Effect of g-C3N4 on biodiversity and structure of bacterial community in sediment of Xiangjiang River under tetracycline pressure.

Photocatalysts have been widely prepared and used in wastewater treatment. Although the influence of photocatalyst application on survival and activity of organisms has been examined, its impact on composition and diversity of microbial community is not fully understood. In this study, the impact of photocatalyst g-C3N4 (Graphitic carbon nitride) on microbial communities in riverbed sediments polluted by antibiotic tetracycline (TC) was investigated. The sediment samples collected from the Xiangjiang River of China were exposed to different concentrations of TC, g-C3N4 and TC/g-C3N4 and the bacterial community were analyzed by Illumina sequencing. The results showed that the dominant bacterial phyla were Acidobacteriota, Proteobacteria, Actinobacteriota, and Chloroflexi in the study site. When compared to the control treatments, the application of TC, g-C3N4 and TC/g-C3N4 exhibited distinguishable effects on bacterial community structure in sediments. The presence of TC had greater influence on bacterial composition, while g-C3N4 and TC/g-C3N4 had less influence on bacteria. The diversity and richness of microorganisms in sediment increased under g-C3N4 application and reached the highest values when g-C3N4 was 75 mg/kg. The photocatalyst g-C3N4 restored bacterial community diversity affected by TC, reduced the TC residues in aquatic environment, and eliminated the side effects of TC application in sediments. Our study indicated that g-C3N4 was an environmentally friendly photocatalyst with lightly negative effects on microbial community in riverbed sediments, and could be used for effective remediation of TC-contaminated environments.

Streptomyces phaeolivaceus sp. nov. and Streptomyces broussonetiae sp. nov., isolated from the leaves and rhizosphere soil of Broussonetia papyrifera.

Two novel actinobacteria, designated strains GY16T and T44T, were isolated from the leaves and rhizosphere soil of Broussonetia papyrifera, respectively. A polyphasic approach was used for determining their taxonomic position. Results of 16S rRNA gene sequence analysis indicated that strain GY16T exhibited highest similarities to Streptomyces cinereoruber subsp. fructofermentans CGMCC 4.1593T (98.82 %), Streptomyces deccanensis KCTC 19241T (98.76 %), Streptomyces scabiei NRRL B-16523T (98.69 %), Streptomyces europaeiscabiei KACC 20186T (98.69 %) and Streptomyces rishiriensis NBRC 13407T (98.69 %), and strain T44T showed 99.2, 99.1, 99.1 and <98.7 % sequence similarities to Streptomyces filipinensis CGMCC 4.1452T, Streptomyces achromogenes subsp. achromogenes DSM 40028T, Streptomyces durhamensis DSM 40539T and other Streptomyces species, respectively. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain GY16T formed an independent subclade, which indicated that strain GY16T should belong to a potential novel species; and strain T44T was closely related to S. filipinensis CGMCC 4.1452T, S. achromogenes subsp. achromogenes DSM 40028T, S. durhamensis DSM 40539T and S. yokosukanensis DSM 40224T. However, the multilocus sequence analysis evolutionary distance, average nucleotide identity and DNA-DNA hybridization values between closely related relatives were far from the species-level thresholds. In addition, phenotypic and chemotaxonomic characteristics further confirmed that strains GY16T and T44T belonged to two distinct species. Based on these results, it is concluded that the isolated strains represent novel species within the genus Streptomyces, for which the names Streptomyces phaeolivaceus sp. nov. (type strain GY16T=CICC 24807T=KCTC 49326T) and Streptomyces broussonetiae sp. nov. (type strain T44T=CICC 24819T=JCM 33918T) are proposed.

Pseudonocardia broussonetiae sp. nov., an endophytic actinomycete isolated from the roots of Broussonetia papyrifera.

A novel endophytic actinomycete, designated strain Gen 01T, was isolated from the roots of Broussonetia papyrifera and characterized by using a polyphasic approach. The predominant cellular fatty acids were iso-C16 : 0, summed feature 3, iso H-C16 : 1, C16 : 0 and iso-C14 : 0. The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol mannosides, phospholipids of unknown structure containing glucosamine inositol, phosphatidylinositol and unidentified phospholipids. The major menaquinone was MK-8 (H4). The DNA G+C content of the genome sequence, consisting of 7 177 725 bp, was 74.5 mol%. Phylogenetic analysis of the full-length 16S rRNA gene sequences showed that strain Gen 01T belongs to the genus Pseudonocardia with the highest sequence similarity to Pseudonocardia petroleophila CGMCC 4.1532T (98.9 %) and lower than 98.7 % similarity to other species of the genus Pseudonocardia with validly published names. The average nucleotide identity and digital DNA-DNAhybridization values between strain Gen 01T and P. petroleophila CGMCC 4.1532T were 84.6 and 30.9 %, respectively. Furthermore, the morphological, physiological and biochemical characteristics were sufficient to categorize strain Gen 01T as being distinct from P. petroleophila CGMCC 4.1532T. Consequently, based on phenotypic and genotypic characteristics, strain Gen 01T represents a novel species of the genus Pseudonocardia, for which the name Pseudonocardia broussonetiae sp. nov. is proposed. The type strain is Gen 01T (=CICC 24820T=JCM 33840T).

Physiological responses of Broussonetia papyrifera to manganese stress, a candidate plant for phytoremediation.

Effective phytoremediation of Mn contaminated soil requires the selection of a species with good manganese tolerance. Broussonetia papyrifera is an important economic plant and pioneer species, it could be well adapted to drought and saline-alkali environment. In order to understand the effect of Mn stress on B. papyrifera, the effects of different concentrations of Mn (0-50 mmol/L) stress on the growth, morphology, Mn tolerance and physiological indexes of the plant were explored. The results showed that the biomass, surface area, length, root volume, tips, forks, and crossings of B. papyrifera reached the maximum at the Mn concentration of 1 mmol/L. Mn content in the tissue and TF in plants increased with the increase of concentration, while the BCF increased first and then decreased, and the maximum BCF was 0.154 at 10 mmol/L. The accumulation of Mn lead to cell membrane lipid peroxidation, which increased toxic substances in plants, resulting in the increase of MDA and PRO, and affected the synthesis of chlorophyll. However, B. papyrifera could effectively alleviate oxidative stress by increasing the activities of antioxidant enzymes (SOD, POD, CAT), protein and soluble sugar. The results suggested that B. papyrifera had a good oxidative stress mechanism to Mn stress and could be used as candidates for remediation of pollution in mining areas.

New insight into the molecular basis of cadmium stress responses of wild paper mulberry plant by transcriptome analysis.

BACKGROUND: Heavy metal contamination is becoming a limitation to the utilization of soil and the distribution of vegetation. In particular, cadmium (Cd) pollution has had a serious impact on the food chain. Broussonetia papyrifera is a widely distributed pioneer tree species of heavy metal contaminated areas with important economic value. However, little is known about the genomic background of the Cd-tolerance mechanism in B. papyrifera. RESULTS: The CdCl2 responsive physiology was evaluated and proved to be involved in antioxidase activity and active oxygen species (ROS) accumulation. The leaf and root transcriptomes derived from B. papyrifera grown under normal and CdCl2 stress conditions were systematically investigated using the Illumina HiSeq method. A total of 180,678,660 bp (27.1 GB) clean reads were assembled into 589,487 high-quality unigenes, of which 256,025 (43.43% of the total) and 250,251 (42.45% of the total) were aligned in Gene Ontology (GO) and Protein family (Pfam), respectively. A total of 24,414 differentially expressed genes (DEGs) were GO-annotated into 53, 23, 55, and 60 terms from the transcriptomes of root and leaf tissues under Cd stress and control conditions. A total of 117,547 Kyoto Encyclopedia of Genes and Genomes (KEGG) Orthology (KO)-annotated DEGs were enriched in at least 47 KEGG pathway terms among the four comparisons. Many genes encoding important transcription factors (e.g., auxin/indole-3-acetic acid (AUX/IAA), basic helix-loop-helix (bHLH), DNA-binding one zinc finger (Dof), and MYB) and proteins involved in plant-pathogen interactions, phenylpropanoid biosynthesis, plant hormone signal transduction, oxidative phosphorylation, carbon fixation, peroxisomes, flavonoid biosynthesis, and glutathione metabolism, among others, were substantially upregulated under CdCl2 stress. CONCLUSIONS: These genes represent important candidates for studying Cd-response mechanisms and molecular biology of B. papyrifera and related species. Our findings provide a genomic sequence resource for functional genetic assignments in B. papyrifera, which will help elucidate the molecular mechanisms of its Cd-stress responses and facilitate the bioremediation of heavy metal contaminated areas via breeding of new stress-tolerant cultivars.

Exogenous spermidine elevating cadmium tolerance in Salix matsudana involves cadmium detoxification and antioxidant defense.

In this study, exogenous spermidine role on Salix matsudana tolerance to cadmium was evaluated. Spermidine and cadmium presented antagonistic effects on the biomass, copper and zinc concentrations in S. matsudana. cadmium mainly distributed in the cell wall of subcellular fraction; 46.97%-60.43% of cadmium existed in a sodium chloride-extracted form. Cadmium contents in roots, leaves, and twigs ranged from 2002.67 to 3961.00, 111.59 to 229.72, and 102.56 to 221.27 mg/kg, respectively. Spermidine application elevated cadmium concentrations in the roots, cuttings, and cell wall and the ratio of deionized water-extracted cadmium, but decreased cadmium levels in the twigs and leaves and the fractions of cadmium extracted by ethanol and sodium chloride, respectively. Putrescine and malondialdehyde were important indicators of cadmium-induced oxidative damage. Exogenous spermidine alleviated the accumulation of superoxide anion, hydrogen peroxide, malondialdehyde via promoting the levels of spermidine, soluble protein, superoxide dismutase, reductive ascorbate, glutathione reductase, and glutathione peroxidase in S. matsudana leaves under the corresponding cadmium stress. The results indicated that S. matsudana was a candidate for cadmium rhizoremediation and extraction in leaves; the spermidine application enhanced the cadmium tolerance of S. matsudana through promoting cadmium accumulation in roots, cell wall, and less bioactive chemical forms and the antioxidative ability.

The walnut JrVHAG1 gene is involved in cadmium stress response through ABA-signal pathway and MYB transcription regulation.

BACKGROUND: Vacuolar H+-ATPase (V-ATPase) is a vital protein complex involved in abiotic stress response in plants. The G subunit of Juglans regia (JrVHAG1) was previously identified as a drought tolerance-related gene involved in the ABA (abscisic acid)-signal pathway. Heavy metal stress is becoming a major detriment for plant growth, development, and production. In order to understand the role of JrVHAG1, the potential function mechanism of JrVHAG1 exposed to CdCl2 stress was confirmed in this study. RESULTS: Transcription of JrVHAG1 was induced by ABA and increased to 58.89-fold (roots) and 7.38-fold (leaves) and by CdCl2 to 2.65- (roots) and 11.42-fold (leaves) relative to control, respectively. Moreover, when treated simultaneously with ABA and CdCl2 (ABA+CdCl2), JrVHAG1 was up-regulated to 110.13- as well as 165.42-fold relative to control in the roots and leaves, accordingly. Compared to the wild type (WT) Arabidopsis plants, the transgenic plants with overexpression of JrVHAG1 (G2, G6, and G9) exhibited increased seed germination rate, biomass accumulation, proline content, and activities of superoxide dismutase (SOD) and peroxidase (POD) under ABA, CdCl2, and ABA+CdCl2 treatments. In contrast, the reactive oxygen species (ROS) staining, malondialdehyde (MDA) content, hydrogen dioxide (H2O2) content, as well as electrolyte leakage (EL) rates of transgenic seedlings were all lower than those of WT exposed to ABA, CdCl2 and ABA+CdCl2 stresses. Furthermore, a 1200 bp promoter fragment of JrVHAG1 was isolated by analyzing the genome of J. regia, in which the cis-elements were identified. This JrVHAG1 promoter fragment showed expression activity that was enhanced significantly when subjected to the above treatments. Yeast one-hybrid assay and transient expression analysis demonstrated that JrMYB2 specifically bound to the MYBCORE motif and shared similar expression patterns with JrVHAG1 under ABA, CdCl2 and ABA+CdCl2 stress conditions. CONCLUSIONS: Our results suggested that the JrVHAG1 gene functions as a CdCl2 stress response regulator by participating in ABA-signal pathway and MYB transcription regulation network. JrVHAG1 gene is a useful candidate gene for heavy metal stress tolerance in plant molecular breeding.

Characterization of a vacuolar H+-ATPase G subunit gene from Juglans regia (JrVHAG1) involved in mannitol-induced osmotic stress tolerance.

KEY MESSAGE: JrVHAG1 is an important candidate gene for plant osmotic tolerance regulation. Vacuolar H+-ATPase (V-ATPase) is important for plant responses to abiotic stress; the G subunit is a vital part of V-ATPase. In this study, a G subunit of V-ATPase was cloned from Juglans regia (JrVHAG1) and functionally characterized. JrVHAG1 transcription was induced by mannitol that increasing 17.88-fold in the root at 12 h and 19.16-fold in the leaf at 96 h compared to that under control conditions. JrVHAG1 was overexpressed in Arabidopsis and three lines (G2, G6, and G9) with highest expression levels were selected for analysis. The results showed that under normal conditions, the transgenic and wild-type (WT) plants displayed similar germination, biomass accumulation, reactive oxygen species (ROS) level, and physiological index. However, when treated with mannitol, the fresh weight, root length, water-holding ability, and V-ATPase, superoxide dismutase, and peroxidase activity of G2, G6, and G9 were significantly higher than those of WT. In contrast, the ROS and cell damage levels of the transgenic seedlings were lower than those of WT. Furthermore, the transcription levels of V-ATPase subunits, ABF, DREB, and NAC transcription factors (TFs), all of which are factors of ABA signaling pathway, were much higher in JrVHAG1 transgenic plants than those in WT. The positive induction of JrVHAG1 gene under abscisic acid (ABA) treatments in root and leaf tissues indicates that overexpression of JrVHAG1 improves plant tolerance to osmotic stress relating to the ABA signaling pathway, which is transcriptionally activated by ABF, DREB, and NAC TFs, and correlated to ROS scavenging and V-ATPase activity.

Rodent-Proof Wall: An Efficient Physical Method for Controlling Rodents and its Efficiency Statistics.

Rodent damage poses a significant threat to crops, human life, and health. Compared to chemical rodent control, such as placing poisonous baits, it is more economical and environmentally friendly to use physical methods, such as building a rodent-proof wall. This study introduces a method of physically controlling harmful rodents and four methods of calculating the effect of rodents control. To understand the controlling effect of the rodent-proof wall, an investigation was conducted on the Dongting Lake beach and corresponding farmland in the embankment in April and July 2012. Our findings illustrated that the density of the reed vole Microtus fortis in the farmland with rodent-proof walls was 0.52%, significantly lower than that in the farmland without rodent-proof walls (1.76%) after artificial trapping and drug extermination (χ2 = 3.900, P = 0.048). The density of M. fortis that had migrated into the farmland in dikes with a rodent-proof wall decreased by 98.53%, significantly higher than the decrease of density in dikes without a rodent-proof wall (86.61%) (χ2 = 11.060, P = 0.01). The results demonstrated the effectiveness of rodent-proof wall control. Therefore, building a rodent-proof wall should be advocated and vigorously promoted to prevent the migration of rodents into the Dongting Lake area and similar environments, as they cause harm.

Viral infection and spread are inhibited by the polyubiquitination and downregulation of TRPV2 channel by the interferon-stimulated gene TRIM21.

Interferon (IFN) contributes to the host's antiviral response by inducing IFN-stimulated genes (ISGs). However, their functional targets and the mechanism of action remain elusive. Here, we report that one such ISG, TRIM21, interacts with and degrades the TRPV2 channel in myeloid cells, reducing its expression and providing host protection against viral infections. Moreover, viral infection upregulates TRIM21 in paracrine and autocrine manners, downregulating TRPV2 in neighboring cells to prevent viral spread to uninfected cells. Consistently, the Trim21-/- mice are more susceptible to HSV-1 and VSV infection than the Trim21+/+ littermates, in which viral susceptibility is rescued by inhibition or deletion of TRPV2. Mechanistically, TRIM21 catalyzes the K48-linked ubiquitination of TRPV2 at Lys295. TRPV2K295R is resistant to viral-infection-induced TRIM21-dependent ubiquitination and degradation, promoting viral infection more profoundly than wild-type TRPV2 when reconstituted into Lyz2-Cre;Trpv2fl/fl myeloid cells. These findings characterize targeting the TRIM21-TRPV2 axis as a conducive strategy to control viral spread to bystander cells.

Ecological function zoning based on ecosystem service bundles and trade-offs: a study of Dongjiang Lake Basin, China.

Although the research framework of ecological function zoning is complex and diverse, there are not many spatially continuous zoning results, which can be effectively applied to watershed management practices. Ecosystem service bundles and trade-offs can identify interactions among multiple ecosystem services, and achieve better social-ecosystem management when applying to ecological function zoning. Taking the Dongjiang Lake Basin, China, as research area, the study used the InVEST model to investigate the trade-offs and synergies of ecosystem services at township and grid scales, respectively. Then, the study conducted ecological function zoning based on the bundles and trade-off intensity among ecosystem services. The results showed that food production showed extremely significant trade-offs with other services in the two scales, in which the trade-off intensity between food production and water purification was the largest, and the water areas were the hotspots of trade-off intensity. Based on the ecosystem service bundles at the township, combined with the trade-off intensity, the watershed was finally divided into four ecological functional zones, namely, agricultural product supply area (southern part in the study area), economic forestry area (northeast regions in the study area), water supply area (western areas of the study area), and forest conservation area (northern areas in the study area), accounting for 29.27%, 14.63%, 17.07%, and 39.03%, respectively. The study contributed to the ecological function maintenance and sustainable development in Dongjiang Lake Basin and provided an important reference in ecological zoning.

Paper mulberry leaves as a potential sterilant: evidence from Microtus fortis-a laboratory study.

Introduction: The Yangtze vole (Microtus fortis) is a small herbivorous rodent that usually causes damage to crops and forests in China. Various measures were used to control their population including chemical rodenticides. However, rodenticides may cause secondary damage to the environment and the ecosystem. Therefore, the development of new rodent sterilants is urgent. Considering that some compounds of paper mulberry leaves have been verified that can inhibit the biosynthesis of sexual hormone, we aimed to explore the antifertility effect of paper mulberry leaves on M. fortis. Methods: In this study, voles were divided into three groups including a male group, a female group, and a breeding group, and paper mulberry leaves were added into basal fodder of voles maintained in laboratory, of which the proportion of leaf weight was 50%. In each group, voles were fed with mixed fodder as treatment (BP) and voles were fed with basal fodder as contrast (CK). Results and discussion: After feeding for more than 1 month, the results indicated that paper mulberry leaves attracted voles to feed, but inhibited their growth and reproduction. Since the second week, food intakes of BP have been significantly higher than CK (p< 0.05). However, weights of voles in male and female groups were 72.283 ± 7.394 g and 49.717 ± 2.278 g in the fifth week, and both were significantly reduced compared with their original weight (p< 0.05). Meanwhile, testicular volumes of male voles fed with BP were significantly smaller than CK (former: 318.000 ± 44.654 mm3, latter: 459.339 ± 108.755 mm3); the testosterone level, sperm number, and vitality of BP were obviously weaker than CK. Female uteruses and oophoron of BP grew slower, and the organ coefficients of uterus and oophoron fed BP were both significantly lower than CK (p< 0.05). The first reproduction of BP couple voles spent 45 days, while CK spent only 21 days. These results suggest that paper mulberry leaves could be the potential resource to produce sterilants to control rodent populations by delaying their sexual growth and reproduction. If it was practical, the apparent advantages of paper mulberry are that it is an abundant resource and the inhibitory effect could be effective in both male and female individuals. Our conclusion also supports the transformation of rodent management from lethal management to fertility control, which would be more ecologically friendly to agriculture and the ecosystem.

Novel ZnFe2O4/BC/ZnO photocatalyst for high-efficiency degradation of tetracycline under visible light irradiation.

Developing broad-spectrum light reactions, effective charge separation, and easily recoverable photocatalysts were considered cost-effective pollution remediation methods. The ZnFe2O4/BC/ZnO composite was prepared to achieve these objectives, where biochar (BC) was used as a conductive channel and ZnFe2O4 as a magnetic substance. Among them, the 0.6-ZBO composite performed the best, with photocatalytic removal of tetracycline (TC) reaching 85.6%. The photocatalytic degradation rated constant of 0.6-ZBO composite was 23.36 × 10-3 min-1, which was 7.6, 4.1, and 2.5 times higher than that of ZnFe2O4/BC, ZnO, and ZnFe2O4/ZnO samples, respectively. According to several characterization data, it was demonstrated that successful Z-scheme heterojunctions were constructed between ZnFe2O4 and ZnO. The 0.6-ZBO complex increased the range of light absorption and strengthened the separation of electron-hole pairs, thus improving the redox ability of the complex. In the different water matrices, the stability of 0.6-ZBO was excellent and its ability to remove TC decreased slightly to about 11% after 5 cycles. This work provided a valuable approach to design a novel and efficient system for degrading organic pollutants in wastewater using magnetic biochar.

Woody plants have the advantages in the phytoremediation process of manganese ore with the help of microorganisms.

The serious ecological damage caused by mining activities cannot be ignored. The use of an environmentally friendly restoration method to rebuild the vegetation and soil environment in the mining area has attracted more and more attention. This paper aims to study soil quality as well as vegetation characteristics of four woody species including Pinus massoniana (P. massoniana), Broussonetia papyrifera (B. papyrifera), Koelreuteria paniculata (K. paniculata), Osmanthus fragrans (O. fragrans), and two herbaceous species including Setaria viridis (S. viridis) and Cynodon dactylon (C. dactylon). In addition, we further clarified the effects of B. papyrifera and K. paniculata on soil nutrients and microbial communities after restoration. The results showed that the vegetation restoration area had better soil quality and plant community diversity, and the woody plants restoration effect were better. Compared with slag, B. papyrifera and K. paniculata remediation could improve soil pH and mitigate heavy metal contamination in mining areas, but was not effective in enhancing Soil Organic Matter (SOM), Total Nitrogen (TN), Total Potassium (TK) and Total Phosphorus (TP). In addition, the abundance and diversity of soil bacterial communities were increased. Of all the study sites, Proteobacteria had the greatest dominance. Vegetation restoration resulted in an increase in the relative abundance of Acidobacteria, while a decrease in Actinobacteria, Cyanobacteria and Firmicutes. With the restoration of vegetation, the increase of pH, the change of TN, SOM, TK, TP and the mitigation of Manganese (Mn) pollution were the main reasons affecting the soil microbial community. This study has great significance for understanding the ecological changes in the mining area after artificially mediated vegetation restoration, including changes in soil environment, plant community and microbial community, and woody plants will be more encouraged for the restoration of manganese mining areas.

Integrating Broussonetia papyrifera and Two Bacillus Species to Repair Soil Antimony Pollutions.

Heavy metal resistant bacteria play an important role in the metal biogeochemical cycle in soil, but the benefits of microbial oxidation for plants and soil have not been well-documented. The purpose of this study was to explore the contribution of two Bacillus spp. to alleviate the antimony (Sb) toxicity in plants, and, then, to propose a bioremediation method for Sb contaminated soil, which is characterized by environmental protection, high efficiency, and low cost. This study explored the effects of Bacillus cereus HM5 and Bacillus thuringiensis HM7 inoculation on Broussonetia papyrifera and soil were evaluated under controlled Sb stressed conditions (0 and 100 mmol/L, antimony slag) through a pot experiment. The results show that the total root length, root volume, tips, forks, crossings, and root activities of B. papyrifera with inoculation are higher than those of the control group, and the strains promote the plant absorption of Sb from the soil environment. Especially in the antimony slag treatment group, B. cereus HM5 had the most significant effect on root promotion and promoting the absorption of Sb by B. papyrifera. Compared with the control group, the total root length, root volume, tips, forks, crossings, and root activities increased by 64.54, 70.06, 70.04, 78.15, 97.73, and 12.95%, respectively. The absorption of Sb by root, stem, and leaf increased by 265.12, 250.00, and 211.54%, compared with the control group, respectively. Besides, both B. cereus HM5 and B. thuringiensis HM7 reduce the content of malondialdehyde, proline, and soluble sugars in plant leaves, keeping the antioxidant enzyme activity of B. papyrifera at a low level, and alleviating lipid peroxidation. Principal component analysis (PCA) shows that both B. cereus HM5 and B. thuringiensis HM7 are beneficial to the maintenance of plant root functions and the improvement of the soil environment, thereby alleviating the toxicity of Sb. Therefore, B. cereus HM5 and B. thuringiensis HM7 in phytoremediation with B. papyrifera is a promising inoculant used for bacteria-assisted phytoremediation on Sb contaminated sites.

The effects of g-C3N4/biochar and g-C3N4 on bacterial community in riverbed sediment.

Biochar had been widely used to improve the activity of photocatalysts, the biochar-based photocatalysts had more potential for environmental pollution remediation, but their effect on the sediment remained unknown. To understand these, the typical photocatalyst g-C3N4 was modified by biochar to develop g-C3N4/biochar with enhanced photocatalytic ability. Riverbed sediment was exposed to g-C3N4 and g-C3N4/biochar respectively for 30 days, and Illumina sequencing was utilized to examine the changes in the bacterial community in the sediment. The results showed that in riverbed sediment, g-C3N4 exposure had a concentration-dependent effect on the diversity of bacteria, while g-C3N4/biochar exposure had a slight influence on the bacterial diversity and the diversity almost maintained stable with different g-C3N4/biochar concentration. The application of g-C3N4 exhibited an inhibition influence on the growth of Acidobacteria, Gemmatimonadetes, and Rokubacteria in sediment, whose relative abundance increased when g-C3N4 was 25 mg/kg, and then decreased when g-C3N4 beyond this concentration. The presence of g-C3N4/biochar increased the relative abundance of Cyanobacteria in sediment and showed no obvious impact on other dominant phyla. Both g-C3N4 and g-C3N4/biochar could alter the levels of TP, NN, and AN in the sediment, but the magnitude of the changes of these physicochemical factors caused by g-C3N4/biochar was much smaller than those caused by g-C3N4. In addition, the complexity of the bacterial community network was reduced in a high concentration of g-C3N4, while it remained stable with different concentrations of g-C3N4/biochar treatments. Totally, this study demonstrated that, compared to g-C3N4, g-C3N4/biochar was able to maintain the relative stability of the bacterial community in riverbed sediment and mitigate the negative effects of photocatalysts to some extent, making biochar an ecological remediation agent with great potential for application.

Effects of g-C3N4 on bacterial community and tetracycline resistance genes in two typical sediments in tetracycline pollution remediation.

Photocatalysis, as a novel technique, has been widely used for antibiotic pollution remediation in wastewater. In the processes of degradation and removal of antibiotics, the impact of photocatalysts on microenvironment is very important but remains poorly understood. In the present study, the effect of typical photocatalyst g-C3N4 (Graphitic carbon nitride) on microbial community was investigated in two sediment types (riverbed sediment and pig-farm sediment) polluted by tetracycline (TC) in central southern China. The riverbed sediment and pig farm sediment samples were respectively exposed to g-C3N4 (25, 75, 125 mg⋅kg-1) and TC (60, 120, 180 mg⋅L-1) treatments alone or combination for 30 days, respectively. The bacterial community and antibiotic resistance genes (ARGs) of the treated sediments were analyzed by Illumina sequencing and metagenomic sequencing. Studies had shown that: TC, g-C3N4, and TC/g-C3N4 have significant effects on the changes of microbial communities and components in riverbed sediment, but they do not exist in pig farm sediment. The most alterations of microbial taxa were Acidobacteriota, Actinobacteriota, and Desulfobacterota in riverbed sediment, and Elusimicrobiota in the pig farm sediment under various treatments. Through network analysis, it was found that the distribution of microorganisms in the pig farm sediment is more complex and more stable. The addition of g-C3N4 reduced the absolute abundance of ARGs in the two examined sediments, but not significantly changed their relative abundance of ARGs. The g-C3N4 application was beneficial to the removal of TC residues and to the prevention of the generation and transmission of ARGs in sediments. Our results suggested that g-C3N4 was a suitable photocatalyst with excellent application prospect for the removal of TC residues and the control of ARGs in environment.

Exploring the evolutionary characteristics between cultivated tea and its wild relatives using complete chloroplast genomes.

BACKGROUND: Cultivated tea is one of the most important economic and ecological trees distributed worldwide. Cultivated tea suffer from long-term targeted selection of traits and overexploitation of habitats by human beings, which may have changed its genetic structure. The chloroplast is an organelle with a conserved cyclic genomic structure, and it can help us better understand the evolutionary relationship of Camellia plants. RESULTS: We conducted comparative and evolutionary analyses on cultivated tea and wild tea, and we detected the evolutionary characteristics of cultivated tea. The chloroplast genome sizes of cultivated tea were slightly different, ranging from 157,025 to 157,100 bp. In addition, the cultivated species were more conserved than the wild species, in terms of the genome length, gene number, gene arrangement and GC content. However, comparing Camellia sinensis var. sinensis and Camellia sinensis var. assamica with their cultivars, the IR length variation was approximately 20 bp and 30 bp, respectively. The nucleotide diversity of 14 sequences in cultivated tea was higher than that in wild tea. Detailed analysis on the genomic variation and evolution of Camellia sinensis var. sinensis cultivars revealed 67 single nucleotide polymorphisms (SNPs), 46 insertions/deletions (indels), and 16 protein coding genes with nucleotide substitutions, while Camellia sinensis var. assamica cultivars revealed 4 indels. In cultivated tea, the most variable gene was ycf1. The largest number of nucleotide substitutions, five amino acids exhibited site-specific selection, and a 9 bp sequence insertion were found in the Camellia sinensis var. sinensis cultivars. In addition, phylogenetic relationship in the ycf1 tree suggested that the ycf1 gene has diverged in cultivated tea. Because C. sinensis var. sinensis and its cultivated species were not tightly clustered. CONCLUSIONS: The cultivated species were more conserved than the wild species in terms of architecture and linear sequence order. The variation of the chloroplast genome in cultivated tea was mainly manifested in the nucleotide polymorphisms and sequence insertions. These results provided evidence regarding the influence of human activities on tea.

In-situ synthesis of biochar modified PbMoO4: An efficient visible light-driven photocatalyst for tetracycline removal.

For highly efficient photocatalytic remediation of organic pollutants, broad-spectrum light response and effective charge separation are two key goals. To achieve these goals, a novel biochar (BC) modified PbMoO4 composite catalyst was successfully synthesized in situ by combining coprecipitation with pyrolysis treatment of poplar sawdust and the technical feasibility of degradation of tetracycline (TC) with compound photocatalyst prepared from recovered agricultural and forestry residues was preliminarily demonstrated. The characterization demonstrated that the presence of BC narrowed the bandgap, enhanced visible light absorption as well as facilitated charge separation. Three composites (with the mass ratio of PbMoO4 to BC = 1:4; 1:1; and 4:1, respectively) displayed higher activity than pure PbMoO4. The results showed that the composite with the PbMoO4 to BC ratio of 1:4 exhibited the best photocatalytic activity, for 150 mg L-1 TC the removal rate was 61.0%, and the rate constant was 8.1 × 10-3 min-1, while the photocatalytic activity of PbMoO4 was 26.0% and 3.9 × 10-3 min-1. The reactions in the presence of radical quenchers indicated that holes (h+) and superoxide radicals (O2-) were the dominant active species for photodegradation. In different water matrices, for 150 mg L-1 TC solution the photocatalytic activity of optimal photocatalyst decreased as follows: ultrapure water > artificial sewage > farm sewage > municipal sewage. Moreover, the catalyst exhibited good stability over five cycles. Therefore, BC doped PbMoO4 provides a useful strategy for improving the photocatalytic ability of PbMoO4-based photocatalysts and offers a promising method for water purification.

Improvement of manganese phytoremediation by Broussonetia papyrifera with two plant growth promoting (PGP) Bacillus species.

Combining phytoremediation plants and microorganisms is a promising method of remediating heavy metal contaminated soil. In this study, two manganese-tolerant strains were isolated from Mn slag and identified as Bacillus cereus HM5 and Bacillus thuringiensis HM7. These two Bacillus spp. have the ability to dissolve phosphorus, produce IAA and iron carrier. A pot experiment of Broussonetia papyrifera was conducted to explore potential of B. cereus HM5 and B. thuringiensis HM7 to improve effect of remedying Mn pollution by B. papyrifera. The strains were inoculated under different Mn treated (5 mmol/L, 50 mmol/L, Mn slag) respectively and the growth, root structure, root activity, physiological and biochemical characteristics of the leaves and accumulation of Mn for B. papyrifera were determinated. The effects of the soil environment to remediation were observed, the results showed that the biomass, total root length, surface area, crossings, tips, forks and root activity of B. papyrifera with inoculated strain were higher than those of the control group. The inoculation of these two Bacillus spp. increased the absorption of Mn by B. papyrifera and the concentration of Mn in the aerial parts of plants, indicating that the two strains could promote the growth of B. papyrifera and the accumulation of Mn. In addition, microbes reduced malonaldehyde content and the activities of antioxidant enzymes in leaves, suggesting that the two Bacillus spp. reduced Mn-induced oxidative stress. The principal component analysis showed that the added Bacillus strain prefer to promote plant root function maintenance and improve soil environment, rather than direct adsorption of heavy metals. These observations indicated that B. cereus HM5 and B. thuringiensis HM7 were valuable microorganisms, which could improve the remediating efficiency of B. papyrifera under Mn-contaminated soil.