I need to monitor the expression of some genes or gene clusters in E.coli or Corynebacterium or Streptomyces. we plan to insert a reporter gene after our target promoter or the gene or the operon. We have very good reasons to believe their expression level is very low. so a high sensitive reporter gene is the key.

among the common reporter genes, which is the most sensitive one? eGFP, mCherry (RFP), lacZ, or lux (bioluminate)?