In a pioneering study ADAm and VIS~NIAC (1958) first demonstrated cyanocobalamin (B12) auxotrophy for a fungus (Thraustochytrlum globosum). VISK~IAC (1961) has also reported a thiamine (Bi) requirement for a number of unidentified lower marine Phycomycetes and has shown the utility of isolate S-3 for assaying this vitamin in sea water. Subsequently, T. globosum and S-3 were used to measure changes in the levels of Bi~ and B i in Long Island Sound over the course of a year (VIsI~IAC and RrLEY 1961). The present study describes the requirement of 3 other non-filamentous marine Phycomycetes for these growth factors.
Methods
The organisms used were Thraustochytrium aureum (GoLDSTEIN 1963a), T. roseum (GOL])STEI~ 1963b), and Schizochytrium aggregatum (GOLDST]~I~ and BELSKY). The glucose-glutamate medium and the methods employed were essentially those previously described (AD~R and VISH~IAe 1958; VIsm~I),c 1961). The pyrimidine moiety of thiamine was examined chromatographically (ST]~PKi 1952) for evidence of contamination with the vitamin. Cultures were incubated in the dark at 20~ for 2 weeks and growth was measured turbidometrically using Klett-Summerson photoelectric colorimeter with a No. 42 filter.