Transcriptional analyses of an ethanol inducible promoter in Escherichia coli and tobacco for production of cellulase and green fluorescent protein

Abstract

Cellulase is a widely used enzyme for saccharification of plant cell walls for the production of biofuels. In our work, we tested an ethanol inducible native alcA promoter from Aspergillus nidulans in Escherichia coli (E. coli) and tobacco. The alcA promoter was fused with a cellulase gene and then the promoter was compared with other widely used promoters, namely, T5 and cauliflower mosaic virus (CaMV) 35S in E. coli. We also tested the activity of alcA promoter in tobacco by transiently expressing a green fluorescent protein gene under the control of alcA promoter. We concluded from our quantitative polymerase chain reaction (qPCR) results that when alcA promoter was expressed along with AlcR transcription factor, the alcA promoter was 11 times more active than the T5 promoter. The qPCR data suggested that there may be a direct correlation between AlcR concentrations and alcA activity, indicating a key role of the activator AlcR in the regulation of the alcA promoter. Our work on inducible promoter system for cellulase production may open new avenues of research in the field of biofuel development from living cells.