Construction of mini‐chemostats for high‐throughput strain characterization

Abstract

To achieve large‐scale, high‐throughput experiments for systems biology research of microorganisms, reliable data from robust cultivation systems are needed. Chemostats are such systems, ensuring reproducibility and quality by providing a stable, well‐controlled environment for the cells. However, many of the available chemostat systems require large amounts of media and are complex to set up and expensive to purchase and maintain. To address these concerns, we developed a mini‐chemostat (MC) system with 16 reactors, each at a working volume of 40 ml. Sensors measure dissolved oxygen in the reactor, while OD600 is measured in the outflow. We further developed a CO2 and pH sensor array that can be plugged into the outflow of the reactors. The system was used to characterize yeast physiology at four metabolically different conditions: limitations of glucose, both aerobic and anaerobic, nitrogen, and ethanol. The physiology of yeast cells grown at the four different conditions in the MC system was compared with the yeast cells grown in a DASGIP 1 L system using RNAseq analysis. The results show that the MC system provides the same environmental conditions as the DASGIP system and that the MC system is reproducible between different runs. The system is built to be easily scalable with more reactors and to include more sensors, if available. Our study shows that a robust, reproducible chemostat system for high‐throughput and large‐scale experiments can be built at low costs.

Exploring small-scale chemostats to scale up microbial processes: 3-hydroxypropionic acid production in S. cerevisiae

“…The for continuous cultivations modified single-use stirred-tank bioreactor system (bioREACTOR, 2mag AG) operates with eight parallel reactors at a working volume of 10 mL [26]. The mini-chemostat (MC) system developed by Bergenholm et al [27] comprises 16 parallel reactors and requires a working volume of 40 mL. Our system is therefore well applicable for the simple and cost-effective screening of microbial performance in continuous mode.…”

Recent Developments in Bioprocessing of Recombinant Proteins: Expression Hosts and Process Development

“…A membrane-based fed-batch shake flask with a Respiration activity monitoring system (RAMOS) device was also used to study the effect of substrate-limited fed-batch conditions (Habicher et al, 2019b). A mini-chemostat (MC) system (16 reactors with 40 ml working volume) was developed to characterize yeast physiology, and it was shown that the MC system provided the same environmental conditions as the DASGIP R parallel bioreactor system (Eppendorf) (Bergenholm et al, 2019). In a recent review, a systematic approach toward scale-down model (SDM) development in ambr 15 systems was described, and it was suggested that ambr SDMs are suitable for future regulatory submissions (Sandner et al, 2018).…”

In situ characterisation and manipulation of biological systems with Chi.Bio

“…This can be partially achieved using continuous culture devices such as a turbidostat, which dilutes cells during growth to maintain a constant optical density (OD). In recent years, a number of turbidostat platforms have been developed and are beginning to find widespread applications in systems, synthetic, and evolutionary biology [11][12][13][14][15][16][17][18][19]. There has also been significant development of open-source platforms for optogenetics [20,21], which have been used to implement real-time measurement [22] and feedback control [23] and to demonstrate orthogonal regulation of multiplexed optogenetic regulators [24].…”