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ST7 Staphylococcus aureus is highly prevalent in humans, pigs, as well as food in China; however, staphylococcal food poisoning (SFP) caused by this ST type has rarely been reported. On May 13, 2017, an SFP outbreak caused by ST7 S. aureus strains occurred in two campuses of a kindergarten in Hainan Province, China. We investigated the genomic characteristics and phylogenetic analysis of ST7 SFP strains combined with the 91 ST7 food-borne strains from 12 provinces in China by performing whole-genome sequencing (WGS). There was clear phylogenetic clustering of seven SFP isolates. Six antibiotic genes including blaZ, ANT (4′)-Ib, tetK, lnuA, norA, and lmrS were present in all SFP strains and also showed a higher prevalence rate in 91 food-borne strains. A multiple resistance plasmid pDC53285 was present in SFP strain DC53285. Among 27 enterotoxin genes, only sea and selx were found in all SFP strains. A ФSa3int prophage containing type A immune evasion cluster (sea, scn, sak, and chp) was identified in SFP strain. In conclusion, we concluded that this SFP event was caused by the contamination of cakes with ST7 S. aureus. This study indicated the potential risk of new emergencing ST7 clone for SFP.

The dietary choices of bacterial-feeding nematodes could control the structure and ecological functions of soil bacterial communities. However, the physiological basis for the selection of particular bacterial species as food, and the consequences of these dietary choices for the survival of bacterial-feeding nematodes, is poorly understood. The objectives of this study were (1) to determine how nematode feeding preference was related to bacterial traits (cell size, gram stain and growth rate) and quality (water content, carbohydrate content, protein content and metabolite concentration), and (2) to evaluate how dietary choices affected the reproduction and lifespan of two soil-dwelling bacterial-feeding nematodes of the species Mesorhabditis and Acrobeloides. Their food sources included one model bacterium, Escherichia coli OP50, and four soil-dwelling bacterial species: Bacillus amyloliquefaciens, Bacillus megaterium, Variovorax paradoxus and Pseudomonas fluorescens. Both nematode species exhibited a similar hierarchy of diet choice, with P. fluorescens and E. coli OP50 being the most preferred food, whereas B. megaterium was the least preferred bacteria. Nematode feeding preference was strongly related to the water content, growth rate and metabolite concentration of bacterial cells, which explained 63–75% of the variation in the feeding preference index (PI, which indicates the number of nematodes attracted to specific bacteria), and the rest of the variation was attributed to bacterial cell size, gram stain, carbohydrate content and protein content. We propose two physiological mechanisms to explain dietary choices of bacterial-feeding nematodes: 1) chemical attraction to higher carbon dioxide levels around rapidly-growing bacteria or repulsion to volatile organic molecules released from bacterial cells, and 2) selective ingestion of bacterial cells with preferred characteristics (e.g., high water content in cells). Nematodes feeding on preferred bacteria always had higher reproduction, but dietary choices were not a good predictor of their lifespan. For example, Acrobeloides feeding on their preferred food P. fluorescens had the largest brood size but a moderate survival time. However, when Acrobeloides consumed their least-preferred food B. megaterium, they produced the smallest brood size and had the shortest survival time. This may be due to the fact that dietary resources are allocated first towards reproduction, and second to prolong the lifespan of bacterial-feeding nematodes. Our findings suggest that dietary choices are important for the survival of bacterial-feeding nematodes, and their ability to find and selectively ingest preferred bacterial species may have implications for soil bacterial community structure and ecological functions.

International audience; Extracellular vesicles (EVs) are small, heterogeneous and difficult to measure. Flow cytometry (FC) is a key technology for the measurement of individual particles, but its application to the analysis of EVs and other submicron particles has presented many challenges and has produced a number of controversial results, in part due to limitations of instrument detection, lack of robust methods and ambiguities in how data should be interpreted. These complications are exacerbated by the field's lack of a robust reporting framework, and many EV-FC manuscripts include incomplete descriptions of methods and results, contain artefacts stemming from an insufficient instrument sensitivity and inappropriate experimental design and lack appropriate calibration and standardization. To address these issues, a working group (WG) of EV-FC researchers from ISEV, ISAC and ISTH, worked together as an EV-FC WG and developed a consensus framework for the minimum information that should be provided regarding EV-FC. This framework incorporates the existing Minimum Information for Studies of EVs (MISEV) guidelines and Minimum Information about a FC experiment (MIFlowCyt) standard in an EV-FC-specific reporting framework (MIFlowCyt-EV) that supports reporting of critical information related to sample staining, EV detection and measurement and experimental design in manuscripts that report EV-FC data. MIFlowCyt-EV provides a structure for sharing EV-FC results, but it does not prescribe specific protocols, as there will continue to be rapid evolution of instruments and methods for the foreseeable future. MIFlowCyt-EV accommodates this evolution, while providing information needed to evaluate and compare different approaches. Because MIFlowCyt-EV will ensure consistency in the manner of reporting of EV-FC studies, over time we expect that adoption of MIFlowCyt-EV as a standard for reporting EV- FC studies will improve the ability to quantitatively compare results from different laboratories and to support the development of new instruments and assays for improved measurement of EVs.

Vibrio cholerae can be differentiated into epidemic and non-epidemic strains by sorbitol fermentation speed, but little research has been done on its mechanisms. In this study, we investigated differential protein expression of the two strains in response to sorbitol metabolism. V. cholerae strains were cultured in media with and without sorbitol, respectively. Proteins were separated by 2-DE, and those that showed different expression in the two media were identified by MALDI-TOF MS. Fifteen proteins in epidemic strains and 11 proteins in non-epidemic strains showed a different expression in sorbitol medium. Among them, 4 proteins were common to epidemic and non-epidemic strains. Gene sequence analysis showed that some mutations occurred in these proteins between the two strains. Potential functions of these proteins included sugar uptake, amino acid uptake, electron transport, sulfate and thiosulfate transport.

Based on the methane spectral absorption characteristic and difference absorption technology, a method of detecting methane concentration is presented. Taking distributed feedback (DFB) laser as the light source, the light with central wavelength 1650 nm is be divided into two-way by beam splitter, and one beam passes the methane gas in a gas cell, the other directly passes another reference gas cell. The useful light signal is converted in to electric signal by hardware circuit. The relation ship between concentration and voltage is obtained by virtual instrument software processing the voltage signal, and the experimental result accord with the actual methane concentration. At last, the factors influencing on the experimental detecting resolution are analyzed. The esults of the experiments show that the real time detection and monitor of the methane gas can be completed in this system.

The last decade has seen a sharp increase in the number of scientific publications describing physiological and pathological functions of extracellular vesicles (EVs), a collective term covering various subtypes of cell-released, membranous structures, called exosomes, microvesicles, microparticles, ectosomes, oncosomes, apoptotic bodies, and many other names. However, specific issues arise when working with these entities, whose size and amount often make them difficult to obtain as relatively pure preparations, and to characterize properly. The International Society for Extracellular Vesicles (ISEV) proposed Minimal Information for Studies of Extracellular Vesicles (“MISEV”) guidelines for the field in 2014. We now update these “MISEV2014” guidelines based on evolution of the collective knowledge in the last four years. An important point to consider is that ascribing a specific function to EVs in general, or to subtypes of EVs, requires reporting of specific information beyond mere description of function in a crude, potentially contaminated, and heterogeneous preparation. For example, claims that exosomes are endowed with exquisite and specific activities remain difficult to support experimentally, given our still limited knowledge of their specific molecular machineries of biogenesis and release, as compared with other biophysically similar EVs. The MISEV2018 guidelines include tables and outlines of suggested protocols and steps to follow to document specific EV-associated functional activities. Finally, a checklist is provided with summaries of key points.