title: Turnover of proteins, cell walls and ribosomal constituents during the growth of actinomycetes.
abstract: Biochemical reorganizations occurring during the slowdown of growth following the exponential phase in liquid batch cultures of some species of actinomycetes, have been studied. Three main events occur during the reduction of the growth rate. Firstly, there is a decrease of the ribosomal fraction with a drop in r-RNA and ribosomal proteins, and, secondly, protein turnover occurs. This was indicated by changes in the cell protein content, by the appearance of aminated material in the extracellular medium and by drops of the specific activity of some enzymes. Thirdly, there are changes in the cell envelope with a periodic release into the medium of soluble radioactivity from cells prelabelled with tritiated diaminopimelic acid. These cellular reorganizations may be biochemical mechanisms of adaptation of actinomycetes during the transition from nutrient-rich to poorer environments.
mesh_terms: D000192:Actinomycetales / Q000254:growth & development / Q000378:metabolism*; D002473:Cell Wall / Q000378:metabolism; D003470:Culture Media; D005656:Fungal Proteins / Q000378:metabolism*; D012270:Ribosomes / Q000032:analysis*
chemical_list: D003470:Culture Media; D005656:Fungal Proteins