In situ near infrared spectroscopy for analyte‐specific monitoring of glucose and ammonium in streptomyces coelicolor fermentations

Abstract

There are many challenges associated with in situ collection of near infrared (NIR) spectra in a fermentation broth, particularly for highly aerated and agitated fermentations with filamentous organisms. In this study, antibiotic fermentation by the filamentous bacterium Streptomyces coelicolor was used as a model process. Partial least squares (PLS) regression models were calibrated for glucose and ammonium based on NIR spectra collected in situ. To ensure that the models were calibrated based on analyte-specific information, semisynthetic samples were used for model calibration in addition to data from standard batches. Thereby, part of the inherent correlation between the analytes could be eliminated. The set of semisynthetic samples were generated from fermentation broth from five separate fermentations to which different amounts of glucose, ammonium, and biomass were added. This method has previously been used off line but never before in situ. The use of semisynthetic samples along with validation on an independent batch provided a critical and realistic evaluation of analyte-specific models based on in situ NIR spectroscopy. The prediction of glucose was highly satisfactory resulting in a RMSEP of 1.1 g/L. The prediction of ammonium based on NIR spectra collected in situ was not satisfactory. A comparison with models calibrated based on NIR spectra collected off line suggested that this is caused by signal attenuation in the optical fibers in the region above 2,000 nm; a region which contains important absorption bands for ammonium. For improved predictions of ammonium in situ, it is suggested to focus efforts on enhancing the signal in that particular region.

Monitoring and Control of a Continuous Grignard Reaction for the Synthesis of an Active Pharmaceutical Ingredient Intermediate Using Inline NIR spectroscopy

“…The difference between the 3 calibration experiments was the initial alkoxide concentration (135, 225, and 290 g/L) and the Grignard strength used (0.6, 1.1, and 2 M, respectively). This calibration procedure was followed with the purpose of (a) eliminating correlation between the change in concentration of the two analytes and thereby obtain PLS models specific to each analyte; 38 (b) obtaining a robust PLS model for CTX, including variability in alkoxide concentration around the expected set point (∼215 g/ L); and (c) generating a very rough alkoxide PLS model.…”

In situNIR spectroscopy monitoring of plasmid production processes: effect of producing strain, medium composition and the cultivation strategy

“…A number of publications describe the use of NIR fiber optic probes to monitor in situ biomass growth of bacteria and mammalian cells, carbon source consumption, by‐product formation and consumption, and their corresponding products, which include amino acids and protein complexes . NIR spectroscopy provides less informative spectra compared with mid‐infrared (MIR) spectra, as the former represents combinations and overtones of molecular vibrations, and not fundamental vibrations modes provided by MIR spectroscopy, which makes the extraction of quantitative relevant information possible only by the use of multivariate data analysis, such as partial least square (PLS) regression.…”

At-line monitoring of key parameters of nisin fermentation by near infrared spectroscopy, chemometric modeling and model improvement

“…There are several papers on the at-line analysis with NIR spectroscopy in bioprocesses (Roychoudhury et al 2007b;Cervera et al 2009;Petersen et al 2010;Vaidyanathan et al 2001;Franco et al 2006), though some results have been depended on the same fermentor, the same batch, the fixed conditions or a defined chemical fermentation medium, good results have been achieved. It showed the feasibility of at-line and on-line analysis with NIR spectroscopy in fermentation processes.…”