title: Biosurfactant production from novel air isolate NITT6L: screening, characterization and optimization of media.
abstract: In this paper, an air isolate (NITT6L) has been screened based on hemolytic activity, emulsification activity, drop collapsing test, and oil displacement test, as well as lipase activity. It was found that strain NITT6L was able to reduce the surface tension of the medium from 61.5 to 39.83 mN/m and could form stable emulsions with tested vegetable oils. Morphological, biochemical, 16S rRNA sequencing analyses, and fatty acid methyl ester analysis using gas chromatography confirmed that the air isolate under study was Pseudomonas aeruginosa. Characterization of the biosurfactant using agar double diffusion assay revealed that the biosurfactant was anionic in nature, and CTAB-methylene blue assay and Molisch test revealed its glycolipid nature. The FT-IR spectrum confirmed that the crude biosurfactant was a rhamnolipid. Using unoptimized medium containing sucrose as the carbon source, the isolate was found to produce 0.3 mg/ml of rhamnolipid in batch cultivation (shake flask) at 37°C and pH 7. Optimization of the medium components was carried out using design of experiments and the yield of rhamnolipid has been enhanced to 4.6 mg/ml in 72 h of fermentation.
authors.affiliation: Department of Chemical Engineering, National Institute of Technology, Tiruchirappalli, 620 015, India.
authors.forename: Balakrishnan
authors.initials: B
authors.lastname: Vanavil
authors.forename: Muthiah
authors.initials: M
authors.lastname: Perumalsamy
authors.forename: Ambati Seshagiri
authors.initials: AS
authors.lastname: Rao
mesh_terms: D003470:Culture Media / Q000737:chemistry* / Q000378:metabolism; D004783:Environmental Microbiology; D005285:Fermentation; D006017:Glycolipids / Q000737:chemistry* / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D017550:Spectroscopy, Fourier Transform Infrared; D013500:Surface Tension; D013501:Surface-Active Agents / Q000737:chemistry* / Q000378:metabolism*; D013696:Temperature
chemical_list: D003470:Culture Media; D006017:Glycolipids; D013501:Surface-Active Agents; C418382:rhamnolipid