A microrespirometric method for the determination of stoichiometric and kinetic parameters of heterotrophic and autotrophic cultures

Abstract Respirometry, which consists in the measurement of the oxygen uptake rate, is a method commonly used to determine kinetic and stoichiometric parameters of biological processes. In the present work, a novel microrespironetry method, which involves standard respirometry procedures but in a microreactor array, was developed and assessed, based on a standard commercial apparatus. First, the volumetric oxygen transfer coefficient ( K L a ), which is important for the interpretation of respirometric data, was determined under an exhaustive set of experimental conditions. K L a ranged from 2.2 to 48.0 h −1 , which is similar to K L a typically found in standard respirometers. Then, the method was assessed through the determination of the maximum specific growth rate, the half-saturation constant and the growth yield of axenic and mixed cultures of autotrophic and heterotrophic bacteria. The selected cultures were Pseudomonas putida F1, Nitrobacter winogradskyi , an activated sludge and a nitrifying consortium. Additionally to reporting parameters for these cultures, this report shows that the microrespirometry method allowed for the determination of stoichiometric and kinetic parameters. Simultaneous tests done with a single culture sample, made possible by the microreactor array, allowed parameters determination with a lower standard error than observed with traditional respirometry and with much less experimental effort.