Alvarez H M, Kalscheuer R, Steinbüchel A
Institut für Mikrobiologie der Westfälischen Wilhelms-Universität Münster, Germany.
Appl Microbiol Biotechnol. 2000 Aug;54(2):218-23. doi: 10.1007/s002530000395.
The time course of the accumulation of triacylglycerols (TAGs) in Rhodococcus opacus PD630 or of TAGs plus polyhydroxyalkanoates (PHA) in Rhodococcus ruber NCIMB 40126 with gluconate or glucose as carbon source, respectively, was studied. In addition, we examined the mobilization of these storage compounds in the absence of a carbon source. R. opacus accumulated TAGs only after the exhaustion of ammonium in the medium, and, with a fixed concentration of the carbon source, the amounts of TAGs in the cells increased with decreasing concentrations of ammonium in the medium. When these cells were incubated in the absence of an additional carbon source, about 90% of these TAGs were mobilized and used as endogenous carbon source, particularly if ammonium was available. R. ruber accumulated a copolyester consisting of 3-hydroxybutyrate and 3-hydroxyvalerate already during the early exponential growth phase, whereas TAGs were synthesized and accumulated mainly during the late exponential and stationary growth phases. In the stationary growth phase, synthesis of TAGs continued, whereas PHA was partially mobilized. In the absence of an additional carbon source but in the presence of ammonium, mobilization of TAGs started first and was then paralleled by the mobilization of PHA, resulting in an approximately 90% and 80% decrease of these storage compounds, respectively. During the accumulation phase, interesting shifts in the composition of the two storage compounds occurred, indicating that the substrates of the PHA synthase and the TAG synthesizing enzymes were provided to varying extents, depending on whether the cells were in the early or late exponential or in the stationary growth phase.
研究了分别以葡萄糖酸或葡萄糖作为碳源时，不透明红球菌PD630中三酰甘油（TAGs）的积累时间进程，以及红球菌NCIMB 40126中TAGs与聚羟基脂肪酸酯（PHA）的积累时间进程。此外，我们还检测了在无碳源情况下这些储存化合物的动员情况。不透明红球菌仅在培养基中铵耗尽后才积累TAGs，并且在碳源浓度固定的情况下，细胞中TAGs的量随着培养基中铵浓度的降低而增加。当这些细胞在没有额外碳源的情况下培养时，约90%的这些TAGs被动员并用作内源性碳源，特别是在有铵存在的情况下。红球菌在指数生长早期就已经积累了由3-羟基丁酸酯和3-羟基戊酸酯组成的共聚酯，而TAGs主要在指数生长后期和稳定生长期合成并积累。在稳定生长期，TAGs的合成继续，而PHA则被部分动员。在没有额外碳源但有铵存在的情况下，TAGs的动员首先开始，随后PHA也被动员，导致这些储存化合物分别减少约90%和80%。在积累阶段，两种储存化合物的组成发生了有趣的变化，这表明PHA合酶和TAG合成酶的底物供应程度不同，这取决于细胞处于指数生长早期、晚期还是稳定生长期。
