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BackgroundIncreased inclusion of plant proteins in aquafeeds has become a common practice due to the high cost and limited supply of fish meal but generally leads to inferior growth performance and health problems of fish. Effective method is needed to improve the plant proteins utilization and eliminate their negative effects on fish. This study took a unique approach to improve the utilization of soybean meal (SBM) by fish through autochthonous plant-degrading microbe isolation and subsequent fermentation.ResultsA strain of Shewanella sp. MR-7 was isolated and identified as the leading microbe that could utilize SBM in the intestine of turbot. It was further optimized for SBM fermentation and able to improve the protein availability and degrade multiple anti-nutritional factors of SBM. The fishmeal was able to be replaced up to 45% by Shewanella sp. MR-7 fermented SBM compared to only up to 30% by SBM in experimental diets without adverse effects on growth and feed utilization of turbot after feeding trials. Further analyses showed that Shewanella sp. MR-7 fermentation significantly counteracted the SBM-induced adverse effects by increasing digestive enzymes activities, suppressing inflammatory responses, and alleviating microbiota dysbiosis in the intestine of turbot.ConclusionsThis study demonstrated that plant protein utilization by fish could be significantly improved through pre-digestion with isolated plant-degrading host microbes. Further exploitation of autochthonous bacterial activities should be valuable for better performances of plant-based diets in aquaculture.

BackgroundStaphylococcal food poisoning (SFP) is one of the most common food-borne diseases in the world. Pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST) and spa typing methods were used to characterize Staphylococcus aureus isolates from food surveillance during 2013–2015 in southwest China, and Staphylococcal cassette chromosome mec (SCCmec) typing was used for methicillin-resistant S. aureus (MRSA). Isolates were also examined for their antibiotic resistance and carriage of virulence genes.ResultsIsolation rate of S. aureus was 2.60% during the three years’ surveillance and 29.50% of them were MRSA. All the S. aureus had hla genes (100%), 14.34% of the strains had tst, and 16.73% had PVL. 163 PFGE-SmaI patterns, 41 ST types and 36 spa types were obtained for all the S. aureus. Among them, ST6-t701 (13.15%), ST7-t091 (12.75%), ST59-t437 (9.96%) and ST5-t002 (7.57%) were the prevalent genotypes. Most of MRSA in this study belonged to SCCmec IV and V, accounted for 74.32% and 20.27% respectively. ST6-SCCmec IV-t701 (36.50%) was the most prevalent clone among isolates from food, followed by ST59-SCCmec V-t437 (20.30%), ST5-SCCmec IV-t002 (12.20%) and ST59-SCCmec IV-t437 (12.20%). Some strains had the identical PFGE patterns, ST and spa types with isolates from patients.ConclusionsS. aureus isolated from food in southwest China displayed heterogeneity. Isolates had the same genotype profiles with isolates from patients, indicating high homology.Electronic supplementary materialThe online version of this article (10.1186/s12866-018-1239-z) contains supplementary material, which is available to authorized users.

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The reactive oxygen species (ROS) produced during exercise act as a double-edged sword because they may cause oxidative damage but also play a role in the signaling pathways. A supplementation of exogenous antioxidants can reduce the total amount of ROS during exercise while it may also affect the ROS’ role in the signaling pathways of mitochondrial biogenesis. It has been suggested that hydrogen gas, as an antioxidant, can selectively scavenge hydroxyl radicals but does not affect superoxide anion’s signal transduction. The aim of this study was to compare the effects of 1-h hydrogen gas inhalation 30min prior to a treadmill exercise on the key biomarkers of mitochondrial biogenesis and related signaling pathways, and the activities of endogenous antioxidant enzymes, with those of vitamin C, in the rat skeletal muscle. Eighty-one 8-week-old male Sprague–Dawley (SD) rats were randomly assigned to three interventions (exercise-only, exercise+4%H2, and exercise+vitamin C at 500mg/kg weight, with 27 rats under each intervention), and sampled at pre-, immediately post and 4h post a 60-min treadmill exercise at speed of 27m/min and flat inclination, with nine rats in each sub-group. Expression of mitochondrial biogenetic markers and related signaling molecules in gastrocnemius muscle, and concentrations of oxidative stress markers in serum were measured. Two-way ANOVA or Kruskal–Wallis analyses showed that both hydrogen inhalation and vitamin C supplementation significantly reduced serum levels of MDA immediately after exercise and AGEs 4h after exercise. The pre-exercise supplement of vitamin C significantly reduced mitochondrial complex IV concentrations and PGC-1α, NRF-1, TFAM gene expression levels compared to the pre-exercise group, but the hydrogen gas intervention did not result in a reduction in these measurements. Unlike vitamin C, hydrogen inhalation did not blunt post-exercise mitochondrial biogenetic signals, but resulted in an increase in complex IV concentration, activation of PGC-1α, and TFAM and NRF-2 gene transcription, and up-regulation of PGC-1α protein expression. The findings indicated that hydrogen gas inhalation could play the role as an effective antioxidant in response to the exercise, whilst it did not significantly affect mitochondrial biogenesis. The dose–response relationship and antioxidant effects in different types of exercise for hydrogen inhalation require further investigation.