Journal of Applied Phycology

, Volume 14, Issue 5, pp 385-390

First online:

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

  • Ji-Young ChoAffiliated withDepartment of Biotechnology, Pukyong National University
  • , Jae-Suk ChoiAffiliated withDepartment of Biotechnology, Pukyong National University
  • , In-Soo KongAffiliated withDepartment of Biotechnology, Pukyong National University
  • , Soo-Il ParkAffiliated withDepartment of Aquatic Life Medicine, Pukyong National University
  • , Russell G. KerrAffiliated withDepartment of Chemistry and Biochemistry, Center for Molecular Biology and Biotechnology, Florida Atlantic University
  • , Yong-Ki HongAffiliated withDepartment of Biotechnology, Pukyong National University

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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.

Antibiotics Axenic isolation Gelling agent Isochrysis galbana Microalgae Percoll