Production of biosurfactant by lactic acid bacteria using whey as growth medium

Abstract

The aim of this study was to produce biosurfactants from whey waste using Streptococcus thermophilus, Lactobacillusacidophilus, and Lactobacillus rhamnosus as well as to determine oil spreading, emulsification index, surface tension, and antiadhesiveproperties in these biosurfactants. Additionally, the capability of biosurfactant production from whey waste in the dairy industry wascompared with that of MRS broth, a commercial culture medium. The presence of biosurfactants by all lactic acid bacteria was detectedusing the oil spreading test. Zone diameter due to the surface activity of lactic acid bacteria strains ranged from 1.87 to 5.92 cm.Biosurfactants from both whey medium and MRS broth reduced surface tension. Differences between data from whey medium and MRSbroth were statistically insignificant in terms of the biomass, oil spreading, and surface tension of biosurfactants. Emulsification indexvalues recorded after 1 h, 24 h, and 1 week were significantly different and ranged from 19.50% to 58.00%. The highest emulsificationactivity was exhibited by L. acidophilus from whey medium in the first hours. A 10 mg/mL concentration of biosurfactants was ableto prevent S. aureus, P. aeruginosa, and E. coli adhesion 37.25%–52.5%, 10.25%–23.25%, and 5.32%–11.50%, respectively. E. coli wasmore resistant to the biosurfactants than the other pathogens were. On the other hand, biosurfactants from L. rhamnosus had the lowestantiadhesive effects. In general, biosurfactants from whey medium and MRS broth were similar in terms of antiadhesion properties.The present study showed that dairy wastes could be an appropriate medium for cost-effective biosurfactant production by lactic acidbacteria for the benefit of the food, pharmaceutical, and cosmetic industries.