The polycyclic aromatic hydrocarbons (PAHs) that accumulate during the coking wastewater treatment process are hazardous for the surrounding environment. High molecular weight (HMW) PAHs account for ...more than 85% of the total PAHs in coking wastewater and sludge, respectively. The degradation of total PAHs increased by 18.97% due to the increased bioavailability of PAHs, after the biosurfactant-producing bacteria Pseudomonas aeruginosa S5 was added. The toxicity of total PAHs to humans was reduced by 26.66% after inoculation with S5. The results suggest biosurfactant-producing bacteria Pseudomonas aeruginosa S5 not only increase the biodegradation of PAHs significantly, but also have a better effect on reducing the human toxicity of PAHs. Kinetic analyses show that PAHs biodegradation fits to first-order kinetics. The degradation rate constant (k) value decreases as the number of PAH rings increases, indicating that HMW PAHs are more difficult to be biodegraded than low molecular weight (LMW) PAHs. The results indicate the bioaugmentation with the biosurfactant-producing strain has significant potential and utility in remediation of PAHs-polluted sites.
Acid mine drainages (AMD) contain high concentrations of heavy metals, and their discharges into streams and rivers constitute serious environmental problems. This article examines the effects of AMD ...on soil, plant and human health at Dabaoshan mine in Guangdong Province, China. Although the large scale mining was stopped in 2011, the heavy metal pollution in soil continues to endanger crops and human health in that region. The objectives of this study were to elucidate distribution and migration of Cd, Cu, Zn, As and Pb and associated health implications to local inhabitants. We collected and analyzed 74 crop samples including 28 sugarcane, 30 vegetables, 16 paddy rice and the corresponding soil samples, used correlation and linear relationship for transformation process analysis, and applied carcinogenic and non-carcinogenic risk for hazard evaluation. Results showed that the local soils were heavily polluted with Cd, Cu and As (especially for Cd) and the mean Igeo value was as high as 3.77. Cadmium, Cu, and Zn in rice and vegetables were comparable with those found four years ago, while As and Pb in edible parts were 2 to 5 times lower than before. The root uptake of Cd and Zn contributed mainly to their high concentrations in crops due to high exchangeable fraction of soil, while leafy vegetables accumulated elevated As and Pb contents mainly due to the atmospheric deposition. Metal concentrations in sugarcane roots were higher than those in rice and vegetable roots. The risk assessment for crops consumption showed that the hazard quotients values were of 21 to 25 times higher than the threshold level for vegetables and rice, indicating a potential non-carcinogenic risk to the consumers. The estimated mean total cancer risk value of 0.0516 more than 100 times exceeded the USEPA accepted risk level of 1×10−4, indicating unsuitability of the soil for cultivating the food crops. Therefore, the local agricultural and the land-use policies need to be reevaluated.
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•Root uptake of Cd and Zn contributed to high contents in edible parts of crops.•Leafy vegetables accumulated elevated As and Pb from atmospheric deposition.•As and Cd in crops contributed to high non-cancer and cancer risk, respectively.•Land use pattern can be revaluated based on risk estimates from crops in acid mine soil.
Understanding sources and fate of heavy metals in river basin is crucial for assessing risks associated with human and ecosystem exposure. To provide basic information for agriculture and industry ...transferring in future, environmental development planning and decision-making, and drinking water source protecting associated with human health in the region, compound heavy metal pollution in the Maba River, South China, was investigated to evaluate spatial distribution and pollution levels using geo-accumulation index (Igeo). In addition, heavy metal concentrations in sediments were measured and compared with sediment quality guidelines (SQGs). The main contamination sources of heavy metals and the concrete contribution were identified and calculated using multivariate statistical analysis (MSA) and factor analysis-multiple linear regression (FA-MLR) methods. The results showed that the heavy metals exposed in sediments of the Maba River largely due to anthropogenic sources, such as smelting and mining. The heavy metal concentrations found in surface sediments were significantly higher than the local background values, especially in the mixed region. The migration and transformation process of river metals was mainly affected by hydraulic conditions and sediment characteristics. The Igeo and SQGs produced similar levels of heavy metals pollution in sediments, thereby confirming each other's results, indicating that the Maba River is heavily contaminated, and As, Hg, Pb, Zn, Cd and Cu were likely to effect on the aquatic ecosystem. Based on MSA and FA-MLR, the results showed that about 87% of Cu came from the mine tailing wastewater runoff, 77%, 66% and 72% of Tl, Hg and Cd respectively originated from the smelting wastewater discharge. Results of this study will be useful in assessing and managing regional point source pollution. Further investigation on fate and toxicity of heavy metals associated with human health risks is needed in future studies.
•Igeo, SQGs, MSA and FA-MLR were applied to study the distribution, level and source of heavy metals in river sediments.•The distribution of heavy metals were mainly affected by point sources, river characteristics and sediment properties.•Arsenic, Hg, Pb, Zn, Cd and Cu in the Maba River were likely to effect on the aquatic ecosystems.•84% of Cu in the mixed region came from mine tailing, 77%, 66%, 72% of Tl, Hg, Cd originated from smelting.
Functional identification and elimination of activity-decayed sludge are helpful for improving the performance of biological treatment process. However, cell decay-associated changes in biological ...functions have not been explored for gravity-separated sludge. In this work, sludge flocs from the aerobic basin of a wastewater treatment plant treating high-concentration organic coking wastewater was fractionated according to settling velocity, i.e. sludge F (fast settling), sludge M (moderate settling) and sludge S (slow settling). Sludge volume index (SVI), mean floc size, dehydrogenase activity, specific oxygen uptake rate (SOUR), extracellular polymeric substances (EPS) content and aggregation interaction were investigated in the fractionated sludges. Apoptosis-like decayed cell distribution (ALDCD), a novel property of sludge, was proposed to describe sludge decay based on cell membrane variation. ALDCD of sludge F was 6.64% and 13.5% lower than sludge M and S, respectively. Microbial community and functional prediction revealed that sludge F exhibited the highest microbial potential for organic removal and sludge M had the highest potential for nitrogen metabolism while sludge S had the lowest potential for both. Our analysis suggests that the treatment efficiency might be enhanced by retaining compact sludge flocs while eliminating dispersive sludge flocs. This study also facilitates the identification and elimination of functional microbial groups from decayed sludge in wastewater treatment.
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•Aerobic floccular sludge was gravity-separated into different fractions.•The light fraction showed the highest SVI and the lowest aggregation ability.•Apoptosis-like decayed cell distribution was proposed to evaluate sludge decay.•The apoptosis-like decay was associated with variations in microbial functions.•Slow-settling flocs have the lowest potential in COD and nitrogen removal.
•16s rDNA, MLSA, MLST, DDH estimation as well as phylogenomic analysis of ET080813-like strains from eel.•phenotype comparisons of ET080813-like strains with other species.•ET080813-like strains ...proposed as Edwardsiella anguillarum sp. nov.•Edwardsiella anguillarum sp. nov. bacteria have the largest genomes in Edwarsiella bacteria.•Edwardsiella anguillarum sp. nov. bacteria contain 3 distinct sets of T6SS and 2 T3SS presumably by gene horizontal transfer events.
As important zoonotic organisms causing infections in humans, Edwardsiella bacteria are also notorious leading fish pathogens haunting worldwide aquaculture industries. However, the taxa are now widely recognized to be misclassified, which hurdled the understanding of the epidemiology and development of effective diagnostics and vaccines. Currently the genus Edwardsiella consists of three species Edwardsiella tarda, E. ictaluri, and E. hoshinae. Previous phylogenomic analysis revealed that E. tarda strains display two major highly divergent genomic types (genotypes), EdwGI and EdwGII, and the former represents a genotype of fish-pathogenic isolates and being recently proposed as a novel species E. piscicida, sp. nov. Here multiple phylogenetic analyses and the genome-level comparisons of EdwGI strains disclose that the phylogroup strains from diseased eel formed an obviously distinct cluster that could be equated with a new species status. The phylogenetic evidence for the new species assignment was also supported by corresponding DNA–DNA hybridization estimation values and by phenotypic characteristics. Interestingly, further comparative genomics reveals that these strains have acquired the locus of enterocyte effacement (LEE) genes and as a result these bacteria contain at least 2 sets of distinct T3SS and 3 sets of T6SS gene clusters, respectively. It is therefore proposed that the phylogroup strains from diseased eel should be classified as Edwardisella anguillarum sp. nov., and the type strain is ET080813T (=DSM27202T=CCUG 64215T=CCTCC AB2013118T=MCCC 1K00238T). These findings will contribute to development of species-specific control measures against Edwardsiella bacterium in aquatic animals, while also shedding light on the pathogenesis evolution in Edwardsiella bacterium.
Polycyclic aromatic hydrocarbons (PAHs) and phenol are persistent pollutants that coexist in coking wastewater (CWW). Fluoranthene (Flu) is the predominant PAH species in the CWW treatment system. ...Our work emphasized on distinguishing the effects of phenol on Flu biodegradation by co-culture of Stenotrophomonas sp. N5 and Advenella sp. B9 and illustrated the molecular mechanisms. Results showed Flu biodegradation by co-culture was enhanced by phenol. According to the first-order degradation kinetic analysis of Flu, phenol significantly increased the biodegradation rate constant and shortened the half-life of Flu. Transcriptome analysis pointed out the up-regulation of DNA repair activity and 3717 significantly differentially expressed genes (DEGs), were triggered by 800 mg/L phenol. GO enrichment analysis suggested these DEGs are mainly concentrated in biochemical processes such as metal ion binding and alpha-amino acid biosynthesis, which are closely associated with Flu biodegradation, indicating that phenol promotes DNA repair activity and reduces Flu genotoxicity. qRT-PCR was performed to detect the gene expression of aromatic ring-opening dioxygenase. Combined with transcriptome analysis, the qRT-PCR results suggested phenol did not induce the expression of related PAHs-degrading enzymes. RNA extraction and microbial growth curves of COC and COC + Ph provided further evidence that phenol serves as co-substrate which increases biomass and the concentration of degrading enzymes, therefore promoting the Flu degradation.
•Phenol significantly facilitated the degradation of fluoranthene.•Phenol was served as the growth substrate to increase biomass.•DNA repair activity was enhanced by addition of phenol.•3717 differentially expressed genes was triggered by phenol.•Gene expression regulation by phenol promoted degradation of fluoranthene.
The pre-aerobic process of coking wastewater treatment has strong capacity of decarbonization and detoxification, which contribute to the subsequent dinitrogen of non-carbon source/heterotrophic ...denitrification. The COD removal rate can reach > 90% in the first aerobic bioreactor of the novel O/H/O coking wastewater treatment system during long-term operation. The physico-chemical characteristics of influent and effluent coking wastewater in the first aerobic bioreactor were analyzed to examine how they correlated with bacterial communities. The diversity of the activated sludge microbial community was investigated using a culture-independent molecular approach. The microbial community functional profiling and detailed pathways were predicted from the 16S rRNA gene-sequencing data by the PICRUSt software and the KEGG database. High-throughput MiSeq sequencing results revealed a distinct microbial composition in the activated sludge of the first aerobic bioreactor of the O/H/O system. Proteobacteria, Bacteroidetes, and Chlorobi were the decarbonization and detoxification dominant phyla with the relative abundance of 84.07 ± 5.45, 10.89 ± 6.31, and 2.96 ± 1.12%, respectively. Thiobacillus, Rhodoplanes, Lysobacter, and Leucobacter were the potential major genera involved in the crucial functional pathways related to the degradation of phenols, cyanide, benzoate, and naphthalene. These results indicated that the comprehensive understanding of the structure and function diversity of the microbial community in the bioreactor will be conducive to the optimal coking wastewater treatment.
Microalgae are often used as nutritional supplements for aquatic animals and are widely used in the aquaculture industry, providing direct or indirect nutrients for many aquatic animals. Microalgae ...are abundant in nature, of high nutritional value, and some of them are non-toxic and rich in antioxidants so that they can be explored as a medicinal carrier for human or animals. Natural wild-type microalgae can be adopted as an immunostimulant to enhance non-specific immune response and improve growth performance, among which
Haematococcus pluvialis, Arthrospira (Spirulina) platensis, and Chlorella
spp. are commonly used. At present, there have been some successful cases of using microalgae to develop oral vaccines in the aquaculture industry. Researchers usually develop recombinant vaccines based on
Chlamydomonas reinhardtii, Dunaliella salina
, and cyanobacteria. Among them, in the genetic modification of eukaryotic microalgae, many examples are expressing antigen genes in chloroplasts. They are all used for the prevention and control of single infectious diseases and most of them are resistant to shrimp virus infection. However, there is still no effective strategy targeting polymicrobial infections and few commercial vaccines are available. Although several species of microalgae are widely developed in the aquaculture industry, many of them have not yet established an effective and mature genetic manipulation system. This article systematically analyzes and discusses the above problems to provide ideas for the future development of highly effective microalgae recombinant oral vaccines.
A candidate vaccine, live attenuated Vibrio anguillarum developed in our laboratory could prevent vibriosis of fish resulted from V. anguillarum and V. alginolyticus. To elucidate the molecular ...mechanisms underlying the vaccine protection, we used microarray technology to compare the spleen transcriptomes of bath-vaccinated and unvaccinated zebrafish at 28 days post vaccination.
A total of 2164 genes and transcripts were differentially expressed, accounting for 4.9% of all genes represented on the chip. In addition to iron metabolism related to the innate immunity and the signaling pathways, these differentially expressed genes also involved in the adaptive immunity, mainly including the genes associated with B and T cells activation, proliferation and expansion. Transcription profiles of Th17-related transcription factors, cytokines and cytokine receptors during 35 days post-vaccination implied that Th17 cells be activated in bath-vaccinated zebrafish.
The transcriptome profiling with microarray revealed the Th17-like immune response to bath-vaccination with the live attenuated V. anguillarum in zebrafish.
Antibiotics biosynthesis is usually regulated by the cluster-situated regulatory gene(s) (CSRG(s)), which directly regulate the genes within the corresponding biosynthetic gene cluster (BGC). ...Previously, we have demonstrated that LmbU functions as a cluster-situated regulator (CSR) of lincomycin. And it has been found that LmbU regulates twenty non-lmb genes through comparative transcriptomic analysis. However, the regulatory mode of CSRs' targets outside the BGC remains unknown.
We screened the targets of LmbU in the whole genome of Streptomyces lincolnensis and found fourteen candidate targets, among which, eight targets can bind to LmbU by electrophoretic mobility shift assays (EMSA). Reporter assays in vivo revealed that LmbU repressed the transcription of SLINC_0469 and SLINC_1037 while activating the transcription of SLINC_8097. In addition, disruptions of SLINC_0469, SLINC_1037, and SLINC_8097 promoted the production of lincomycin, and qRT-PCR showed that SLINC_0469, SLINC_1037, and SLINC_8097 inhibited transcription of the lmb genes, indicating that all the three regulators can negatively regulate lincomycin biosynthesis.
LmbU can directly regulate genes outside the lmb cluster, and these genes can affect both lincomycin biosynthesis and the transcription of lmb genes. Our results first erected the cascade regulatory circuit of LmbU and regulators outside lmb cluster, which provides the theoretical basis for the functional research of LmbU family proteins.
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