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Adhesion of Bacteria to Solid Surfaces
Published in Girma Biresaw, K.L. Mittal, Surfactants in Tribology, 2019
Nabel A. Negm, Dina A. Ismail, Sahar A. Moustafa, Maram T.H. Abou Kana
Caulobacter crescentus is an attractive illustration of a bacterium species that takes advantage of surface attachment to optimize nutrient uptake. C. crescentus oscillates between stalked cells that adhere tightly to surfaces using a protein holdfast and motile cells that lack this organelle and instead have a polar flagellum. This phenotypic switch makes it possible for cells to adapt to both nutrient-rich (favoring motility) and nutrient-poor (favoring adhesion) environments [60].
A critical review of uranium in the soil-plant system: Distribution, bioavailability, toxicity, and bioremediation strategies
Published in Critical Reviews in Environmental Science and Technology, 2023
Qingliang Cui, Zhiqin Zhang, Jingzi Beiyuan, Yongxing Cui, Li Chen, Hansong Chen, Linchuan Fang
Diverse types of microorganisms (e.g., bacteria and fungi) have varied tolerability to U. Hu et al. (2019) found that E. coli, Pseudomonas putida, and Caulobacter crescentus (C. crescentus) had significantly different intolerance to U. At 200 μM U, C. crescentus growth rate was not significantly affected and it was not until a concentration of 1.0 × 103 μM U was reached that C. crescentus growth slowed. The growth of E. coli was significantly affected at 500 μM U, while the growth of P. putida was initially inhibited at 800 μM U. This is because the calcium-uranium-phosphate complex is formed outside the cell of C. crescentus, separating U from the cell. Similarly, Suzuki and Banfield (2004) studied the accumulation of U by three bacteria of D. radiodurans, Arthrobacter ilicis (A. ilicis), and E. coli and evaluated the resistance of these bacteria to U(VI). The results presented that the total number of viable cells of the three bacteria exposed to U decreased by 8.51 × 107, 8 × 108, and 2.53 × 108 CFU (Colony-Forming Units), respectively, compared to the treatment without U. This could be due to the first two bacteria had polyphosphates, which could produce uranyl phosphate minerals outside cells. In addition, the tolerance of U-contaminated cells was also found to vary depending on the fungal species. Pleurotus ostreatus (P. ostreatus) and Leucoagaricus naucinus (L. naucinus) show lower tolerance to U(VI) than S. commune. After 48 h of U exposure, the cell viability of the three was S. commune (55.9 ± 3.8%) > L. naucinus (13.9 ± 4.1%) > P. ostreatus (11.3 ± 0.9%) (Wollenberg et al., 2021). This is due to the stable immobilization of U by phosphatic bioligands (autunite, (UO2)3(OH)5+, and UO2HPO4) on the cell membrane and cell wall of S. commune. Moreover, (UO2)3(OH)5+ and (UO2)3(PO4)2 are only associated on the surface of the L. naucinus. Moreover, the effects of U on microorganisms can be studied in depth by advanced techniques, such as X-ray absorption fine structure (XAFS) and omics techniques. The molecular morphology of U on microbial surfaces can be examined by XAFS (Li et al., 2018). The toxicity mechanisms of U to microorganisms can be scrutinized by proteomics and genomics tests (Kolhe et al., 2018; Lai et al., 2020).