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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.


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Journal ArticleDOI
TL;DR: The heterogeneity of the population, calculated from the microcolony areas, decreased with recovery from pH 3 over a period of a few hours, and specific regions within single filamentous cells were more able to form rapidly dividing cells, i.e., there was heterogeneity even within single recovering cells.
Abstract: Within an isogenic microbial population in a homogenous environment, individual bacteria can still exhibit differences in phenotype. Phenotypic heterogeneity can facilitate the survival of subpopulations under stress. As the gram-positive bacterium Lactobacillus plantarum grows, it acidifies the growth medium to a low pH. We have examined the growth of L. plantarum microcolonies after rapid pH downshift (pH 2 to 4), which prevents growth in liquid culture. This acidification was achieved by transferring cells from liquid broth onto a porous ceramic support, placed on a base of low-pH MRS medium solidified using Gelrite. We found a subpopulation of cells that displayed phenotypic heterogeneity and continued to grow at pH 3, which resulted in microcolonies dominated by viable but elongated (filamentous) cells lacking septation, as determined by scanning electron microscopy and staining cell membranes with the lipophilic dye FM4-64. Recovery of pH-stressed cells from these colonies was studied by inoculation onto MRS-Gelrite-covered slides at pH 6.5, and outgrowth was monitored by microscopy. The heterogeneity of the population, calculated from the microcolony areas, decreased with recovery from pH 3 over a period of a few hours. Filamentous cells did not have an advantage in outgrowth during recovery. Specific regions within single filamentous cells were more able to form rapidly dividing cells, i.e., there was heterogeneity even within single recovering cells.

59 citations

Journal ArticleDOI
TL;DR: Various concentrations of oxygen were used to determine the optimum culture medium P O 2 for survival and proliferation of attached human and mouse fibroblasts grown from different inoculum sizes.
Abstract: Various concentrations of oxygen were used to determine the optimum culture medium PO2 for survival and proliferation of attached human and mouse fibroblasts grown from different inoculum sizes. When T-15 flasks were seeded with less than or equal to 2 X 10(4) cells (less than or equal to 1.3 X 10(3) cells/cm2), the highest plating efficiencies and cell yields were obtained with a culture medium PO2 of 40-60 mm Hg. At higher inoculum sizes (10(5) cells per T-15) used routinely for mass cultured, no difference in cell yield or glycolytic activity was observed between cultures gassed with atmospheric, i.e., 18% O2 (growth medium PO2 approximately equal to 125-135 mm Hg) and those gassed with 1% O2 (growth medium PO2 approximately euqal to 40-60 mm Hg). The enhanced clonal growth observed at the latter PO2 results from an increased proliferation rate rather than more efficient attachment and survival of inoculated cells. Glucose uptake and lactic acid accumulation were increased in sparse cultures sparged with 1% O2. A slight extension of lifespan was observed in WI-38 cells serially subcultured with a gas phase of 1% O2.

59 citations

Journal ArticleDOI
TL;DR: Researchers study the effects of lactic acid bacteria upon yeast fermentative performance in connection with sugarcane-based fuel ethanol fermentation process to stimulate the search for more strain-specific antimicrobial agents to treat bacterial contaminations during industrial ethanol fermentation.
Abstract: Bacterial contamination during industrial yeast fermentation has serious economic consequences for fuel ethanol producers. In addition to deviating carbon away from ethanol formation, bacterial cells and their metabolites often have a detrimental effect on yeast fermentative performance. The bacterial contaminants are commonly lactic acid bacteria (LAB), comprising both homo- and heterofermentative strains. We have studied the effects of these two different types of bacteria upon yeast fermentative performance, particularly in connection with sugarcane-based fuel ethanol fermentation process. Homofermentative Lactobacillus plantarum was found to be more detrimental to an industrial yeast strain (Saccharomyces cerevisiae CAT-1), when compared with heterofermentative Lactobacillus fermentum, in terms of reduced yeast viability and ethanol formation, presumably due to the higher titres of lactic acid in the growth medium. These effects were only noticed when bacteria and yeast were inoculated in equal cell numbers. However, when simulating industrial fuel ethanol conditions, as conducted in Brazil where high yeast cell densities and short fermentation time prevail, the heterofermentative strain was more deleterious than the homofermentative type, causing lower ethanol yield and out competing yeast cells during cell recycle. Yeast overproduction of glycerol was noticed only in the presence of the heterofermentative bacterium. Since the heterofermentative bacterium was shown to be more deleterious to yeast cells than the homofermentative strain, we believe our findings could stimulate the search for more strain-specific antimicrobial agents to treat bacterial contaminations during industrial ethanol fermentation.

59 citations

Journal ArticleDOI
TL;DR: A mutant of Escherichia coli that has an alteration in the structural gene for the alkaline phosphatase has been found to synthesize an anomalous subunit that is unable to dimerize under normal conditions of cell growth and, thus, cannot form active enzyme.

59 citations

Journal ArticleDOI
TL;DR: Thin layer chromatographic analysis of the reaction mixture suggested 4-nitrocatechol was an intermediate of p-nitrophenol transformation by UG30.
Abstract: Pentachlorophenol-degrading Sphingomonas sp. UG30 and Sphingomonas chlorophenolica strains RA2 and ATCC 39723 can transform p-nitrophenol in either mineral salts-glutamate or mineral salts-glucose medium after an initial lag period. However, mineralization of p-nitrophenol by these bacterial strains was observed only in mineral salts-glucose medium. When p-nitrophenol was the sole nitrogen source in the growth medium, UG30 mineralized 32% of 140 mM [14C]p-nitrophenol which was 10% higher than the amount of [14C]p-nitrophenol mineralized in mineral salts-glucose medium. UG30 did not transform or mineralize p-nitrophenol (in a growth medium) in the absence of glucose or glutamate. All three strains released nitrite during p-nitrophenol degradation in mineral salts-glucose medium and mineral salts-glutamate medium. The transformation rate of p-nitrophenol by UG30 was dependent on the initial p-nitrophenol concentration, with the optimal rate being found at 310 μM of p-nitrophenol and inhibition observed at ≥1100 μM of p-nitrophenol. Pre-exposure of UG30 cells to p-nitrophenol eliminated the initial lag phase of p-nitrophenol transformation. However, pre-growth of UG30 cells on pentachlorophenol did not reduce the lag period for p-nitrophenol transformation. Both p-nitrophenol- and pentachlorophenol-induced UG30 cells degraded pentachlorophenol without any lag phase. Thin layer chromatographic analysis of the reaction mixture suggested 4-nitrocatechol was an intermediate of p-nitrophenol transformation by UG30.

58 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20233
20226
202126
202032
201926
201829