Molecular characterization of methicillin-resistant and -susceptible Staphylococcus aureus recovered from hospital personnel

Introduction Methicillin resistant Staphylococcus aureus (MRSA) is one of the major causes of hospital acquired infections. Over the past two decades MRSA has become ‘epidemic’ in many hospitals worldwide. However, little is known about the genetic background of S. aureus recovered from hospital personnel in China. Aim The aim of this study was to determine the genetic diversity of MRSA and methicillin susceptible S. aureus (MSSA) recovered from hospital personnel in Tianjin, North China. Methodology Three hundred and sixty-eight hand or nasal swabs were collected from 276 hospital personnel in four tertiary hospitals in Tianjin, North China between November 2017 and March 2019. In total, 535 gram-positive bacteria were isolated, of which 59 were identified as S. aureus. Staphylococcal cassette chromosome mec (SCCmec) typing, multi-locus sequence typing (MLST) and spa typing were performed to determine molecular characteristics of S. aureus. Results Thirty-one out of 276 (11%) hospital personnel were S. aureus carriers, whereas 11/276 (4%) carried MRSA. Fifty out of 59 (85%) of S. aureus isolates were resistant or intermediate resistant to erythromycin. The dominant genotypes of MRSA recovered from hospital personnel were ST398-t034-SCCmecIV/V, and ST630-t084/t2196, whereas major genotypes of MSSA included ST15-t078/t084/t346/t796/t8862/ t8945/t11653 and ST398-t189/t034/ t078/t084/t14014. Conclusion Although, the predominant genotypes of MRSA recovered from hospital personnel in this study were different from those main genotypes that have previously been reported to cause infections in Tianjin and in other geographic areas of China, the MRSA ST398-t034 genotype has previously been reported to be associated with livestock globally. The dominant MSSA genotypes recovered from hospital personnel were consistent with those previously reported MSSA genotypes recovered from the clinic. The diversity of S. aureus genotypes warrantee further surveillance and genomic studies to better understand the relatedness of these bacteria with those recovered from patients and community

The role of protein concentration in heat‐induced particulation of soy proteins at different pHs: Structure and functional properties

Abstract Protein particulation is a modification strategy for the optimization of the use of protein materials. The development and subtypes of particulate structures are largely dependent on the aggregated state of proteins after heat‐induced interactions, which is profoundly influenced by protein concentration (PC). In this work, the impact of PC below and above the critical gelation point, that is, 5% (w/v) and 10% (w/v), on the structure and functional properties of heat‐treated soy protein isolates (SPIs) at different pHs (2.0, 4.0, and 7.0), was investigated. The results showed that heat‐induced aggregation of SPIs was promoted by increasing the PC, leading to a β‐sheet‐dominated secondary structure. At pH 2.0 and 7.0, the 10% SPIs exhibited larger particle size and lower solubility, surface hydrophobicity index, and oil‐holding capacity compared to the 5% SPIs after heating. Furthermore, at neutral pH, the 10% SPI microgels had higher storage modulus (G′) and loss modulus (G″) than their acidifying counterparts, as well as the excellent emulsifying property for oil droplet stabilization. These findings would provide the theoretical basis for the structure modification and function improvement of plant proteins and, therefore, broaden the application of plant proteins in the food industry

Fabrication and Characteristic of Rhamnolipid-chitosan Coated Emulsions for Loading Ergocalciferol

To overcome the intrinsic limitations of ergocalciferol, layer-by-layer oil-in-water emulsions were formulated and applied in the microencapsulation of ergocalciferol. The primary emulsions were prepared using rhamnolipids to stabilize oil droplets, and then the secondary emulsions were formed by electrostatic deposition of cationic chitosan onto anionic rhamnolipids-coated droplets. The effects of pH, ionic strength, and thermal treatment on the stability of emulsions were investigated. Secondary emulsions were more stable than primary emulsions at low pH and high NaCl concentrations. Both emulsions showed excellent physicochemical stability during long-term storage. The droplet size of ​emulsions remained stable, and the ergocalciferol retention in emulsions was still maintained at over 95% after 30 days of storage. These results indicate that the resistance of prepared emulsions to different environmental stresses is enhanced. Moreover, this study gives important information for extending the utilization of rhamnolipids and chitosan in the delivery system for functional ingredients

Rice Curled Its Leaves Either Adaxially or Abaxially to Combat Drought Stress

Leaf rolling (LR) is one of the defensive mechanisms that plants have developed against adverse environmental conditions. LR is a typical drought response, promoting drought resistance in various gramineae species, including wheat, maize, and rice. Rice cultivation faces the formidable challenge of water deprivation because of its high water requirements, which leads to drought-related symptoms in rice. LR is an important morphological characteristic that plays a key role in controlling water loss during water insufficiency, thereby regulating leaf area and stature, which are crucial agronomic traits determining yield criteria. Bulliform, sclerenchyma, mesophyll, and vascular bundles are the cells that engage in LR and commonly exhibit adaxial or abaxial types of rolling in rice. The specific genes linked to rolling, either adaxially or abaxially, are discussed here. In addition to the factors influencing LR, here is a short review of the morphological, physiological and molecular responses of this adaptation under drought stress. Moreover, this review highlights how LR combats the consequences of drought stress. The eco-physiological and molecular mechanisms underlying this morphological adaptation in rice should be further explored, as they might be useful in dealing with various degrees of drought tolerance

Sensitivity parameters of tight sand gas: A case study of Lower Cretaceous Yingcheng Formation of Yingtai gas field in Songliao Basin, NE China

In tight sandstone, the gas-bearing sensitivity parameters are studied to improved prediction accuracy of thin gas layer due to the small impedance differences between gas-bearing layers and surrounding rocks. In this paper, we propose a new combined elastic parameter, i.e., the ratio of the first Lame coefficient to S-wave velocity based on elastic parameters sensitivity analysis for tight sandstone gas. By considering different geological conditions, we introduce the extending attribute (the ratio of Russell fluid phase to S-wave velocity), which can reduce to the ratio of the first Lame coefficient to S-wave velocity in specific condition. Both Gassmann equation and Brie empirical relationship are applied to calculate elastic parameters of different gas saturation in fluid replacement process. The results verify the validity of the new combined elastic parameter, which is more sensitive to gas saturation than conventional parameters, such as the product of the first Lame coefficient and density and the ratio of P-wave to S-wave velocity. The pre-stack inversion is applied in the second member of Lower Cretaceous Yingcheng Formation in Yingtai gas field. Compared to the section of the product for the first Lame coefficient and density, the results show the new combined elastic parameter presented improves the accuracy of identifying gas-bearing layers, well conforms to the logging interpretation, and greatly enhances the identification ability and prediction accuracy of gas-bearing layers. Key words: Tight sand gas, Gas-bearing, Elastic parameters, Sensitivity parameters, Pre-stack inversio

Properties of Ternary Biopolymer Nanocomplexes of Zein, Sodium Caseinate, and Propylene Glycol Alginate and Their Functions of Stabilizing High Internal Phase Pickering Emulsions

A pH-cycle method based on preparing an alkaline solution of zein followed by neutralization with an acid can be used to prepare zein nanoparticles. In the present work, partial alkaline hydrolysis of propylene glycol alginate (PGA) to a lower pH was studied to prepare binary zein–PGA nanocomplexes and ternary complexes with additional sodium caseinate (NaCas). 0.5% or more PGA was sufficient to reduce the pH to 7.5 or lower, eliminating the need for titration, and resulted in simultaneous nanocomplex formation. The addition of NaCas into alkaline zein–PGA solution resulted in smaller complexes with all biopolymers, whereas adsorption on binary zein–PGA complexes was observed when NaCas was added into the neutral zein–PGA dispersions. The formation of nanocomplexes involved with hydrophobic and electrostatic attractions and hydrogen bonds and was further affected by the amount of NaCas. The ternary nanocomplexes with equal masses of zein and NaCas had an excellent capacity to prepare gel-like Pickering emulsions with as much as 80% v/v oil with characteristics suitable for texture modification and delivery systems of bioactive compounds in food and consumer products. Therefore, PGA can be used to possibly scale-up the pH-cycle method to produce zein-based nanoparticles with unique functional properties

Binary Complex Based on Zein and Propylene Glycol Alginate for Delivery of Quercetagetin

Propylene glycol alginate (PGA) was found to be able to dissolve in aqueous ethanol solution and applied to interact with zein to form a noncovalent binary complex by the antisolvent coprecipitation method at pH 4.0. Quercetagetin (Q) was employed to explore the Q-delivery potential of Zein-PGA binary complex. A fruit tree-like microstructure was observed for Zein-PGA binary complex as its “branches” were closely adsorbed by zein particles. A solid sponge-like entity was formed after lyophilization of Zein-PGA binary complex colloidal dispersion. A synergistic effect was found between zein and PGA on improving the entrapment efficiency and loading capacity of Q. The incorporation of Q at a high concentration induced a significant effect on the tertiary structure of zein. Electrostatic attraction, hydrogen bond, and hydrophobic effects were mainly involved in the interactions between zein and PGA. Schematics with four possible structures were proposed to explain the formation mechanism of composites

Binary Complex Based on Zein and Propylene Glycol Alginate for Delivery of Quercetagetin

Propylene glycol alginate (PGA) was found to be able to dissolve in aqueous ethanol solution and applied to interact with zein to form a noncovalent binary complex by the antisolvent coprecipitation method at pH 4.0. Quercetagetin (Q) was employed to explore the Q-delivery potential of Zein-PGA binary complex. A fruit tree-like microstructure was observed for Zein-PGA binary complex as its “branches” were closely adsorbed by zein particles. A solid sponge-like entity was formed after lyophilization of Zein-PGA binary complex colloidal dispersion. A synergistic effect was found between zein and PGA on improving the entrapment efficiency and loading capacity of Q. The incorporation of Q at a high concentration induced a significant effect on the tertiary structure of zein. Electrostatic attraction, hydrogen bond, and hydrophobic effects were mainly involved in the interactions between zein and PGA. Schematics with four possible structures were proposed to explain the formation mechanism of composites