Using CO2 level monitoring to adjust the stress conditions of morbidostats

Abstract

In a conventional morbidostat, cell growth is monitored by measuring OD, and stress conditions are automatically adjusted using OD values. However, phenomena such as biofilm formation, agglomeration, and the presence of opaque substrates or products can result in inaccurate OD measurements of population size, causing morbidostat systems to fail to adjust stress conditions appropriately.This study offers a solution for circumstances where it is impractical to determine vital activity based on OD by developing a novel morbidostat system that adjusts stress conditions based on measurements of exhaust CO2. As a proof of concept, the adaptation of E. coli ATCC 47076 to 48 °C was performed with two morbidostats using this new strategy. Both populations evolved in the morbidostats were confirmed to grow at 48 °C, a temperature their ancestral strain cannot withstand.

Keywords

• Morbidostat
• Adaptive laboratory evolution
• High-temperature adaptation
• Bioprocess control
• Off-gas analysis
• Continuous culture