Transcriptome analysis of Corynebacterium glutamicum ΔtrpP

For the establishment of synthetic microbial communities comprising complementary auxotrophic strains, transport processes for common goods are extremely important. Most auxotrophic strains reach wild type level growth with external supplementation of the required metabolite. One exception was the tryptophan auxotrophic strain Corynebacterium glutamicum ΔTRP ΔtrpP, which grew about 35% slower than the wild type in supplemented minimal medium. Corynebacterium glutamicum ΔTRP ΔtrpP lacks the whole tryptophan biosynthesis cluster (TRP) as well as the putative tryptophan transporter TrpP. We wanted to explore the role of TrpP in tryptophan transport or synthesis and to unravel the cause for the growth limitation of the auxotrophic strain. We performed a transcriptome comparison of WT ΔtrpP and WT in CGXII minimal medium with 2% (w/v) glucose as carbon source. The growth of these two strains was slightly different, thus we might detect altered genes as secondary effects due to the different growth rates. Overall, in WT ΔtrpP, 82 genes had an at least 2-fold reduced transcription and 18 genes had an at least 2-fold increased transcription (3 out of 4 experiments, p<0.05, signal to noise ratio >2). The trpP gene exhibited the strongest downregulated apparent gene expression, thereby confirming its deletion.