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Loop-mediated isothermal amplification (LAMP) is a novel nucleic acid amplification method performed under isothermal conditions with high specificity and efficiency. We developed a diagnostic method based on LAMP for detection of Actinobacillus pleuropneumoniae. Using six specific primers targeting the apxIVA gene, the LAMP assay rapidly amplified the target gene within 30 min, requiring only a laboratory water bath for the reaction to occur. The resulting amplificon was visualized by adding SYBR Green I to the mixture. The results obtained from testing 15 A. pleuropneumoniae reference strains and other seven bacterial species strains showed that the LAMP was as specific as and 10 times more sensitive than nested PCR. Sixty-five tonsil samples were collected from 65 healthy pigs. All the samples were negative for A. pleuropneumoniae by immunomagnetic separation-based (IMS) bacterial isolation, nested PCR and LAMP, respectively. Meanwhile, 115 tonsil samples were also collected from 115 pigs with apparent respiratory problems. Twenty-two were positive by IMS bacterial isolation. All the samples that were positive by IMS bacterial isolation were also positive by nested PCR and LAMP. The LAMP assay demonstrated exceptionally higher sensitivity than nested PCR by picking up 14 additional positive cases (chi(2) test, P<0.0001); we concluded that LAMP was a highly sensitive and reliable method for detection of A. pleuropneumoniae infection.

This paper describes the effect of sodium selenite on the growth and fermentation properties of Bacillus subtilis J‐2 (BSJ‐2) which was isolated from the water of Chinese fermented pickles. The results of the optimum Se‐added conditions are as follows: addition concentration 45 μg/mL, addition time 4 h and inoculation quantity 2%. At this site, the Se conversion ratio was 73.8 ± 3.4%. With the increasing of selenium concentration, the alkaline protease activity has a slight increase at the optimum growth conditions, while the variation of the neutral protease activity had no significant difference among the five samples in the 1,000–1,100 μg/mL range. Added selenium had a positive impact on the antimicrobial ability of strains. Practical Applications The increasing popularity of Se‐enriched microorganism among food preservatives and food fermentation was well concerned about in the recent years. The present study has demonstrated that Bacillus subtilis has a suitable Se‐enriched condition and can enhance the growth and protease activities applied in food fermentation which can promote efficiency and cost savings. Health‐promoting effect is shown through the relatively high conversion on Se‐enriched Bacillus subtilis J‐2. It is expected that Se‐enriched B. subtilis J‐2 could be applied in food industries as an antiseptic agent to improve the antimicrobial ability. Our previous studies demonstrated that Se‐enriched B. subtilis can be applied as a safe and healthy potential dietary resource of nontoxic selenium to food fermentation and effective functional substance in food and medical industry.

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