Isolation of Lactic Acid Bacteria from Ewe Milk, Traditional Yoghurt and Sour Buttermilk in Iran
Published: 2012-10-18
Page: 79-92
Issue: 2012 - Volume 2 [Issue 3]
Mahdieh Iranmanesh
Department of Food Science and Technology, Science and Research Branch, Islamic Azad University, P.O. Box 14515.775, Tehran-Iran.
Hamid Ezzatpanah *
Department of Food Science and Technology, Science and Research Branch, Islamic Azad University, P.O. Box 14515.775, Tehran-Iran.
Naheed Mojgani
Biotechnology Department, Razi Vaccine and Serum Research Institute, Karaj-Iran.
Mohammad Amir Karimi Torshizi
Department of Poultry Science, Faculty of Agriculture, Tarbiat Modares University, Tehran-Iran.
Mehdi Aminafshar
Department of Animal Science, Science and Research Branch, Islamic Azad University, P.O. Box14515.775, Tehran-Iran.
Mohamad Maohamadi
Department of Food Science and Technology, Science and Research Branch, Islamic Azad University, P.O. Box 14515.775, Tehran-Iran.
*Author to whom correspondence should be addressed.
Abstract
A total of 63 samples including ewe milk, yoghurt and traditional buttermilk were collected from Myaneh and Hashrood (Azarbayjan-e-Sharqi, Iran) and screened for the presence of Lactic Acid Bacteria (LAB). Based on routine cultural characteristic, general morphological and biochemical assay, 77 out of 168 bacterial isolates were identified as LAB. These isolates were examined for the presence of inhibitory activity against other randomly selected LAB isolates. Thirty-three strains showed antagonistic activity against the closely related LAB strains and were further challenged against other gram-positive and gram-negative pathogens including Listeria monocytogenes, Staphylococcus aureus and Salmonella entritidis. Based on their zones of inhibition diameters the isolates showing maximum inhibitory activity against these pathogens were selected for detailed investigations. The selected isolates were identified to species level by 50CHL API system and were challenged to heat, acid and bile salt. Most of the strains were able to survive at different pH ranges, while one strain of Pedicoccus acidilactici and Lactobacillus paracasei were able to tolerate all ranges of pH during 24 h of incubation. In addition, Lactobacillus brevis was found as the most resistant strain being able to resist all concentrates of bile after 4 h. The results indicated the probiotic potential of the isolates, as majority of the selected LAB isolates were capable of resisting high temperatures, acidic pH values and bile concentrations of 0.7%.
Keywords: Traditional buttermilk, lactic acid bacteria, antimicrobial activity, probiotic bacteria