Isolation and functional characterization of novel biosurfactant produced by Enterococcus faecium

Area of Science:

• Microbiology
• Biochemistry
• Food Science

Background:

• Biosurfactants (BS) are amphiphilic compounds with diverse applications.
• Lactic acid bacteria (LAB) are known producers of functional biomolecules.
• Traditional fermented foods are potential sources of novel microbial strains and their products.

Purpose of the Study:

• To isolate and characterize biosurfactant (BS)-producing lactic acid bacteria (LAB) from buttermilk.
• To determine the functional properties and structural characteristics of the isolated BS.
• To evaluate the stability, toxicity, and anti-adhesion activity of the BS.

Main Methods:

• Isolation of LAB from traditional fermented buttermilk.
• Characterization of BS properties including surface tension reduction, critical micelle concentration (CMC), and emulsification efficiency (E24).
• Structural elucidation using silica gel column chromatography, gas chromatography-mass spectrometry (GC-MS), and hydrophilic moiety determination.
• Assessment of BS stability across a range of pH and temperatures.
• Evaluation of cellular toxicity and anti-adhesion activity.

Main Results:

• A LAB strain (MRTL9) was isolated, producing BS that reduced surface tension from 72.0 to 40.2 mN m⁻¹.
• The BS exhibited a CMC of 2.25 mg ml⁻¹ and 64% emulsification efficiency against kerosene.
• Structural analysis identified the BS as a glycolipid, primarily composed of hexadecanoic acid and xylose.
• The BS demonstrated remarkable stability across pH 4.0-12.0 and retained activity after heat treatment at 120°C for 15 min.
• The BS showed significantly lower cellular toxicity compared to SDS and rhamnolipids, with confirmed preventive anti-adhesion activity.

Conclusions:

• The study successfully isolated and characterized a novel glycolipid biosurfactant from LAB in buttermilk.
• The BS exhibits excellent functional properties, stability, and low toxicity, indicating its potential as an eco-friendly alternative to synthetic surfactants.
• The anti-adhesion properties suggest applications in preventing microbial colonization in various settings.