Correlation between changes in microbial/physicochemical properties and persistence of human norovirus during cabbage Kimchi fermentation
OPEN Journal of microbiology and biotechnology | 12 Oct 2017
HM Lee, JH Lee, SH Kim, SR Yoon, JY Lee and JH Ha
Recently, cabbage Kimchi have occasionally been associated with the food-borne diseases of enteric viruses such as human norovirus (HuNoV). This study aimed to evaluate the correlation between microbial/physicochemical properties and persistence of human norovirus in experimentally contaminated cabbage Kimchi fermented and stored at 4 °C or 10 °C for 28 days. Changes in organic acid content, lactic acid bacteria (LAB), acidity, pH, and salinity were analyzed. The recovery of structurally intact HuNoV was examined for up to 28 days post-inoculation, using a NoV GII.4 monoclonal antibody-conjugated immuno-magnetic separation (IMS) method combined with quantitative real-time reverse transcription polymerase chain reaction (RT-qPCR). On day 0, LAB loads were 4.70 log10 colony forming units/g and HuNoV GII.4 titers were 2.57 log10 genomic copies/µL, at both temperatures. After 28 days, intact HuNoV titers decreased to 1.58 (4 °C) and 1.04 (10 °C) log10 genomic copies/µL, whereas LAB density increased. This correlated with a gradual increase in lactic acid and acetic acid at both temperatures. Our findings support a statistical correlation between changes in physicochemical properties and the recovery of structurally intact HuNoV GII.4. Moreover, we determined that the production of organic acid and low pH could affect HuNoV GII.4 titers in cabbage Kimchi during fermentation. However HuNoV GII.4 was not completely eliminated by microbial/physicochemical factor during fermentation although HuNoV GII.4 was reduced. Based on this, we speculate that the persistence of HuNoV GII.4 may be affected by the continually changing conditions during Kimchi fermentation.
* Data courtesy of Altmetric.com