Journal of Applied Phycology

, Volume 14, Issue 5, pp 385–390

A procedure for axenic isolation of the marine microalga Isochrysis galbana from heavily contaminated mass cultures


  • Ji-Young Cho
    • Department of BiotechnologyPukyong National University
  • Jae-Suk Choi
    • Department of BiotechnologyPukyong National University
  • In-Soo Kong
    • Department of BiotechnologyPukyong National University
  • Soo-Il Park
    • Department of Aquatic Life MedicinePukyong National University
  • Russell G. Kerr
    • Department of Chemistry and Biochemistry, Center for Molecular Biology and BiotechnologyFlorida Atlantic University
  • Yong-Ki Hong
    • Department of BiotechnologyPukyong National University

DOI: 10.1023/A:1022199332224

Cite this article as:
Cho, J., Choi, J., Kong, I. et al. Journal of Applied Phycology (2002) 14: 385. doi:10.1023/A:1022199332224


Isochrysis galbana, one of the most widely usedmarine microalgae in the rearing of finfish and shellfish larvae, is masscultured frequently in outdoor tanks. Under prolonged and repeated culture,severe contamination occurs. Axenic isolation of I.galbanafrom such cultures was best achieved by using a ternary procedure involvingpercoll-gradient centrifugation, treatment with antibiotics, and growth on agarmedium. Protozoa and other algae were removed most effectively by isolation ofI. galbana at the 30–40% density layer on apercoll-gradient. Removal of bacteria was accomplished using a mixture of 5antibiotics (250 μg mL−1 ampicillin, 50μg mL−1 gentamycin, 100 μgmL−1 kanamycin, 500 μgmL−1 neomycin, 50 μgmL−1 streptomycin). Axenic colonies were isolated fromasolid medium prepared from 1% purified agar. The ternary procedure isconsideredapplicable to the isolation of other axenic single-celled microalgae fromheavily contaminated cultures.

AntibioticsAxenic isolationGelling agentIsochrysis galbanaMicroalgaePercoll

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© Kluwer Academic Publishers 2002