Open AccessCanary in the coliform mine: Exploring the industrial application limits of a microbial respiration alarm system
Author(s) -
Wendy Stone,
Tobias M. Louw,
M.J. Booysen,
Gideon Wolfaardt
Publication year - 2021
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0247910
Subject(s) - environmental science , bioreactor , contamination , respiration , fecal coliform , environmental chemistry , water quality , environmental engineering , pulp and paper industry , biology , chemistry , ecology , botany , engineering
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.