›› 2018, Vol. 45 ›› Issue (10): 2856-2865.doi: 10.16431/j.cnki.1671-7236.2018.10.023

Previous Articles     Next Articles

Study on Antibacterial Mechanisim of Lactobacillus fermentum Isolated from Koumiss on Pathogenic Escherichia coli O8

GUO Xuemei1, WANG Chunjie2, SIMUJIDE1, JIMISI1, CUI Yinxue1, AORIGELE1   

  1. 1. College of Animal Science, Inner Mongolia Agricultural University, Hohhot 010018, China;
    2. College of Veterinary Medicine, Inner Mongolia Agricultural University, Hohhot 010018, China
  • Received:2018-04-11 Online:2018-10-20 Published:2018-10-20

PDF (PC)

119

Abstract:

In order to study the antibacterial mechanism of Lactobacillus fermentum isolated from natural fermented koumiss on pathogenic Escherichia coli O8 (E.coli O8),the strains with best bacteriostasis isolated from koumiss was screened out in this study,and then 16S rDNA sequence was identified by BLAST of NCBI website.After fermentation,the cell-free fermentation supernatant (CFS) was prepared.The properties and content of antibacterial substances in CFS were preliminarily determined by acid excretion,hydrogen peroxide excretion and different protease treatments.The best inhibitory concentration of CFS on the growth curve of pathogenic E.coli O8 within 24 h was determined using the Oxford cup method and two fold dilution method.The influence of CFS on cell membrane and cell wall permeability of pathogenic E.coli O8 was determined by kit method.The results showed that there were 22 strains which had antibacterial effects on pathogenic E.coli O8 isolated from koumiss,and the best strain was Lactobacillus fermentum after 16S rDNA sequence and phylogenetic tree analysis.Protein was the main bacteriostatic substance of CFS,and its content was 399.5 μg/mL.The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) were 25.0 and 49.9 μg/mL,respectively.CFS could rapidly increase the AKP content of pathogenic E.coli O8 within 1 h and then increase slowly.Moreover,it could obviously increase the protein content in the culture of the pathogen.In conclusion,the protein of Lactobacillus fermentum was the antibacterial substance on pathogenic E.coli O8.And with the increase of protein concentration,the bacteriostasis ability was stronger.CFS could release AKP and intracellular proteins by destroying or altering the permeability of cell membrane and cell wall.Thus,it could inhibit the growth of pathogenic E.coli O8 in a short time.

Key words: koumiss; Lactobacillus fermentum; pathogenic E.coli O8; bacteriostasis; cell-free fermentation supernatant (CFS)

CLC Number: