Synthetic biology approaches to hydrocarbon biosensors

Abstract

Biosensors offer the possibility of rapid and accurate detection of small amounts of hydrocarbon gases in environments where traditional lab-based methods cannot be used. Such biosensors could address current issues in many industries in Australia. LNG is one of Australia’s biggest exports, with over 100,000km of natural gas pipelines spanning the country. A gaseous alkane biosensor would enable detection of leaks in liquified natural gas (LNG) pipelines and plants, minimising environmental impacts and improving safety outcomes. In agriculture, a quarter of all fruits and vegetables grown each year are wasted due to mismanagement of produce ripeness. A gaseous alkene biosensor would enable detection of ethylene, a key plant ripening hormone, decreasing produce losses. A suite of transcription-factor driven, cell-based hydrocarbon gas biosensors was developed using the regulatory components from Mycobacterium chubuense NBB4 monooxygenases to facilitate quick, reliable, and easy quantification of gases in remote environments. A genetic toolbox to enable the characterisation of the regulatory proteins/promoters was also developed. EtnR1, EtnR2 and Petn were successfully identified as the regulatory components of the EtnABCD monooxygenase and developed into a biosensor. Key promoter elements of the Petn promoter were validated through a series of promoter truncation assays. Ethylene oxide was identified as the primary inducer of the EtnR12P regulatory system, and a biosensor for EtO with a detection range of 8-2,200 ppb was characterised. The EtO biosensor was successfully adapted to detect ethene when the EtnABCD cluster was co-expressed in a mixed culture assay.