Elahe Lashani; Abolfazl Davoodabadi; Mohammad Mehdi Soltan Dallal
Volume 11, Issue 2 , June 2020, , Pages 121-126
Abstract
Lactobacilli commonly used as a probiotic and they can be isolated from various sources such as fermented foods and gastrointestinal tracts of humans and animals. The aims of this study were isolation and identification of lactobacilli from honey and investigation of some probiotic properties ...
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Lactobacilli commonly used as a probiotic and they can be isolated from various sources such as fermented foods and gastrointestinal tracts of humans and animals. The aims of this study were isolation and identification of lactobacilli from honey and investigation of some probiotic properties and antimicrobial effects against foodborne bacterial pathogens. A total of 88 honey samples were collected from different areas in Iran. About 1.00 g of each honey was cultured in de Man, Rogosa, and Sharpe (MRS) broth and then sub-cultured on MRS agar. The isolates were assessed for probiotic potentials such as tolerance to acid and bile. Then, antimicrobial activity of isolates against seven foodborne pathogens including Listeria monocytogenes, Shigella flexneri, Staphylococcus aureus, Salmonella enteritidis, Enteropathogenic Escherichia coli, Escherichia coli O157 H7 and Bacillus cereus was investigated. From 88 honey samples, 39 isolates were identified by 16S rDNA gene sequencing method. Fructophilic lactic acid bacteria (FLAB) with 29 (74.00%) isolates were dominant identified bacteria (27 L. kunkeei and two Fructobacillus fructosus). Also, four L. plantarum, two L. paracasei, one L. brevis, one L. rhamnosus, one L. casei and one L. fermentum were identified. Two L. kunkeei isolates and one F. fructosus isolate were resistant to acid and bile salt. Two L. rhamnosus isolates and one L. paracasei isolate inhibited all pathogens (100%). This is the first study in Iran that isolated lactobacilli from honey. The FLAB especially L. kunkeei were isolated as dominated species from honey. Some lactobacilli isolates have probiotic potential and may be useful for the prevention and treatment of infections, but more investigations are needed.
Food Hygiene
Mobin Koohestani; Mehran Moradi; Hossein Tajik; Armen Badali
Volume 9, Issue 4 , December 2018, , Pages 301-306
Abstract
This study was carried out to investigate the stability, antibacterial properties and biofilm removal potential of cell-free supernatant (CFS) of Lactobacillus acidophilus LA5 and Lactobacillus casei 431 against Staphylococcus aureus ATCC 25923. Antibacterial activity of both Lactobacillus strains was ...
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This study was carried out to investigate the stability, antibacterial properties and biofilm removal potential of cell-free supernatant (CFS) of Lactobacillus acidophilus LA5 and Lactobacillus casei 431 against Staphylococcus aureus ATCC 25923. Antibacterial activity of both Lactobacillus strains was measured according to the agar spot method. The CFS was prepared by centrifugation of bacterial suspension at 4000 g for 10 min and the antimicrobial activity was measured using agar-well diffusion. The stability of CFSs during storage at 4.00 ± 2.00 °C and 25.00 ± 2.00 °C for a period of 4 weeks was measured based on the method of broth micro-dilution assay. Moreover, biofilm removal potential of CFS on 2-days-old biofilm of S. aureus developed on polystyrene and glass surfaces was also determined. The efficacy of CFS on bacterial biofilm established on the glass surface was also observed using fluorescence microscope. Results showed that inhibition zones of L. acidophilus (50.26 mm) were greater than L. casei (37.06 mm). The minimum inhibitory concentration of both CFSs remained stable (40 mg mL-1) during the storage for 28 days at 4.00 and 25.00 °C and storage temperature did not affect the antibacterial effectiveness of CFS. The addition of both CFSs significantly removed biofilm developed on both tested surfaces in a concentration-dependent manner. Biofilm removal property of L. acidophilus CFS was generally better than L. casei CFS which was confirmed by fluorescence microscope. The application of CFS of probiotic strains (i.e. Lactobacillus) as antibacterial and biofilm removal compounds could be very suitable to control the growth of food-borne pathogens.
