Antagonistic effect of Bacillus and Pseudomonas combinations against Fusarium oxysporum and their effect on disease resistance and growth promotion in watermelon.

AIMS: We aimed to develop an effective bacterial combination that can combat F. oxysporum infection in watermelon using in vitro and pot experiments. METHODS AND RESULTS: In total, 53 strains of Bacillus and 4 strains of Pseudomonas were screened. Pseudomonas strains P3 and P4 and Bacillus strains XY-2-3, XY-13, and GJ-1-15 exhibited good antagonistic effects against F. oxysporum. P3 and P4 were identified as P. chlororaphis and P. fluorescens, respectively. XY-2-3 and GJ-1-15 were identified as B. velezensis, and XY-13 was identified as B. amyloliquefaciens. The three Bacillus strains were anti-fungal, promoted the growth of watermelon seedlings and had genes to synthesize antagonistic metabolites such as bacilysin, surfactin, yndj, fengycin, iturin, and bacillomycin D. Combinations of Bacillus and Pseudomonas strains, namely, XY-2-3+P4, GJ-1-15+P4, XY-13+P3, and XY-13+P4, exhibited a good compatibility. These four combinations exhibited antagonistic effects against 11 pathogenic fungi, including various strains of F. oxysporum, F. solani, and Rhizoctonia. Inoculation of these bacterial combinations significantly reduced the incidence of Fusarium wilt in watermelon, promoted plant growth, and improved soil nutrient availability. XY-13+P4 was the most effective combination against Fusarium wilt in watermelon with the inhibition rate of 78.17%. The number of leaves; aboveground fresh and dry weights; chlorophyll, soil total nitrogen, and soil available phosphorus content increased by 26.8%, 72.12%, 60.47%, 16.97%, 20.16%, and 16.50%, respectively, after XY-13+P4 inoculation compared with the uninoculated control. Moreover, total root length, root surface area, and root volume of watermelon seedlings were the highest after XY-13+P3 inoculation, exhibiting increases by 265.83%, 316.79%, and 390.99%, respectively, compared with the uninoculated control. CONCLUSIONS: XY-13+P4 was the best bacterial combination for controlling Fusarium wilt in watermelon, promoting the growth of watermelon seedlings, and improving soil nutrient availability.

Hypobaric treatment augments the efficacy of 1-MCP in apple fruit.

This research aimed to extend the postharvest shelf life of Royal Gala apple during cold storage and maintain its market value in simulated retail conditions. Apples were treated with hypobaric pressure (50 kPa for 4 h) followed by 1-MCP (0.5 µL L-1, 0.7 µL L-1, and 1.0 µL L-1) treatment for 24 h individually and in combinations, stored at (1 ± 1 °C, 85 ± 3% RH) for 120 d and analyzed for different quality parameters (Peel color, firmness, weight loss, TSS, acidity, ethylene production rate, and respiration rate) at each 30 d interval, followed by a 20 d simulated retail condition at 20 ± 3 °C with 4 d interval. Results indicated that all 1-MCP concentrations were more effective in retaining quality compared to individual hypobaric treatment. However, a synergistic effect was observed by combining 1-MCP with hypobaric treatment. Among the combined treatments, 1.0 µL L-11-MCP + 50 kPa more effectively and significantly retained quality during cold storage. Furthermore, the apples were more juicy, tasty, and attractive in color than others in simulated conditions. Addition of hypobaric treatment to 1-MCP might reduce endogenous ethylene in fruit by outward diffusion and blocking further ethylene synthesis by the action of 1-MCP. However, in-depth study is required for further understanding the phenomena.

Biodegradable Films Prepared from Pulp Lignocellulose Adhesives of Urea Formaldehyde Resin Modified by Biosulfonate.

Traditional low-density polyethylene (LDPE) film causes environmental pollution; there is a pressing need to make new bio-based polymers for alternative products, to meet agricultural production needs and for sustainable ecological development. In this study, urea-formaldehyde resin (UF) was modified with polyvinyl alcohol (PVA) and 1-2.5% bio-based sulfonate (BBS). The influence of BBS inducing on the functional groups, microstructure, and thermal behavior was evaluated by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). A biodegradable film was prepared with modified UF resin as adhesive and pulp lignocellulose as raw material. The biodegradable mulch film samples were tested for biodegradability, water retention, and cooling soil temperature characters using LDPE and no mulching (NM) as a control. The results showed that with the increase of BBS content, the viscosity and reactivity of modified PUF resin increased, and the free formaldehyde content decreased. A 2%BBS modified PUF resin (2.0BBS/PUF) accelerated the curing process of the PUF resin, formed a flexible macromolecular network structure, and enhanced the toughness of the resin. The biodegradable mulch prepared with PUF, BBS, and 2.0BBS/PUF as adhesives had good water retention. BBS modification increased the degradation rate of mulch by 17.53% compared to the PUF. Three biodegradable films compared with LDPE and NM significantly reduced the soil temperature under summer cucumber cultivation, and the 2.0BBS/PUF coating had the lowest diurnal temperature difference, which provided a suitable soil environment for crop growth.

Dynamic Performance of Partially Orifice Porous Aerostatic Thrust Bearing.

The aerostatic thrust bearing's performance under vibration brings certain changes in stiffness and stability, especially in the range of 100 to 10,000 Hz, and it is accompanied by significant increase in fluctuations due to the changes in frequency, and the size of the gas film damping. In this research work, an analysis is carried out to evaluate the impact of throttling characteristics of small size orifice on stiffness and stability optimization of aerostatic thrust bearings. There are two types of thrust bearing orifices such as: partial porous multiple orifice and porous thrust bearings and their effects on variations in damping and dynamic stiffness are evaluated. A simulation based analysis is carried out with the help of the perturbation analysis model of an aerostatic thrust bearing simulation by using FLUENT software (CFD). Therefore, two models of aerostatic thrust bearings-one with the porous and other with partial porous orifice are developed-are simulated to evaluate the effects of perturbation frequencies on the damping and dynamic stiffness. The results reveal a decrease in the amplitude of dynamics capacity with an increase in its frequency, as well as a decrease in the damping of partial porous aerostatic thrust bearings with an increase in the number of orifices. It also reveals an increase in the radius of an orifice with an increment of damping of bearing at the same perturbation frequency and, with an increase in orifice height, a corresponding decrease in the damping characteristics of bearings and in the dynamic stiffness and coefficient of damping of bearing film in the frequency range less than 100 Hz.

Mesorhizobium hankyongi sp. nov. Isolated from Soil of Ginseng Cultivating Field.

A Gram-negative, non-spore-forming and rod-shaped, bacterium (designated Gsoil 531T) was isolated from soil of a ginseng field. On the basis of 16S rRNA gene sequence, strain Gsoil 531T clustered with species of the genus Mesorhizobium and was closely related to M. camelthorni CCNWXJ 40-4T (98.9%) and M. alhagi CCNWXJ12-2T (98.7%). The DNA G + C content was 62.9 mol% and the predominant quinone was ubiquinone-10 (Q-10). The major cellular fatty acids were C16:0, C19:0 cyclo ω8c and summed feature 8 (C18:1 ω7c/C18:1 ω6c). The DNA-DNA hybridization values were less than 35.0% between novel isolate and its closest reference strains M. camelthorni HAMBI 3020T, M. alhagi HAMBI 3019T and M tamadayense LMG 26736T. Physiological, biochemical and low values of DNA-DNA hybridization results enabled strain Gsoil 531T to be differentiated genotypically and phenotypically from all known species of the genus Mesorhizobium. Therefore, strain Gsoil 531T signifies a novel species of the genus Mesorhizobium, for which the name Mesorhizobium hankyongi sp. nov. is proposed. The type strain Gsoil 531T (= KACC 19443T = LMG 30463T).

Genome Sequence of Escherichia coli O157:H7 Strain 2886-75, Associated with the First Reported Case of Human Infection in the United States.

First identified in 1982 as a human pathogen, enterohemorrhagic Escherichia coli of the O157:H7 serotype is a major cause of food-borne acquired human infections. Here, we report the genome sequence of the first known strain of this serotype isolated in the United States.

Corrosion protection of reusable surgical instruments.

To understand the corrosion properties of surgical scissors, 416 stainless steel disks and custom electrodes were used as simulated surfaces under various conditions. These simulated surfaces were exposed to tap water and 400-ppm synthetic hard water as Ca2CO3 under different conditions. The samples were evaluated by various techniques for corrosion potential and the impact of environmental conditions on the integrity of the passive film. The electrodes were used to monitor the corrosion behavior by potentiodynamic polarization technique in water both in the presence and absence of a cleaning product. The surface topography of the 416 stainless steel disks was characterized by visual observations and scanning electron microscopy (SEM), and the surface chemistry of the passive film on the surface of the scissors was characterized by x-ray photoelectron spectroscopy (XPS). The results suggest that surgical instruments made from 416 stainless steel are not susceptible to uniform corrosion; however, they do undergo localized corrosion. The use of suitable cleaning products can offer protection against localized corrosion during the cleaning step. More importantly, the use of potentiodynamic polarization techniques allowed for a quick and convenient approach to evaluate the corrosion properties of surgical instruments under a variety of simulated-use environmental conditions.