1.Lactic acid bacteria from kefir grains: Potential probiotics with antagonistic activity against multidrug resistant Gram-negative bacteria
Maryam Ghane ; Laleh Babaeekhou ; Babak Montazeri Najafabadi ; Mahara Sadat Mirmostafa
Malaysian Journal of Microbiology 2021;17(4):414-423
Aims:
This study aimed to isolate and identify lactobacilli strains that have antagonistic activity against multidrug
resistant (MDR) isolates of Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa and evaluate their
probiotic properties.
Methodology and results:
Twenty-one Lactobacillus isolates were collected, and their antimicrobial activity was
assessed by agar well diffusion, broth microdilution and time-kill test. The probiotic potential of the isolates was
evaluated as well. The bacterial culture and cell free supernatant (CFS) of all isolates exhibited antibacterial activity
against all MDR isolates. Out of 21 isolates, 4 isolates (A31, B35, S20 and S25) displayed the highest antimicrobial
activity and further evaluated. The minimum inhibitory percentages of CFS from selected isolates against pathogens
ranged from 10 to 30% and the bactericidal percentages ranged from 20 to 50%. The inhibitory activity of CFS was not
changed after heating but abrogated as the pH neutralized. The growth kinetic of the MDR pathogens was significantly
reduced in the presence of the CFS of all isolates. The isolates had a less than 1-log reduction in their viability in acid
tolerance test and could grow in the presence of 0.3% bile salts. Strains S20, S25 and B35 exhibited high coaggregation with E. coli (51.7-73.3%), P. aeruginosa (53.7-69.3%) and K. pneumoniae (49.7-65.3%). Molecular
identification revealed that the isolates were Lactobacillus rhamnosus (B35) and Lactobacillus paracasei (S20, S25,
A31).
Conclusion, significance and impact of study
The results suggest that these lactobacilli isolates may have potential
applications for controlling and preventing colonization of infections caused by MDR pathogens.
Lactobacillales
;
Kefir
;
Probiotics
;
Gram-Negative Bacteria