Figure 4.

Requirement of the aspartase gene in the alternative pathway for glutamate utilization. The SPABBATS algorithm (see Figure 2) and the transcription analysis (see Figure 3) suggested that the overexpression of the asparaginase and aspartase genes (ansAB) is the cause for the metabolic gain of function of the mutant strain GP717. To prove this, the ansAB operon was deleted in the GP717 strain. The resulting strain GP1154 lost the capacity to utilize glutamate as single carbon source. This strongly indicates that the induction of the aspartase gene is required and sufficient for the newly activated catabolic pathway. CE = Minimal medium containing 0.5% glutamate, CE-Glc = CE medium with an addition 0.5% glucose.