PubMed · 9255020
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K Rajeshwari. 1997. Partial liquid ventilation in neonates.. https://pubmed.ncbi.nlm.nih.gov/9255020/
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Perfluorooctane sulfonate (PFOS) is a prominent perfluorinated compound commonly found in the environment, known to pose various risks to human health. However, the removal of PFOS presents significant challenges, primarily due to the limited discovery of bacteria capable of effectively degrading PFOS. Moreover, single degradation bacteria often encounter obstacles in individual cultivation and the breakdown of complex pollutants. In contrast, microbial consortia have shown promise in pollutant degradation. This study employed a continuous enrichment method, combined with multiple co-metabolic substrates, to investigate a microbial consortium with the potential for PFOS degradation. By employing this methodology, we effectively identified a microbial consortium that demonstrated the capacity to reduce PFOS when exposed to an optimal concentration of methanol. The consortium predominantly comprised of Hyphomicrobium species (46.7%) along with unclassified microorganisms (53.0%). Over a duration of 20 days, the PFOS concentration exhibited a notable decrease of 56.7% in comparison to the initial level, while considering the exclusion of adsorption effects. Furthermore, by comparing the predicted metabolic pathways of the microbial consortium with the genome of a known chloromethane-degrading bacterium, Hyphomicrobium sp. MC1, using the KEGG database, we observed distinct variations in the metabolic pathways, suggesting the potential role of the unclassified microorganisms. These findings underscore the potential effectiveness of a "top-down" functional microbial screening approach in the degradation of stubborn pollutants.
Polymers with perfluoroalkyl side chains have recently attracted a great deal of interest as additives to surface hydrophobicity to values higher than these corresponding to polytetrafluoroethylene. The structure and surface free energy of random and diblock copolymers of methyl methacrylate and 2-perfluorooctylethyl methacrylate (PMMA-r-PFEMA and PMMA-b-PFEMA, respectively) were compared using dynamic contact angle, X-ray photoelectron spectroscopy, X-ray diffraction, and reflection-adsorption FT-IR spectroscopy. The PMMA-b-PFEMA solution cast film showed a surface free energy of 7.8 mJ/m2. This value was lower than that of PMMA-r-PFEMA solution cast film (13.4 mJ/m2) but is comparable to the lowest value (6.7 mJ/m2) reported in literature. The surface of PMMA-b-PFEMA was almost covered with the CF3 groups of self-assembled perfluoroalkyl side chains. On the other hand, more CF2 groups and methacrylate main chain were exposed on the PMMA-r-PFEMA film surface due to parallel orientation of the perfluoroalkyl side chains, which determined the relatively higher surface free energy of the PMMA-r-PFEMA film.
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