Direct optical density determination of bacterial cultures in microplates for high-throughput screening applications

Publication date: Available online 3 July 2018Source: Enzyme and Microbial TechnologyAuthor(s): Annika Meyers, Christoph Furtmann, Joachim JoseAbstractA convenient and most abundantly applied method to determine the growth state of a bacterial cell culture is to determine the optical density (OD) spectrophotometrically. Dilution of the samples, which is necessary to measure within the linear range of the spectrophotometer, is time-consuming and not compatible with high-throughput applications. Here we present a direct approach to estimate the OD at 578 nm (OD578) of bacterial cultures in microplates without the need for sample dilution. This could be advantageous for high-throughput analysis of bacterial cells in microplates for example when optimizing growth conditions, screening for new substrates of a bacterial strain or monitoring enzymatic activity after enzyme evolution. Pseudomonas putida cells were grown in shake flasks. The OD578 was determined in parallel in a microplate directly without dilution and in a spectrophotometer cuvette after dilution. The resulting data set was used to identify a conversion formula, which enables direct and reliable transformation of OD measurements of undiluted samples into the corrected OD values as would have been obtained for diluted samples measured in a standard spectrophotometer.Subsequently we could show that just a few OD calibration points are required to adjust this conversion formula and make it suitable for other suspensio...
Source: Enzyme and Microbial Technology - Category: Biotechnology Source Type: research