Lactobacillus reuteri cell-free extracts against antibiotic-resistant bacteria

Abstract

The aim of the research was to evaluate the antimicrobial potential of cell-free extracts obtained in various ways from the probiotic strain Lactobacillus reuteri DSM 17938 with respect to their ability to influence the proliferation of antibiotic-resistant bacteria. Materials and methods. Cell-free extracts were obtained: 1) from L. reuteri cell suspension, subjected to disintegration by repeated freezing-thawing, L; 2) from L. reuteri culture, cultivated in its own disintegrate (ML); 3) from L. reuteri culture, cultivated in its own disintegrate supplemented with glycerol (73.7 mg/ml) and glucose (72.1 mg/ml) (MLG); 4) from L. reuteri culture, cultivated in its own disintegrate supplemented with ascorbic acid (20 mg/ml) (MLA). Multidrug-resistant (MDR) and extensively drug-resistant (XDR) clinical isolates: Escherichia coli, Klebsiella pneumoniae, Lelliottia amnigena and Corynebacterium xerosis were used as a test cultures. The investigation of the inhibitory activity of cell-free extracts was carried out by spectrophotometric method using a microplate analyzer “Lisa Scan EM” (“Erba Lachema s.r.o.”,CzechRepublic). Results. Cell-free extract L exerted predominantly stimulatory effect on the proliferation of all studied test cultures. Cell-free extract ML had significant inhibitory effect on the proliferation of E. coli and C. xerosis (growth inhibition indices were 24.8 % and 96.1 %, respectively) and did not have significant effect on the proliferation of K. pneumoniae and L. amnigena. Cell-free extracts MLG and MLA caused pronounced inhibition of the proliferative activity of all tested microorganisms. Growth inhibition indices were: 75 % and 90.7 % (E. coli), 77.9 % and 88.9 % (K. pneumoniae), 40.9 % and 77.9 % (L. amnigena), 99 % and 100 % (C. xerosis), respectively. Conclusions. The cell-free extracts obtained by cultivation of L. reuteri DSM 17938 in its own disintegrate supplemented with glycerol and glucose or ascorbic acid have shown a pronounced antimicrobial activity against antibiotic-resistant bacteria in vitro. After confirming safety and efficacy in vivo, they can be used to increase the efficiency of the therapy of diseases caused by antibiotic-resistant microorganisms. The results of the study indicate the prospects of obtaining probiotic derivatives with high antimicrobial activity by applying a combinatorial (precursor directed) biosynthesis strategy.

Keywords

• lactobacillus reuteri derivatives
• inhibitory activity
• combinatorial (precursor-directed) biosynthesis