Co-incineration of medical waste in municipal solid waste incineration increased emission of chlorine/brominated organic pollutants.

Co-incineration of medical waste (MW) in municipal solid waste incinerators (MSWIs) is a crucial disposal method for emergency disposal of MW and the management of MW in small and medium-sized towns. This study aims to analyze and compare the levels and distribution patterns of chlorine/brominated dioxins and their precursors in fly ash from MSWIs and medical waste incinerators (MWIs) while also focusing on identifying the new pollution concerns that may arise from the co-incineration of municipal solid waste (MSW) mixed with MW (MSW/MW). The concentration of chlorobenzene (CBzs), polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) in fly ash from co-incineration of MSW/MW are 887.4, 134.4 and 27.6 µg/kg, respectively, which are 5.1, 2.0 and 2.9 times higher than that from MSWIs. The levels of polybrominated dibenzo-p-dioxins/dibenzofurans (PBDD/Fs) are about three orders of magnitude lower than that of PCDD/Fs. For the fly ash from MSWIs, the predominant PCDD/Fs congener is OCDD, which prefers synthesis and adsorption on fine-grained fly ash. For fly ash from MWIs, the major PCDD/Fs congeners are 1, 2, 3, 4, 6,7, 8-HpCDF, and OCDF, which prefer synthesis and adsorption on coarse-grained fly ash. Correlation analysis exhibited that both 1,2,3-TriCBz and 1,2,4-TriCBz in fly ash have a markedly linear correlation with PCDD/Fs and PCBs, but PBDD/Fs shows a poor negative correlation with PCDD/Fs.

Effects of Salmonella Enteritidis infection on TLRs gene expression and microbial diversity in cecum of laying hens.

Salmonella Enteritidis (SE) is an important foodborne pathogen primarily causing human disease through contaminated food and water. In the current study, to assess the effect of Salmonella Enteritidis infection on the immune system and the microbial diversity of cecum and oviduct in chickens, twelve 24-week-old SE-negative White Leghorn layers were randomly selected and divided into 2 groups. Chickens in the challenge group were orally inoculated with SE, and chickens in the control group received an equal amount of sterilized Phosphate Buffered Saline solution. Serum and tissue samples (cecum, oviduct, ovary, liver, spleen, and pancreas) were collected at 7 days and 14 days post-infection (dpi). Quantitative PCR was used to detect the expression of Toll-like receptors (TLRs) in the cecum, oviduct and ovary. To understand the influence of SE infection on the microbial profile of the cecum and oviduct, microbial community composition of the cecal contents and oviducal contents were analyzed through 16S rRNA sequencing. Results showed that SE infection caused damage to the digestive organs, reproductive organs, and immune organs in laying hens. The expression of TLR1a, TLR1b, TLR2, TLR4, TLR5, TLR7 and TLR15 in the cecum were induced, and the content of IFN-γ, TNF-α, IL-2 and IL-18 in serum increased after SE infection. The composition of the microbial community significantly changed in cecal content, the dominant phylum of Firmicutes increased, and Bacteroidetes decreased significantly. In the oviduct, the microbial diversity became complicated, the dominant bacteria Faecalibacterium was significantly increased, and Bacteroides was significantly decreased. This study investigated the effects of SE infection in laying hens, including host innate immunity, the expression of TLRs, and changes in the composition of microbes in the cecum and reproductive tract. Our results may provide a scientific basis for the Salmonella Enteritidis control in chicken, the maintenance of oviduct function, and the guarantee of clean egg production.

The identification and health risk assessment of odor emissions from waste landfilling and composting.

Odor nuisance is the main incentive for Not In My Back Yard campaigns around municipal solid waste (MSW) waste disposal facilities, and the odor identification is of significance for the understanding of the odor properties from MSW with different disposal methods. In this study, odor emissions from different stages at two large-scale working MSW disposal facilities, i.e., landfill (LF) and compost plant (CP), were distinguished with the same MSW feedstock in one city. It was found that CP suffered the heavier odor pollution and the characteristics of odorants changed significantly, especially the pile-turning workshop. Sulfides and aromatics were the main concentration contributors for LF, while that for CP were NH3 and oxygenated compounds. Significant correlations between odor concentration and halogenated compounds, sulfides (r2 = 0.945, 0.898, p<0.05, n = 12) were merely observed in CP. The priority odor pollutants of LF were H2S, benzene and NH3, while that of CP was NH3, ethyl acetate and benzene with a descending order. With regarding to their contributions for occupational exposure, the carcinogenic risk was negligible for these facilities, but H2S of LF might bring non-carcinogenic risk to on-site workers.

Distinct distribution patterns of ammonia-oxidizing archaea and bacteria in sediment and water column of the Yellow River estuary.

Ammonia oxidation is a critical process of estuarine nitrogen cycling involving ammonia-oxidizing archaea (AOA) and bacteria (AOB). However, the distribution patterns of ammonia-oxidizing microorganisms (AOMs) between different habitats in the same area remain unclear. The present study investigated the AOMs' abundance and community compositions in both sediment and water habitats of the Yellow River estuary. Quantitative PCR (qPCR) revealed that AOA showed significant higher abundance than AOB both in sediment and water samples. AOA and AOB abundance distribution trends were consistent in sediment but distinct in water along the sampling sites. Clone library-based analyses showed that AOA sequences were affiliated with Nitrososphaera, Nitrosopumilus and Nitrosotalea clusters. Generally, Nitrososphaera was predominant in sediment, while Nitrosopumilus and Nitrosotalea dominated in water column. AOB sequences were classified into genera Nitrosospira and Nitrosomonas, and Nitrosospira dominated in both habitats. Principal coordinate analysis (PCoA) also indicated AOA community structures exhibited significant differences between two habitats, while AOB were not. Ammonium and carbon contents were the potential key factors to influence AOMs' abundance and compositions in sediment, while no measured variables were determined to have major influences on communities in water habitat. These findings increase the understanding of the AOMs' distribution patterns in estuarine ecosystems.

Distinct distribution patterns of proteobacterial nirK- and nirS-type denitrifiers in the Yellow River estuary, China.

Denitrification is considered to be the critical process in removing reactive nitrogen in estuarine ecosystems. In the present study, the abundance, diversity, and community structure of nirK- and nirS-type denitrifiers were compared in sediments from the Yellow River estuary. Quantitative polymerase chain reaction showed that the 2 types of denitrifiers exhibited different distribution patterns among the samples, indicating their distinct habitat preference. Phylogenetic analysis revealed that most of the sequences from clusters I, III, IV, and V for nirK-type denitrifiers were dominant and were distributed at sites where dissolved oxygen (DO) was lower, and the sequences in the other clusters were dominant at sites with higher DO. However, there was no spatially heterogeneous distribution for the nirS-type denitrifier community. Canonical correlation analysis and correlation analysis demonstrated that the community structure of nirK was more responsive to environmental factors than was that of nirS. Inversely, the abundance and α-diversity targeting nirS gene could be more easily influenced by environmental parameters. These findings can extend our current knowledge about the distribution patterns of denitrifying bacteria and provide a basic theoretical reference for the dynamics of denitrifying communities in estuarine ecosystem of China.

The typical MSW odorants identification and the spatial odorants distribution in a large-scale transfer station.

Odorants from municipal solid waste (MSW) were complex variable, and the screening of key offensive odorants was the prerequisite for odor control process. In this study, spatial odor emissions and environmental impacts were investigated based on a large-scale working waste transfer station (LSWTS) using waste container system, and a comprehensive odor characterization method was developed and applied in terms of the odor concentration (OC), theory odor concentration (TOC), total chemical concentration (TCC), and electric nose (EN). The detected odor concentration ranged from 14 to 28 (dimensionless), and MSW container showed the highest OC value of 28, EN of 78, and TCC of 35 (ppm) due to the accumulation of leachate and residual MSW. Ninety-two species odorants were identified, and H2S, NH3, benzene, styrene, ethyl acetate, and dichloromethane were the main contributors in the container, while benzene, m,p,x-xylene, butanone, acetone, isopropanol, and ethyl acetate were predominant in the compression surface (CS) and compression plant (CP). Side of roads (SR) and unload hall (UH) showed low odorous impact. Based on this odor list, 20 species of odor substances were screened for the priority control through the synthetic evaluation method, considering the odorants concentrations, toxicity, threshold values, detection frequency, saturated vapor pressure, and appeared frequency. Graphical abstract.

Adaptive mutations in PB2 gene contribute to the high virulence of a natural reassortant H5N2 avian influenza virus in mice.

The highly pathogenic A/chicken/Hebei/1102/2010 (HB10) H5N2 virus is a natural reassortant derived from circulating H5N1 and endemic H9N2 avian influenza viruses (AIV). To evaluate the potential of its interspecies transmission, we previously serially passaged the non-virulent HB10 virus in the mouse lung and obtained a high virulence variant (HB10-MA). Genomic sequencing revealed five mutations (HA-S227N, PB2-Q591K, PB2-D701N, PA-I554V and NP-R351K) that distinguished HB10-MA virus from its parental HB10 virus. In this study, we further investigated the molecular basis for the enhanced virulence of HB10-MA in mice. By generating a series of reassortants between the two viruses and evaluating their virulence in mice, we found that both PB2 and PA genes contribute to the high virulence of HB10-MA in mice, whereas PB2 gene carrying the 591K and/or 701N had a dominant function. In addition, the two amino acids showed a cumulative effect on the virulence, virus replication, and polymerase activity of HB10 or HB10-MA. Therefore, our results collectively emphasized the crucial role of PB2 gene, particularly the paired mutations of Q591K and D701N in the host adaptation of the novel reassortant H5N2 AIV in mammals, which may provide helpful insights into the pathogenic potential of emerging AIV in human beings.

Novel reassortant H5N5 viruses bind to a human-type receptor as a factor in pandemic risk.

Highly pathogenic avian influenza A(HPAI) H5N1 viruses pose a serious pandemic threat due to their virulence and high mortality in humans, and their increasingly expanding host range and significant ongoing evolution could enhance their human-to-human transmissibility. Recently, various reassortant viruses were detected in different domestic poultry, with the HA gene derived from the A/goose/Guangdong/1/96-like (Gs/GD-like) lineage and the NA gene from influenza viruses of other subtypes. It is reported that some natural reassortant H5N5 highly pathogenic avian influenza viruses were isolated from poultry in China. And their HA genes were belonged to a new clade 2.3.4.4. We evaluated the receptor binding property and transmissibility in guinea pigs of these reassortant H5N5 HPAIVs. The results showed that these viruses bound to both avian-type (α-2,3) and human-type (α-2,6) receptors. In addition, we found that one of these viruses, 031, not only replicated but also transmitted efficiently in guinea pigs. Therefore, such reassortant influenza viruses may pose a pandemic threat.

Novel H5 clade 2.3.4.6 viruses with both α-2,3 and α-2,6 receptor binding properties may pose a pandemic threat.

The emerging H5 clade 2.3.4.6 viruses of different NA subtypes have been detected in different domestic poultry in China. We evaluated the receptor binding property and transmissibility of four novel H5 clade 2.3.4.6 subtype highly pathogenic avian influenza viruses. The results show that these viruses bound to both avian-type (α-2,3) and human-type (α-2,6) receptors. Furthermore, we found that one of these viruses, GS/EC/1112/11, not only replicated but also transmitted efficiently in guinea pigs. Therefore, such novel H5 subtype viruses have the potential of a pandemic threat.

Effect of nitrogen and temperature on the transcription of an ACAT gene in Isochrysis galbana.

Thiolases are functionally divided into two groups: 3-ketoacyl-CoA thiolase and acetoacetyl-CoA thiolase (ACAT). Acetoacetyl-CoA thiolase plays a key role in the mevalonate pathway. In this study, a novel gene, IgACAT, which encodes ACAT was cloned from Isochrysis galbana and characterized. The cDNA of IgACAT was 1551 bp in length, consisting of an open reading frame of 1173 bp, a 5' untranslated region of 69 bp and a 3' untranslated region of 309 bp. The deduced amino acid sequence of IgACAT was 390 amino acid residues in length with a predicted molecular weight of 53.59 kDa and an isoelectric point of pH 9.04. The triterpenes content and the expression of IgACAT under nitrogen and temperature stress were analyzed. When I. galbana was treated with excessive nitrogen and at 35 °C, respectively, both the triterpenes content and the abundance of IgACAT gene transcript increased. Our findings will facilitate the regulation of gene expression and genetic modification of the triterpenes synthesis pathway of I. galbana.

Adaptation of a natural reassortant H5N2 avian influenza virus in mice.

It is reported that the H5N2 highly pathogenic avian influenza virus A/chicken/Hebei/1102/2010 (HB10) is a natural reassortant between circulating H5N1 and endemic H9N2 influenza viruses. To evaluate the potential of its interspecies transmission, the wild-type HB10 was adapted in mice through serial lung passages. Increased virulence was detectable in 5 sequential lung passages in mice and a highly virulent mouse-adapted strain (HB10-MA) with a 50% mouse lethal dose of 10(2.5) 50% egg infectious dose was obtained in 15 passages. The virulence and the replication efficiency of HB10-MA in mice were significantly higher than those of HB10 while HB10-MA grew faster and to significantly higher titers than HB10 in MDCK and A549 cells. Only five amino acid mutations in four viral proteins (HA-S227N, PB2-Q591K, PB2-D701N, PA-I554V and NP-R351K) of HB10-MA virus were found when compared with those of HB10, indicating that they may be responsible for the adaptation of the novel reassortant H5N2 avian influenza virus in mice with increased virulence and replication efficiency. The results in this study provide helpful insights into the pathogenic potential of novel reassortant H5N2 viruses to mammals that deserves further attentions.

Cloning, expression and stress-respondent transcription of long-chain acyl-coenzyme A synthetase cDNA gene of Nannochloropsis gaditana and its involvement in the biosynthesis of eicosapentaenoic and decosahexaenoic acids.

A novel cDNA gene, NgLACS, that encodes a long-chain acyl-CoA sythetase (LACS), was cloned from Nannochloropsis gaditana and characterized. The cDNA was 2,360 bp in length, consisting of an ORF of 1,950 bp, a 5'-untranslated region of 88 bp and a 3'-untranslated region of 322 bp. The deduced amino acid sequence of LACS was 649 amino acid residues in length with a predicted molecular weight of 71 kDa and an isoelectric point of pH 7.8. When the alga was treated with excessive nitrogen and iron, and at 15 °C, the proportion of long-chain polyunsaturated acyl-CoAs in the total acyl-CoAs and the abundance of NgLACS cDNA gene transcript were up-regulated. Over-expression of NgLACS in Saccharomyces cerevisiae caused the accumulation of eicosapentaenoic acid and docosahexaenoic acid.

Biodegradation of p-nitrophenol by Rhodococcus sp. CN6 with high cell surface hydrophobicity.

Rhodococcus sp. CN6, isolated from a pesticide industry's effluent-sediment, was able to completely degrade and utilize 100mg/L p-nitrophenol (PNP) as the sole carbon, nitrogen and energy sources for growth in the minimal salt media (MSM) within 12h. To study the applicability of the strain for bioremediation of PNP, its degradation potential was examined in the presence of different supplemented carbon and nitrogen sources in MSM with 100mg/L PNP. Dextrin was experienced as the best supplemented carbon source used by the strain CN6 during degrading PNP. Addition of ammonium nitrate could also increase the PNP degradation rate. Preliminary studies on the surface characters of Rhodococcus sp. CN6 were undertaken for the sake of exploring its high efficiency on the degradation of PNP. Microbial adherence to hydrocarbons (MATH) assays illuminated that the strain CN6 was of higher hydrophobicity while grown on higher concentration of PNP. The results suggested that the strain CN6 could be used as a potential and efficient PNP degrader for the bioremediation of contaminated sites.

Response surface optimization of fermentation conditions for producing xylanase by Aspergillus niger SL-05.

Fermentation conditions were statistically optimized for producing extracellular xylanase by Aspergillus niger SL-05 using apple pomace and cotton seed meal. The primary study shows that culture medium with a 1:1 ratio of apple pomace and cotton seed meal (carbon and nitrogen sources) yielded maximal xylanase activity. Three significant factors influencing xylanase production were identified as urea, KH(2)PO(4), and initial moisture content using Plackett-Burman design study. The effects of these three factors were further investigated using a design of rotation-regression-orthogonal combination. The optimized conditions by response surface analysis were 2.5% Urea, 0.09% KH(2)PO(4), and 62% initial moisture content. The analysis of variance indicated that the established model was significant (P < 0.05), "while" or "and" the lack of fit was not significant. Under the optimized conditions, the model predicted 4,998 IU/g dry content, whereas validation experiments produced an enzymatic activity of xylanase at 5,662 IU/g dry content after 60 h fermentation. This study innovatively developed a fermentation medium and process to utilize inexpensive agro-industrial wastes to produce a high yield of xylanase.