A simple method for rapid screening of biosurfactant-producing strains using bromothymol blue alone

• Published in: Biocatalysis and agricultural biotechnology 2018-10, Vol.16, p.121-125
• Main Authors: Ong, Shufen Angeline, Wu, Jin Chuan
• Format: Article
• Language: English
• Subjects: Bromothymol blue; Colorimetric method; Fengycin; Iturin; Lipopeptide; Surfactin
• ISSN: 1878-8181; 1878-8181
• DOI: 10.1016/j.bcab.2018.07.027

Biosurfactants are deemed as green replacements of synthetic surfactants. Lipopeptides, a class of biosurfactants, have excellent surface active properties along with anti-microbial and anti-tumor activities. Identifying microorganisms producing high titre of lipopeptide is of great importance in reducing production cost as currently lipopeptide production is not commercially competitive. A quantitative colorimetric assay method was developed for detecting lipopeptides and high-throughput screening of lipopeptide-producing strains by mixing bromothymol blue solution (pH 7.2) with lipopeptide-containing samples resulting in an instantaneous and stable color change. This color change is quantified spectrophotometrically at 410 nm and 616 nm showing linearly quantitative response to increased concentrations of 3 major lipopeptides (surfactin, iturin and fengycin) at 0–1 g/l. The assay was used on both cell-free broth and crude extracts of lipopeptide-producing strains and the titre obtained from the assay was supported by HPLC data. This assay can be used for screening lipopeptide-producing strains and quantitatively detecting lipopeptides either in purified form or in cell-free broth. [Display omitted] •A very simple method for rapid detection of biosurfactants.•No pre-incubation of samples is required.•Suitable for quantitative assay of lipopeptides and other surfactants.•Suitable for high throughput screening of biosurfactant-producing strains.