One step antibiotic disk method for obtaining axenic cultures of multicellular marine algae

A simple and rapid method for obtaining axenic plant material has been devised where antibiotic-containing paper disks are applied to nutrient agarose or agar plates upon which small pieces of plant have been spread. By applying multiple disks to the agarose plate, susceptibility to a large number of antibiotics can be tested simultaneously. Clear zones are produced around those disks where contaminating bacteria are susceptible. Plant pieces are then removed from the clear zones and separately tested for sterility to identify the axenic pieces. The method has been successfully applied to multicellular marine algae (e.g.Enteromorpha, Porphyra, laminaria, Gracilaria andAgardhiella). Pieces fromAgardhiella plants survive better on nutrient medium solidified with agarose when -naphthaleneacetic acid and zeatin are present in the medium.