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.

Accumulation of α-tocopherol and β-carotene in Euglena gracilis Cells Under Autotrophic and Mixotrophic Culture Conditions

Abstract: The aim of the work was to find the mode of cultivation of unicellular flagellate Euglena gracilis, favorable for the simultaneous accumulation of α-tocopherol and β-carotene. Cells were grown either in photoautotrophic or photoheterotrophic conditions in the presence of 100 mM ethanol (variant Et) or 40 mM glutamate (variant Gt), or their combination (variant EtGt). The exogenous substrates significantly stimulated light-dependent growth of E. gracilis. The largest increase of biomass was recorded on the 20th day in the variant EtGt and exceeded the autotrophic control by 7 times. The content of β-carotene and chlorophyll (Chl) per cell in mixotrophic cultures exceeded the control by 2-3 and 1.6-2 times, respectively. At the same time, α-tocopherol accumulation in autotrophic cells was greater than in the cells of mixotrophic cultures by 2-7 times. Total yield of tocopherol per unit volume of culture medium, which depended not only on its intracellular content, but also on the amount of accumulated biomass was highest in EtGt variant. A correlation between the accumulation of the antioxidants and the equilibrium concentration of oxygen in the growth medium, which depended on the intensities of photosynthesis and respiration has been analyzed.

Transition metal requirement to express high level NAD+-dependent formate dehydrogenase from a serine-type methylotrophic bacterium

Abstract: Formate dehydrogenase (EC 1.2.1.2) from an aerobic organism was found to be metal-dependent. This NAD+-dependent enxyme required the presence of tungsten or molybdenum to express high enzyme levels in the facultative methylotrophic Methylobacterium sp. RXM. The apparent Vmax of the reaction increased 22-fold in a tungstate-containing medium when compared with a non-metal-supplemented growth medium. The absence of those metals in the culture medium resulted in the partial loss of an energy-yielding step and approx. 50% decrease in the cell yield was observed. Moreover, formate accumulated in the extracellular medium and culture pH dropped. Tungsten produced a higher stimulation of formate dehydrogenase activity than that obtained with molybdenum for batch cultivation of Methylobacterium sp. RXM.

Characterization of the growth inhibited substate induced in murine hepatic tumor cells during in vitro exposure to dimethylsulfoxide.

Abstract: Kinetic events associated with the dimethylsulfoxide (DMSO)-induced inhibition of hepatic tumor cell proliferation were studied using established lines of murine liver tumor cells (BW77-2 and Hepa-1/A1) and conditions of polar solvent treatment (1–3% final concentration in the culture medium for a period of 4 days) previously shown to increase the expression of differentiated functions in BW77-2 cells. Cell-cycle substates of exponentially growing and DMSO-treated liver tumor cell populations were compared by flow cytometric techniques employing recently developed cytochemical criteria to identify hepatocyte cell cycle compartments based on individual cellular RNA and DNA contents (Higgins, 1985). Suppression of hepatic tumor cell proliferation by DMSO (in non-cytotoxic concentrations) persisted only for the duration of the exposure period. Resumption of cell division was readily observed following removal of the polar solvent from the culture medium. During DMSO treatment, BW77-2 and Hepa-1/A1 cells accumulated in the G, phase of the cell division cycle (low-population-density 3% DMSO-treated cultures were composed of 88% G1cells compared to only 48% G1 DNA content cells in control cultures of similar population density) and exhibited a substantial shift to lower mean cellular RNA content. The relatively few S-and G2+M-phase cells in DMSO cultures also possessed lower RNA contents compared to the corresponding cell cycle compartments in exponentially growing cultures. The mean RNA contents for the G1, S, and G2+M compartments of DMSO-treated cells approximated 63.8,78.6, and 74.4%, respectively, of the amounts observed in control cultures. Low-RNA G1 cells in DMSO cultures expressed a continuum of RNA distributions similar in range variation to (but at lower mean cellular RNA content levels than) cycling G1 cells in log-phase growth. Thus, G1 cells in 1% DMSO-treated populations had a mean cellular RNA content of just 25 (arbitrary RNA) units compared to over 40 units for G1 cells in exponential phase growth. Low RNA content, non-replicating, hepatic tumor cells in polar solvent-treated cultures were designated as being in the “Qi” substate (DMSO-induced quiescent-type cells). Release of BW77-2 cells from Qi, after replacement of the DMSO-containlng growth medium by medium without the polar solvent, was characterized by an increase in mean G1 RNA content and recruitment into log-phase growth. Since Qi cells predominate in DMSO-treated hepatic tumor cell cultures (approximating 90% of the total population) and are unresolved, under control exponential-phase growth conditions, it is likely that cells of the Qi phenotype participate in the augmentation of liver functions induced as a consequence of DMSO exposure.

Effect of protein hydrolysates on growth kinetics and aminopeptidase activities of Lactobacillus.

Abstract: The goal of this study was to evaluate how two new hydrolysates from poultry by-products act on ten lactobacilli growth kinetics when supplemented to the growth medium. These effects were compared with ones induced by two most common commercial hydrolysates, i.e., tryptone and peptone. Growth medium, supplemented with one of new hydrolysates, 78T, as only nitrogen source, can sustain the maximum growth rate and the biomass yield in the same way of MRS, reach of different nitrogen sources. Moreover aminopeptidase activities (AA) of each strain were determined to investigate the effect of the growth condition on the modulation of aminopeptidase pattern. Five cell extracts of each ten strains, obtained from their cultivation in MRS and in the presence of the two common hydrolysates and the two new ones, were considered. AA was investigated against five different chromogenic substrates: β-naphthyl amide derivatives of L-anomers of leucine, lysine, proline, glycine-proline, and phenilalanine-proline. A great variability of AA was observed among the strains: also strains belonging to the same species showed peculiar AA profile.