Nutritional Studies of Zygorhynchus Species

SUMMARY: Nutritional experiments were carried out dealing with: (1) the utilization of carbohydrates; (2) the nitrogen source; (3) the action of different mineral salts and their interaction. The results showed that the strains of Zygorhynchus used grew well at 25° at pH 8·0 when buffered with nutritionally inert tris buffer and incubated for 12–14 days. Statistical analysis of the results showed that under the given conditions optimal growth measured as mg. dry wt. was obtained in liquid media containing 4% (w/v) glucose; 0·1 m tris buffer; 0·00625 m-(NH4)2SO4; 2 p.p.m. Fe, Zn and Mn; with the following optimal conditions for the different strains specified: (i) for Z. moelleri CMI 0·002 m-KH2PO4; 0·012 m-MgSO4. 7H2O; (ii) for Z. moelleri Baarn 0·002 m-KH2PO4; 0·006 m-MgSO4. 7H2O; (iii) for Z. vuillemini CMI 0·002 m-KH2PO4; 0·003 m-MgSO4. 7H2O; (iv) for Z. vuillemini Baarn 0·004 m-MgSO4. 7H2O. There was a balance between the possible pairs of the salts from KH2PO4, MgSO4. 7H2O and (NH4)2SO4 (in one case only between KH2PO4 and MgSO4.7H2O). There was an optimal balance between all the salts for two strains. The best carbon sources were glucose, fructose, mannose, xylose and arabinose. The best sources of nitrogen were l-glutamine, l-asparagine, glycine, (NH4)2SO4.