Artificial mixed microbial system for polycyclic aromatic hydrocarbons degradation.

Polycyclic aromatic hydrocarbons (PAHs) are environmental pollutants with major risks to human health. Biological degradation is environmentally friendly and the most appealing remediation method for a wide range of persistent pollutants. Meanwhile, due to the large microbial strain collection and multiple metabolic pathways, PAH degradation via an artificial mixed microbial system (MMS) has emerged and is regarded as a promising bioremediation approach. The artificial MMS construction by simplifying the community structure, clarifying the labor division, and streamlining the metabolic flux has shown tremendous efficiency. This review describes the construction principles, influencing factors, and enhancement strategies of artificial MMS for PAH degradation. In addition, we identify the challenges and future opportunities for the development of MMS toward new or upgraded high-performance applications.

Genomic characterization of three bacteriophages infecting donkey-derived Escherichia coli.

Bacteriophages are an important source of novel genetic diversity. Sequencing of phage genomes can reveal new proteins with potential uses in phage therapy and help unravel the diversity of biological mechanisms by which phages take over the machinery of the host during infection. To expand the available collection of phage genomes, we have isolated, sequenced, and assembled the genome sequences of three phages that infect three pathogenic Escherichia coli strains: vB_EcoM_DE15, vB_EcoM_DE16, and vB_EcoM_DE17. Morphological characterization and genomic analysis indicated that all three phages were strictly lytic and free from integrases, virulence factors, toxins, and antimicrobial resistance genes. All three phages contained tRNAs, and especially, vB_EcoM_DE17 contained 25 tRNAs. The genomic features of these phages indicate that natural phages are capable of lysing pathogenic E.coli and have great potential in the biocontrol of bacteria.

Effects of soil pH and organic carbon content on in vitro Cr bioaccessibility in Ultisol, Alfisol, and Inceptisol.

Hexavalent chromium (Cr(VI)) is a toxic heavy metal and its mobility and bioaccessibility in soils are influenced by soil properties. In this study, the soil pH and organic carbon contents of Ultisol, Alfisol, and Inceptisol were adjusted before they were polluted with 230 mg kg-1 Cr(VI). Alkaline digestion, sequential extraction, and an in vitro experiment were conducted to study the valence state, species, and bioaccessibility of Cr in the soils. The results showed that a high soil pH was not favorable for reduction of Cr(VI); therefore the Cr(VI) and exchangeable Cr contents were positively related to soil pH. Soil organic carbon promoted the reduction of Cr(VI). Almost all Cr(VI) was reduced to Cr(III) when the soil organic carbon content reached 10 g kg-1. Chromium bioaccessibility in simulated gastric and intestinal phase solutions was influenced by Cr(VI) and Cr(III) adsorption/desorption, dissolution/precipitation, and redox reactions. Chromium bioaccessibility differences between the gastric and intestinal phases were associated with the Cr(VI)/Cr(III) ratio. Acidic conditions and a high organic carbon content promoted the conversion of Cr(VI) to Cr(III). When soil pH was increased from 4.01 to 5.85, Cr(VI) in Alfisol without the addition of humic acid increased from 96.38 to 174.78 mg kg-1, the exchangeable Cr proportion increased from 9.7% to 22.6%, and Cr bioaccessibility increased from 41.29% to 49.14% in the gastric phase and from 41.32% to 48.24% in the intestinal phase. When the organic carbon content increased from 3.95 to 9.28 g kg-1 in Alfisol, Cr(VI) content decreased from 167.66 to 20.52 mg kg-1, which led to a decrease in Cr bioaccessibility from 49.15% to 13.8% in the gastric phase and from 45.85% to 7.67% in the intestinal phase. Therefore, acidic conditions and increasing soil organic carbon levels can reduce the health risk posed by Cr in soils.

Surfactant-assisted ethylenediamine for the deconstruction and conversion of corn stover biomass.

Lignocellulosic biomass is a promising feedstock to produce sustainable fuels and energy toward a green bioeconomy. A surfactant-assisted ethylenediamine (EDA) was developed for the deconstruction and conversion of corn stover in this study. The effects of surfactants on the whole conversion process of corn stover was also evaluated. The results showed that xylan recovery and lignin removal in solid fraction were significantly enhanced by surfactant-assisted EDA. The glucan and xylan recoveries in solid fraction reached 92.1% and 65.7%, respectively, while the lignin removal was 74.5% by sodium dodecyl sulfate (SDS)-assisted EDA. SDS-assisted EDA also improved the sugar conversion in 12 h enzymatic hydrolysis at low enzyme loadings. The ethanol production and glucose consumption of washed EDA pretreated corn stover in simultaneous saccharification and co-fermentation were improved with the addition of 0.001 g/mL SDS. Therefore, surfactant-assisted EDA showed the potential to improve the bioconversion performance of biomass.

Characterization and complete genome analysis of a bacteriophage vB_EcoM_DE7 infecting donkey-derived Escherichia coli.

A lytic bacteriophage vB_EcoM_DE7 (hereafter designated DE7) that could infect donkey-derived Escherichia coli was isolated. The bacteriophage was examined by transmission electron microscopy, and the result showed that DE7 belonged to the family Myoviridae. The microbiological characterization revealed that DE7 was stable over a broad range of pHs (3 ∼10) at 40-50 °C. The latent period was 10 min, and the burst size was 43 PFUs/infected cell. The whole-genome sequencing showed that DE7 was a dsDNA virus and had a genome of 86,130 bp. The genome contained 124 predicted open reading frames (ORFs), 35 of which had known functions, including DNA replication and modification, transcriptional regulation, structural and packaging proteins, and host cell lysis. Twenty tRNA genes were identified, but no genes associated with bacterial pathogenicity, lysogeny and drug resistance were identified. BLASTN analysis revealed that phage DE7 had a high sequence identity (96%) with Salmonella phage vB_SPuM_SP116, but it could not lyse any Salmonella strain tested in this study. DE7 was classified as a Felix O1-like virus based on its general characterization and genomic information. Since phage DE7 exhibited high efficacy in lysing E. coli and lacked genes associated with bacterial virulence, antimicrobial resistance and lysogeny, it could be potentially used to control foal diarrhoea caused by E. coli.

The effects of H2O2- and HNO3/H2SO4-modified biochars on the resistance of acid paddy soil to acidification.

Biochar was prepared from rice straw and modified with 15% H2O2 and 1:1 HNO3/H2SO4, respectively. The unmodified biochars and HCl treated biochars for carbonate removal were used as control. The biochars were added to the acid paddy soil collected from Langxi, Anhui Province, China at the rate of 30 g/kg. The paddy soil was flooded and then air-dried, and soil pH and Eh were measured in situ with pH electrode and platinum electrode during wet-dry alternation. Soil pH buffering capacity (pHBC) was determined by acid-base titration after the wet-dry treatment. Then, the simulated acidification experiments were carried out to study the changing trends of soil pH, base cations and exchangeable acidity. The results showed that soil pHBC was effectively increased and the resistance of the paddy soil to acidification was apparently enhanced with the incorporation of H2O2- and HNO3/H2SO4-modified biochars. Surface functional groups on biochars were mainly responsible for enhanced soil resistance to acidification. During soil acidification, the protonation of organic anions generated by dissociation of these functional groups effectively retarded the decline of soil pH. The modification of HNO3/H2SO4 led to greater increase in carboxyl functional groups on the biochars than H2O2 modification and thus HNO3/H2SO4-modified biochars showed more enhancement in soil resistance to acidification than H2O2-modified biochars. After a wet-dry cycle, the pH of the paddy soil incorporated with HNO3/H2SO4-modified biochar increased apparently. Consequently, the addition of HNO3/H2SO4-modified biochar can be regarded as a new method to alleviate soil acidification. In short, the meaning of this paper is to provide a new method for the amelioration of acid paddy soils.

[Chemical Evolution and Formation Mechanism of Groundwater in Hetao Irrigation Area].

Groundwater resources are important sources of water in the arid region of northwestern China, but their overexploitation and utilization has led to a series of ecological and environmental problems. Exploring the characteristics and mechanism of groundwater chemical evolution is important for the rational use of groundwater resources. The characteristics of groundwater chemical evolution were studied in the Yongji Irrigation Area of Hetao Irrigation District and the formation mechanism of the chemical compounds in groundwater were investigated using cluster analysis, factor analysis, and other statistical methods. The influence degree of different factors was calculated. The results showed that the major cations in groundwater in the study area were Na+ and K+, and the major anions were Cl- and HCO3-. Moreover, Na+, K+, and Cl- showed high spatial variability and were the main factors contributing to groundwater salinization. The major chemical compounds in the groundwater in the study area were Cl-Na, HCO3 ·Cl ·SO4-Na, and HCO3-Na. Based on the cluster analysis results, the groundwater was divided into four categories (A1, A2, B1, and B2), of which A1 was highly mineralized by Cl-Na type water, while A2, B1, and B2 were mainly HCO3 ·Cl ·SO4-Na and HCO3-Na type water. Principal component analysis results suggest that groundwater chemistry was mainly affected by salinization, carbonate karstification, and human activities with the influence degrees of 45.976%, 23.853% and 16.678%, respectively. Evaporation, salt rock dissolution, and cation exchange were important sources of Na+ and Cl- accumulation in the irrigation area. Agricultural irrigation (leaching of soil salts) and drought (intense transpiration) were the key drivers of groundwater salinization in the irrigation area.

Comparative Study on Different Remediation Strategies Applied in Petroleum-Contaminated Soils.

Due to the increasing pollution by petroleum hydrocarbons (PHs), it is an important task to develop eco-friendly and highly efficient methods for remediating petroleum-contaminated soils. In this study, bioremediation technology was applied to remediate PHs contaminated soils, and the bacterial community structure and physicochemical characteristics of the soil treated using different bioremediation regimens were analyzed. Compared with the control condition (S0), the PHs removal efficiency of biostimulation (S2) and bioaugmentation (S3) was increased significantly. Combined biostimulation with bioaugmentation (S4) had the highest PHs removal efficiency, up to 60.14 ± 4.12%. Among all the selected remediation strategies (S1-S4, S1: soil moisture content: 25-30%), the bacterial alpha-diversity was higher than in S0. The genera Acinetobacter, Escherichia-Shigella, Bacteroides, Microbacterium, and Parabacteroides were found to greatly contribute to PHs' degradation. In the group S4, the PH-degraders and soil enzyme activity were higher than in the other remediation regimens, and these indices gradually decreased in the mid-to-later periods of all remediation tests. Additionally, the abundance of alkB and nah genes was increased by improving the environmental condition of the microorganism communities. Redundancy analysis (RDA) revealed that the total nitrogen (TN) and total phosphorus (TP) had a positive correlation with total PHs degradation. This study offers insights into the microbial community response to environmental factors during bioremediation, which shows a promoting effect in enhancing the efficiency of PHs remediation.

Effects of Funneliformis mosseae on Root Metabolites and Rhizosphere Soil Properties to Continuously-Cropped Soybean in the Potted-Experiments.

Continuous cropping in soybean is increasingly practiced in Heilongjiang Province, leading to substantial yield reductions and quality degradation. Arbuscular mycorrhizal fungi (AMF) are soil microorganisms that form mutualistic interactions with plant roots and can restore the plant rhizosphere microenvironment. In this study, two soybean lines (HN48 and HN66) were chosen as experimental materials, which were planted in different years of continuous cropping soybean soils and were inoculated or not with Funneliformis mosseae in potted-experiments. Ultimately, analysis of root tissue metabolome and root exudates, soil physicochemical properties, plant biomass, as well as rhizosphere soil properties in different experimental treatments, inoculated or not with F. mosseae, was performed. Experimental results showed that: (a) The disease index of soybean root rot was significantly lower in the treatment group than in the control group, and there were differences in disease index and the resistance effect of F. mosseae between the two cultivars; (b) compared with the control, the root tissue metabolome and root exudates remained unchanged, but there were changes in the relative amounts in the treatment group, and the abundant metabolites differed by soybean cultivar; (c) soybean biomass was significantly higher in the treatment group than in the control group, and the effect of F. mosseae on biomass differed with respect to the soybean cultivar; and (d) there were differences in the physiochemical indexes of soybean rhizosphere soil between the treatment and control groups, and the repairing effect of F. mosseae differed between the two cultivars. Therefore, F. mosseae can increase the biomass of continuously cropped soybean, improve the physicochemical properties of the rhizosphere soil, regulate the root metabolite profiles, and alleviate barriers to continuous cropping in potted-experiments of soybean.

Association between serum leptin levels and breast cancer risk: An updated systematic review and meta-analysis.

BACKGROUND: Many studies have indicated that leptin is correlated with breast cancer occurrence and tumor behavior. However, this issue remains controversial. Therefore, we conducted an updated meta-analysis to investigate the role of leptin in breast cancer. METHODS: We performed a systematic literature search and identified relevant papers up to 1 September 2017. Standardized mean differences (SMDs) with 95% confidence intervals (CIs) were used to evaluate effect sizes. RESULTS: Thirty-five eligible studies were included in the current meta-analysis. Serum leptin levels were related to breast cancer risk as demonstrated by calculations of the overall SMD = 0.46 (95% CI = 0.31-0.60, I = 93.5%). A subgroup analysis of BMI identified an association between breast cancer and serum leptin levels in patients who are overweight and obese (overweight: SMD = 0.35, 95% CI = 0.13-0.57, I = 88.1%; obesity: SMD = 1.38, 95% CI = 0.64-2.12, I = 89.6%). Additionally, menopausal status subgroup analysis revealed a significant association in postmenopausal women (SMD = 0.26, 95% CI = 0.12-0.40, I = 77.9%). Furthermore, we identified a significant association between breast cancer and serum leptin levels in Chinese women (SMD = 0.61, 95% CI = 0.44-0.79, I = 40.6%). CONCLUSION: The results of this meta-analysis suggested that leptin could be a potential biomarker for breast cancer risk in women, especially overweight/obese or postmenopausal women. Therefore, it may be useful for identifying subjects with a high risk for breast cancer who may benefit from preventive treatments.

Genetic and antigenic evolution of H9N2 subtype avian influenza virus in domestic chickens in southwestern China, 2013-2016.

H9N2 avian influenza virus (AIV) has caused significant losses in chicken flocks throughout china in recent years. There is a limited understanding of the genetic and antigenic characteristics of the H9N2 virus isolated in chickens in southwestern China. In this study a total of 12 field strains were isolated from tissue samples from diseased chickens between 2013 and 2016. Phylogenetic analysis of the Hemagglutinin (HA) and Neuraminidase (NA) nucleotide sequences from the 12 field isolates and other reference strains showed that most of the isolates in the past four years could be clustered into a major branch (HA-branch A and NA-branch I) in the Clade h9.4.2 lineages. These sequences are accompanied by nine and seven new amino acids mutations in the HA and NA proteins, respectively, when compared with those previous to 2013. In addition, four new isolates were grouped into a minor branch (HA-branch B) in the Clade h9.4.2 lineages and two potential N-glycosylation sites were observed due to amino acid mutations in the HA protein. Three antigenic groups (1-3), which had low antigenic relatedness with two commonly used vaccines in China, were identified among the 12 isolates by antigenMap analysis. Immunoprotection testing showed that those two vaccines could efficiently prevent the shedding of branch A viruses but not branch B viruses. In conclusion, these results indicate the genotype of branch B may become epidemic in the next few years and that a new vaccine should be developed for the prevention of H9N2 AIV.