Biosensors (Dec 2022)

A Selective Fluorescent <span style="font-variant: small-caps">l</span>-Lactate Biosensor Based on an <span style="font-variant: small-caps">l</span>-Lactate-Specific Transcription Regulator and Förster Resonance Energy Transfer

  • Xianzhi Xu,
  • Rong Xu,
  • Shuang Hou,
  • Zhaoqi Kang,
  • Chuanjuan Lü,
  • Qian Wang,
  • Wen Zhang,
  • Xia Wang,
  • Ping Xu,
  • Chao Gao,
  • Cuiqing Ma

DOI
https://doi.org/10.3390/bios12121111
Journal volume & issue
Vol. 12, no. 12
p. 1111

Abstract

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Selective detection of l-lactate levels in foods, clinical, and bacterial fermentation samples has drawn intensive attention. Many fluorescent biosensors based on non-stereoselective recognition elements have been developed for lactate detection. Herein, the allosteric transcription factor STLldR from Salmonella enterica serovar Typhimurium LT2 was identified to be stereo-selectively respond to l-lactate. Then, STLldR was combined with Förster resonance energy transfer (FRET) to construct a fluorescent l-lactate biosensor FILLac. FILLac was further optimized by truncating the N- and C-terminal amino acids of STLldR between cyan and yellow fluorescent proteins. The optimized biosensor FILLac10N0C exhibited a maximum emission ratio change (ΔRmax) of 33.47 ± 1.91%, an apparent dissociation constant (Kd) of 6.33 ± 0.79 μM, and a limit of detection of 0.68 μM. FILLac10N0C was applied in 96-well microplates to detect l-lactate in bacterial fermentation samples and commercial foods such as Jiaosu and yogurt. The quantitation results of FILLac10N0C exhibited good agreement with that of a commercial l-lactate biosensor SBA-40D bioanalyzer. Thus, the biosensor FILLac10N0C compatible with high-throughput detection may be a potential choice for quantitation of l-lactate in different biological samples.

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