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

• A microrespirometry method was developed in a 24-well microreactor system.
• The method was tested for the determination KS, μmax and YX/S of four cultures.
• These parameters were determined with lower error than with standard respirometry.
• This method is of interest for meaningful process developments in short times.

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 (KLa), which is important for the interpretation of respirometric data, was determined under an exhaustive set of experimental conditions. KLa ranged from 2.2 to 48.0 h−1, which is similar to KLa 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.