Procedures for the axenic isolation of conchocelis and monospores from the red seaweed Porphyra yezoensis

Abstract

In order to maintain axenic seedstock cultures axenically of thecommercially important red seaweed, Porphyra yezoensis, aprocedure was developed for axenic isolation and culture of conchocelis andmonospores. For axenic isolation of the conchocelis, contaminated microalgaewere most effectively removed by filtering contaminated samples through a100-μm mesh after sonication. Removal of bacteria and otheralgaewas accomplished using a mixture of 5 agents (0.02% chitosan, 100 μgml⁻¹ GeO₂, 10 μgml⁻¹ ampicillin, 40 μgml⁻¹ kanamycin and 200 μgml⁻¹ streptomycin). Axenic single colonies wereisolatedfrom a semi-solid medium prepared from 1% transfer gel. After collectingmonospores from the 40–50% density layer on a percoll-gradient, removalofbacteria and fungi from the monospores was accomplished using a mixture of 5antibiotics (3.5 μg ml⁻¹ nystatin, 2 mgml⁻¹ ampicillin, 400 μgml⁻¹ kanamycin, 50 μgml⁻¹ neomycin and 800 μgml⁻¹ streptomycin). Axenic single juvenile blades wereisolated from a semi-solid medium prepared from 0.5% transfer gel.