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Updated: Jan 26, 2026

An Assay for Measuring the Activity of Escherichia coli Inducible Lysine Decarboxyase
Published on: December 19, 2010
Deciphering functional redundancy of lysine decarboxylases in probiotic E. coli Nissle 1917 via an integrated
Yiqing Zhang1, Mingyu Wu2, Feng Geng3
1School of Pharmacy, Binzhou Medical University, Yantai 264003, China; Key Laboratory of Molecular Pharmacology and Drug Evaluation, Ministry of Education, School of Pharmacy, Yantai University, Yantai 264005, China; Jinan Microecological Biomedicine Shandong Laboratory, Jinan 250000, China.
Abstract:
Fourier transform infrared (FTIR) microspectroscopy is a rapid, label-free tool for microbial metabolic phenotyping. Here, we integrate synchrotron-based FTIR microspectroscopy with CRISPR-Cas9 editing to decipher the functional redundancy of lysine decarboxylases (LdcC1 and LdcC2) in probiotic Escherichia coli Nissle 1917. Under lysine stress, isogenic mutants (ΔldcC1, ΔldcC1ΔldcC2) exhibited distinct FTIR fingerprints. Spectral analysis revealed: (i) CH shifts (2950-2850 cm-1) indicating ΔldcC1-specific membrane remodeling; (ii) Amide I band profile alterations (∼1650 cm-1) suggesting protein structural perturbations; and (iii) a constitutive elevation in 1220-1260 cm-1 band area in the double mutant, revealing a basal state of metabolic frailty. Principal component analysis of second-derivative spectra revealed clear separation trends among strain phenotypes. We establish LdcC2 as a crucial functional complement, while LdcC1 uniquely contributes to membrane homeostasis. The compensatory stress response activated in the double mutant underscores metabolic redundancy as a cornerstone of intrinsic cellular robustness. Collectively, this work validates a CRISPR-FTIR phenomics platform that bridges targeted genetics with global biochemistry, offering a rapid alternative for functional genomics and metabolic engineering in microbes.
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