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.

Preparation and testing of an autolysate of fish viscera as growth substrate for bacteria.

Abstract: The aqueous soluble phase of acidified and autolyzed fish viscera was used as the nitrogen source in a growth medium for bacteria. The bacteria tested grew faster and produced higher yields of cell mass on this growth medium than on corresponding media with standard tryptone preparations as the nitrogen source.

A Low-CO2-Inducible Gene Encoding an Alanine:[alpha]-Ketoglutarate Aminotransferase in Chlamydomonas reinhardtii

Abstract: At low-CO2 (air) conditions, the unicellular green alga Chlamydomonas reinhardtii acquires the ability to raise its internal inorganic carbon concentration. To study this adaptation to low CO2, cDNA clones induced under low-CO2 growth conditions were selected through differential screening. One full-length clone is 2552 bp, with an open reading frame encoding 521 amino acids. The deduced amino acid sequence shows about 50% identity with alanine:[alpha]-ketoglutarate aminotransferase (Ala AT, EC 2.6.1.2) from plants and animals, and the mRNA of this clone increased 4- to 5-fold 4 h after cells were switched from high-CO2 to low-CO2 growth conditions. The expression of the enzyme and its activity also increased accordingly at low-CO2 growth conditions. To study the physiological role of Ala AT, a pyridoxal phosphate inhibitor, aminooxyacetic acid, was added at 40 [mu]M to the growth medium when cells were beginning to adapt to low CO2. This caused a 30% decrease in the maximum photosynthetic rate in air-adapting cells 8 h later. The addition of the inhibitor also caused the cells to excrete glycolate, a photorespiratory intermediate, but did not change the apparent affinity of the cell for external CO2. These physiological studies are consistent with the assumption that Ala AT is involved in the adaptation to low-CO2 conditions.

Phagocytosis of mastitis isolates of Staphylococcus aureus and expression of type 5 capsular polysaccharide are influenced by growth in the presence of milk.

Abstract: Phagocytosis by bovine polymorphonuclear granulocytes of seven capsular polysaccharide type 5 Staphylococcus aureus strains isolated from mastitis [corrected] was investigated by means of luminol-dependent chemiluminescence. Bacteria were grown on four different agar media (brain heart infusion, Columbia broth, modified staphylococcus medium 110, and skim milk) and were opsonized by normal bovine serum. When compared to growth on brain heart infusion agar, Columbia agar, and modified staphylococcus medium 110 agar, growth on skim milk agar rendered five of the strains more resistant to opsonization. The other two strains were resistant in all culture media used. Short periods of incubation in milk after growth on brain heart infusion agar did not augment resistance to phagocytosis, indicating that mere adsorption of milk components on bacteria was not responsible. The variability of the chemiluminescence response of polymorphonuclear leukocytes was pronounced among strains with each growth medium except milk. Growth on modified staphylococcus medium 110 and on milk agar favored the masking of teichoic acid, as shown by inagglutinability with rabbit antiserum. Interestingly, agglutination by a monoclonal antibody to capsular polysaccharide type 5 was optimal when bacteria were grown on skim milk agar. This suggests that capsular polysaccharide participated in the masking effect. These findings indicate that masking of the bacterial target of most of the naturally acquired opsonins present in normal bovine serum occurred when bacteria grew in the presence of milk, resulting in an increased resistance to phagocytosis by polymorphonuclear leukocytes.

Cell death and unbalanced growth in Neurospora.

Abstract: Mutant spores of Neurospora crassa incubated on minimal medium showed two main types of behaviour. One mutant type survived incubation for a week on minimal medium and then responded to the addition of growth substance. The second mutant type died after incubation for one or two days. Strains which died were characterized by an ability to germinate in minimal medium and to begin immediately synthetic processes such as the synthesis of protein and nucleic acid. Addition of ethionine to minimal medium prolonged the survival of strains which committed ‘suicide’. Non-germinated Neurospora conidia withstood freezing and storage at -10° for extended periods, whereas conidia which had been incubated in growth medium died, indicating a difference between dormant and synthetically active spores in their response to the environment. The suicide phenomenon is reminiscent of the cell death due to ‘unbalanced growth’ reported for the thymine-requiring mutant of Escherichia coli. In this case, however, cells requiring substances other than nucleic acid constituents display the effect.