FOOD SCIENCE ›› 2020, Vol. 41 ›› Issue (7): 1-7.doi: 10.7506/spkx1002-6630-20190222-143

• Basic Research •     Next Articles

Inhibitory Effect of Lactic Acid on Biofilm Formation of Enterobacter cloacae

LIU Yawen, JIN Panpan, XU Xiaoxi, LIU Fang, SUN Zhilan   

  1. (1. School of Food Science, Northeast Agricultural University, Harbin 150030, China; 2. Institute of Agricultural Products Processing, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China; 3. Qinghai Lake Meat Industry Co. Ltd., Hainanzhou 813000, China)
  • Online:2020-04-15 Published:2020-04-20

Abstract: The inhibitory activity of lactic acid against the biofilm formation of Enterobacter cloacae CY4 was evaluated by a crystal violet staining assay, and its potential molecular mechanism was explored by studying cell swimming and swarming motilities, exopolysaccharide production, biofilm microstructure and gene expression levels. The results showed that lactic acid at subinhibitory concentrations could significantly inhibit biofilm formation and decrease cell swimming and swarming motilities of E. cloacae CY4 (P < 0.05), as well as decrease biofilm polysaccharide production. Laser confocal microscopy and scanning electron microscopy showed that lactic acid at subinhibitory concentrations could greatly reduce the thickness of the biofilm and increase its surface roughness and porosity, as well as loosen the biofilm structure with greater cell length and wider gaps between cells. Lactic acid decreased the expression of genes involved in the synthesis of pili and polysaccharides as evaluated by real-time polymerase chain reaction (PCR). This study demonstrates that lactic acid has a significant inhibitory effect on biofilm formation of E. cloacae CY4, which may be related to its influence on cell adhesion and aggregation, and the production of extracellular polysaccharides.

Key words: Enterobacter cloacae, biofilm, lactic acid, extracellular polysaccharides, cell motility

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