Limited uptake as a mechanism for the nonrecoverability of arginine auxotrophs in Chlamydomonas eugametos

To address the problem of amino acid auxotroph scarcities in algae, an explanation was sought specifically for the nonrecoverability of arginine auxotrophs in the unicellular green alga Chlamydomonas eugametos. Chlamydomonas reinhardtii, in which the auxotroph has been recovered, was taken as a reference. In C. eugametos, unlike previously reported in C. reinhardtii, the use of selective media free of [Formula: see text] appeared not to affect the mutation spectrum. Arginine supported growth as the sole nitrogen source and canavanine sulfate inhibited growth, but both effects were less pronounced in C. eugametos. The concentration ratios (based on intracellular arginine accumulation) in C. eugametos remained less than 23% that of C. reinhardtii. The results indicate that nonrecoverability of arginine auxotrophs in C. eugametos is due to insufficient cellular accessibility to arginine.