Metabolism of various carbon sources by Azospirillum brasilense

Abstract

Azospirillum brasilense Sp7 and two mutants were examined for 19 carbon metabolism enzymes. The results indicate that this nitrogen fixer uses the Entner-Doudoroff pathway for gluconate dissimilation, lacks a catabolic but has an anabolic Embden-Meyerhof-Parnas hexosephosphate pathway, has amphibolic triosephosphate enzymes, lacks a hexose monophosphate shunt, and has lactate dehydrogenase, malate dehydrogenase, and glycerokinase. The mutants are severely deficient in phosphoglycerate and pyruvate kinase and also have somewhat reduced levels of other carbon enzymes.

Fructose catabolism in Azospirillum brasilense and Azospirillum lipoferum

“…The occurrence of 6-phosphofructokinase activity and a complete EMP pathWay in fructose-grown A. brasilense (Table 1) is in contrast to results reported for this species when grown on glycerol, lactate, malate, and gluconate (38). Total acid products + 1,847 1,759 ammonium used aTitratable acidity of culture was 1,800 x 10-3 meq/100 ml for either strain.…”

“…Neither A. brasilense nor A. lipoferum appears to possess an HMP pathway when grown on fructose, owing to the absence of 6phosphogluconate dehydrogenase activity. Similarly, Westby et al (38) reported the absence of the HMP pathway in A. brasilense grown on gluconate and other substrates.…”

“…Although fructose-grown A. brasilense does exhibit 6-phosphogluconate dehydratase and KDPG aldoiase activities, it cannot use the ED pathway for growth on fructose because of the absence of glucose-6phosphate dehydrogenase activity. Westby et al (38) have shown that glucose-6-phosphate dehydrogenase activity does occur at low levels at A. brasilense grown on gluconate, glycerol, lactate, and tnalate and that this species does use the ED pathway for gluconate dissimilation. Neither A. brasilense nor A. lipoferum appears to possess an HMP pathway when grown on fructose, owing to the absence of 6phosphogluconate dehydrogenase activity.…”

“…An oxidative pathway whereby the pentose L-arabinose is converted to 2-oxoglutarate has been identified in A. brasilense (23). When grown on gluconate, A. brasilense catabolizes this substrate by the Entner-Doudoroff (ED) pathway but lacks a catabolic Embden-Meyerhof-Parnas (EMP) pathway and a hexose monophosphate (HMP) pathway (38). The present report deals with the pathways for fructose catabolism used by A. brasilense and A. lipoferum, the nature of the acidic end products resulting from growth on fructose, and the basis for the inability of A. brasilense to use glucose.…”

Polyhydroxyalcanoates of strains of Azospirillum spp. isolated of roots of Lycopersicon esculentum Mill. “tomato” and Oryza sativa L. “rice” in Lambayeque

“…Ellos concluyeron que A. brasilense alcanza el mayor rendimiento de PHAs cuando utiliza ácidos orgánicos como málico, succínico, láctico, pirúvico y algunos aminoácidos. Por su parte, Westby et al (1983) investigaron el metabolismo de 19 fuentes carbonadas en una concentración de 5 gL -1 obteniendo un crecimiento excelente (+++) con tiempos de generación más cortos con DL malato y DL lactato frente a D-gluconato.…”