Isolation, Identification, and Investigation of Biological Properties of Biosurfactant-Producing Probiotics and Magnesium Nanoparticles from Local Dairy Samples: A Laboratory Study

Probiotics are common and well-known microorganisms in human and animal microflora and have been widely studied for medical and food productions. The present research was conducted with the aim of isolating and identifying probiotic bacteria and the ability to produce biosurfactant and magnesium oxide nanoparticles from local dairy products in Rafsanjan, Iran.

In this laboratory study, the local dairy samples were transported to the laboratory under sterile conditions, observing the cold chain, and cultured in MRS (de Man Rogosa Sharpe) agar medium. In order to isolate biosurfactant-producing isolates, oil spreading and emulsification tests were performed, then the isolates were further studied in terms of the production of magnesium oxide nanoparticles. The size and morphology of nanoparticles, antioxidant activity, FTIR (Fourier Transform Infrared Spectroscope), and their antibacterial effects were determined. Then polymerase chain reaction, sequencing, and phylogeny tree drawing were performed for the identification of superior strain.

Nine probiotic isolates had the ability to produce biosurfactants, all of which had a significant emulsifying activity. The produced biosurfactants had antibacterial properties. One of the biosurfactant-producing isolates was able to produce magnesium oxide nanoparticles, which was named Enterococcus faecium L8 based on the molecular identity. The size of 90% of nanoparticles was 107 nm, which showed significant antibacterial and antioxidant effects.

Enterococcus faecium L8 has a favorable probiotic ability, and this native strain can be used in the formulation of multipurpose foods by conducting more tests.