Madden T, Ward J M, Ison A P
Department of Chemical and Biochemical Engineering, University College London, UK.
Microbiology (Reading). 1996 Nov;142 ( Pt 11):3181-5. doi: 10.1099/13500872-142-11-3181.
Cultures of Streptomyces lividans TK24 grown in defined media containing certain rapidly used carbon and nitrogen sources excreted high levels of organic acids. These were identified by HPLC and enzymic assays as pyruvic acid and 2-oxoglutaric acid. Acidification occurred only with glucose as the principal carbon source, and depended on the nitrogen source used. With nitrate as the sole nitrogen source, high levels of pyruvate and small amounts of 2-oxoglutarate were produced. Carbon from D[U-14C]glucose was converted into both organic acids. Combining glucose with a selection of amino acids as primary nitrogen/secondary carbon sources yielded less pyruvate and more 2-oxoglutarate. Carbon from both 14C-labelled glucose and amino acids was metabolized to both organic acids. Adding nitrate to this combination caused a reversion of the acid production pattern to that of the glucose-nitrate combination, as if the amino acids were absent. Addition of ammonium salts to any combination of carbon and nitrogen sources completely prevented organic acid formation.
在含有某些快速利用的碳源和氮源的限定培养基中生长的淡紫灰链霉菌TK24培养物会分泌高水平的有机酸。通过高效液相色谱法（HPLC）和酶法测定，这些有机酸被鉴定为丙酮酸和2-氧代戊二酸。酸化仅在以葡萄糖作为主要碳源时发生，并且取决于所使用的氮源。以硝酸盐作为唯一氮源时，会产生高水平的丙酮酸和少量的2-氧代戊二酸。D-[U-¹⁴C]葡萄糖中的碳被转化为这两种有机酸。将葡萄糖与一系列氨基酸作为主要氮源/次要碳源组合使用时，产生的丙酮酸较少，而2-氧代戊二酸较多。¹⁴C标记的葡萄糖和氨基酸中的碳都被代谢为这两种有机酸。向这种组合中添加硝酸盐会导致产酸模式恢复为葡萄糖-硝酸盐组合的模式，就好像不存在氨基酸一样。向任何碳源和氮源组合中添加铵盐会完全阻止有机酸的形成。
