Bacillus velezensis WLYS23 strain possesses antagonistic activity against hybrid snakehead bacterial pathogens.

AIM: The aims of this study were to screen an antagonistic probiotic for the prevention and control of bacterial diseases in snakehead fish and to evaluate the antimicrobial activities, biosafety and biocontrol effect of the antagonistic strain. METHODS AND RESULTS: In this study, the WLYS23 strain exhibiting the most effective antagonistic properties against several fish pathogens was selected from the intestine of healthy snakehead fish. The strain was identified as Bacillus velezensis based on morphological, physiological and biochemical characteristics, and phylogenetic analysis. This strain showed amylase, cellulase, protease and lipase activities according to extracellular enzyme activity assays. Moreover, the cell-free extract of the WLYS23 strain exhibited strong antibacterial activity, with MICs of ≤64 µg ml-1 for most fish pathogens. Additionally, the cell-free extract was heat and pH stable, and resistant to protease, whereas their antimicrobial activities were significantly influenced by metal ions at high concentration. The WLYS23 strain and its cell-free extract were safe for snakehead and zebrafish. The disease resistance of snakehead fish was significantly increased following administration of the WLYS23 strain and its cell-free extract respectively. The complete genome of the WLYS23 strain was sequenced and found to harbour seven gene clusters encoding secondary metabolites with antimicrobial activity. CONCLUSION: The WLYS23 strain possesses great potential as a biocontrol agent, which can be commercially developed to improve disease control in freshwater aquaculture. SIGNIFICANCE AND IMPACT OF THE STUDY: Snakehead fish are important commercially farmed fish worldwide. However, the bacterial diseases caused by Aeromonas sp. and Nocardia seriolae in farmed snakehead fish lead to huge economic losses. Safe, economical and efficient probiotics are limited to prevent and control these diseases. Here, we provide a promising biocontrol agent with antagonistic activity against bacterial diseases of snakehead.

Aeromonas shuberti as a cause of multi-organ necrosis in internal organs of Nile tilapia, Oreochromis niloticus.

A disease with white spots in internal organs of Nile tilapia occurred in Zhanjiang, southern China. Multiple, white nodules, 0.8-2.2 mm in diameter, were scattered throughout the liver, spleen and kidney of diseased fish. Signs of nodules reproduced after artificial infection with the isolated strain. Isolated bacteria were Gram-negative, facultative anaerobic, motile, short rod-shaped, with a length of 1.2-2.2 µm. Morphological and biochemical tests, as well as phylogenetic analysis, all strongly indicated that the isolate from tilapia is identical to Aeromonas schubertii (A. schubertii) which temporary named LF1708 strain. Antibiotic sensitivity assays showed the LF1708 is sensitive to 24 of 27 tested antibiotics. Pathogenicity test revealed that the isolate at the dose of 3.75 × 106 CFU/g killed 100% of experimental tilapia within 2 days and the dose of 1 × 107 CFU/g killed 100% of experimental zebrafish within 1 day. Histopathology of diseased tilapia infected with A. schubertii showed numerous necrotic lesions widely distributed in spleen, liver and kidney, and infiltration with a large number of bacteria. To our knowledge, this was the first report that associated A. schubertii with mortality in tilapia.

[Relationship between occupational stress and working ability of workers in a petroleum processing enterprise in high altitude area].

Objective: To investigate the relationship between occupational stress and working ability of workers in a petroleum processing enterprise in a high altitude area. Methods: A total of 728 workers in a petroleum processing enterprise at an altitude of 2850 m were subjected to a survey using Occupational Stress Inventory (OSI) , Work Ability Index (WAI) Scale, Occupational Role Questionnaire (ORQ) , Personal Strain Questionnaire (PSQ) , and Personal Resource Questionnaire (PRQ) from May 2014 to August 2016. Results: Of the 728 workers, 55 (7.6%) had a poor working ability, moderate in 262 (35.9%) , and good in 411 (56.5%). There were significant differences in WAI between the workers with different types of work, sexes, ages, and working years (P<0.05). There was a significant difference in WAI between different occupational stress groups (P<0.05). WAI was negatively correlated with ORQ score and PSQ score (r(s)=-0.387, P<0.05; r(s)=-0.467, P<0.05) and positively correlated with PRQ score (r(s)=0.343, P<0.05). The multiple linear regression analysis showed that high ORQ score and PSQ score were the inhibitory factors for high WAI (B=-0.058; B=-0.082) and high PRQ score was a contributing factor for high WAI (B=0.029) . Conclusion: Occupational stress is an influencing factor for the working ability of workers in the petroleum processing enterprise in the high altitude area. Hypoxia in high altitude area may further reduce the working ability. In order to reduce occupational stress and improve work ability, it should be considered to strengthen skills training, improve the working environment, and pay attention to mental health.

IgE-mediated allergy: a rare cause of chronic spontaneous urticarial with allergen-specific immunotherapy as treatment option - a systematic review with meta-analysis from China.

BACKGROUND: Allergen-specific immunotherapy (SIT) has long been a controversial treatment for chronic urticaria (CU), although SIT has been used in patients with allergic diseases for more than 90 years. OBJECTIVES: To evaluate the efficacy and safety of SIT vs. conventional treatment (CT) in the treatment of CU. METHODS: Systematic searches were conducted without language restrictions in MEDLINE, EMBASE, the Cochrane Library, ISI Web of Knowledge, China National Knowledge Infrastructure, and Chinese Scientific Journals Full Text Database. The primary outcomes were efficacy and quality of life (QOL) and the secondary outcomes were relapse rate and adverse events (AEs). RESULTS: Fourteen studies (1838 patients) were included. None of them was double-blind placebo controlled. Our study demonstrated that SIT seemed to show more clinical efficacy rate (OR 2.39; 95% CI, 1.73-3.30; I(2) = 55%, P = 0.008), more complete recovery rate (OR 2.13; 95% CI, 1.55-2.91; I(2) = 61%, P=0.008) and less relapse rate 2 weeks after treatment (OR 0.38; 95% CI, 0.24-0.61; I(2) = 6%, P=0.20) than CT. Only one study reported improved QOL and no study reported serious AEs after SIT. CONCLUSIONS: Current evidence indicates that IgE-mediated allergy may be causative in a small number of CU patients and specific immunotherapy with these allergens may be beneficial in those patients. However, the number of included studies was small and those qualities were low. So, available evidence is not adequate to draw an affirmative conclusion and larger studies of high quality are needed to provide increasingly convincing data and cases.