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ARS Home » Midwest Area » Peoria, Illinois » National Center for Agricultural Utilization Research » Renewable Product Technology Research » Research » Publications at this Location » Publication #394227

Research Project: Antimicrobials for Biorefining and Agricultural Applications

Location: Renewable Product Technology Research

Title: Milk kefir microbial compositions and two isolated cultures with antibacterial activities

item Liu, Siqing
item Lu, Shao
item Qureshi, Nasib
item EL ENSHASY, HESHAM - University Technology Malaysia
item Skory, Christopher - Chris

Submitted to: Society of Industrial Microbiology Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 8/7/2022
Publication Date: 8/7/2022
Citation: Liu, S., Lu, S.Y., Qureshi, N., El Enshasy, H.A., Skory, C.D. 2022. Milk kefir microbial compositions and two isolated cultures with antibacterial activities. [abstract]. Submitted to Society of Industrial Microbiology 72nd Annual Meeting 2022. San Francisco, CA, United States August 7-10, 2022. (

Interpretive Summary:

Technical Abstract: Milk kefir fermentation refers to the process of creating carbonated, acidic, and lightly alcoholic milk beverages from dairy milk by using kefir grains as starter cultures. Consumption of milk kefir has been associated with various health benefits, presumably from the potential probiotic traits of yeast and bacteria that make up the kefir grains. In addition, many of the microbes are known to produce novel antimicrobial compounds that can be used for other applications. The microbes living inside kefir grains differ significantly depending on geographical location and production methods. In this study, three kefir grain sources (Kefir 1, Kefir 2 and Kefir 3) from different US commercial sources were analyzed by metagenomic analysis. It was revealed that each sample contains unique and distinct groups of microbes. Kefir 1 showed the least diversity and Kefir 3 showed the highest diversity. Kefir 3 is rich in Proteobacteria while Kefir 2 is dominated by the Firmicutes. Using bacterial indicator growth analyses carried out by continuous readings from microplate-based bioreactor assays suggested that Kefir 2 fermentation filtrate had higher antibacterial property. We screened 30 purified cultures of Kefir 2 sample and isolated two lactic acid bacteria strains with high antibacterial activities of fermentation filtrate after growing under both aerobic and anaerobic conditions. The two strains were identified as Leuconostoc mesenteroides 28-1 and Lactobacillus kefiri 25-2 by 16S rRNA gene sequencing. This research could be valuable in the discovery of new antimicrobial compounds.