Hao Zhou,Lin Che,Zhaoming Guo,Minghuo Wu,Wenqing Li,Weiping Xu,Lifen Liu
Bismuth selenide (Bi2Se3) attracts a lot of attention nowadays due to its unique electronic and thermoelectric properties. In this study, fabrication of Bi2Se3 nanosheets by selenite-reducing bacterium (SeRB) was first reported. Morphology, size, and location of the biogenic Bi2Se3 are bacteria-dependent. It is difficult to separate Bi2Se3 generated by Bacillus cereus CC-1 (Bi2Se3-C) from the biomass because of strong interaction with the cell membrane. However, Bi2Se3 produced by Lysinibacillus sp. ZYM-1 (Bi2Se3-Z), is highly dispersed in extracellular space with high stability. Further characterization by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM) on Bi2Se3-Z indicates that the product is a rhombohedral-phase, ultrathin nanosheet-like structure with an average size of ∼100 nm. Subsequently, the photothermal performance of Bi2Se3-Z with the irradiation of 808 nm near-infrared (NIR) laser was determined. When the Bi2Se3-Z concentration was 26 mg L–1, and irradiation power was 2 W, the photothermal conversion efficiency was calculated as 30.7%. At the same condition, 100% of the MCF7 and A549 cancer cells were killed within 10 min of irradiation in vitro. Moreover, using 1% (v/v) PVP as surfactant, a novel nanodumbbell structure of Bi2Se3 was obtained. Overall, this bacteria-driven Bi2Se3 fabrication paves a new way for biocompatible photothermal nanomaterials.
Membrane biofouling is a challenge to be solved for the stable operation of the seawater reverse osmosis (SWRO) membrane. This study explored the regulation mechanism of quorum sensing (QS) inhibition on microbial community composition and population-level behaviors in seawater desalination membrane biofouling. A novel antibiofouling SWRO membrane (MA_m) by incorporating one of quorum sensing inhibitors (QSIs), methyl anthranilate (MA) was prepared. It exhibited enhanced anti-biofouling performance than the exogenous addition of QSIs, showing long-term stability and alleviating 22 % decrease in membrane flux compared with the virgin membrane. The results observed that dominant bacteria Epsilon- and Gamma-proteobacteria ( Shewanella, Olleya, Colwellia, and Arcobacter ), which are significantly related to ( P ≤ 0.01) the metabolic products (i.e., polysaccharides, proteins and eDNA), are reduced by over 80 % on the MA_m membrane. Additionally, the introduction of MA has a more significant impact on the QS signal-sensing pathway through binding to the active site of the transmembrane sensor receptor. It effectively reduces the abundance of genes encoding QS and extracellular polymeric substance (EPS) (exopolysaccharides (i.e., galE and nagB ) and amino acids (i.e., ilvE, metH, phhA , and serB )) by up to 50 % and 30 %, respectively, resulting in a reduction of EPS by more than 50 %, thereby limiting the biofilm formation on the QSI-modified membrane. This study provides novel insights into the potential of QSIs to control consortial biofilm formation in practical SWRO applications.
危险品化学品经营许可证（带存储）