Flavonoids influence growth and saccharide metabolism ofRhizobium meliloti

Supplementation of the growth media with flavonoids,viz. naringenin, flavone, quercetin and syringaldehyde, a phenolic compound and alfalfa seed exudate, differently affected the growth and saccharide metabolism ofRhizobium meliloti. Quercetin increased while syringaldehyde, flavone and alfalfa exudate decreased the growth and protein content ofR. meliloti cells. Naringenin had no effect on growth and protein content though it increased the exopolysaccharide production. Application of naringenin increased the activities of enzymes of the citrate cycle and the 6-phosphogluconate pathway, the major pathways of sugar metabolism in fast growing rhizobia, and decreased activities of glycolytic enzymes. The activities of enzymes of the pentose phosphate pathway remained unaffected by various treatments.     

Influence of oxygenation and carbon dioxide on the growth ofRhizobium meliloti in a fermenter

A decrease in dissolved O₂ from 90% to 50% saturation in a fermenter adversely affected both blomass production ofRhizobium meliloti ATCC 9930 and viable cell number, although oxygen was never limiting. Lower amounts of dissolved oxygen, or accidental decreases in dissolved oxygen concentration, also caused appreciable acidification of the culture broth, which was the result of CO₂ accumulation in the medium. Adding CO₂ to the aeration gas mixture affected both biomass production and mean generation time in proportion to the CO₂ concentration; the effect on viable cell number was less pronounced.R. meliloti may be considered as a microorganism moderately sensitive to CO₂. GoodR. meliloti growth requires, among other things, not only sufficient aeration (oxygenation) but also good ventilation of the CO₂ evolved during the fermentation.

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Résumé La diminution de l'O₂ dissous de 90 à 50% de la saturation dans un fermenteur, a affecté de manière négative tant la production de biomasse deRhizobium meliloti ATCC 9930 que le nombre de cellules revivifiables, bien que l'oxygène ne fut jamais limitant. Des quantités diminuées d'oxygène dissous ou une diminution accidentelle de la concentration en oxygène dissous, ont également causé une acidification appréciable du milieu de culture résultant de l'accumulation de CO₂ dans le milieu. L'ajout de CO₂ au gaz d'aération a affecté tant la production de biomasse que le temps moyen de génération, proportionnellement à la concentration de CO₂; l'effet sur le nombre de cellules revivifiables était moins prononcé.R. meliloti peut être considéré comme un microorganisme modérément sensible au CO₂. Une bonne croissance deR. meliloti requiert, entre autres, non seulement une aération (oxygénation) suffisante, mais aussi une bonne ventilation du CO₂ engendré pendant la fermentation.

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Publication Number NRCC No. 32389     

Effect of heterologous bacteria and combined nitrogen on the adsorption ofRhizobium meliloti to lucerne seedling roots

Summary The binding ofRhizobium meliloti strains A₂ (effective) and V₆ (ineffective),Agrobacterium tumefaciens strain B₆S₃ andR. trifolii strain TL₅ to lucerne seedling roots was studied by using¹⁴C or³H-labelled bacteria. When added singly or in combination with the heterologous bacteria, the number of A₂ cells attached to the roots was significantly less than the number of B₆S₃ or TL₅ cells. However, the presence of the heterologous bacteria did not decrease the proportion of A₂ cells added in the inoculum that bind to the roots, suggesting thatR. meliloti is attached to specific sites. In fact, the same number of A₂ or V₆ cells bind to the roots and in mixed inoculation the 2 strains share equally the binding sites. When added to the seedlings growth medium NO ₃ ^– at 5 or 16 mM significantly decreased the number of A₂ cells adhering to lucerne seedling roots. The results suggest that the lectin-recognition hypothesis is probably involved in the attachment ofR. meliloti to lucerne seedling roots.Contribution No. 252 Station de recherches, Agriculture Canada     

Histochemical demonstration of proteins, lipids and polysaccharides in Japanese monkey oocytes

A histochemical study of proteins, lipids and polysaccharides was carried out in the oocytes of Japanese monkey (Macaca fuscata) during development of follicles. There were a small number of protein granules reactive to acrolein-Schiff in the cytoplasm of oocytes from primordial, secondary and vesicular follicles, while there were no lipid droplets, granules of neutral polysaccharides or acid polysaccharides in the cytoplasm. Proteins reactive to acrolein-Schiff, neutral polysaccharides reactive to periodic acid-Schiff and acid polysaccharides stainable with alcian blue were observed in the zona pellucida of the oocytes of secondary and vesicular follicles. The zona pellucida contained sudanophilic lipids composed of neutral fats and lipoids, besides the proteins and polysaccharides.     

Detection of loci in theleu region ofRhizobium meliloti chromosome

A multi-marked strain ofRhizobium meliloti was developed by the co-mutation method and employed to contribute to the genetic map ofR. meliloti chromosome. Seven loci were placed at 5 sites in theleu region in the orderman-aba, fix, leu-cro-azt, ost-thi.     

Effect of indoleacetic acid on the growth ofRhizobium in culture

After inoculation ofRhizobium lupini strain A98 andR. leguminosarum strain PRE into a medium containing IAA, growth was initially suppressed. However, when IAA was added in the course of the logarithmic phase, growth was not inhibited. Apparently, IAA affects primarily the lag phase cells.Neither adaptation ofRhizobium to IAA was observed, nor spontaneous breakdown or biological degradation of IAA.The lag phase prolongation depended on the ratio: amount of IA A/number of cells.The authors wish to thank Professor Dr. A. Quispel for his interest and valuable discussions.     

Effect of iron on siderophore production and on outer membrane proteins ofRhizobium leguminosarum IARI 102

Rhizobium leguminosarum IARI 102 produced a phenolate type siderophore (a derivative of 2,3-DHBA) under iron-limited conditions. Addition of Fe³⁺ to the culture medium increased the growth yield significantly, but repressed the production of the iron-chelating compound. Iron level of culture medium also had a significant role in the composition of outer membrane proteins ofR. leguminosarum IARI 102. Maximum iron uptake was observed only in the presence of its own siderophore.     

Effect of lipids on insect cell growth and expression of recombinant proteins in serum-free medium

The lipid emulsion components of a serum-free insect cell medium were varied and evaluated for effects on cell growth and recombinant protein expression. The growth of High-Five^TM cells was significantly affected by polyol Pluronic F-68 and Tween-80, but not by lipids. Pluronic was essential for cell growth, while Tween-80 was required to achieve maximum cell densities. A dose response effect was observed for Tween-80 with optimal cell growth at a concentration of 25 mg/l. Cholesterol had a minor effect on cell growth, but was essential for the expression of recombinant proteins. The expression of -galactosidase (-gal) was directly affected by cholesterol with optimal expression at a concentration of 5.4 mg/l. Vitamin E, important as an antioxidant to stabilize lipids, did not directly affect recombinant protein expression. Although lipids were not required for cell growth, the presence of lipids were required during the cell growth phase in order to achieve efficient infection with baculovirus. These studies help to define the important components, and range of concentrations, for lipid emulsions which can effectively replace serum in insect cell culture.Abbreviations -gal galactosidase (E.C. 3.2.1.23) - Sf-9 Spodoptera frugiperda - High-5 Trichoplusia ni 5Bl-4     

Effect ofRhizobium inoculation and the application of phosphate on the growth,yield and nitrogen fixation of soybeans

Summary Application of phosphate at 60, 90 and 120 kg P ha^–1 to the Bragg variety of soybeans inoculated with a mixture of three strains ofRhizobium japonicum (TAL 102 + TAL 377 + TAL 379) and grown in silty loam soil in a pot experiments, significantly improved the number of nodules per plant and increased production of shoots and roots by 65, 36 and 17%, the yield of pods by 38, 12 and 3% and N₂-fixing capacity by 57, 29 and 20%, respectively. Rhizobium inoculation alone with the test strains caused a positive but poor nodulation of the crop and increased its dry-matter production of shoots and roots by 22%, pods yield by 7% and N₂-fixing capacity by 6%. Soybean plants from uninoculated treatments were without nodules indicating that indigenous rhizobia associated with this crop are absent in the test soil. Phosphate concentration in the total dry matter of mature crop exhibited an increasing tendency as a result of all the applied levels of phosphorus.

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Resumen La adición de fosfato (60, 90, y 120Kg P ha^–1) a plantas de soja de la variedad Bragg inoculadas con una mezcla de tres cepas deRhizobium japonicum (TAL 102 + TAL 377 + TAL 379) cultivada en contenedores en un suelo arcillo-limoso, mejoró significativamente el número de nódulos por planta, aumentó la producción de tallos y raíces en un 65, 36 y 17%, el rendimiento de la cosecha en un 38, 12 y 3%, y la capacidad fijadora de N₂ en un 57, 29 y 20% respectivamente. La sola inoculación con las cepas deRhizobium ya mencionadas produjo una nodulación positiva aunque pobre del cultivo, incremetando la producción de tallos y raíces en un 22%, el rendimiento de la cosecha en un 7% y la capacidad fijadora de nitrógeno en un 6%. Las plantas de soja de los tratamientos no inoculados no tenían nódulos lo que indica que no habían rizobios específicos para esta planta en el suelo ensayado. La concentración de fosfato en la materia seca de las plantas maduras mostraba una tendencia a incrementarse como resultado de la aplicación de los distintos niveles de fosfato.

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Résumé L'application du phosphate à raison de 60, 90 et 120 kg en phosphore par hectare à la variété Bragg de soja inoculée avec un mélange de 3 souches deRhizobium japonicum (TAL 102, TAL 377 et TAL 379) et cultivée sur un sol gras limoneux dans des expériences en jarre de croissance, a augmenté de manière significative le nombre de nodules par plant et a augmenté la production des pousses et racines respectivement de 65, 36 et 17%, le rendement des cosses respectivement de 38, 12 et 3% ainsi que la capacité de fixer l'azote, respectivement de 57, 29 et 20%. L'inoculation seule avec les souches testées de Rhizobium a causé une nodulation positive mais faible de la plante, et a augmenté la production en matière sèche des racines et pousses de 22%, le rendement en cosses de 7% et la capacité de fixer l'azote de 6%. Les plants de soja dans les expériences sans inoculation ne présentaient pas de nodules, indiquant par là que les rhizobia endogènes associés avec cette plante étaient absents dans le sol expérimental. La concentation en phosphate dans la matière sèche totale de la plante mûre a marqué une tendance à l'augmentation comme suite aux applications du phosphore à tous les niveaux.

     

Marine fungal abilities to enzymatically degrade algal polysaccharides,proteins and lipids: a review

Journal of Applied Phycology - Over the last decades, metabolites with biotechnological application produced by marine resources and notably macroalgae have seen increasing interest. Among these...     

Oxygen and mannitol consumption ofRhizobium meliloti in relation to symbiotic nitrogen fixation efficiency

Summary The rate of oxygen and total mannitol consumption were studied with 48 strains ofRhizobium meliloti in relation to their symbiotic nitrogen fixation efficiency as expressed by the plants dry weight yields. The rate of oxygen consumption is positively correlated to the total mannitol consumption and significant inverse relationship between these two physiological properties and symbiotic efficiency are apparent. The possibility of using the rate of oxygen consumption as a preselection tool is discussed.Contribution no159.     

Enzymes phosphorylating lipids and polysaccharides

Phosphorylation plays an important role in regulation of living functions of organisms; phosphorylation may significantly alter chemical properties of proteins, lipids, and carbohydrates. Canonical kinases catalyze transfer of terminal phosphate group from ATP (or other NTPs) to specific nucleophilic groups of proteins, lipids, and polysaccharides. Recently, unique kinases, catalytically active antibodies (abzymes) phosphorylating proteins, lipids, and polysaccharides have also been discovered. This review highlights biological functions and enzymatic characteristics of canonical kinases and abzymes phosphorylating lipids and polysaccharides.