Physico‐chemical methods for characterization of the physiological state of microorganisms

Zentgraf, B.

doi:10.1002/jctb.280640204

Cited by 2 publications

(1 citation statement)

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“…The PS can thus be considered as a fitness indicator of culturing systems for their correct function and successful operation, which is a concept applicable to monocultures or mixed consortia. Hence, the compilation of key features of the biotic phase can provide better insights regarding the physiological state, such as morphology (shape and size of cells), the state of nucleic acids, the functionality of certain enzymes or redox cofactors, the status of transport mechanisms, and the membrane potential, among others [24].…”

Section: Introductionmentioning

confidence: 99%

Monitoring the Physiological State in the Dark Fermentation of Maize/Grass Silage Using Flow Cytometry and Electrooptic Polarizability Measurements

et al. 2020

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Dark fermentation (DF), a key biohydrogen-producing process, is generally operated as a black-box, by monitoring different operative macroscopic process parameters without evaluating or tracking the physiology of the biotic phase. The biotic phase in DF is constituted by a large variety of microorganisms, mainly fermentative bacteria. The present study uses two (electro)optical techniques, flow cytometry (FC) and frequency-dependent polarizability anisotropy (FDPA) measurements, to gain insights into the physiology of open mixed consortia throughout the DF process. The mixed consortia for DF were obtained from a methanogenic sludge, selecting spore-forming bacteria by means of an acid treatment. Then, DF systems with and without pH control were studied, using as substrate a mixture of maize and grass silage (9:1 w/w). Over the course of fermentation, the butyric pathway was dominant in both systems, and relevant titers of acetate, formate, and ethanol were detected; while hydrogen yields amounted to 20.80 ± 0.05 and 17.08 ± 0.05 NmL/gVS under pH-regulated and non-regulated conditions, respectively. The cytometric pattern analysis of the culture together with microscopic observations made it possible, over the course of fermentation, to identify and track the predominant morphologies in play (i.e., free spore, rod-shaped, and endospore, which are typical of Clostridium spp.). Furthermore, the use of the fluorescent dye DiBAC 4 (3) in FC and FDPA measurements provided similar information regarding the physiological state (PS) of the mixed consortia during the different phases of the culture.

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Section: Introductionmentioning

confidence: 99%