title: Optimization of environmental factors for improved production of rhamnolipid biosurfactant by Pseudomonas aeruginosa RS29 on glycerol.
abstract: A biosurfactant producing Pseudomonas aeruginosa RS29 (identified on the basis of 16S rDNA analysis) with good foaming and emulsification properties has been isolated from crude oil contaminated sites. Optimization of different environmental factors was carried out with an objective to achieve maximum production of biosurfactant. Production of biosurfactant was estimated in terms of surface tension reduction and emulsification (E24) index. It was recorded that the isolated strain produced highest biosurfactant after 48 h of incubation at 37.5 °C, with a pH range of 7-8 and at salinity <0.8% (w/v). Ammonium nitrate used in the experiment was the best nitrogen source for the growth of biomass of P. aeruginosa RS29. On the other hand sodium and potassium nitrate enhanced the production of biosurfactant (Surface tension, 26.3 and 26.4 mN/m and E24 index, 80 and 79% respectively). The CMC of the biosurfactant was 90 mg/l. Maximum biomass (6.30 g/l) and biosurfactant production (0.80 g/l) were recorded at an optimal C/N ratio of 12.5. Biochemical analysis and FTIR spectra confirmed that the biosurfactant was rhamnolipid in nature. GC-MS analysis revealed the presence of C(8) and C(10) fatty acid components in the purified biosurfactant.
authors.affiliation: Environmental Biotechnology Laboratory, Life Sciences Division, Institute of Advanced Study in Science & Technology, Paschim Boragaon, Guwahati, Assam, India. rashmi.saikia@gmail.com
authors.forename: Rashmi Rekha
authors.initials: RR
authors.lastname: Saikia
authors.forename: Suresh
authors.initials: S
authors.lastname: Deka
authors.forename: Manab
authors.initials: M
authors.lastname: Deka
authors.forename: Hemen
authors.initials: H
authors.lastname: Sarma
mesh_terms: D002244:Carbon / Q000378:metabolism; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D004655:Emulsions / Q000378:metabolism; D005990:Glycerol / Q000378:metabolism*; D006017:Glycolipids / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D009566:Nitrates / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism; D010578:Petroleum; D011550:Pseudomonas aeruginosa / Q000145:classification / Q000254:growth & development / Q000302:isolation & purification / Q000378:metabolism*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D054712:Salinity; D017422:Sequence Analysis, DNA; D012988:Soil Microbiology; D012989:Soil Pollutants; D017550:Spectroscopy, Fourier Transform Infrared; D013501:Surface-Active Agents / Q000378:metabolism*; D013696:Temperature; D013997:Time Factors
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D004655:Emulsions; D006017:Glycolipids; D009566:Nitrates; D010578:Petroleum; D012336:RNA, Ribosomal, 16S; D012989:Soil Pollutants; D013501:Surface-Active Agents; C418382:rhamnolipid; D002244:Carbon; D009584:Nitrogen; D005990:Glycerol; C006568:ammonium nitrate