Preliminary research on the antimicrobial mechanism of Dictyophora echinovolvata extracts against Listeria monocytogenes

Based on the observation of cell ultrastructure,the method of real-time fluorescent quantitative PCR was used to evaluate the antimicrobial mechanism of Dictyophora echinovolvata extracts against Listeria monocytogenes. The strain was treated with 15.0mg/m L(minimum inhibitory concentration,MIC) of Dictyophora echinovolvata extracts under 0.5,1.0 and 1.5h. Total RNA of the control and treated group strains were extracted,c DNA were obtained by reverse transcription and the relevant gene primers were selected for Real-time PCR method respectively. The strains of 16 S r RNA as reference gene,prf A,Act A and Iap as feature genes. It was showed that the cell wall become thinner,the integrity of cell membrane was changed and the contents released from intracellular when treated with Dictyophora echinovolvata extracts by the ultrastructure of cell observations. Compared with the control group,the level of gene expression in prf A was up-regulated at 0.5h,the speed of up-regulated became slower at 1h,the trend of up-regulation stopped at 1.5h with the prolong of treatment time,which proved that extracts could affect the activities of Listeria monocytogenes in transcription.While the level of gene expression in Act A and Iap were up-regulated in 0.5h,the amount of up-regulated expression was increased fast at 1h. The level of gene expression in Act A was decreased at 1.5h and that in Iap was down-regulated, which showed that extracts could regulate the level of transcription in Listeria monocytogenes,especially on the expression of virulence factors. Dictyophora echinovolvata extracts had a significant impact on Listeria monocytogenes for the process of transcription and the resistant of bacteria,which could make the damage of cell membrane and the dissolution of cytoplasm leading to the death of cell.