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Petroleum hydrocarbons are hazardous to ecosystems and human health, commonly containing n-alkanes and polycyclic aromatic hydrocarbons. Previous researches have studied alkane degraders and degrading genes under aerobic or anaerobic conditions, but seldom discussed them in the intermittent saturation zone which is a connective area between the vadose zone and the groundwater aquifer with periodic alteration of oxygen and moisture. The present study investigated the difference in alkane degradation efficiency, bacterial community, and alkane degrading gene diversity in aerobic, anaerobic, and aerobic-anaerobic fluctuated treatments. All biotic treatments achieved over 90% of n-alkane removal after 120 days of incubation. The removal efficiencies of n-alkanes with a carbon chain length from 16 to 25 were much higher in anaerobic scenarios than those in aerobic scenarios, explained by different dominant microbes between aerobic and anaerobic conditions. The highest removal efficiency was found in fluctuation treatments, indicating an accelerated n-alkane biodegradation under aerobic-anaerobic alternation. In addition, the copy numbers of the 16S rRNA gene and two alkB genes (alkB-P and alkB-R) declined dramatically when switched from aerobic to anaerobic scenarios and oppositely from anaerobic to aerobic conditions. This suggested that water level fluctuation could notably change the presence of aerobic alkane degrading genes. Our results suggested that alkane degradation efficiency, soil microbial community, and alkane-degrading genes were all driven by water level fluctuation in the intermittent saturation zone, helping better understand the effects of seasonal water table fluctuation on the biodegradation of petroleum hydrocarbons in the subsurface environment. [ABSTRACT FROM AUTHOR]

Microorganisms are an important part of atmospheric particulate matter and are closely related to human health. In this paper, the variations in the characteristics of the chemical components and bacterial communities in PM10 and PM2.5 grouped according to season, pollution degree, particle size, and winter heating stage were studied. The influence of environmental factors on community structure was also analyzed. The results showed that seasonal variations were significant. NO3− contributed the most to the formation of particulate matter in spring and winter, while SO42− contributed the most in summer and autumn. The community structures in summer and autumn were similar, while the community structure in spring was significantly different. The dominant phyla were similar among seasons, but their proportions were different. The dominant genera were no-rank_c_Cyanobacteria, Acidovorax, Escherichia-Shigella and Sphingomonas in spring; Massilia, Bacillus, Acinetobacter, Rhodococcus, and Brevibacillus in summer and autumn; and Rhodococcus in winter. The atmospheric microorganisms in Beijing mainly came from soil, water, and plants. The few pathogens detected were mainly affected by the microbial source on the sampling day, regardless of pollution level. RDA (redundancy analysis) showed that the bacterial community was positively correlated with the concentration of particulate matter and that the wind speed in spring was positively correlated with NO3− levels, NH4+ levels, temperature, and relative humidity in summer and autumn, but there was no clear consistency among winter samples. This study comprehensively analyzed the variations in the characteristics of the airborne bacterial community in Beijing over one year and provided a reference for understanding the source, mechanism, and assessment of the health effects of different air qualities. [ABSTRACT FROM AUTHOR]

In this study, particulate matter (PM) with aerodynamic diameters of ≤2.5 and ≤10 μm (PM 2.5 and PM 10 , respectively), which was found at different concentrations in spring, was collected in Beijing. The chemical composition and bacterial community diversity of PM were determined, and the relationship between them was studied by 16S rRNA sequencing and mathematical statistics. Chemical composition analysis revealed greater relative percentages of total organic compounds (TOC) and secondary ions (NO 3 − , SO 4 2− , and NH 4 + ). The concentrations of Ca 2+ , Na + , Mg 2+ , K + and SO 4 2− increased in high-concentration PM, which was associated with the contribution of soil, dust and soot. Microbiological analysis revealed 1191 operational taxonomic units. Microbial community structure was stable at the phylum level. The most abundant phyla were Proteobacteria, Actinobacteria, Firmicutes, Bacteroidetes and Cyanobacteria. Community clustering analysis at the genus level showed that the difference in bacterial community structure between different PM concentrations (clean air vs. smog) was greater than that between different particle sizes. The dominant genera varied in different concentrations of PM. An unclassified genus of Cyanobacteria and Comamonadaceae were most abundant in low- and high-concentration PM, respectively. The microbial community structure was dynamic at the genus level due to different environmental factors. The dominant bacteria in high-concentration PM were widely distributed in soils, indicating that the soil contributed more to the increase in the PM. The individual microbes that were detected did not increase significantly as the PM concentration increased. The bacterial community structure was strongly correlated with K + , Ca 2+ , Na + , Mg 2+ , SO 4 2− and TOC in high-concentration PM and had a good correlation with NO 3 − , Cl − , NH 4 + and TIC in low-concentration PM. Soil and dust contributed to the increase in the concentration of the particles, and the relevant chemical components also produced differences in the bacterial community structure in different concentrations of PM. [ABSTRACT FROM AUTHOR]

Total petroleum hydrocarbon (TPH) contamination poses threats to ecological systems and human health. Many studies have reported its negative impacts on soil microbes, but limited information is known about microbial change and response to multiple TPH contamination events. In this study, we investigated TPH contamination level, microbial community structure and functional genes at a multi-contaminated industrial site in Lanzhou, where a benzene spill accident caused the drinking water crisis in 2014. TPHs distribution in soils and groundwater indicated multiple TPH contamination events in history, and identified the spill location where high TPH level (6549 mg kg−1) and high ratio of low-molecular-weight TPHs (>80%) were observed. In contrast, TPH level was moderate (349 mg kg−1) and the proportion of low-molecular-weight TPHs was 44% in soils with a long TPH contamination history. After the spill accident, soil bacterial communities became significant diverse (p = 0.047), but the dominant microbes remained the same as Pseudomonadaceae and Comamonadaceae. The abundance of hydrocarbon-degradation related genes increased by 10–1000 folds at the site where the spill accident occurred in multi-contaminated areas and was significantly related to 2-ring PAHs. Such changes of microbial community and hydrocarbon-degradation related genes together indicated the resilience of soil indigenous microbes toward multiple contamination events. Our results proved the significant change of bacterial community and huge shift of hydrocarbon-degradation related genes after the spill accident (multiple contamination events), and provided a deep insight into microbial response at industrial sites with a long period of contamination history. [Display omitted] • First report on petroleum contamination profiles of Lanzhou benzene exceedance accident. • Multiple contaminated sites were recognized by high concentration of light molecular weight hydrocarbons. • Significant change of microbial community diversity after multiple contamination events. • Increasing abundance of hydrocarbon degradation related genes after multiple contamination events. [ABSTRACT FROM AUTHOR]

[Display omitted] • Using magnetic-nanoparticles to accelerate the enrichment process of bacteria. • Efficient liquid-phase single-cell separation efficiency compared to pure culture. • Enrichment of acetonitrile degrading bacterial strain resource library. Although there are many microorganisms in nature, the limitations of isolation and cultivation conditions have restricted the development of artificial enhanced remediation technology using functional microbial communities. In this study, an integrated technology of Magnetic Nanoparticle-mediated Enrichment (MME) and Microfluidic Single Cell separation (MSC) that breaks through the bottleneck of traditional separation and cultivation techniques and can efficiently obtain more in situ functional microorganisms from the environment was developed. MME technology was first used to enrich rapidly growing active bacteria in the environment. Subsequently, MSC technology was applied to isolate and incubate functional bacterial communities in situ and validate the degradation ability of individual bacteria. As a result, this study has changed the order of traditional pure culture methods, which are first selected and then cultured, and provided a new method for obtaining non-culturable functional microorganisms. [ABSTRACT FROM AUTHOR]