Journal Article

Canary in the coliform mine: Exploring the industrial application limits of a microbial respiration alarm system

Stone, Wendy, Booysen, Marthinus J., Wolfaardt, Gideon M., Louw, Tobi M.

2021

Overview

Fundamental ecological principles of ecosystem-level respiration are extensively applied in greenhouse gas and elemental cycle studies. A laboratory system termed CEMS (Carbon Dioxide Evolution Measurement System), developed to explore microbial biofilm growth and metabolic responses, was evaluated as an early-warning system for microbial disturbances in industrial settings: in (a) potable water system contamination, and (b) bioreactor inhibition. Respiration was detected as CO 2 production, rather than O 2 consumption, including aerobic and anaerobic metabolism. Design, thresholds, and benefits of the remote CO 2 monitoring technology were described. Headspace CO 2 correlated with contamination levels, as well as chemical (R 2 > 0.83–0.96) and microbiological water quality indicators (R 2 > 0.78–0.88). Detection thresholds were limiting factors in monitoring drinking water to national and international standards (0 CFU/100 mL fecal coliforms) in both open- (>1500 CFU/mL) and closed-loop CO 2 measuring regimes (>100 CFU/100 mL). However, closed-loop detection thresholds allow for the detection of significant contamination events, and monitoring less stringent systems such as irrigation water (<100 CFU/mL). Whole-system respiration was effectively harnessed as an early-warning system in bioreactor performance monitoring. Models were used to deconvolute biological CO 2 fluctuations from chemical CO 2 dynamics, to optimize this real-time, sustainable, low-waste technology, facilitating timeous responses to biological disturbances in bioreactors.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Alarm systems / Biodegradability / Biodegradation / Biofilms / Biology and Life Sciences / Carbon dioxide / Carbon dioxide atmospheric concentrations / Carbon dioxide measurements / Carrier gases / Contamination / Data logging / Developing countries / Drinking water / Drought / Earth Sciences / Ecology and Environmental Sciences / Editing / Enterobacter / Enterobacteriaceae / Environmental aspects / Environmental monitoring / Environmental pollution / Failure / Flow velocity / Headspace / Industrial applications / Industrial wastes / Laboratories / LDCs / Logging / Metabolism / Methodology / Microbial contamination / Microbial mats / Microbial respiration / Microbiology / Microorganisms / Physical Sciences / Physiological aspects / Process engineering / Reactors / Remote monitoring / Respiration / Reviews / River ecology / Safety and security measures / Sensors / Waste management / Wastewater treatment / Water pollution / Water scarcity / Water treatment