Polysaccharides Produced by Plant Growth-Promoting Rhizobacteria Strain Burkholderia sp. BK01 Enhance Salt Stress Tolerance to Arabidopsis thaliana.

Salt stress is one of the most serious abiotic stresses leading to reduced agricultural productivity. Polysaccharides from seaweed have been used as biostimulants to promote crop growth and improve plant resistance to abiotic stress. In this study, PGPR strain Burkholderia sp. BK01 was isolated from the rhizosphere of wheat, and it was characterized for phosphorus (Pi) dissolution, indole-3-acetic acid (IAA) production, ammonia (NH3) and exopolysaccharides (EPS). In particular, strain BK01 can efficiently produce extracellular polysaccharide with a yield of 12.86 g/L, using sorbitol as carbon source. BK01 EPS was identified as an heteropolysaccharide with Mw 3.559 × 106 Da, composed of (D)-galactose (75.3%), (D)-glucose (5.5%), (L)-rhamnose (5.5%), (D)-galactouronic acid (4.9%) and (D)-glucuronic acid (8.8%). The present work aims to highlight the effect of the BK01 EPS on growth and biochemical changes in Arabidopsis thaliana under salt stress (100 mM). The purified BK01 EPS at a concentration of 100 mg/L efficiently promoted the growth of plants in pot assays, improved the chlorophyll content, enhanced the activities of SOD, POD and CAT, and decreased the content of MDA. This results suggested that the polysaccharides produced by PGPR strain Burkholderia sp. BK01 can be used as biostimulants to promote plant growth and improve plant resistance to salt stress.

Oncolytic Newcastle disease virus inhibits IL-6 induced migration and invasion of human glioblastoma U87MG cells / 中国肿瘤生物治疗杂志

@#[摘 要] 目的：探讨溶瘤新城疫病毒（NDV）对IL-6诱导的人胶质母细胞瘤U87MG细胞增殖、迁移和侵袭的作用及其可能的机制。方法：将U87MG细胞分为对照组、IL-6组、NDV组、NDV+IL-6组，其中IL-6组与NDV+IL-6组用75 ng/mL IL-6预处理1 h，其余组用DMEM预处理1 h，后分别用DMEM、75 ng/mL IL-6、1 HU NDV、1 HU NDV+75 ng/mL IL-6处理24 h。MTT法、细胞划痕实验和Transwell侵袭实验分别检测IL-6、NDV对U87MG细胞增殖、迁移和侵袭的影响，WB法检测各组细胞JAK2、p-JAK2、STAT3、p-STAT3和MMP2蛋白的表达水平。结果：与对照组相比，IL-6组细胞迁移率显著升高（P<0.05），侵袭细胞数目显著增多（P<0.01）；与IL-6组相比，NDV+IL-6组U87MG细胞增殖率显著降低（P<0.05），细胞迁移率和侵袭细胞数目均显著降低（均P<0.01）。WB实验结果显示，与对照组相比，IL-6组p-STAT3/STAT3比值显著升高（P<0.01），NDV组p-JAK2/JAK2、p-STAT3/STAT3比值显著降低（P<0.05，P<0.01），MMP-2蛋白表达量显著降低（P<0.01）；与IL-6组相比，NDV+IL-6组p-STAT3/STAT3比值、MMP-2蛋白表达量均显著降低（均P<0.05）。结论：NDV能抑制IL-6对人脑胶质瘤U87MG细胞迁移和侵袭的诱导作用，其机制可能与JAK2/STAT3信号通路的参与调控有关。

Emulsifying Properties of Rhamnolipids and Their In Vitro Antifungal Activity against Plant Pathogenic Fungi.

Rhamnolipids have significant emulsifying activity and the potential to become a component of pesticide emulsifier. Rhamnolipids are usually composed of two main components: mono-rhamnolipids (Rha-C10-C10) and di-rhamnolipids (Rha2-C10-C10). The proportion of di-rhamnolipids in the products ranged between 15% and 90%, affected by the production strains and fermentation process. In this paper, three kinds of rhamnolipid products containing di-rhamnolipids proportions, of 25.45, 46.46 and 89.52%, were used to test their emulsifying ability toward three conventional solvents used in pesticide (S-200, xylene, cyclohexanone) and antifungal activities against five strains of plant pathogenic fungi (Phytophthora capsici, Phytophthora parasitica var.nicotianae, Colletotrichum destructivum, Colletotrichum sublineolum, Fusarium oxysporum). The results indicated that although the CMC of the three rhamnolipids were significantly different, their emulsification properties had no remarkable differences, at a concentration of 10 g/L. However, their antifungal activities were significantly different: the more di-rhamnolipids, the stronger the antifungal activity. This work helps to promote the application of rhamnolipids as pesticides adjuvants.

A Functionalized Polysaccharide from Sphingomonas sp. HL-1 for High-Performance Flocculation.

The characterization and flocculation mechanism of a biopolymer flocculant produced by Sphingomonas sp. HL-1, were investigated. The bio-flocculant HL1 was identified as an acidic polysaccharide, mainly composed of glucose, and also contained a small amount of mannose, galacturonic acid and guluronic acid. The flocculating activity of the purified HL1 polysaccharide could be activated by trivalent cations, and its flocculation mechanism was mainly charge neutralization and bridging. The working concentration of fermentation broth HL1 in a kaolin suspension was only 1/10,000 (v/v), in which the polysaccharide concentration was about 2 mg/L. The bio-flocculant HL1 maintained high efficiency at a wide range of pH (pH 3-10). It also exhibited good flocculating activity at a temperature range of 20-40 °C; it could even tolerate high salinity and kept activity at a mineralization degree of 50,000 mg/L. Therefore, the bio-flocculant HL1 has a good application prospect in the treatment of wastewater over a broad pH range and in high salinity.

Production of the biosurfactant serrawettin W1 by Serratia marcescens S-1 improves hydrocarbon degradation.

With the frequent occurrence of oil spills, the bioremediation of petroleum hydrocarbons pollution has attracted more and more attention. In this study, we investigated the biodegradation of crude oil by the biosurfactant-producing strain S-1. The strain was isolated from petroleum-contaminated soil and identified as Serratia marcescens according to partial 16S rDNA gene analysis. It was able to effectively degrade hydrocarbons with the concomitant production of biosurfactants at 20-30 °C, while there was no biosurfactant production and the degradation rate was lower at 37 °C. The biosurfactant was identified as serrawettin W1 by UPLC-ESI-MS, and was found to reduce the surface tension of water to 30 mN/m, with stable surface activity and emulsion activity at temperatures from 20 to 100 °C, pH of 2-10 and NaCl concentrations of 0-50 g/L. Serrawettin W1 significantly increased the cell surface hydrophobicity (CSH) and enhanced the bioavailability of hydrocarbon pollutants, which was conducive to the degradation of crude oil, including long-chain alkanes and aromatic hydrocarbons. Serratia marcescens S-1 has potential applications in bioremediation at low temperature.

Biodegradation of aliphatic and polycyclic aromatic hydrocarbons by the thermophilic bioemulsifier-producing Aeribacillus pallidus strain SL-1.

The utilization of thermophilic hydrocarbon-degrading microorganisms is a suitable strategy for improving biodegradation of petroleum hydrocarbons and PAHs, as well as enhancing oil recovery from high-temperature reservoirs. In this study, the thermophilic strain Aeribacillus pallidus SL-1 was evaluated for the biodegradation of crude oil and PAHs at 60 °C. Strain SL-1 was found to preferentially degrade short-chain n-alkanes (

Designer bioemulsifiers based on combinations of different polysaccharides with the novel emulsifying esterase AXE from Bacillus subtilis CICC 20034.

BACKGROUND: Bioemulsifiers are surface-active compounds, which exhibit advantages including low toxicity, higher biodegradability and biocompatibility over synthetic chemical surfactants. Despite their potential benefits, some obstacles impede the practical applications of bioemulsifiers, including low yields and high purification costs. Here, we aimed to exploit a novel protein bioemulsifier with efficient emulsifying activity and low-production cost, as well as proposed a design-bioemulsifier system that meets different requirements of industrial emulsification in the most economical way. RESULTS: The esterase AXE was first reported for its efficient emulsifying activity and had been studied for possible application as a protein bioemulsifier. AXE showed an excellent emulsification effect with different hydrophobic substrates, especially short-chain aliphatic and benzene derivatives, as well as excellent stability under extreme conditions such as high temperature (85 °C) and acidic conditions. AXE also exhibited good stability over a range of NaCl, MgSO4, and CaCl2 concentrations from 0 to 1000 mM, and the emulsifying activity even showed a slight increase at salt concentrations over 500 mM. A design-bioemulsifier system was proposed that uses AXE in combination with a variety of polysaccharides to form efficient bioemulsifier, which enhanced the emulsifying activity and further lowered the concentration of AXE needed in the complex. CONCLUSIONS: AXE showed a great application potential as a novel bioemulsifier with excellent emulsifying ability. The AXE-based-designer bioemulsifier could be obtained in the most economical way and open broad new fields for low-cost, environmentally friendly bioemulsifiers.

Geobacillus strains that have potential value in microbial enhanced oil recovery.

Bacteria from the genus Geobacillus are generally obligately thermophilic, with a unique bioenergy production capacity and unique enzymes. Geobacillus species were isolated primarily from hot springs, oilfields, and associated soils. They often exhibit unique survival patterns in these extreme oligotrophic environments. With the development of the microbial resources found in oilfields, Geobacillus spp. have been proven as valuable bacteria in many reports related to oilfields. After the isolation of Geobacillus by culture methods, more evidence was found that they possess the abilities of hydrocarbon utilization and bioemulsifier production. This paper mainly summarizes some characteristics of the Geobacillus species found in the oilfield environment, focusing on the inference and analysis of hydrocarbon degradation and bioemulsifier synthesis based on existing research, which may reveal their potential value in microbial enhanced oil recovery. It also provides references for understanding microbes in extreme environments.

Homoethanol Production from Glycerol and Gluconate Using Recombinant Klebsiella oxytoca Strains.

Gluconic acid, an oxidized cellulose degradation product, could be produced from cellulosic biomass. Glycerol is an inexpensive and renewable resource for fuels and chemicals production and is available as a byproduct of biodiesel production. Gluconate is a more oxidized substrate than glucose, whereas glycerol is a more reduced substrate than glucose. Although the production of homoethanol from glucose can be achieved, the conversion of gluconate to ethanol is accompanied by the production of oxidized byproduct such as acetate, and reduced byproducts such as 1,3-propanediol are produced, along with ethanol, when glycerol is used as the carbon source. When gluconate and glycerol are used as the sole carbon source by Klebsiella oxytoca BW21, the ethanol yield is about 62 to 64%. Coutilization of both gluconate and glycerol in batch fermentation increased the yield of ethanol to about 78.7% and decreased by-product accumulation (such as acetate and 1,3-propanediol) substantially. Decreasing by-product formation by deleting the pta, frd, ldh, pflA, and pduC genes in strain BW21 increased the ethanol yield to 89.3% in the batch fermentation of a glycerol-gluconate mixture. These deletions produced the strain K. oxytoca WT26. However, the utilization rate of glycerol was significantly slower than that of gluconate in batch fermentation. In addition, substantial amounts of glycerol remain unutilized after gluconate was depleted in batch fermentation. Continuous fed-batch fermentation was used to solve the utilization rate mismatch problem for gluconate and glycerol. An ethanol yield of 97.2% was achieved in continuous fed-batch fermentation of these two substrates, and glycerol was completely used at the end of the fermentation.IMPORTANCE Gluconate is a biomass-derived degradation product, and glycerol can be obtained as a biodiesel byproduct. Compared to glucose, using them as the sole substrate is accompanied by the production of by-products. Our study shows that through pathway engineering and adoption of a fed-batch culture system, high-yield homoethanol production that usually can be achieved by using glucose as the substrate is achievable using gluconate and glycerol as cosubstrates. The same strategy is expected to be able to achieve homofermentative production of other products, such as lactate and 2,3-butanediol, which can be typically achieved using glucose as the substrate and inexpensive biodiesel-derived glycerol and biomass-derived gluconate as the cosubstrates.

Characterization of a novel bioemulsifier from Pseudomonas stutzeri.

This study describes a novel and efficient alasan-like bioemulsifier produced by Pseudomonas stutzeri NJtech 11-1, which was isolated from the Shengli Oilfield. The strain was found to produce a new and interesting emulsion stabilizer. The crude bioemulsifier showed super stability with 50% salinity and broad pH 3-10. The emulsion index (EI24) was increased to 100% after heating from 45 to 95 °C and the emulsion could be stable for at least 30 days. The yield of Ps-bioemulsifier (pure bioemulsifier) was 0.68 ± 0.05 mg mL-1. The Ps-bioemulsifier was composed of carbohydrates (80 ± 2.6%) and proteins (9.5 ± 0.5%). A low concentration (0.2 mg mL-1) of the Ps-bioemulsifier was obtained maximum emulsifying activity at pH 7.1 and its emulsifying activity strengthened by suitable salinity. Furthermore, Ps-bioemulsifier could also emulsify cyclohexane, hexadecane, kerosene, xylene hydrocarbons efficiently. Therefore, the Ps-bioemulsifier showed emulsifying characteristics which make it a good candidate for potential applications in bioremediation and microbial enhanced oil recovery.

Extracorporeal membrane oxygenation combined with continuous renal replacement therapy in cutaneous burn and inhalation injury caused by hydrofluoric acid and nitric acid.

RATIONALE: Hydrofluoric acid (HF) is a highly corrosive agent and can cause corrosive burns. HF can penetrate deeply into tissues through intact skin and the lipid barrier, leading to painful liquefactive necrosis, and inducing hypocalcemia and hypomagnesemia. In this study, we hypothesize that continuous renal replacement therapy (CRRT) may be beneficial in addressing hemodynamic instability in cases of HF poisoning. PATIENT CONCERNS: A 25-year-old man fell into an electroplating pool containing 10% HF and 50% nitric acid. DIAGNOSES: He had severe cutaneous injuries involving approximately 60% of his total body surface area including the head, face, neck, right upper arm, right hand, trunk, perineum, and both lower limbs and feet. Examination at admission showed the following electrolyte concentrations: ionic calcium 0.192 mmol/L, total calcium 0.72 mmol/L, magnesium 0.4 mmol/L, potassium 5.49 mmol/L, and sodium 136.8 mmol/L. INTERVENTIONS: An initial 20 mL intravenous bolus of 10% calcium gluconate was followed by a continuous infusion at 6 g/h plus continuous intravenous drip 25% magnesium sulfate at 1.5 g/h. Continuous cardiac monitoring was performed in the intensive care unit. Extracorporeal membrane oxygenation (ECMO) was used to improve oxygenation function at 38 hours post exposure. Antibiotic therapy using imipenem/cilastin plus vancomycin was required. OUTCOMES: After treatment for 12 hours, electrolyte concentrations returned to normal. On day 11, the hemodynamic parameters were stable and oxygenation function had improved. On day 26, the patient was weaned off CRRT. One month later, the patient twice received skin grafting, then was discharged from the hospital without pulmonary, cardiac, or neurological complications 3 months later. LESSONS: The present case study demonstrates that CRRT may be an effective and potentially lifesaving therapy after severe exposure to HF. Prolonged hemodialysis is recommended to remove delayed release fluoride ions to avoid delayed systemic injury. When conventional therapy can not improve oxygenation and/or carbon dioxide retention, ECMO should be performed as soon as possible.