Ribosomes are a crucial component of the physiological state of a cell. Therefore, we aimed to monitor ribosome dynamics using a fast and easy fluorescence readout. Using fluorescent-labeled ribosomal proteins, the dynamics of ribosomes during batch cultivation and during nutritional shift conditions was investigated. The fluorescence readout was compared to the cellular rRNA content determined by capillary gel electrophoresis with laser-induced fluorescence detection during exponentially accelerating and decelerating growth. We found a linear correlation between the observed fluorescence and the extracted rRNA content throughout cultivation, demonstrating the applicability of this method. Moreover, the results show that ribosome dynamics, as a result of slowing growth, are accompanied by the passive effect of dilution of preexisting ribosomes, de novo ribosome synthesis and ribosome degradation. In light of the challenging task of deciphering ribosome regulatory mechanisms, our approach of using fluorescence to follow ribosome dynamics will allow more comprehensive studies of biological systems.

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cis -Dihydrodiendiols are valuable compounds, finding multiple application as chiral synthons in organic chemistry. The biotechnological route for the generation of cis -dihydrodiendiols involves the dihydroxylation of aromatic compounds, catalyzed by Rieske non-heme iron dioxygenases. To date, numerous examples of recombinant E. coli , harboring such dioxygenases, can be found in the literature. Nevertheless, there is only a minor number of publications, addressing the E. coli catalyzed degradation of cis -dihydrodiendiols into catechols via dehydrogenases. Identification and elimination of such dehydrogenase catalyzed degradation is key for the establishment of enhanced recombinant E. coli platforms pursuing the production of cis -dihydrodiendiols. Here, we provide a fast and easy strategy for the identification of promiscuous alcohol dehydrogenases in E. coli BW25113, catalyzing the degradation of cis -dihydrodiendiols into catechols. This approach is based on the screening of dehydrogenase deficient KEIO strains, regarding their incapability of degrading a cis -dihydrodiendiol of choice. Novel screening strategy for E. coli BW25113 dehydrogenase knock-outs, incapable of degrading cis -dihydrodiendiols was validated for cis -1,2-dihydrocatechol as substrate Corresponding knock-outs can be used for recombinant production of cis -dihydrodiendiols Simple analysis based on liquid chromatography with diode array detector (HPLC-DAD)