Real-time monitoring of bacterial growth kinetics in suspensions using laser speckle imaging

Abstract

In microbiology, monitoring the growth of any microorganism in culture is important for studying and optimizing the growth kinetics, the biomass and the metabolite production. In this work, we show that laser speckle imaging is a reliable technique that can be used to perform real-time monitoring of bacteria growth kinetic in liquid culture media. Speckle parameters, specifically speckle grain size and the spatial contrast of the speckle images, and standard analytical parameters (optical density, pH and colony forming units) were measured during the culture of different strains of Bacillus thuringiensis. Our results show that both speckle grain size and spatial contrast decrease with bacterial growth. Furthermore, speckle parameters are sensitive to the fermentation conditions. Statistical analysis revealed a relatively high correlation between speckle and analytical parameters.

Holographic Imaging of Insect Cell Cultures: Online Non-Invasive Monitoring of Adeno-Associated Virus Production and Cell Concentration

“…Most cell culture monitoring methods employing label-free methodologies are based on spectroscopic techniques, which have been widely used for cell culture process monitoring. Examples include the use of dielectric spectroscopy and turbidimetry/light scattering probes for the determination of cell concentration [4,5], as well as the use of Raman [6,7], infrared [8] and fluorescence [9] spectroscopy, which allow the quantification of metabolites based on direct spectra quantification, but also the indirect determination of cell concentration and product formation based on chemometric analysis.…”

Advances in Optical Detection of Human-Associated Pathogenic Bacteria

“…Kim et al exploited this finding to analyze differences in the swarming growth behaviors of Bacillus species using LSCI, and they found that the average speckle grain size and spatial contrast decreased while the number speckles increased during bacterial colony growth [191]. Because LSCI is low-cost, label-free, and requires very little laser power, the speckle parameters measured by this technique offer a scattering-based optical strategy for the real-time monitoring of bacterial growth kinetics over extended periods [201]. Though Bacillus produces the most notable speckle contrast, all bacteria are motile to some degree during colony growth, and so LSCI is capable of monitoring growth behavior across many genera.…”

“…In vivo biofilms [173][174][175][176][177][178][179][180][181] NA LSCI Bacterial cultures [191,194,200,201] NA…”

Morphological Study of Bacillus thuringiensis Crystals and Spores

“…An in-depth investigation of all aspects involved in B. thuringiensis biopesticidal activity-be they genomic, proteomic, morphological, related to crystal and spore production kinetics and stability or otherwise-is a necessity created by the increased use of B. thuringiensis spore-crystal mixtures in the environment. One of the most recent techniques used to monitor the growth kinetics and production of B. thuringiensis spores and crystals is laser speckle imaging, a reliable and non-invasive technique based on light scattered by an illuminated medium [18]. In order to have accurate results and to understand the interaction between the light and the bacterial density, the size and shape of the scatterers in question should be known, along with whether these scatterers are in suspensions [19] or embedded in agar plates [20].…”