title: Production and partial characterization of biosurfactant produced by Streptomyces sp. R1.
abstract: The present study focused on developing a wild-type actinomycete isolate as a model for a non-pathogenic filamentous producer of biosurfactants. A total of 33 actinomycetes isolates were screened and their extracellular biosurfactants production was evaluated using olive oil as the main substrate. Out of 33 isolates, 32 showed positive results in the oil spreading technique (OST). All isolates showed good emulsification activity (E24) ranging from 84.1 to 95.8%. Based on OST and E24values, isolate R1 was selected for further investigation in biosurfactant production in an agitated submerged fermentation. Phenotypic and genotypic analyses tentatively identified isolate R1 as a member of the Streptomyces genus. A submerged cultivation of Streptomyces sp. R1 was carried out in a 3-L stirred-tank bioreactor. The influence of impeller tip speed on volumetric oxygen transfer coefficient (kLa), growth, cell morphology and biosurfactant production was observed. It was found that the maximum biosurfactant production, indicated by the lowest surface tension measurement (40.5 ± 0.05 dynes/cm) was obtained at highest kLa value (50.94 h-1) regardless of agitation speed. The partially purified biosurfactant was obtained at a concentration of 7.19 g L-1, characterized as a lipopeptide biosurfactant and was found to be stable over a wide range of temperature (20-121 °C), pH (2-12) and salinity [5-20% (w/v) of NaCl].
authors.affiliation: School of Biological Sciences, Universiti Sains Malaysia, 11800, Penang, Malaysia.
authors.forename: Nor Syafirah
authors.initials: NS
authors.lastname: Zambry
authors.affiliation: School of Biological Sciences, Universiti Sains Malaysia, 11800, Penang, Malaysia.
authors.forename: Adilah
authors.initials: A
authors.lastname: Ayoib
authors.affiliation: School of Biological Sciences, Universiti Sains Malaysia, 11800, Penang, Malaysia.
authors.forename: Nur Asshifa
authors.initials: NA
authors.lastname: Md Noh
authors.affiliation: School of Biological Sciences, Universiti Sains Malaysia, 11800, Penang, Malaysia. armyahya@usm.my.
authors.forename: Ahmad Ramli Mohd
authors.initials: ARM
authors.lastname: Yahya
mesh_terms: D039903:Actinobacteria; D054712:Salinity; D013302:Streptomyces; D013501:Surface-Active Agents; D013696:Temperature
chemical_list: D013501:Surface-Active Agents
keywords: Actinomycetes; Bioreactor; Fermentation; Lipopeptide biosurfactant; Morphology; Streptomyces