Aeromonas hydrophila recently has received increased attention because it is opportunistic and a primary human pathogen. A. hydrophila biofilm formation and its control are a major concern for food safety because biofilms are related to virulence. Therefore, we investigated biofilm formation, motility inhibition, quorum sensing, and exoprotease production of this opportunistic pathogen in response to various glucose concentrations from 0.05 to 2.5% (wt/vol). More than 0.05% glucose significantly impaired (P < 0.05) quorum sensing, biofilm formation, protease production, and swarming and swimming motility, whereas bacteria treated with 0.05% glucose had activity similar to that of the control (0% glucose). A stage shift biofilm assay revealed that the addition of glucose (2.5%) inhibited initial biofilm formation but not later stages. However, addition of quorum sensing molecules N-3-butanoyl-DL-homoserine lactone and N-3-hexanoyl homoserine lactone partially restored protease production, indicating that quorum sensing is controlled by glucose concentrations. Thus, glucose present in food or added as a preservative could regulate acyl-homoserine lactone quorum sensing molecules, which mediate biofilm formation and virulence in A. hydrophila.

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Purpose The purpose of this paper is to analyze the fat, saturated fatty acid and trans fatty acid contents in ready-to-eat foods distributed at amusement parks to develop an appropriate food safety management system for children. Design/methodology/approach In all, 322 ready-to-eat food samples categorized into 17 types were collected from nine Korean amusement parks and their fat, saturated fatty acid and trans fatty acid contents were assessed. Findings Fat, saturated fatty acid and trans fatty acid contents were relatively high in flour-based products. On the basis of the Korea Food and Drug Administration classification, the samples in 12 categories were classified as high-fat foods. The samples in nine categories were classified as high-saturated fatty acid foods. Most samples also contained non-negligible levels of trans fatty acids. The fat, saturated fatty acid and trans fatty acid contents of samples even in the same category varied markedly. Social implications This research will inform the necessity of an appropriate safety management system for ready-to-eat foods distributed at amusement. Originality/value Although the fat contents of foods distributed around school area were often observed, the potential risk of those in ready-to-eat foods distributed at amusement parks have rarely been assessed. As patterns of food intakes vary world-widely, a periodic monitoring data like this study may be useful for international organizations and researchers.

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