Biotechnology Bulletin ›› 2017, Vol. 33 ›› Issue (4): 191-197.doi: 10.13560/j.cnki.biotech.bull.1985.2017.04.025

• Orignal Article • Previous Articles     Next Articles

Screening and Identification of Rhamnolipid-producing Strains and Characterization of the Product

WANG Jiang1, 2, JU Jiu2, 3, CAO Hai-long2, GUO Wei-hua1, YIN Heng2   

  1. 1. College of Fisheries and Life Science,Dalian Ocean University,Dalian 116023;
    2. Natural Products and Glyco-Biotechnology,Dalian Institute of Chemical Physics,Chinese Academy of Sciences,Dalian 116023;
    3. College of Food Science and Engineering,Dalian Ocean University,Dalian 116023
  • Received:2016-10-28 Online:2017-04-25 Published:2017-04-25

Abstract: Rhamnolipid is the most common biosurfactant that has been deepest studied and the most widely applied. Total 25 strains were isolated from soil of the near oil field and biogas plant. The strains that produced rhamnolipid were screened and characterized by sulfuric acid-phenol reaction,emulsification experiment,oil-spreading experiment,and thin layer chromatography experiment. The strains were identified by 16S rDNA sequence analysis. The sulfuric acid-phenol reaction showed that 2 strains might produce rhamnolipid;the fermentation supernatants of 5 strains showed emulsified effect and the emulsifying index of the strain was up to 58.97%. The oil-spreading diameter of the fermentation supernatant,diluted 10 times,of one strain reached 3.53 cm. The thin layer chromatography experiment verified that the strain “Qihong” did produce rhamnolipid. The rhamnolipid in the strain “Qihong” was detected by all four experiments,confirming that strain “Qihong” produced rhamnolipid. The 16S rDNA sequence analysis revealed that the strain “Qihong” belonged to Shewanella,and was the most similar to Shewanella putrefaciens LMG 26268(T).

Key words: surfactant, rhamnolipid, strain isolation, product characterization, Shewanella