查看更多>>摘要：? 2022 Elsevier LtdChitosan (C) is a natural antimicrobial compound that has been widely explored for wood protection, but its application is limited by its high leachability. Genipin is a biobased crosslinking agent that can crosslink with chitosan under mild conditions. This study aims at examining the decay resistance and leachability of genipin-crosslinked chitosan (GC) treated wood against common wood-decaying fungi. GC formation was confirmed using Fourier transform infrared spectroscopy and Thermogravimetric analysis. The antifungal efficacy of GC against two brown-rot fungi, Gloeophyllum trabeum (G.t.) and Rhodonia placenta (R.p.) and two white-rot fungi, Trametes versicolor (T.v.) and Irpex lacteus (I.l.) was first determined using malt-gar as substrate, which revealed that GC exhibited similar efficacy as C treatments in inhibiting the growth of all fungi studied. Micrographs of light and fluorescence microscopy showed changes in fungi morphology and nuclei deformation due to the effect of GC. GC-treated wood samples show an increased retention and mass gain as the function of treating concentrations, which were as high as 21 kg/m2 and 3.6%, respectively. However, upon leaching test, the mass gain of 3% GC treated softwood and hardwood was reduced to 1.6% and 0.9%, respectively, indicating cross-linking chitosan with genipin did not reduce the leaching rate of chitosan. In terms of durability testing, GC treated wood samples showed significantly lower mass loss ranging from 11 to 15% than those of the control groups of ≥30% regardless of the leaching test.
查看更多>>摘要：? 2022 Elsevier LtdThe spherical polyvinylpyrrolidone (PVP) stabilized red Se NPs (PVP–Se NPs) with a mean size of ～45 nm were prepared via upgraded one-step wet chemical reduction by L-cysteine, which considerably shortened the synthesis procedure. Their morphological features were characterized by high-resolution scanning transmission electron microscopy, UV-VIS spectroscopy, and small-angle X-ray scattering method. The toxicological properties of PVP-Se NPs were analyzed by colorimetric cell viability assay based on the reduction of a yellow tetrazolium salt (XTT) in mitochondria, a further assay based on the measurement of lactate dehydrogenase (LDH) release from damaged cell membrane, and finally by cell proliferation assay. The antifungal effect of PVP-Se NPs alone, or in a mixture of commercial fungicide containing 2% of boric acid, 2% alkylbenzyldimethylammonium chloride, and ～0.9% ethanolamine in distilled water was tested on the brown-rot fungus Serpula lacrymans The fungus belongs to important basidiomycetes causing economically significant decay of wood, mainly in houses and particularly cold soil cellars. The average mass loss tests performed on spruce wood blocks after four months of inoculation with S. lacrymans showed an enhanced antifungal effect of the mixture of PVP-Se NPs with a commercial fungicide than a PVP-Se NPs or commercial fungicide alone, which proved their synergistic effect on inhibiting fungi growth. Finally, scanning electron microscopy analysis of outer and inner parts of wood blocks treated with our novel mixture was performed.
查看更多>>摘要：? 2022 Elsevier LtdThe aim of the study was to incorporate a multidimensional approach to the biodeteriorative influence of aerophytic algal biofilms colonising building materials, such as bricks and plasters in temperature climate zones. Stichococcus sp., Klebsormidium sp., Chlorococcum infusionum, Chlorella vulgaris and Pseudochlorella signiensis were detected in green biofilms covering internal and external walls of buildings in Poland. Their growth led to changes in the material's colour in the range of ΔE = 10.82–37.67, as well high water retention and absorptivity. The moisture content of analysed materials ranged from 9.00 to 14.59%. Further, the direct influence of algal growth on the mechanical properties of the analysed materials was not found. For metabolome analysis laser desorption/ionisation time-of-flight mass spectrometry with silver-109 and gold nanoparticles was used. Derivatives of sulfuric compounds and organic acids were detected but this was not the case for metabolites with well-documented biodeteriorative potential. 109AgNPET LDI MS allowed for the detection of 43 different metabolic pathways, using AuNPET LDI MS 25 pathways. In total, 110 metabolites were found. Although the spectrum of metabolites detected using 109AgNPET LDI MS was broader, AuNPET LDI MS allowed for the detection of pathways that were not found by 109AgNPET LDI MS. The combination of both methods allowed for the widest range of results.
查看更多>>摘要：? 2022 Elsevier LtdEndolithic micro-environments of rock are unique, ranging from high mountains and deep-sea floors to deserts and the Arctic and Antarctic regions colonized by high diversity of microbes. Endolithic microorganisms survive the extreme environmental conditions of rock pores and fissures with their survival strategies. In addition, the bulk rock provides mineral nutrients and protects the inhabitants from drastic ecological stresses from changes in the local conditions. Thus, endolithic microbes are at pivotal interface between geology and biology that offers a model system for unique microbial ecology, astrobiology, and geomicrobiology. This review provides comprehensive information on the diversity of endolithic microbial communities in cold, arid, aquatic, and terrestrial ecosystems and their survival strategies under ecological stresses. Furthermore, rock architecture for the colonization of endoliths, their biochemical functions and potential applications are discussed. It is clear that integrating modern molecular methods with physical and chemical analytical instrumentation will further advance our knowledge about endolithic microbial ecology, diversity, unique adaptive mechanisms, ecological functioning, and biochemical processes that shape the past, current, and future biosphere.
查看更多>>摘要：? 2022The use of functional microbial strains is an emerging strategy for exploiting heavy oil reserves. The aim of this study was to obtain bacterial strains potentially applicable in enhanced heavy oil recovery. A biosurfactant-producing and oil-degrading strain, designated HoB-1, was isolated from a heavy oil sample collected at the Yanchang oilfield (Northwest China). Strain HoB-1 was identified as Bacillus siamensis on the basis of 16S rRNA gene sequence analysis. It showed the potential to produce biosurfactant, which lowered the surface tension of a 7-d-old fermentation broth by 38.6% compared with that of the control. In the presence of the biosurfactant, stable emulsions were formed with different hydrocarbons such as n-hexane, petroleum ether, and light oil. The biosurfactant exhibited high stability, even under extreme temperature (20–100 °C), pH (3.0–13.0), and salinity (0%–30% NaCl) conditions. Bacterial treatment with strain HoB-1 led to the transformation and redistribution of all four heavy oil fractions by reducing the saturates and asphaltenes contents and increasing the aromatics and resins contents. The individual contents of n-alkanes were also increased in the heavy oil upon bacterial treatment. Therefore, B. siamensis HoB-1 is a potential candidate for enhanced heavy oil recovery through biosurfactant production and oil biodegradation.
查看更多>>摘要：? 2022 Elsevier LtdAnammox and deammonification processes under different five-day biochemical oxygen demand (BOD5) to total nitrogen (TN) ratios (0, 0.1, and 0.2) were investigated in a lab-scale anaerobic sequencing batch reactor (ASBR) and full-scale moving bed bioreactor (MBBR) and integrated fixed-film activated sludge (IFAS) systems operated under different conditions (dissolved oxygen (DO) concentrations, solids retention time (SRTs), organic and ammonia-nitrogen (NH3-N) loading rates). Nitrogen removal efficiencies for the lab-scale ASBR anammox process using synthetic wastewater as substrate and two full-scale deammonification processes (MBBR with anaerobic digester centrate as substrate and IFAS with stored landfill leachate as substrate) were >90%, ～60%, and ～75%, respectively. Quantitative polymerase chain reaction and polymerase chain reaction-denaturing gradient gel electrophoresis were used to investigate microbial communities on three different attached-growth media: scrub sponges (ASBR), AnoxKaldnes K5 (MBBR) and polypropylene (IFAS). The anammox species, Candidatus Brocadia fulgida was dominant only in the lab-scale anammox system and Candidatus Kuenenia sp. was dominant under DO concentration of 0.3 mg l?1 and organic loading of 0.04 kg-BOD·m?3·d?1. Candidatus Jettenia caeni was dominant at BOD5:TN ratio of 0.2 and organic loading up to 0.39 kg-BOD·m?3·d?1 and NH3-N loading 1.95 kg-N·m?3·d?1. Furthermore, abundance of amoA-AOA populations in lab-scale and two full-scales treatment systems were similar (around 8.04 × 104 to 1.56 × 105 copies/g-sludge) but different predominant AOA species were observed on the different media. Based on the results from this work, maintaining low BOD5:TN ratios could be applied to improve the nitrogen removal efficiency of deammonification processes. While very low BOD5:TN ratio was the primary determinant of deammonification efficiency, other beneficial influences include high specific surface area carriers, low DO concentration, high temperature, and long SRT.
查看更多>>摘要：? 2022 Elsevier LtdUpstream oil and gas systems are negatively impacted by microbial activities that produce hydrogen sulfide gas, enhance corrosion rates of metals, and cause costly damage to infrastructure through biofouling. Although alternatives to biocides such as sulfate removal membranes and corrosion resistant coatings and materials have been developed, biocides and inhibitors still provide the main defense against microbial activity. However, the environmental and economic challenges of employing biocides necessitate oil and gas industries devise better strategies for their use and application. Since oil and gas environments represent physically controlled environments with highly stressed microbial communities experiencing episodes of intermittent slow growth and dormancy, one such strategy can take advantage of environmental stressors (e.g., salinity, starvation, oxygen) to enhance biocide efficacy. Although it is generally thought environmental stressors recruit determinants of resistance in bacteria, there are instances where stress decreases the energy or metabolic state of a cell increasing its susceptibility to some biocides. This review examines stressors in oil and gas environments and provides examples where stress can both increase and decrease biocidal susceptibility. By describing how these stressors and biocides impact metabolic activity as well as affect regulation of genes involved in energy production and conversion, this knowledge can be used to develop new strategies that take advantage of vulnerabilities in bacteria to improve biocide efficacy and reduce environmental threats and operator costs.
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