Photocatalytic performance of an [alpha]-Fe.sub.2O.sub.3 electrode and its effects on the growth and metabolism of Citrobacter freundii

Electronic exchanges occur between semiconductor minerals and microorganisms. However, researchers have focused on the photocatalytic degradation of pollutants by semiconductor minerals, and there is a limited amount of studies on semiconductor photogenerated electrons that influence the growth and...

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Bibliographic Details
Published in:Applied microbiology and biotechnology 2022-09, Vol.106 (18), p.6253
Main Authors: Bai, Long, Wang, Jueyu, Wang, Yuelei, Wang, Yongqi, Yang, Yue, Cui, Daizong, Zhao, Min
Format: Article
Language:English
Subjects:
Analysis
Chemical synthesis
Diffraction
Electric properties
Electrodes
Enterobacter
Enterobacteriaceae
Growth
Hematite
Mechanical properties
Methods
Photoelectron spectroscopy
Photoionization
X-ray spectroscopy
X-rays
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Summary:Electronic exchanges occur between semiconductor minerals and microorganisms. However, researchers have focused on the photocatalytic degradation of pollutants by semiconductor minerals, and there is a limited amount of studies on semiconductor photogenerated electrons that influence the growth and energetic mechanisms of bacteria. Bioelectrochemical systems (BES) are important new bioengineering technologies for investigating the mechanisms by which bacteria absorb electrons. In this work, we built a BES that used [alpha]-Fe.sub.2O.sub.3 nanorods as a photoanode and Citrobacter freundii as bio-cathode bacteria to explore the effect of photoelectrons on C. freundii growth and metabolism. The photoanode was prepared by a hydrothermal synthesis method. As confirmed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), the photoanode was made of [alpha]-Fe.sub.2O.sub.3. Corresponding scanning electron microscope (SEM) images showed that [alpha]-Fe.sub.2O.sub.3 nanorod arrays formed with a diameter of 50 nm, and the band gap was 2.03 eV, as indicated by UV-vis diffuse reflectance spectroscopy (UV-vis DRS). The C. freundii growth metabolism changed significantly because of photoelectrons; under light conditions, the growth rate of C. freundii significantly accelerated, and as inferred from the three-dimensional fluorescence spectrum, the protein, humic acid, and NADH concentrations were significantly higher at 72 h. According to the changes in the organic acid content, photoelectrons participated in the reductive tricarboxylic acid cycle (rTCA) to enhance growth and metabolism. The results of the study have broad implications for advancing fields that study the effects of semiconductor minerals on electroactive microorganisms and the semiconductor-photoelectronic transport mechanisms of electroautotrophic microorganisms.
ISSN:0175-7598
1432-0614
DOI:10.1007/s00253-022-12120-9