Transcriptome Analysis Reveals the Growth Promotion Mechanism of Enteropathogenic Escherichia coli Induced by Black Phosphorus Nanosheets

With the extensive production and application of black
phosphorus
(BP) nanosheets, release to the environment is inevitable, which raises
concerns about the fate and effects of this two-dimensional (2D) material
on sensitive receptors such as environmental microbes. Although the
bacterial toxicity of BP nanosheets has been demonstrated, whether
the biological response differs in pathogenic and nonpathogenic strains
of a microorganism is unknown. Here, enteropathogenic Escherichia coli (EPEC) and nonpathogenic Escherichia coli DH5α (E. coli DH5α), Escherichia coli k12
(E. coli k12), and Bacillus
tropicus (B. tropicus) are used to
comparatively study the microbial toxicity of BP nanosheets. Upon
exposure to BP nanosheets across a range of doses from 10 to 100 μg
mL–1 for 12 h, EPEC experienced enhanced growth
and E. coli DH5α and E. coli k12 were not affected, whereas B. tropicus exhibited clear toxicity. By combining transcriptome sequencing,
proteome analysis, and other sensitive biological techniques, the
mechanism of BP-induced growth promotion for EPEC was uncovered. Briefly,
BP nanosheets activate the antioxidation system to resist oxidative
stress, promote protein synthesis and secretion to attenuate membrane
damage, enhance the energy supply, and activate growth-related pathways.
None of these impacts were evident with nonpathogenic strains. By
describing the mechanism of strain-dependent microbial effects, this
study not only highlights the potential risks of BP nanosheets to
the environment and to human health but also calls attention to the
importance of model strain selection when evaluating the hazard and
toxicity of emerging nanomaterials.