfied on the interface. In the higher order approximation, the nonlinear effective stress term was expanded by Taylor series. An iteration method is proposed for the determination of singular fields around interface edge. Multiple stress singular terms exist for in the higher order approximation. The order of stress singularity has a dependency with the combination of hardening exponents, .

Shock Waves in Dynamic Cavity Expansion

High velocity cavitation fields are investigated in the context of large strain J2 plasticity with strain hardening and elastic compressibility. The problem setting is that of an internally pressurized spherical cavity, embedded in an unbounded medium, which grows spontaneously with constant velocity and pressure. Expansion velocity is expected to be sufficiently high to induce a plastic shock wave, hardly considered in earlier dynamic cavitation studies. Jump conditions across singular spherical surfaces (shock waves) are fully accounted for and numerical illustrations are provided over a wide range of power hardening materials. Simple formulae are derived for shock wave characteristics and for the asymptotic behavior within near cavity wall boundary layer.

The Role of IL-10 in Mice Infected with Neurotropic Murine Coronavirus (43.14)

Abstract Mice infected with the neurotropic coronavirus mouse hepatitis virus (MHV), attenuated strain J2.2 develop acute and chronic demyelinating disease with histopathological similarities to multiple sclerosis (MS). The process of demyelination is immune-mediated, as RAG1-/- or RAG2-/- (mice deficient in recombination activation enzyme), which lack B and T lymphocytes, do not develop demyelination upon infection with J2.2; however, if RAG1-/- mice are reconstituted with either MHV-immune CD4 or CD8 T cells, demyelination proceeded as in the immunocompetent mouse. While the pathogenic role of virus-specific CD4 and CD8 T cells and bystander CD8 T cells in this model has been demonstrated, less is known about the immune mechanisms that are controlling this anti-viral immune response. The cytokine IL-10 has been shown to be able to suppress an excessive immune response and protect the host against immune-mediated damage in EAE, an autoimmune model of multiple sclerosis. We investigated the role of IL-10 in demyelination using IL-10-/- mice. Additionally, we characterized the time, location, and antigen-specificity of IL-10 producing cells using IL-10gfp mice. Here, we demonstrate that IL-10 has a protective role in an animal model of MS and that the majority of IL-10 producing cells are MHV-specific T-cells located at the site of infection. Funded in part by grants from the NIH and National Multiple Sclerosis Society.

Dynamic cylindrical cavity expansion in an incompressible elastoplastic medium

Self-similar dynamic expansion of a pressurized circular cylindrical cavity, embedded in an infinite elastoplastic incompressible medium, is here investigated with the large strain J2 flow theory. Assuming steady-state conditions, thus bypassing the initial loading history, it is shown that plane-strain fields are sustained with no diverging logarithmic stress appearing in the remote elastic field. Yet, even in the absence of remotely applied stress, the appearance of small stresses at infinity is unavoidable. The present solution is exact but limited to relatively low cavity expansion velocities. A closed form expression is given for the cavitation pressure with elastic/perfectly-plastic response. A fairly general result is derived for the cavitation pressure in hardening media with a definite yield point and in linear-hardening solids as a special case. Contact is made with earlier results of quasi-static cavity expansion along with a comparison to the self-similar dynamic expansion of a spherical cavity in an incompressible Mises solid. Upper and lower bounds for penetration depth tests are suggested by using the present cylindrical cavitation model and the incompressible spherical cavitation model.

Elastic-Plastic Analysis of Cracks on Bimaterial Interfaces: Part III—Large-Scale Yielding

In Parts I and II, the structure of small-scale yielding fields of interface cracks were described in the context of small strain plasticity and J2 deformation theory. These fields are members of a family parameterized by the plastic phase angle ξ which also determines the shape or phase of the plastic zone. Through full-field analysis, we showed the resemblance between the plane-strain interface crack-tip fields and mixed-mode HRR fields in homogeneous material. This connection was exploited, to the extent possible, inasmuch as the interface fields do not appear to have a separable form. The present investigation is focused on “opening” dominated load states (| ξ | ≤ π/6) and the scope is broadened to include finite ligament plasticity and finite deformation effects on near-tip fields. We adopt a geometrically rigorous formulation of J2 flow theory taking full account of crack-tip blunting. Our results reveal several surprising effects, that have important implications for fracture, associated with finite ligament plasticity and finite strains. For one thing the fields that develop near bimaterial interfaces are more intense than those in homogeneous material when compared at the same value of J or remote load. For example, the plastic zones, plastic strains, and the crack-tip openings, δt, that evolve near bimaterial interfaces are considerably larger than those that develop in homogeneous materials. The stresses within the finite strain zone are also higher. In addition, a localized zone of high hydrostatic stresses develops near the crack tip but then expands rapidly within the weaker material as the plasticity spreads across the ligament. These stresses can be as much as 30 percent higher than those in homogeneous materials. Thus, the weaker material is subjected to large stresses as well as strains—states which promote ductile fracture processes. At the same time, the accompanying high interfacial stresses can promote interfacial fracture.

Elastoplastic Buckling of Annular Plates in Pure Shear

A linear buckling analysis is presented for annular elastoplastic plates under shear loads. The standard plate buckling equations are used in conjunction with the small strain J2 flow and deformation theories of plasticity. The main numerical finding is that deformation theory predicts critical loads which are considerably below the predictions obtained with the flow theory. Furthermore, comparison with experimental data for different metals shows a good agreement with the deformation theory results over a wide range of geometries. The limiting buckling problem of a long narrow panel under shear stresses is treated separately. This problem admits an exact solution and it is shown that the critical loads for the panel are approached asymtotically by the annular plate results. Contact is made with earlier studies on the buckling of elastic-orthotropic and elastoplastic shear panels.

Collapse of hydrostatically loaded cylindrical shells

A long circular cylindrical shell subjected to external pressure may collapse through the development of a propagating buckle. In this work a method has been developed for the theoretical prediction of the smallest propagation pressure in the case of path-dependent material descriptions. The method is illustrated by comparing predictions of the propagation pressure based on J2 flow theory with predictions based on J2 deformation theory for two different radius to thickness ratios. The modelling is based on thin shell theory and small strain approximations, allowing for large deformations. Results for two different non-linear bending strain measures are compared, and the effect of using a finite strain J2 flow theory is investigated.