Isolation and structural characterization of Coryxin, a novel cyclic lipopeptide from Corynebacterium xerosis NS5 having emulsifying and anti-biofilm activity.

Herein we reported the structure and several properties of a new biosurfactants produced by Corynebacterium xerosis strain NS5. This strain was capable of producing a novel lipopeptide biosurfactant that we have named coryxin. The biosurfactant structure was characterized by using Fourier transform infrared spectroscopy (FTIR), Nuclear magnetic resonance spectroscopy (NMR), and Liquid chromatography-mass spectrometry (LC-MS). It contained a hydrophobic moiety of 3-hydroxydecanoic acid and a peptide part predicted as a sequence of seven amino acids including Asn-Arg-Asn-Gln-Pro-Asn-Ser. Coryxin lowered the surface tension of water to 31.4 mN/m, with a critical micelle concentration of 25mg/l. It was a strong emulsifier with an emulsification index of 61% against n-hexane. Coryxin showed antibacterial activity against test organisms belonging to Gram-positive and Gram-negative bacteria and disrupted preformed biofilms of Staphylococcus aureus (82.5%), Streptococcus mutans (80%), Escherichia coli (66%) and Pseudomonas aeruginosa (30%). In conclusion, microbial surfactant from C. xerosis exhibited inhibitory and disruptive activities against biofilm formation that could be of use in biofilm-related menace.