ISOLATION AND CHARACTERIZATION OF L. parafarraginis (KU495926) INHIBITING MULTIDRUG-RESISTANT AND EXTENDED SPECTRUM Î’ETA-LACTAMASE GRAM-NEGATIVE BACTERIA

Abstract

A new strain of Lactobacillus parafarraginis was isolated from a sample of commercial yogurt and identified by phenotypic and molecular methods. Phenotypic characterization showed bacilli sizes ~ 0.75-2.75 μm × 0.25-0.75 μm, a generation time of ~3.04 h under anaerobic conditions, halotolerance, lactose fermentation, production of hydrogen sulfide gas from Kliger iron agar, and the presence of an unusual fatty-acid methyl ester, cis- 10-nonadecenoic acid. Based on 16S rRNA gene sequencing, the isolate was identified as Lactobacillus parafarraginis and given the GenBank accession number (KU495926). L. parafarraginis ((KU495926)) inhibited 14 multidrug-resistant (MDR) and extended spectrum β-lactamase (ESBL) Gram-negative clinical isolates, as well as 11 other pathogens by spot-test and well-diffusion assays. The MDR/ESBL clinical isolates and other pathogens included Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumannii/haemolyticus, Enterobacter aerogenes, Proteus mirabilis and Klebsiella pneumonia, Staphylococcus aureus, Listeria monocytogenes, Escherichia coli (O157:H7), Bacillus cereus, Yersinia enterocolitica, Pseudomonas aeruginosa, Shigella sonnei, Streptococcus pyogenes and Enterococcus faecalis. Analyses of the semi-purified inhibitory fraction by SDS-PAGE, fast perfusion liquid chromatography (FPLC) inferred antimicrobial properties, characteristic of bacteriocins, with a protein band of ~75 kDa. Four bacteriocin structural genes which include sakT-β for sakacinT-β chain, sakT-α (sakacinT-α chain), acd T (acidocin), and plnc8A (plantaricin-α chain) were detected by PCR. The data suggest that L. parafarraginis (KU495926) may be a novel strain with potential therapeutic application. To our knowledge, this is the first report of the isolation of this strain from yogurt.