Response Reaction on Composition Changes of Cell Membrane Fatty Acid of Two Lactobacillus acidophilus Strains on the condition of Acid Stress

Lactobacillus acidophilus is important probiotic bacteria in human's intestines with a strong resistance to acid. The response reaction on composition changes of cell membrane fatty acids of Lactobacillus acidophilus on acidic conditions of different pH was researched in this study. The composition of cell membrane fatty acids of strains Lactobacillus acidophilus Ind-1(La-XH1) and Lactobacillus acidophilus Lakcid (La-XH2) was determined using GC-MS method. Results showed that the species of cell membrane fatty acids of La-XH1 and La-XH2 have not changed under different acidic conditions, but the relative content of fatty acid has changed, especially C18:1 and C19:0 which have greater changes. The relative mass fraction of La-XH1 of C18:1 and C19:0 ranged from 50.12% to 53.91% and from 2.18% to 6.22% respectively and that of La-XH2 of C18:1 and C19:0 ranged from 45.62% to 48.14% and from 4.34% to 6.56% respectively. Meanwhile, the relative mass fraction of La-XH1 of total unsaturated fatty acids of bacteria cell membrane (C16:1, C18:1 and C18:2) rose from 67.9% to 70.69% and that of La-XH2 rose from 61.85% to 65.06%. The relative mass fraction of La-XH1 of total long chain fatty acids (C18:0, C19:0 and C20:0) rose from 6.35% to 7.78% and that of La-XH2 rose from 11.9% to 13.06%. However, the relative amount of short chain fatty acids (C14:0 and C16:0) of La-XH1 declined from 25.70% to 21.53% and that of La-XH2 declined from 26.25% to 21.88%.