Proteolysis modification targeting protein corona affects ultrasound-induced membrane homeostasis of saccharomyces cerevisiae: Analysis of lipid relative contributions on membrane properties.

Introduction: Protein corona (PCN) adsorbed on the surface of nanoparticles has brought new research perspectives for the interaction between nanoparticles and microorganisms. In this study, the responses of saccharomyces cerevisiae' membrane lipid composition, the average length of the fatty acyl chains and the average number of unsaturation of fatty acids to ultrasound combined with nano-Fe3O4@PCN with time-limited proteolysis (nano-Fe3O4@TLP-PCN) was investigated. Methods: Lipidomic data was obtained using Ultra-high performance liquid chromatography coupled with a Q-Exactive plus mass spectrometer. The membrane potential, proton motive force assay and the membrane lipid oxidation were measured using Di-BAC4(3), DISC3(5) and C11-BODIPY581/591 as the probes. Combined with the approach of feasible virtual samples generation, the back propagation artificial neural network (BP-ANN) model was adopted to establish the mapping relationship between lipids and membrane properties. Results: The time-limited proteolysis targeting wheat PCN-coated Fe3O4 nanoparticles resulted in regular changes of hydrodynamic diameters, ζ-potentials, and surface hydrophobicity. In addition, with the prolongation of PCN proteolysis time, disturbances of 3 S.cerevisiae membrane characteristics, and membrane lipidomic remodeling in response to ultrasound+ nano-Fe3O4@PCN were observed. The analysis of relative importance which followed revealed that ergosterol, phosphatidylserine, and phosphatidylinositol phosphate had the greatest influence on membrane potential. For membrane lipid oxidation, ceramide, phosphatidylethanolamine, and sitosterol ester contribute 16.2, 14.9, and 13.1%, respectively. The relative contributions of six lysolecithins to the dissipation of proton motive force remained limited. Discussion: An adaptation mechanism of cell membrane to proteolyzed PCN, wherein lipidome remodeling could preserved functional membrane phenotypes was revealed. Furthermore, it is highlighted that the relative importances of SiE, Cer, PE and PIP in determining membrane potential, PMF dissipation and membrane lipid oxidation by establishing FVSG-BP-ANN model.

Cultivation-dependent and cultivation-independent characterization of the microbial community in acid mine drainage associated with acidic Pb/Zn mine tailings at Lechang, Guangdong, China.

Cultivation-based and molecular approaches were used to characterize the phylogenetic composition and structure of the microbial community in an extremely acidic (pH 2.0) acid mine drainage (AMD) associated with Pb/Zn mine tailings that were undergoing vigorous acid generation. Acidophilic bacteria were isolated and enumerated on solid media, and were found to be restricted to isolates related to Acidithiobacillus ferrooxidans and Acidiphilium cryptum. By contrast, cloning and phylogenetic analysis of 16S rRNA genes revealed that, although low in total taxonomically distinct groups, the tailings AMD ecosystem harbored a wide range of phylogenetically diverse microbes. Of the 141 clones examined, 104 were phylogenetically affiliated with the recently discovered, iron-oxidizing Leptospirillum group III within the Nitrospira. It thus appears that iron serves as the major electron donor in this habitat. Thirty clones were affiliated with the Proteobacteria, half of which belonged to organisms related to Alphaproteobacteria species capable of ferric iron reduction. Other clones were grouped with Betaproteobacteria and Gammaproteobacteria (six clones each), and even with Deltaproteobacteria (three clones), a subdivision with anaerobic sulfate or metal (iron) reduction as the predominant physiological trait of its members. Finally, four clones were clustered within the Firmicutes and the Acidobacteria. Approximately half of the sequence types representing the majority of the total clones fell into lineages that are poorly represented by cultured organisms or have thus far been represented by only a few environmental sequences. Thus, the present study extends our knowledge of the biodiversity of microorganisms populating highly acidic AMD environments.

Seasonal and spatial variations in microbial community structure and diversity in the acid stream draining across an ongoing surface mining site.

This study examined the microbial community in an acidic stream draining across the Yun-Fu pyrite mine (Guangdong, China), where extremely acidic mine water is a persistent feature due to the intensive surface mining activities. Analysis of terminal restriction fragment length polymorphism (TRFLP) of 16S rRNA gene sequences showed that microbial populations varied spatially and seasonally and correlated with geochemical and physical conditions. After the stream moves from underground to the surface, the microbial community in the acidic water rapidly evolves into a distinct community close to that in the downstream storage pond. Comparisons of TRFLP peaks with sequenced clone libraries indicated that bacteria related to the recently isolated iron-oxidizer Ferrovum myxofaciens dominated the acidophilic community throughout the year except for the samples collected in spring from the storage pond, where Ferroplasma acidiphilum-like archaea represented the most abundant group. Acidithiobacillus ferrooxidans-affiliated organisms increased along the acid stream and remained common over the year, whereas Leptospirillum ferrooxidans-like bacteria were negligible or even not detected in the analyzed samples. The data indicate that changes in environmental conditions are accompanied by significant shifts in community structure of the prokaryotic assemblages at this opencast mining site.

Culturable and molecular phylogenetic diversity of microorganisms in an open-dumped, extremely acidic Pb/Zn mine tailings.

A combination of cultivation-based and molecular-based approaches was used to reveal the culturable and molecular diversity of the microbes inhabiting an open-dumped Pb/Zn mine tailings that was undergoing intensive acid generation (pH 1.9). Culturable bacteria found in the extremely acidic mine tailings were Acidithiobacillus ferrooxidans, Leptospirillum ferriphilum, Sulfobacillus thermotolerans and Acidiphilium cryptum, where the number of acidophilic heterotrophs was ten times higher than that of the iron- and sulfur-oxidizing bacteria. Cloning and phylogenetic analysis revealed that, in contrast to the adjacent AMD, the mine tailings possessed a low microbial diversity with archaeal sequence types dominating the 16S rRNA gene library. Of the 141 clones examined, 132 were represented by two sequence types phylogenetically affiliated with the iron-oxidizing archaea Ferroplasma acidiphilum and three belonged to two tentative groups within the Thermoplasma lineage so far represented by only a few environmental sequences. Six clones in the library were represented by the only bacterial sequence type and were closely related to the well-described iron-oxidizer L. ferriphilum. The significant differences in the prokaryotic community structures of the extremely acidic mine tailings and the AMD associated with it highlights the importance of studying the microbial communities that are more directly involved in the iron and sulfur cycles of mine tailings.