Study On Screening, Identification And Structural Characteristics Of Biosurfactant-producing Bacteria In Slduge

Biosurfactants have been widely studied as a substitute for chemically synthesized surfactants because of their non-toxicity,natural degradation and high efficiency.Among them,rhamnolipid produced by Pseudomonas was the most promising biosurfactant.Because rhamnolipid synthesis strains have been reported limited production capacity,higher carbon cost,diverse structure and other factors,resulting in a higher synthesis cost,limited production scale fermentation,limiting its application development in different fields.In order to reduce the synthesis cost of biosurfactants and expand their application fields,this study screened the strains that produce surfactants from the sewage sludge in the western suburbs.This strain was a Gram-negative bacterium,which has a shiny short rod shape under a microscope.The single colony was small,the edges were regular,the surface was smooth,and the middle was convex.The identification of the 16S rRNA based sequence indicated that the strain belongs to the genus Pseudomonas and was named Pseudomonas sp.PbA?GenBank ID:MH930445?.The strain was extracted with 0.54 g/L of yellow biosurfactant at pH 8.0,27?,180 rpm.The medium was added with 1%?w/v?glucose and 1%?w/v?potassium nitrate in an inorganic salt medium without MgSO₄.CTAB,TLC,GC-MC,FT-IR analysis showed that the biosurfactant was a glycolipid anionic surfactant,the hydrophilic end was rhamnolipid and the hydrophobic end was Hexadecanoic acid..The emulsification index of the biosurfactant was 60.3%.This study enriched the surfactant-producing bacteria,expanded the structure of rhamnolipid,and provided a theoretical basis for the development of bio-surfactant development.