Physiological Comparison of a Newfoundland and a North Carolina Isolate of Saprolegnia australis

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Abstract
Two isolates of S. australis [a water mold], one from Newfoundland (NFLD) [Canada], and one from North Carolina (NC) [USA], were compared physiologically. The NFLD isolate had a temperature optimum of 26.degree. C for mycelial growth, and the NC isolate grew best at 29.degree. C. The optimum pH ranges for growth were 4.75-5.7 for the NFLD isolate and 5.3-5.7 for the NC isolate. Any effects of various pH indicators on dry-weight yield were not detected. The optimum concentrations for P were 10-15 mM for the NFLD isolate and 2.5-12.5 mM for the NC isolate. The optimum concentrations of vitamin-free casamino acids were 4 g/l for the NFLD isolate and 12 g/l for the NC isolate. In the presence of glucose, both isolates utilized L-aspartic acid L-threonine, L-serine, L-proline, L-glutamic acid, glycine, L-alanine, L-.alpha.-amino-n-butyric acid, L-valine, L-methionine, L-isoleucine, L-leucine, L-tyrosine, L-phenylalanine, L-lysine, L-histidine and L-arginine from casamino acids. The NC isolate was unique in producing L-1-methylhistidine and in utilizing L-ornithine. Both isolates produced ammonia and spermidine and utilized glucose during growth.