Optimizing the production of the biosurfactant lichenysin and its application in biofilm control

Abstract

Aims: Apply response surface methodology (RSM) to develop and optimize an economical medium for lichenysin production, which is a surfactant produced by Bacillus licheniformis and evaluate the application of lichenysin in the prevention and disruption of pathogenic micro-organism biofilm that creates health problems in the food industry and hospitals. Results: An economical medium containing molasses was optimized to enhance lichenysin production by RSM. A production of 3.2 g l 1 of lichenysin was achieved with an optimum medium containing 107.82 g l 1 of molasses, 6.47 g l 1 of NaNO3 and 9.7 g l 1 of K2HPO4/KH2PO4, in which molasses and phosphate salts had a significant effect on biosurfactant production. Lichenysin was effectively applied in a surface pre-treatment to avoid microbial biofilm development of methicillin-resistant Staphylococcus aureus (MRSA) (68.73%) and Candida albicans (74.35%), with ED50 values of 8.3 and 17.2 lg ml 1 respectively. It was also very efficient in a surface posttreatment to remove biofilms of MRSA (55.74%) and Yersinia enterocolitica (51.51%), with an ED50 of 2.79 and 4.09 lg ml 1 respectively. Conclusions: Lichenysin was found to have notable anti-adhesion activity, being able to prevent and eliminate the biofilm formation by pathogenic strains associated with foodborne illness. This new medium resulted in a fourfold increase in production compared with the nonoptimized medium. Significance and Impact of the Study: Molasses can be regarded as a useful resource for biotechnological applications, such as the production of lichenysin. The use of agro-industrial substrates has an important role in the sustainable and competitive development of several industrial sectors, as well as in industrial residues management. Additionally, lichenysin is particularly effective in preventing biofilm formation by strains problematic for the food industry and in the hospital environment. Lichenysin also efficiently disrupts biofilm.