Succinate Medium Research Articles

Protection of β-galactosidase messenger RNA from decay during anaerobiosis in Escherichia coli

Escherichia coli grown in succinate medium is starved of energy when deprived of oxygen. Under these anaerobic conditions β-galactosidase-specific messenger RNA can be partially protected from decay in functional form. This protection can be reversed in part by treatment with puromycin in anacrobiosis.

Studies on growth response of some pathogenic species of Phyllosticta in different nitrogen media

Summary The growth response of twelve species Phyllosticta was studied on eighteen different nitrogen sources. Amongst the nitrates, potassium nitrate was a very good source while ammonium nitrate was much inferior. Ammonium sulphate was a very poor source. None of the Phyllosticta species were capable of utilizing sodium nitrite. Most of the organic nitrogen substances like glycine, DL-alanine, L-glutamic acid, DL-aspartic acid, DL-valine, L-proline, asparagine and glutamine were invariably good sources. The value of L-arginine and DL-phenylalanine were variable for these isolates of Phyllosticta . L-histidine as well as two sulphur containing amino acids viz., L-cystine and DL-methionine were poor sources for all the present species. Varying pH patterns were recorded on different sources of nitrogen. The p h of potassium nitrate solution drifted towards neutrality after attaining considerable acidity by the 6th day. The final p h of the ammonium nitrate medium had also a tendency of drifting towards neutrality but the initial acidic trend continued for a longer time. The final p h of the ammonium nitrate solution did not reach beyond 5.2 in any case. Ammonium sulphate medium developed extreme acidity in shortest time and no upward trends were recorded during the incubation period. Addition of sodium salts of succinic or fumaric acid to ammonium sulphate solution prevented the fall of p h and normal growth was accomplished. The efficiency of the supplemented ammonium sulphate medium was better than asparagine for some of the organisms. Phyllosticta rnorifolia and P. pandanicola had better growth on supplemented ammonium sulphate medium while the influence of both the abon media was almost similar for P. bauhiniae , P. buteae and P. carica papayae . All the remaining species of Phyllosticta achieved better growth on asparagine than on ammonium sulphate fumarate or succinate media. The author is grateful to Professor R. N. T andon for his valuable suggestions

Carbon Nutrition and Metabolism of Polytomella caeca*

SYNOPSIS. Polytomella caeca utilizes as sole carbon sources in chemically defined media: acetate, propionate, butyrate, valerate, pyruvate, succinate, ethyl, butyl, amyl, and hexyl alcohols. Glyceraldehyde and α‐ketoglutarate sustain very small populations. Caproate, caprylate, fumarate, malate, propyl, heptyl, and octyl alcohols and the iso‐compounds iso‐butyrate, iso‐butyl and iso‐hexyl alcohols are inadequate.Acetate is not assimilated <pH 5.0, propionate and butyrate <pH 6.0, and valerate <pH 7.0. Optimum for utilization of succinate is pH 3.0, for pyruvate pH 4.0, utilized also at pH 2.0 Fatty acids are utilized dissociated; succinate and pyruvate are utilized undissociated. Alcohols are assimilated throughout pH 4.0–7.4, except hexanol at pH 7.4. Alcohol availability is proportional to molecular length‐1.pH after growth of fatty acid media is 8.4 ± 0.4; stable in pH 2.0 pyruvate and pH 3.0 succinate media; 3.5 ± 0.3 in alcohol media with initial pH <6.0. Longer alcohols cause less pH decrease during growth.Acetate concentrations <0.2% do not support maximum populations; concentrations of 0.2–1.0% do. pH after growth increases in these media to pH 8.5 with maximum populations.Malate, fumarate, α‐ketoglutarate, and lactate seem not to penetrate the cell, but are metabolized by homogenates. Methylene blue reduction by homogenates indicates the presence of lactic, malic, succinic and α‐ketoglutaric dehydrogenases, fumarase and glutamic transaminase. Extracts contain Embden‐Meyerhof phosphate esters, ATP, and ADP.

Variations in catalase activity during a bacterial growth cycle

The variation in the relative rate of catalase synthesis byBact. lactis aerogeneshas been studied by measuring the enzyme activity of samples of cells taken at intervals from growing cultures, under different conditions. In the normal growth cycle in a glucose-ammonium sulphate medium the rate of catalase synthesis is small during the early part of the logarithmic phase, but the content per cell increases rapidly as the pH of the medium falls. The increased activity is not a direct result of the acidity itself, but may be attributed to modification of the cell metabolism under acid conditions so that more catalase is required. Continued growth under anaerobic conditions tends to reduce catalase activity, although the characteristic variation of the relative rate of synthesis through the growth cycle is maintained. The variation of the rate of formation of the enzyme in cells growing in a succinate medium is similar to that in glucose, although synthesis is now appreciable even in the early stages of growth.

The Study of “Resting” or Non-proliferating Bacteria

If a medium containing either 1 per cent. ammonium succinate or 1 per cent. ammonium fumarate together with certain inorganic salts be inoculated with B. pyocyaneus and incubated aerobically at 37° C. a vigorous growth of the organism will ensue, the rates of growth in both cases not being markedly different from each other. If the growth be allowed to proceed for a fortnight, analysis of the media shows that essentially similar products (mixtures of the lower fatty acids) have been produced in both cases. If the growth be allowed to proceed for not longer than three days, analysis shows that in the succinate medium over 80 per cent. of the succinic acid has not been utilised, whilst in the other medium the entire fumaric acid has disappeared, giving rise in its stead to pyruvic acid which is further utilised as growth proceeds(1). Quantitative data support the view that the breakdown of succinic acid occurs through the intermediate production of fumaric acid, the rate of fermentation of fumaric acid being greater than that of succinic acid, so that fumaric acid is not detected among the products of fermentation of succinic acid. If this view is true, it should be possible to show that B. pyocyaneus has the power of oxidising succinic acid to fumaric acid. It is clear that the proliferating organism cannot be used to demonstrate this experimentally, for the fumaric acid is utilised as quickly as it is formed. Hence it is necessary to use the organism in such a condition that proliferation is completely (or almost completely) eliminated. Under such circumstances the fumaric acid will accumulate and its detection will be made possible.