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.

Variation in the chemical composition of the cell walls of Bacillus subtilis during growth in different media.

Abstract: DURING recent years the chemical composition of the cell wall has been used as an aid in the classification of micro-organisms1. Although differences in the composition of the cell wall have been demonstrated during growth of organisms with: (a) variable morphological forms2; (b) complex auxotrophic requirements3; (c) addition of D-amino-acids4, many investigations have not considered the variations which occur in the amino-acid and amino-sugar content of more stable stains of bacteria during the growth cycle and in response to different growth media. The results presented here demonstrate that the amino-acid and amino-sugar content of the cell wall of Bacillus subtilis varies not only with growth but is also significantly influenced by the composition of the growth medium. Furthermore, galactosamine, one of the major components of the cell wall of the highly transformable strain B. subtilus 168 I-C+, is consistently decreased when this strain is grown under conditions which do not permit the development of the capacity to bind deoxyribonucleic acid (competence). A marked decrease in galactosamine is also observed in three poorly transformable strains of B. subtilis.

Identification of trehalose and glycine betaine as compatible solutes in the moderately halophilic sulfate reducing bacterium, Desulfovibrio halophilus

Abstract: Increasing NaCl concentrations in the growth medium inhibited the growth of Desulfovibrio halophilus due to both an increase in the lag phase of growth and a reduction in the specific growth rate. Addition of 1 mM glycine betaine to the growth medium partially relieved this inhibition. Natural abundance 13C nuclear magnetic resonance spectroscopy identified the disaccharide α-α trehalose and glycine betaine as the major organic solutes accumulated by D. halophilus during growth in mineral salts medium and mineral salts medium supplemented with 1 mM glycine betaine, respectively. The presence of a weak glycine betaine transport system was confirmed by following the accumulation of [methyl-14C]glycine betaine during osmotic upshock. In the absence of exogenous glycine betaine the intracellular trehalose concentration of D. halophilus was dependent upon the osmolarity of the growth medium, with a maximum concentration of 8.3 μmol trehalose mg protein−1 recorded in cultures grown in the presence of 15% w/v NaCl. Intracellular K+ concentrations were also dependent upon the osmolarity of the growth medium over the range 3–9% w/v NaCl, but showed little further increase at higher NaCl concentrations.

The Escherichia coli CsrB and CsrC small RNAs are strongly induced during growth in nutrient-poor medium.

Abstract: The carbon storage regulatory (Csr) system is a complex network controlling various phenotypes in many eubacteria. So far, the external conditions by which the system is regulated are poorly understood. Here we show that the expression of the two noncoding small RNAs CsrB and CsrC in Escherichia coli is strongly increased in cultures grown in minimal medium. Addition of tryptone, casamino acids or a mixture of amino acids to a culture grown in minimal medium led to a rapid reduction in the levels of CsrB. Based on this we propose that the expression of the Csr sRNAs is controlled by the amino acid availability in the growth medium.