ABSTRACT
Amphiphilic biosurfactant/s (BSs) produced by lactic acid bacteria (LAB) have effective antibacterial and antifungal activities in addition to some antiadhesive and antibiofilm potentials, all of which are properties useful for future applications. Other innovative characteristics such as antioxidative, nanoparticles synthesis and antiproliferative capabilities have been reported. The main constrains in exploring LAB derived BS is their structural complexity and diverse chemical composition. Overall, 75 research papers report on BS production by LAB out of which eight were loosely classified as cell free supernatant (CFBS) and 68 as cell associated or cell bound biosurfactants (CABS). Structural elucidation of LAB derived BS is extremely challenging and the majority of reports (53%) had no structural details. Of the remaining, 22% reported a 'protein rich-surlactin types of BS, 10% reported detecting mainly glycolipid (including structural similarity to rhamnolipid, xylolipid) and 7% glycoprotein. Around 8% of the reports suggested lipopeptides, glycopeptides or mixed types BS. Literature reported a wide range of different concentrations (1 to 130 mg/ml) of BS for effective antimicrobial potential. However, concentrations between 20-25 mg/ml were the most frequently reported. Similarly, the abilities of BS to reduce surface tension measurements to values between 30-55 mN/m were mainly within a range of critical micelle concentration (cmc) values of 1-20 mg/ml. Even though LAB is mainly used in food and related industries, synergistic combinations of BS with conventional antibiotics have the most promising applications in medical health related sectors. It has become possible to achieve broad spectrum activities against several opportunistic pathogens and therefore can be exploited for such purposes. LAB derived BS have also been utilized for designing various pharmaceutical and cosmetic formulations due to their low toxicity and ability to combat spoiling microorganisms. Therefore, microbial BSs derived from LAB may provide a choice of molecules for many future applications.
