Evaluation of the probiotic and postbiotic potential of lactic acid bacteria from artisanal dairy products against pathogens.

Nazar Hussain,Arsalan Zaidi,Muhammad Tariq,Per Erik Joakim Saris

doi:10.3855/jidc.13404

Abstract

Probiotic and postbiotic potential of thirty-two strains of lactic acid bacteria (LAB), obtained earlier from artisanal dairy sources in Pakistan, have been investigated against major multi-drug resistant (MDR) and food borne pathogenic bacteria. LAB strains were identified by 16S rRNA gene sequencing and their antibacterial activity was assessed by the microdilution method. Four LAB isolates, Weissella confusa PL6, Enterococcus faecium PL7, and Lactobacillus delbrueckii PL11 and PL13 were shortlisted. Their ability to degrade lactose and safety for human consumption in terms of hemolysis and antibiotic susceptibility were assessed in vitro. The antibacterial components in the cell-free supernatants (CFSs) of isolate cultures were characterized biochemically by HPLC. Acid neutralization but not protease treatment abolished the antibacterial activity of CFSs. Lactic, acetic and propionic acids were the main acids in the CFSs, and acid production peaked in the stationary phase of growth. The antibacterial activity of the LAB cultures resulted from secretion of organic acids that lowered the pH. The strains exhibited variable ability to degrade lactose and were non-hemolytic and susceptible to the most common antibiotics. These LAB strains are probiotic candidates for further investigation of their postbiotic role in naturally preserving processed foods and for attenuation of lactose intolerance.

Highlights

Probiotic and postbiotic potential of thirty-two strains of lactic acid bacteria (LAB), obtained earlier from artisanal dairy sources in Pakistan, have been investigated against major multi-drug resistant (MDR) and food borne pathogenic bacteria
The thirty-two LAB isolates were obtained from the culture collection of the National Probiotic Lab, National Institute for Biotechnology and Genetic Engineering (NIBGE) Faisalabad, Pakistan (Table 1) and were regrown on de Man, Rogosa and Sharpe (MRS, Merck, Darmstadt, Germany) agar plates with incubation for 24 hours at 37 ̊C
This study aimed to screen LAB isolated from indigenous dairy sources for those possessing antibacterial activity against MDR and pathogenic bacteria

Summary

Introduction

Probiotic and postbiotic potential of thirty-two strains of lactic acid bacteria (LAB), obtained earlier from artisanal dairy sources in Pakistan, have been investigated against major multi-drug resistant (MDR) and food borne pathogenic bacteria. Conventional antibiotics have been at the forefront of infection treatments [2], but due to the rise in bacterial multidrug resistance (MDR), the standard antibiotic regimens have lost effectiveness [3,4] These MDR pathogens are a cause of public concern in hospitals but lately, foods of animal origin have become a conduit for their spread in communities [5]. The MDR phenotype has shown a high prevalence in Pakistan [6], but the incidence of extensively drug-resistant (XDR) Salmonella spp. has been reported [7] Pseudomonas aeruginosa is another well-known pathogen implicated in 10% of all hospital-acquired infections the world over [8]. Treatment of lactose intolerance is currently restricted to medications and supplements that either have a preventive or a symptom management

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