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To disclose the antimicrobial susceptibility and wide adaptability of commonly occurring genotypes of Salmonella enterica serovar Typhimurium, the antimicrobial resistance and multilocus sequence t...

Continuous data scale growth increases energy consumption and operating cost that cannot be ignored in cloud storage systems. Previous studies have shown that analyzing the characteristics of I/O access and mining data features is effective for reasonable data distribution in storage systems. The granularity and criterion of classification are the key factors in determining the data distribution. To decrease energy consumption and operating cost, this paper puts forward a fine-grained framework of the climatic-season-based energy-aware in cloud storage system called CSEA. The framework concludes the following three aspects: (i) data feature mining. CSEA discovers potential data features by analyzing data access to provide help with data classification. (ii) K-means clustering algorithm. CSEA uses an unsupervised data classification algorithm in machine learning to divide data into categories based on seasonal characteristics by gathering real I/O access. (iii) data distribution of fine-grained. On the basis of seasonal features, CSEA fuses regional features to further refine the data distribution granularity to save on energy consumption and operating cost. Simulation experiments using extended CloudSimDisk and the constructed mathematical models indicate that CSEA reduces the energy consumption and operating cost compared with the single data classification standard and coarse-grained data distribution.

Salmonellosis occurs frequently worldwide, causing serious threats to public health safety. The abuse of antibiotics is increasing the antibiotic resistance in bacteria, thereby making the prevention and control of Salmonella more difficult. A phage can help control the spread of bacteria. In this study, S55, a lytic phage, was isolated from faecal samples obtained from poultry farms using Salmonella Pullorum ( S . Pullorum) as the host bacterium. This phage belongs to Siphoviridae and has a polyhedral head and a retraction-free tail. S55 showed a strong ability to lyse Salmonella serovars, such as S . Pullorum (58/60, 96.67%) and S . Enteritidis (97/104, 93.27%). One-step growth kinetics showed that the latent period was 10 min, burst period was 80 min and burst size was 40 pfu/cell. The optimal multiplicity of infection was 0.01, and the phage was able to survive at a pH of 4-11 and temperature of 40°C-60°C for 60 min. Complete genome sequence analysis revealed that the S55 genome length is 42,781 bp (GC content, 50.28%) and it contains 58 open reading frames (ORF), including 25 ORFs with known or assumed functions, without tRNA genes. Moreover, S55 does not carry genes that encode virulence or resistance factors. At different temperatures (4°C or 25°C), S55 was found to lower the populations of S . Pullorum and S . Enteritidis on chicken skin surface. Its bacteriostatic effect at 4°C was higher than that at 25°C. In conclusion, S55 can be considered a promising biological agent for the prevention and control of Salmonella .

In recent years, foodborne diseases caused by pathogens have been increasing. Therefore, it is essential to control the growth and transmission of pathogens. Bacteriophages (phages) have the potential to play an important role in the biological prevention, control, and treatment of these foodborne diseases due to their favorable advantages. Phages not only effectively inhibit pathogenic bacteria and prolong the shelf life of food, but also possess the advantages of specificity and an absence of chemical residues. Currently, there are many cases of phage applications in agriculture, animal disease prevention and control, food safety, and the treatment of drug-resistant disease. In this review, we summarize the recent research progress on phages against foodborne pathogenic bacteria, including Escherichia coli, Salmonella, Campylobacter, Listeria monocytogenes, Shigella, Vibrio parahaemolyticus, and Staphylococcus aureus. We also discuss the main issues and their corresponding solutions in the application of phages in the food industry. In recent years, although researchers have discovered more phages with potential applications in the food industry, most researchers use these phages based on their host spectrum, and the application environment is mostly in the laboratory. Therefore, the practical application of these phages in different aspects of the food industry may be unsatisfactory and even have some negative effects. Thus, we suggest that before using these phages, it is necessary to identify their specific receptors. Using their specific receptors as the selection basis for their application and combining phages with other phages or phages with traditional antibacterial agents may further improve their safety and application efficiency. Collectively, this review provides a theoretical reference for the basic research and application of phages in the food industry.

As a natural alternative to traditional antimicrobials, phages are being recognised as highly effective control agents for Salmonella and other foodborne bacteria. Due to the high diversity of Salmonella serotypes and the emergence of phage-resistant strains, attempting to isolate more widespread, strictly lytic Salmonella phages is highly warranted. In this study, a lytic phage, LP31, was isolated from poultry faecal samples. Transmission electron microscopy revealed that the phage had a polyhedral head and a retraction-free tail, indicative of the Siphoviridae family. Adsorption rate experiments showed that LP31 required the participation of lipopolysaccharides, but not flagella, during phage adsorption. Host profile identification showed that LP31 could lyse most Salmonella Enteritidis (S. Enteritidis) (96.15%, N = 104) and Salmonella Pullorum (S. Pullorum) (96.67%, N = 60). Initial applications found that LP31 reduced the concentration of static S. Enteritidis on metal surfaces (0.951 log

The study of the interaction mechanism between bacteriophage and host is helpful in promoting development of bacteriophage applications. The mechanism of the interaction with the phage was studied by constructing the rfbN gene deletion and complemented with strains of Salmonella enterica subspecies enterica serovar Typhimurium (Salmonella Typhimurium, S. Typhimurium) D6. The rfbN gene deletion strain could not be lysed by phage S55 and led to a disorder of lipopolysaccharide (LPS) biosynthesis, which changed from the smooth type to rough type. Also, the RfbN protein lacking any of the three-segment amino acid (aa) sequences (90-120 aa, 121-158 aa, and 159-194 aa) produces the same result. Transmission electron microscopy and confocal microscopy assays demonstrated that phage S55 dramatically reduced adsorption to the rfbN deletion strain as compared to the wild strain D6. After co-incubation of the S55 with the purified smooth LPS, D6 could not be lysed, indicating that the smooth LPS binds to the S55 in vitro and then inhibits the cleavage activity of the S55. To sum up, the rfbN gene affects phage adsorption by regulating LPS synthesis. Furthermore, the functioning of the RfbN protein requires the involvement of multiple structures. To the best of our knowledge, this study is the first report of the involvement of the bacterial rfbN gene involved in the phage-adsorption process.

Streptococcus suis is an important zoonotic pathogen that causes severe infections and great economic losses worldwide. Understanding how this pathogen senses and responds to environmental signals during the infectious process can offer insight into its pathogenesis and may be helpful in the development of drug targets. Two-component regulatory systems (TCSs) play an essential role in this environmental response. In S. suis, at least 15 groups of TCSs have been predicted. Among them, several have been demonstrated to be involved in virulence and/or stress response. In this review, we discuss the progress in the study of TCSs in S. suis, focusing on the role of these systems in the virulence of this bacterium.

Motility is important for virulence, biofilm formation, and the environmental adaptation of many bacteria. Vibrio parahaemolyticus (V. parahaemolyticus) contains two flagellar systems that are responsible for motility, and are tightly regulated by transcription regulators and sigma factors. In this study, we identified a novel transcription factor, VPA1701, which regulates the swarming motility of V. parahaemolyticus. The VPA1701 deletion mutant (&Delta, VPA1701) eliminated the swarming motility on the surface of BHI agar plates and reduced colonization in infant rabbits. RNA-seq assays, confirmed by qRT-PCR, indicated that VPA1701 regulated the expression of lateral flagellar cluster genes. Further analyses revealed that VPA1701 directly binds to the promoter region of the flgBCDEFGHIJKL cluster to regulate the expression of lateral flagellar genes. CalR was originally identified as a repressor for the swarming motility of V. parahaemolyticus, and it was inhibited by calcium. In this study, we found that VPA1701 could inhibit the expression of the calR gene to increase the swarming motility of V. parahaemolyticus. Calcium downregulated the expression of calR, indicating that calcium could increase swarming motility of &Delta, VPA1701 by inhibiting calR. Thus, this study illustrates how the transcription factor VPA1701 regulates the expression of lateral flagellar genes and calR to control the swarming motility of V. parahaemolyticus.

Molecular recognition based on hydrogen bond interaction plays a significant role in supramolecular self-assembly. In this work, we successfully developed a class of novel frameworks containing a urea in the recognition site and a carboxylate anion in the guest unit. The self-recognition model based on the interaction between urea and carboxylate anion could induce the molecules to assemble into a highly organized form. The crystal structures showed that they assembled in highly ordered two-dimensional architectures. The optical properties showed that the position of carboxylate anion on the diphenylacetylene backbone had an obvious influence on optical properties. The self-recognition strategy is useful for the construction of highly ordered self-assembled architectures.

Pullorum is a chicken-specific systemic disease caused by Salmonella enterica serovar Gallinarum biovar Pullorum (S. Pullorum). This study was carried out to provide basic data for understanding the trends of S. Pullorum. A total of 652 S. Pullorum isolates collected in China during 1962–2019 were examined. Overall, 525 (80.5%) isolates were resistant to at least one antibiotic; 280 (42.9%) isolates resisted 3 or more classes of antibiotics and showed an increasing trend until 2015 and then decreased significantly. The most common multidrug-resistant pattern was ampicillin–tetracycline–nalidixic acid (13.6%). After 2008, 6 classes of antibiotic-resistant strains began to appear, and they have been prevalent ever since. In 2014, a strain resistant to 7 antibiotics (ampicillin–cefazolin–streptomycin–tetracycline–sulphonamides–nalidixic acid–nitrofurantoin) was isolated. The highest antimicrobial resistance was observed for nalidixic acid (71.9%), and the lowest was found for cefotaxime, meropenem, amikacin, gentamicin, fosfomycin, and polymyxin (0%). Our findings monitored the prevalence of the resistance of S. Pullorum during the past half-century in China. Continued surveillance of antimicrobial resistance and the rational use of antimicrobials is necessary and important to control the rapid increase in antimicrobial resistance in S. Pullorum.

In the process of bacteriophage and bacteria struggle, adsorption is the key factor to determine who is the winner. In this paper, the molecular mechanism of tailed bacteriophage recognition and adsorption to host and the strategy of "fighting wisdom and courage" between them are reviewed.

Three fluorinated 1,8-napthalimides were synthesized from acenaphthene. Their structures were characterized by NMR and EI-MS analyses. The structures of compounds 1b and 1c were also confirmed by X-ray diffraction analysis, which showed that they possessed different packing models. Their optoelectronic properties were investigated. The results indicated that all of the naphthalimides possess good solubility and low LUMO energy level, which make them good solution processing candidates in n-type semiconductor.

N-butyl-4,5-dibutylamine-1,8-naphthylimide with a donor–acceptor structure was successfully synthesized by one-pot method using 4,5-dibromo-1,8-naphthalic anhydride and butylamine as starting materials. The structure was characterized by NMR and elemental analyses, and the optical and electrochemical properties were investigated. The compound can be used to selectively bind Cu2+, along with obvious blueshifts of fluorescence spectrum.

Three fluorinated 1,8-napthalimides were synthesized from acenaphthene. Their structures were characterized by NMR and EI-MS analyses. The structures of compounds 1b and 1c were also confirmed by X-ray diffraction analysis, which showed that they possessed different packing models. Their optoelectronic properties were investigated. The results indicated that all of the naphthalimides possess good solubility and low LUMO energy level, which make them good solution processing candidates in n-type semiconductor.

The construction of coronenes using simple building blocks is a challenging task. In this work, triphenylene was used as a building block to construct functionalized coronenes, and their solid structures and optoelectronic properties were investigated. The single crystal structures showed that coronenes have different packing motifs. Their good solubility and photostability make them potential solution-processable candidates for organic devices.

Polycyclic aromatic hydrocarbons are of great interest as a result of their self-assembly properties and excellent charge-transfer abilities. They are therefore promising candidates for organic semiconducting devices. In order to develop better optoelectronic devices, chemists have made considerable effort to investigate synthetic methods for polycyclic aromatic hydrocarbons. Among many building blocks, arynes are a promising reactive intermediate for the construction of polycyclic aromatic hydrocarbons and so have been studied over many decades. In this review, we will summarize recent progress on the construction of polycyclic aromatic hydrocarbons using arynes as starting materials.