Study on the effects of gene mdoC of Shigella flexneri on the growth of bacteria and biofilm formation in vegetable wash waters

【Objective】 This study was to explore the effect of gene mdoC of Shigella flexneri on the growth of bacteria and biofilm formation in the different vegetable wash water.【Method】 The growth curves of Shigella flexneri and mdoC gene knock-out opgC mutant were measured and the biofilm was quantified by crystal violet assay to study the growth of bacteria and biofilm formation under hypoosmotic and normal conditions in spinach,green celery,lettuce and cabbage wash water.【Result】 The results showed that the growth rate of opgC mutant was lower than wild type in different wash water,while the wild type and opgC mutant grew faster under normal osmolarity than hypoosmotic wash water;there were significant differences between the biofilm formation of wild type and that of opgC mutant in spinach,lettuce and cabbage wash water.After increasing the osmolarity of wash water,the quantity of biofilm formed by wild type in spinach wash water increased significantly,while the biofilm in lettuce and cabbage wash water decreased.There were significant increases for the biofilm formation of opgC mutant in spinach,lettuce and cabbage wash water when the osmolarities were adjusted up to the normal ones.【Conclusion】 The gene mdoC deletion in Shigella flexneri retarded significantly the growth at hypoosmotic condition,while the deletion increased the biofilm formation in cabbage wash water after increasing the osmolarity to normal level.