Evaluation on Antibacterial Activity of <i>Lactobacillus acidophilus</i> Strains Isolated from Honey

Abstract

Problem statement:This study reports the isolation of lactic acid bacteria from 13 honey samples produced in Malaysia, Libya and Saudi Arabia and their antibacterial activity against three Gram negative pathogenic bacteria. Approach: A modified MRS agar with 0.8% CaCO 3 and MRS with 1% glucose was found to facilitate isolation of LAB compared to MRS, tomato juice agar and modified tomato juice agar. 32 isolates were confirmed LAB by catalase test and Gram staining. Six isolates were screened for antibacterial activity and identified as strains of Lactobacillus acidophilus 1 by API CH50. Results: All the isolates showed very good inhibitory activity against target Gram negative bacteria as indicated by the diameter of inhibition zone: Salmonella Typhimurium (23-30 mm), Escherichia coli (7-18 mm) and Enterobacter aerogenes (10-18 mm) after 24 h incubation at 30°C. Supernatants of L. acidophilus 1 strains showed good antibacterial activity against all target bacteria. Heating the supernatants at 90 and 121°C for 1 h enhanced the antibacterial activity against all target bacteria except supernatants H006-A and H010-G against S. Typhimurium. Antibacterial activity of supernatants were maintained after pH adjustment to 3, but at pH5 supernatants H006-A, H008-D and H010-G lost the activity against S. Typhimurium and E. coli within 48 h of incubation while at pH 6 all supernatants lost activity except against E. aerogenes. Enzymes treatments of supernatants with RNase II and Proteinase K for 1 h inhibited all target bacteria except supernatants H008-D, H008-E and H006-A which were relatively sensitive to both enzymes against S. Typhimurium and E. coli. Conclusion/Recommendations: In conclusion, honey from different sources contains strains of L. acidophilus 1 that produced compounds with good antibacterial activity which may be responsible for the antibacterial properties of honey.

Isolation, Characterization and Identification of Probiotic Lactic Acid Bacteria (LAB) from Honey Bees

“…Generally, LAB species may differ from place to place. Hosny et al, (2009) Aween et al, (2012). Lactobacillus is commonly associated with honey bees even in India (Pattabhiramaiah et al, 2012).…”

“…Calcium carbonate (CaCO 3 ) was added to MRS medium to induce more LAB growth (Aween et al, 2012). Cycloheximide was added to the above medium to avoid fungal contamination.…”

Potency of Honey as Antibacterial Agent Against Multiple Antibiotic Resistant Pathogens Evaluated by Different Methods

“…The S. aureus used in this study demonstrated low MAR index 11% compared E. coli and P. aeruginosa with 55 and 66%, respectively. S. Typhimurium and B. subtilis showed highest MAR index (88%) compared to other tested bacteria.Similarly, multiple antibiotic resistant bacteria was shown by several tested pathogens including S. Typhimurium ATCC13311 that was resistant to 10 antibiotics especially to bacitracin, cephalothin, penicillin G, vancomycin and strepromycin; E. coli ATCC25922 was resistant to bacitracin, penicillin G and vancomycin observed by Aween et al (2012b).…”

“…Propolis of Malaysian honey inhibited the growth of Staphylococcus aureus and Escherichia coli as reported by Rahman et al (2010). Honey of Malaysia, Libya, New Zealand and Saud Arabia contain lactic acid bacteria with antibacterial activity against selected Multiple Antibiotic Resistant (MAR) Gram-positive bacteria and Gram-negative bacteria (Aween et al, 2012a;2012b).…”

“…Antibacterial activity of selected honey samples were determined by plate count method on Nutrient Agar (NA) (OXOID) following Aween et al (2012b) with some modifications. 100 µL of overnight pathogenic bacteria culture in NB were added to 100 µL of honey sample and kept at 37°C for 24 h. After that, 10 µL of the mixture were spread on NA and incubated at 37°C for 24 h. Pathogenic bacteria in NB was used as positive control and honey sample with NB as negative control.…”