Inorganic nitrogen metabolism in marine bacteria: The intracellular free amino acid pools of a marine pseudomonad

✍ Scribed by S. O. Stanley; C. M. Brown

• Publisher: Springer-Verlag
• Year: 1976
• Tongue: English
• Weight: 816 KB
• Volume: 38
• Category: Article
• ISSN: 0025-3162
• DOI: 10.1007/bf00390763

✦ Synopsis

The marine pseudomonad bacterium PL I contains an intracellular pool of free amino acids which consist mainly of glutamate with small amounts of glutamine and aspartate when grown in a nutrient medium containing 0.2 M NaCI. When the NaCI concentration of the growth medium is increased to 0.8 M, proline becomes a major component of the intracellular pool together with glutamate --at this molarity and under suitable nutrient conditions these amino acids comprise 20% of total bacterial amino acid nitrogen. When grown in a nutrient growth medium containing a constant level of NaCI, the intracellular pool size can vary by a factor of 4 depending on the concentration of carbon and nitrogen in the medium. Experiments show that the amino acid pool can act as a nitrogen reserve but has little function as a carbon reserve. At high NaC1 concentrations there is a marked dependence for growth on the presence of sufficient potassium in the medium. Howe~er, no correlation between K + and glutamate concentration in either nitrogen or K+-limited cultures has been found. None of the enzymes associated with glutamate biosynthesis was influenced by NaCI levels between 0.2 and 0.5 M. Neither Na + or K + stimulated the activity of these enzymes when tested in vitro.