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.

Free amino acid levels and the regulation of nitrate uptake in maize cell suspension cultures

Abstract: The ability of individual amino acids to regulate nitrate uptake and induction was studied in a Zea mays embryo cell line grown in suspension culture. The maize cells exhibited a marked preference for absorbing amino acids over nitrate when both were present in culture medium. The addition of an individual amino acid (2 mM glutamine, glycine, aspartic acid, or arginine) to the culture medium with 1 mM nitrate completely inhibited nitrate uptake and resulted in a cycle of low levels of nitrate influx followed by efflux to the growth medium. Glutamine was readily absorbed by the cells and was particularly effective in supporting optimum cell growth in the absence of an inorganic nitrogen source as compared to the three other amino acids evaluated. However, neither glutamine nor any of the remaining 19 proteinaceous amino acids appeared to be solely responsible for regulation of nitrate uptake and induction. The ability of amino acids to regulate nitrate uptake and assimilation appears to be more related to their overall levels in the cell rather than to an accumulation of a specific amino acid.

Low-cost cultivation of Sporosarcina pasteurii strain in food-grade yeast extract medium for microbially induced carbonate precipitation (MICP) application

Abstract: Sporosarcina pasteurii is a well-known ureolytic microbial species that proficiently induces the deposition of calcium carbonate through microbially induced carbonate precipitation (MICP) process for various biotechnological and engineering purposes. In view to resolving the concern on high-cost bacterial cultivation due to the conventional use of laboratory-grade growth medium for MICP studies, an inexpensive food-grade yeast medium was investigated in this current study for its feasibility to serve as a suitable alternative media for bacterial growth, urease activity and calcium carbonate precipitation. The effect of different media concentration and initial pH medium on biomass production and urease activity were determined. The performance of this low-cost media was also compared with eight laboratory-grade media (nutrient broth, yeast extract, tryptic soy broth, luria broth, fluid thioglycollate medium, cooked meat medium, lactose broth and marine broth). Results in this current study showed cultivation in low-cost media at 15 g L−1 (w/v) and initial pH 8.5 of the food-grade yeast media both constituted the highest biomass concentration and urease activity when supplemented with urea (4%, w/v). Comparison of the food-grade media with laboratory-grade media indicated that bacterial cultivation cost was significantly reduced to 99.80%. After the biomineralization test, X-ray diffraction (XRD) analysis was used to confirm the elemental composition of CaCO3 and polymorphs which were identified as calcite and vaterite. These findings suggest the food-grade yeast extract can serve as a potential candidate for bacterial cultivation in MICP application from the perspective of cost reduction.

Antibiotic effect of linolenic acid from Chlorococcum strain HS-101 and Dunaliella primolecta on methicillin-resistant Staphylococcus aureus

Abstract: Methanol extracts fromChlorococcum strain HS-101 andDunaliella primolecta strongly inhibited the growth of a strain of methicillin-resistantStaphylococcus aureus (MRSA), which is causing serious problems in Japanese hospitals. So that the anti-MRSA substance(s) could be purified and identified, the growth medium was improved for antibiotic production. When the two strains were cultured in their improved media, antibiotic production byChlorococcum strain HS-101 was 1.8-fold that in the standard BG-11 medium, and production byD. primolecta was 2.3-fold. The activity pattern of fractions eluted by silica-gel or gel-permeation chromatography suggested that both strains produced two antibiotic substances. Identification of the purified substances by NMR and GC-MS showed that one of the active substances in both strains wasα-linolenic acid. Ten fatty acids from other sources were tested, and it was found that unsaturated fatty acids had antibiotic activity against MRSA, with the highest activity that of γ-linolenic acid.

Correlation between the inhibition of cell growth by accumulated polyamines and the decrease of magnesium and ATP

Abstract: The mechanism of the antiproliferation effect of spermidine and spermine was studied using a cell culture system of mouse FM3A cells. The addition of either 10 mM spermidine or 2 mM spermine to the growth medium containing 0.9 mM Mg2+ greatly inhibited cell growth (more than 90%). A decrease in the Mg2+ concentration to 50 μM in the growth medium, but without the polyamine addition, did not influence cell growth. However, the concentrations of spermidine and spermine necessary for the inhibition of cell growth when cells were cultured in the presence of 50 μM Mg2+ were much smaller (2 mM spermidine and 0.15 mM spermine). Nevertheless, the amount of polyamines accumulating in cells which could cause the inhibition of cell growth was almost the same, regardless of the large difference in the added polyamine concentrations. At the early stage of polyamine accumulation, the inhibition of cell growth correlated with the decrease of Mg2+ content, but not with a decrease of the ATP content. The decrease in Mg2+ content correlated well with the inhibition of macromolecular synthesis, especially protein synthesis. Thus, the inhibition of cell growth at the early stage of polyamine accumulation was thought to be due to the inactivation of ribosomes through the replacement of Mg2+ on magnesium-binding sites by polyamines. The decrease in Mg2+ content was mainly caused by the inhibition of Mg2+ transport by polyamines. At the later stage of polyamine accumulation, a decrease in ATP content was also observed. This was followed by swelling of the mitochondria, which may be a symptom of the subsequent cell death.