DIFFERENTIAL AMINO ACID UTILIZATION BY SPIROPLASMAS AND THE EFFECT ON GROWTH KINETICS

Abstract

The amino acid requirements of Spiroplasma citri, S. floricola, S. melliform, SR-3, brevi and S. apis were determined in a chemically defined medium. Deletion of individual amino acids from an otherwise complete growth medium indicated that of the 20 amino acids tested, 14 were essential for good growth in S. citri, 10 in S. floricola, 10 in S. melliform, 10 in brevi, 7 in S. apis and 14 in SR-3. Asparagine, glutamic acid, glycine, leucine, proline, threonine and valine were essential for good growth for all spiroplasmas tested, but deletion of cysteine and serine had marginal or no significant effect on their growth. Requirements for other amino acids varied from nonessential to essential for growth. The specific growth rate of spiroplasmas was affected by the amino acid composition of the growth medium. For example, the specific growth rate of S. floricola in a medium deficient in threonine was 0.06×10^-2 hr^-1, however, the specific growth rate in medium containing 4.8×10^-2M amino acid was 4.2×10^-2 hr^-1.