This study shows that antagonistic effects were observed when Gram-negative bacteria were treated with organic acids of simple structure. It may provide useful information for understanding the acid resistance mechanism of Gram-negative bacteria and developing methods for preserving acidified food.

Aim:  To evaluate the applicability of filtration membranes for detecting Alicyclobacillus spp. spores in apple juice. Methods and Results:  Ten types of nitrocellulose membrane filters from five manufacturers were used to collect and enumerate five Alicyclobacillus spore isolates and results were compared to conventional K agar plating. Spore recovery differed among filters with an average recovery rate of 126·2%. Recovery levels also differed among spore isolates. Although significant difference (P < 0·05) in spore sizes existed, no correlation could be determined between spore size and membrane filter recovery rate. Conclusions:  Recovery of spores using membrane filtration is dependent on the manufacturer and filter pore size. Correlations between spore recovery rate and spore size could not be determined. Significance and Impact of the Study:  Low numbers of Alicyclobacillus spores in juice can be effectively detected using membrane filtration although recovery rate differences exist among different manufacturers. Use of membrane filtration is a simple, fast alternative to the week‐long enrichment procedures currently employed in most quality assurance tests.

Aim:  To test the efficacy of a chemical (chlorous acid) for reducing the numbers of viable Alicyclobacillus acidoterrestris spores in laboratory media and on apples. Methods and Results:  Alicyclobacillus acidoterrestris spores in aqueous suspension and on apple surfaces of four different cultivars were treated with 268 ppm chlorous acid. Treatment with 268 ppm chlorous acid sharply reduced the numbers of spores of A. acidoterrestris in laboratory media by 1·6, 4·3, and 7·0 log10 reductions for 5, 10, and 15 min treatments, respectively. Chlorous acid also effectively reduced the spore load on apple surfaces. Alicyclobacillus acidoterrestris spore counts were significantly reduced by about 5 log10 after 10 min treatment on four different apple cultivars (‘Red Delicious’, ‘Golden Delicious’,’ Gala’, and ‘Fuji’). There was no synergistic effect on spore reduction when chlorous acid treatment was combined with heat. Conclusions:  These results show that chlorous acid is highly efficacious against A. acidoterrestris spores on apple surfaces. Significance and Impact of the Study:  Chlorous acid can be used as an alternative sanitizer of chlorine to control a major A. acidoterrestris contamination source in juice processing plants.

Kudoa septempunctata is a myxosporean parasite that infects the trunk muscles of olive flounder (Paralichthys olivaceus) and has been reported to cause foodborne illnesses in humans. However, the molecular mechanisms underlying K. septempunctata spore toxicity remain largely unknown. In this study, the gastroenteropathy of K. septempunctata was examined in human colon adenocarcinoma cells as well as experimental mice inoculated with spores. We found that K. septempunctata decreased transepithelial resistance and disrupted epithelial tight junctions by deleting ZO-1 in Caco-2 monolayers. Additionally, serotonin (5-HT), an emetic neurotransmitter, was increased in K. septempunctata-inoculated cells. In vivo, K. septempunctata spores induced diarrhea in suckling mice (80% in ddY and 70% in ICR mice), with a minimum provocative dose of 2 × 105 K. septempunctata spores. In house musk shrews, K. septempunctata induced emesis within 1 h and induced serotonin secretion in the intestinal epithelium. In conclusion, K. septempunctata may induce diarrhea and emesis by increasing intestinal permeability and serotonin secretion.

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