Growth medium

About: Growth medium is a research topic. Over the lifetime, 1889 publications have been published within this topic receiving 59171 citations. The topic is also known as: culture medium & culture media.

Control of Lysine Biosynthesis in Yeast by a Feedback Mechanism

Abstract: Homocitric acid (β-hydroxy-β-carboxyadipic acid; HC) is accumulated by a lysine-requiring yeast mutant when grown in a chemically defined medium, supplemented with limited amounts of lysine. A study of the formation of HC in relation to the depletion of lysine from the growth medium indicates that HC accumulated only when the concentration of lysine was low. The enzymatic formation of HC from α-ketoglutarate plus acetyl-coenzyme A in cell-free extracts of the same organism was also inhibited by lysine. The inhibitory effect of lysine on the formation of HC in both whole cells and cell-free extracts is indicative of the functional existence of a feedback control mechanism in the pathway for lysine biosynthesis in yeast.

Physiological response of culture media-grown barley (Hordeum vulgare L.) to titanium oxide nanoparticles

Abstract: Since the fate of nanoparticles after their release in the environment and their possible transfer in plants and subsequent impacts is still largely unknown, this paper evaluates the potential phytotoxic effects of up to 20% w/w TiO2 nanoparticles (nTiO2) on barley cultivated in hydroponics and agar media. The X-ray diffraction analysis confirmed that nTiO2 powder corresponds to anatase phase. On agar medium only high concentrations of nTiO2 (10% and 20% w/w) induced significant inhibition of shoot growth. However, hydroponics treatment with nTiO2 up to 1000 mg L−1 did not show any adverse effect on the shoot growth. In both experiments, (i) root growth inhibition effects became visible with increasing concentration of nTiO2, (ii) plants treated with nTiO2 showed no change in chlorophyll a and b content, even though the plants absorbed nTiO2, (iii) weight of biomass treated with nTiO2 was not significantly different compared to control. Therefore, we assume that transport of nTiO2 into the aerial ...

Effect of Glucose on Thermal Injury of Yeast that may Define the Maximum Temperature of Growth

Abstract: SUMMARY: Anaerobically grown yeast, suspended in glucose solution, leaked cell contents non-selectively. The rate of leakage increased with temperature but reached a maximum rate close to the maximum temperature of growth (T max) of the yeast. The total leakage induced by glucose was much greater above T max than below it, because above T max the yeast lost the ability to take up released material. The rate of uptake of 14C-labelled amino acids was also substantially slowed above T max-Yeast heat-stressed in the presence of glucose lost the ability to establish and maintain a concentration gradient of sorbose, and simultaneously ATPase activity could be measured, all characteristics of yeast with a ruptured cytoplasmic membrane. These effects were uniquely caused by utilizable sugars, were essentially independent of sugar concentration and could be partially inhibited by Ca2+ or inhibitors that prevent sugar utilization. Yeast heated above T max in water suspension was essentially undamaged as determined by the tests used, but if glucose was subsequently added below T max an effect of heat damage could be demonstrated. We conclude that one factor that determines the T max of a yeast is the temperature sensitivity of the cytoplasmic membrane in the presence of the utilizable sugar of the growth medium.

Optimization of Growth Medium and Poly-$\beta$-hydroxybutyric Acid Production from Methanol in Methylobacterium organophilum

Abstract: Methylobacterium organophilum, a facultative methylotroph was cultivated on a methanol as a sole carbon and energy source. The cell growth was affected by the various components of minimal synthetic medium and the medium composition was optimized with 0.5% (v/v) methanol at pH 6.8 and at 3. The maximum specific growth rate of M. organophilum was achieved to 0.26 hr in the optimized medium which has following composition: Methanol, 0.5% (v/v):(NH)SO, 1.0g/l:KHPO, 2.13g/l:KHPO, 1.305g/ι:MgSO.7. 45g/l and trace elements (CaCl.2, 3.3mg:FeSO.7, 1.3mg:MnSO.4, 130:ZnSO.5, 40:NaMoO.2, 40:CoCl.6, 40:HBO, 30 per liter). By the limitation of nitrogen and deficiency of Mn or Fe, the cell growth was significantly repressed. Methanol greatly repressed the cell growth and the complete inhibition was observed at concentration above 4% (v/v). In order to overcome the methanol inhibition and to prevent the methanol limitation, intermittent feeding of methanol was conducted by a D.O.-stat technique. PHB production by M. organophilum was stimulated by deficiency of nutrients such as NH, SO, , , or PO in the medium. The maximum PHB content was obtained as 58% of dry cell weight under deficiency of potassium ion in the optimized synthetic medium.

Influence of auxins on alkaloid accumulation by a transgenic cell line of Catharanthus roseus

Abstract: The transgenic cell line of Catharanthus roseus (L) G Don S10 was used to study the effect of the presence of the synthetic auxins naphthalene acetic acid and 2,4-dichlorophenoxyeacetic acid in the culture medium on the accumulation of terpenoid indole alkaloids Line S10 carries a recombinant, constitutively over-expressed version of the endogenous strictosidine synthase gene The experiments were carried out using a two-stage culture system, consisting of a growth phase of 7 to 10 days and a production phase of 14 or 30 days The hormonal composition was a crucial factor when formulating both the growth and the production media It was determined that the presence of naphthalene acetic acid during the production phase led to lower levels of alkaloid accumulation The presence of 2,4-dichlorophenoxyacetic acid in the growth medium reduced culture aggregation and repressed secondary metabolism Cultures grown in medium containing 2,4-dichlorophenoxyacetic acid showed reduced capacity to supply biosynthetic precursors, which resulted in low levels of accumulation of terpenoid indole alkaloids Cultures grown in 2,4-D-containing medium showed reduced capacity to supply biosynthetic precursors and higher rates of catabolic activity, which resulted in low levels of TIA accumulation The expression of the gus and strictosidine synthase transgenes, measured at the enzyme level, was similarly high under all conditions tested