Effect Of Organic Nutrients Research Articles

Autotrophic growth of four Sulfolobus strains on tetrathionate and the effect of organic nutrients

Autotrophic growth yields of four strains of Sulfolobus using tetrathionate as sole energy substrate fell in the range 6.2–7.8 g dry weight (mol tetrathionate oxidized)-1. Autotrophic organisms lacked ribulose 1,5-bis-phosphate carboxylase, but contained pyruvate and phosphoenolpyruvate carboxylases. S. brierleyi and strains B6-2 and LM exhibited mixotrophic growth, with tetrathionate oxidation, CO2-fixation and organic substrate assimilation occurring concurrently, using media containing glucose or acetate. Yeast extract or succinate supported heterotrophic growth and showed strain-dependent repression of one or both of tetrathionate oxidation and CO2-fixation resulting in biphasic growth. All four carbon atoms of succinate were assimilated to cell-carbon during growth. Acetate was the major source of cell-carbon during mixotrophic growth. These observations are not inconsistent with the possibility of a reductive carboxylic acid cycle in these organisms. Radiorespirometric analysis of glucose oxidation indicated CO2 release to occur by means of an Entner-Doudoroff pathway (followed by pyruvate decarboxylation) and oxidative pentose phosphate pathway reactions. There was little evidence from the glucose radiorespirometry of the large-scale use of an oxidative tricarboxylic acid cycle for terminal oxidation of acetate derived from pyruvate. These results demonstrate the considerable metabolic versatility of Sulfolobus strains and show that there is significant variation among them.

Effects of Organic Nutrients and Hormones on Growth and Development of Tissue Explants from Coconut (Cocos nucifera) and Date (Phoenix dactylifera) Palms Cultured in vitro

AbstractThe growth response (increase in weight) of cultured explants from seedling date (Phoenix dactylifera L.) and mature coconut (Cocos nucifera L. cv. Malayan Dwarf) palms to source and concentration of organic nitrogen. carbohydrate, auxins, cytokinins and gibberellins was examined. Growth was strongly stimulated by the presence of auxins (10−7 to 10−6M), cytokinins (10−6 to 10−5M), high concentrations of sucrose (0.2 M), and in the absence of NH4Cl, by organic sources of reduced nitrogen. Higher concentrations of auxin (2,4‐D or NAA at 10−6 to 10−5M) which still stimulated growth of Phoenix tissue, proved inhibitory to growth of freshly excised Cocos tissues.Explants from both palms initiated roots when subcultured on a medium with increased levels of auxin (NAA, 2.5 × 10−6 to 2.5 × 10−5M) and reduced levels of cytokinin (6‐BAP, 5 × 10−8M). Isolated roots excised from these explants continued growth and produced new laterals when subcultured on media with GA3 (5 × 10−7M) and reduced levels of auxin, cytokinin, and either minerals or sucrose.