Bioinformatics analysis identifies TGF-ß signaling pathway-associated molecular subtypes and gene signature in diabetic foot.

The role of transforming growth factor ß (TGF-ß) in inflammation and immune response is established, but the mechanism of TGF-ß signaling pathway-related genes (TRGs) in diabetic foot ulcer (DFU) is not fully understood. We aimed to investigate the contribution of TRGs in the identification, molecular categorization, and immune infiltration of DFU through bioinformatics analysis. TGF-ß signaling pathway is activated in DFU. 33 TRGs were upregulated. Regression analysis revealed TGFBR1 and TGFB1 as significant differential expression core genes, validated by quantitative real-time PCR. The diagnostic model with core genes had high clinical validity (AUC = 0.909). Core gene expression was associated with immune cell infiltration. A total of 5672 genes showed differential expression in TGF-related patterns, with differences in biological functions and immune infiltration. TGF-ß signaling pathway may be critical in DFU development.

Characteristics of organic pollutants and their effects on the microbial composition and activity in the industrial soils of Pearl River Delta, China.

To investigate the interaction between organic pollutants and soil microorganisms, industrial soils were collected from Pearl River Delta region of China for determining semi-volatile organic pollutants, the community structure and activity of microorganisms. The results showed that polycyclic aromatic hydrocarbons (PAHs) (63.3-4956 µg kg-1) and phthalate esters (PAEs) (272-65,837 µg kg-1) were main organic pollutants in the research area soils. Chemical manufacturing industry and plastics manufacturing industry contributed greatly to PAH pollution and PAE pollution, respectively. Organic pollutants changed the biomass of microorganisms. In most industrial soils, the biomass of actinomycetes was the highest in the industrial soils, followed by G- bacteria, G+ bacteria and fungi. The exception was that the biomass of fungi in the soil near chemical manufacturing industry was greater than that of G+ bacteria. The soil microbial biomass (including soil microbial biomass carbon, soil microbial biomass nitrogen, the biomass of actinomycetes, bacteria, and fungi) and soil enzyme activities (sucrase and urease) positively correlated with the organic pollutant residues, and the microbial species diversity and microbial species abundance decreased with organic pollutant residues increasing. Based on the correlation analysis, the urease activity, actinomycetes biomass, and fungi biomass were appropriate biological indicators for evaluating the stress of organic pollutants. Our research provides a new perspective for understanding the soil biological response in industrial soils.

Contribution of dicarboxylic acids to pyrene biodegradation and transcriptomic responses of Enterobacter sp. PRd5.

The colonization of degrading endophytic bacteria is an effective means to reduce the residues of polycyclic aromatic hydrocarbons (PAHs) in crops. Dicarboxylic acids, as the main active components in crops, can affect the physiological activities of endophytic bacteria and alter the biodegradation process of PAHs in crops. In this study, malonic acid and succinic acid were selected as the representatives to investigate the contribution of dicarboxylic acids to pyrene biodegradation by endophytic Enterobacter sp. PRd5 in vitro. The results showed that dicarboxylic acids improved the biodegradation of pyrene and altered the expression of the functional gene of strain PRd5. Malonic acid and succinic acid reduced the half-life of pyrene by 20.0% and 27.8%, respectively. The degrading enzyme activities were significantly stimulated by dicarboxylic acids. There were 386 genes up-regulated and 430 genes down-regulated in strain PRd5 with malonic acid, while 293 genes up-regulated and 340 genes down-regulated with succinic acid. Those up-regulated genes were distributed in the functional classification of signal transduction, membrane transport, energy metabolism, carbohydrate metabolism, and amino acid metabolism. Malonic acid mainly enhanced the central carbon metabolism, cell proliferation, and cell activity. Succinic acid mainly improved the expression of degrading gene. Overall, the findings of this study provide new insights into the regulation and control of PAH stress by crops. KEY POINTS: • Dicarboxylic acids improved the biodegradation of pyrene by Enterobacter sp. PRd5. • The degrading enzyme activities were stimulated by dicarboxylic acids. • There are different facilitation mechanisms between malonic acid and succinic acid.

[Colonization performance and pyrene degradation characteristics of Stenotrophomonas maltophilia PX1]. / å—œéº¦èŠ½å¯¡å »å•èƒžèŒPX1的降解芘特性及定殖效能.

We screened and identified an endophytic bacterium that could efficiently degrade PAHs, which would expand the library of polycyclic aromatic hydrocarbons (PAHs) degrading microorganisms and reduce the pollution risk of crops. Its degradation mechanism and colonization performance were preliminarily examined. The results showed that strain PX1 belonged to Stenotrophomonas maltophilia. The strain had broad spectrum ability to remove PAHs. In PAH mineral salt (MS) media, almost 100% naphthalene was degraded by strain PX1 after 7-d incubation. In a cultivation system solely containing phenanthrene of 50.0 mg·L-1, pyrene of 20.0 mg·L-1, fluoranthene of 20.0 mg·L-1 or benzo[a]pyrene of 10.0 mg·L-1, the degradation efficiency of phenanthrene, pyrene, fluoranthene and benzo[a]pyrene by strain PX1 reached 72.6%, 50.7%, 31.9%, and 12.9%, respectively. Pyrene was selected as PAHs model to study the degradation characteristics of strain PX1. Enzyme activity tests showed that the activities of phthalate dioxygenase, catechol-1,2-dioxygenase, and catechol-2,3-dioxygenase in strain PX1 were induced by pyrene. Some metabolic intermediates such as 4,5-epoxypyrene, 4,5-dihydroxypyrene, gentilic acid/protocatechuic acid, salicylic acid, cis-hexadienedioic acid/2-hydroxymyxofuroic acid semialdehyde, cis-2'-carboxyphenylpyruvic acid, 1-hydroxy-2-naphthoic acid, and salicylaldehyde were detected during the degradation of pyrene by strain PX1. Results of the seed soaking experiment showed that strain PX1 could efficiently colonize in Ipomoea aquatic and Triticum aestivum. After inoculated with strain PX1, the growth of I. aquatic and T. aestivum was significantly increased, and the pyrene concentration in I. aquatic, T. aestivum and MS media was reduced by 29.8%-50.7%, 52.4%-67.1% and 8.0%-15.3%, respectively. Our results suggested that strain PX1 degraded pyrene mainly through 'salicylate pathway' and 'phthalate pathway', and could be colonized into plants and promote plant growth.

Effects of different oxygen conditions on pollutants removal and the abundances of tetracycline resistance genes in activated sludge systems.

The individual and combined effects of tetracycline (TC) and divalent copper (Cu2+) on the performance of activated sludge systems and the abundances of tetracycline resistance genes (TRGs) in activated sludge, under both aerobic and anaerobic conditions, were studied. Activated sludge systems received TC (0.2 mg L-1) and Cu2+ (5 mg L-1) separately or jointly under either aerobic or anaerobic conditions. The addition of TC did not affect the performance of activated sludge systems and the addition of Cu2+ and mixed TC/Cu2+ inhibited biological phosphorus removal. The TC removal efficiencies in systems under aerobic and anaerobic conditions were 98.4%-99.7% and 96.8%-99.9%, respectively, and Cu2+ promoted TC removal in activated sludge systems. The TC degradation product was 4-epitetracycline (ETC) in activated sludge systems under both aerobic and anaerobic conditions. The total relative abundances of TRGs (tetA, tetC, tetE, tetM, tetO, tetW, tetX and tetB(P)) in activated sludge showed opposite development trends under the two oxygen conditions and aerobic condition was beneficial to the attenuation of high-risk TRGs. The results of this study might improve evaluation of the combined effects of antibiotics and heavy metals on wastewater biological treatment systems.

Spontaneous assembly of microbial extracellular polymeric substances into microcapsules involved in trapping and immobilizing degradation-resistant oxoanions.

Despite the ubiquity of microbial extracellular polymeric substances (EPS) in soils and aquatic environments, the roles played by EPS in the nonreductive transformation of toxic and degradation-resistant oxoanions are poorly understood. Here, we used perchlorate, which is ubiquitous in surface environments, as an initiator to study the spontaneous assembly of EPS into microcapsules involved in trapping and immobilizing oxoanions. The results confirmed that ClO4- oxoanions could be rapidly trapped in 20 min by EPS extracted from a common Bacillus subtilis, whereas no chemical reduction of ClO4- occurred in 48 h. Integrated spectroscopic analyses with florescence quenching microtitration and theoretical models showed that amino functionalities of EPS are responsible for sequestering ClO4-, with lower pH values being more favorable to formation of EPS-ClO4- micelles. Combined molecular dynamics scheme with wave function analyses showed that besides amino residues, the protonated side-chain amino groups in the basic proteins have a greater capacity for sequestering ClO4- through a noncovalent H-bonding mechanism in which dissociable protons serve as the nodes to bridge ClO4-. A quantitative association between the number of hydrogen bonds and bioavailability revealed that immobilization by EPS mitigates the uptake of toxic oxoanions by forage ryegrass, reducing their risk exposure to edible produce. MAIN FINDING OF THE WORK: Micelles formed by freely dissolved EPS mitigate the uptake of toxic oxoanions by forage ryegrass.

Phenanthrene and pyrene disturbed the growth of Microcystis aeruginosa as co-cultured with Chlorella pyrenoidosa.

Significant levels of polycyclic aromatic hydrocarbons (PAHs) were detected in lakes. The competition between algae would be disturbed by PAHs resulted in variations of algal growth. For controlling the cyanobacterial blooms, it is important to understand this disturbed competition between Microcystis aeruginosa and other algae. A 6-day cultivation experiment was designed to investigate the responses of M. aeruginosa to PAHs in presence of green algae. A popular green alga Chlorella pyrenoidosa was used as a representative of green algae, and phenanthrene and pyrene were selected as representatives of PAHs. The results showed that M. aeruginosa outcompeted C. pyrenoidosa under PAH contamination, and PAHs and M. aeruginosa significantly inhibited the survival of C. pyrenoidosa. PAHs disturbed the growth of algae by influencing photosynthetic pigments and phycobiliproteins, and the different alteration of Fv/Fm ratios implied that shifted algal community composition would be induced by PAHs. The Fv/Fm of the two algal mixture and individual C. pyrenoidosa was significantly negatively correlated with phenanthrene levels. However, there were no significant correlations between the Fv/Fm of M. aeruginosa and the exposure levels of phenanthrene or pyrene. Remarkably, the Fv/Fm significantly increased in M. aeruginosa at 0.15 mg L-1 pyrene, suggesting that PSII resistance to pyrene was enhanced in M. aeruginosa. Our results pointed out an increasing frequency and intensity of cyanobacterial blooms could be induced by PAHs in contaminated waters.

Regional-scale investigation for microbial competition-through-environment interactions modulating antibiotic resistance.

Originating from a long history of competition between microbes, antibiotic resistance is a serious global health concern. To avoid the risk of antibiotic resistance, tremendous efforts have been directed towards restricting antibiotic consumption worldwide, but to date with limited success. Resistance is governed by multiple pressures from natural and anthropogenic origins which further create problems with control. This study identifies a chain of links from antibiotic resistant genes (ARGs) to microbial communities to environmental pressures in the surface sediments of forty-two lake clusters across the 1000-km Yangtze Basin of China, and attempts to expound on a control pathway for this resistance risk. Results show that eleven of the 670 bacterial families can be classified as antibiotic-resistant or nonresistant communities which antagonize each other. In natural systems, antagonistic competition controls the increase and decrease in ARGs. Superiority of antibiotic-resistant strains initiates a loss in microbial diversity associated with the prevalence of resistance risk. This study shows that, antibiotics shape the evolution of ARGs in resistant communities through a nonlinear role of orientor; other selected pressures serve as a facilitator to enhance the antibiotic resistance through an investigated chain of links. Furthermore, according to tolerances of the classified communities, abiogenetic development through temperature, salinity and Mg were identified and selected for study from seventy lake parameters. Linear feedbacks to selected pressures make the nonresistant communities outcompete the resistant communities, theoretically modulating the risk of antibiotic resistance.

PAHs would alter cyanobacterial blooms by affecting the microcystin production and physiological characteristics of Microcystis aeruginosa.

The wide presence of polycyclic aromatic hydrocarbons (PAHs) in lakes necessitates a better understanding of cyanobacteria metabolites under the contamination of PAHs. The M. aeruginosa strain PCC7806 was selected to investigate the effects of naphthalene and pyrene on the physiological and biochemical reactions of cyanobacteria, including antioxidant defense system (superoxide dismutase, catalase), intracellular microcystin (MC) content, phycobiliprotein (phycocyanin, allophycocyanin) contents, and specific growth rate. Naphthalene and pyrene altered the growth of the M. aeruginosa strain, reduced the contents of phycocyanin and allophycocyanin, and stimulated the activities of antioxidant enzymes without lipid peroxidation. Remarkably, the intracellular MC content was significantly increased by 68.1% upon exposure of M. aeruginosa to 0.45 mg L-1 naphthalene, and increased by 51.5% and 77.9% upon exposure of M. aeruginosa to 0.45 mg L-1 pyrene and 1.35 mg L-1 pyrene, respectively (P＜0.05). Moreover, significant correlations were observed between these physiological reactions, referring that a series of physiological and biochemical reactions in M. aeruginosa worked together against the PAH contamination. Considering that MCs are the most studied cyanobacterial toxins, our results clarified that the promoting MC production by PAH contamination cannot be neglected when making related risk assessments of eutrophic waters.

Isolation, Characterization, and Degradation Performance of the 17ß-Estradiol-Degrading Bacterium Novosphingobium sp. E2S.

A 17ß-estradiol (E2)-degrading bacterium E2S was isolated from the activated sludge in a sewage treatment plant (STP). The morphology, biological characteristics, and 16S ribosomal RNA (rRNA) gene sequence of strain E2S indicated that it belonged to the genus Novosphingobium. The optimal degrading conditions were 30 °C and pH 7.0. The ideal inoculum volume was 5% (v/v), and a 20-mL degradation system was sufficient to support the removal ability of strain E2S. The addition of extra NaCl to the system did not benefit the E2 degradation in batch culture by this strain. Strain E2S exhibited high degradation efficiency with initial substrate concentrations of 10-50 mg·L-1. For example, in mineral salt medium containing 50 mg·L-1 of E2, the degradation efficiency was 63.29% after seven days. In cow manure samples supplemented with 50 mg·L-1 of E2, strain E2S exhibited 66.40% degradation efficiency after seven days. The finding of the E2-degrading strain E2S provided a promising method for removing E2 from livestock manure in order to reduce the potential environmental risks of E2.

The endophytic bacterium Serratia sp. PW7 degrades pyrene in wheat.

This research was conducted to isolate polycyclic aromatic hydrocarbon-degrading (PAH-degrading) endophytic bacteria and investigate their potential in protecting plants against PAH contamination. Pyrene-degrading endophytic bacteria were isolated from plants grown in PAH-contaminated soil. Among these endophytic bacteria, strain PW7 (Serratia sp.) isolated from Plantago asiatica was selected to investigate the suppression of pyrene accumulation in Triticum aestivum L. In the in vitro tests, strain PW7 degraded 51.2% of the pyrene in the media within 14 days. The optimal biodegradation conditions were pH 7.0, 30 °C, and MS medium supplemented with additional glucose, maltose, sucrose, and peptones. In the in vivo tests, strain PW7 successfully colonized the roots and shoots of inoculated (E+) wheat plants, and its colonization decreased pyrene accumulation and pyrene transportation from roots to shoots. Remarkably, the concentration of pyrene in shoots decreased much more than that in roots, suggesting that strain PW7 has the potential for protecting wheat against pyrene contamination and mitigating the threat of pyrene to human health via food consumption.

Inoculating wheat (Triticum aestivum L.) with the endophytic bacterium Serratia sp. PW7 to reduce pyrene contamination.

This research was conducted to find an optimal inoculation way for a pyrene-degrading endophytic Serratia sp. PW7 to colonize wheat for reducing pyrene contamination. Three inoculation ways, which are soaking seeds in inocula (TS), dipping roots of seedlings in inocula (TR), and spraying inocula on leaves of seedlings (TL), were used in this study. Inoculated seedlings and noninoculated seedlings (CK) were, respectively, cultivated in Hoagland solutions supplemented with pyrene in a growth chamber. The results showed that strain PW7 successfully colonized the inoculated seedlings in high numbers, and significantly promoted the growth of seedlings (TS and TR). More importantly, strain PW7 reduced pyrene levels in the seedlings and the Hoagland solutions. Compared to the noninoculated seedlings, the pyrene contents of the inoculated seedlings were decreased by 35.7-86.3% in the shoots and by 26.8-60.1% in the roots after 8-day cultivation. By comparing the efficiencies of decreasing pyrene residues, it can be concluded that TR was an optimal inoculation way for endophytic strains to colonize the inoculated plants and to reduce the pyrene contamination. Our findings provide an optimized inoculation way to reduce organic contamination in crops by inoculating plants with functional endophytic bacteria.

Phenanthrene and Pyrene Modify the Composition and Structure of the Cultivable Endophytic Bacterial Community in Ryegrass (Lolium multiflorum Lam).

This study provides new insights into the dynamics of bacterial community structure during phytoremediation. The communities of cultivable autochthonous endophytic bacteria in ryegrass exposed to polycyclic aromatic hydrocarbons (PAHs) were investigated with regard to their potential to biodegrade PAHs. Bacterial counts and 16S rRNA gene sequence were used in the microbiological evaluation. A total of 33 endophytic bacterial strains were isolated from ryegrass plants, which represented 15 different genera and eight different classes, respectively. Moreover, PAH contamination modified the composition and structure of the endophytic bacterial community in the plants. Bacillus sp., Pantoea sp., Pseudomonas sp., Arthrobacter sp., Pedobacter sp. and Delftia sp. were only isolated from the seedlings exposed to PAHs. Furthermore, the dominant genera in roots shifted from Enterobacter sp. to Serratia sp., Bacillus sp., Pantoea sp., and Stenotrophomonas sp., which could highly biodegrade phenanthrene (PHE). However, the diversity of endophytic bacterial community was decreased by exposure to the mixture of PAHs, and increased by respective exposure to PHE and pyrene (PYR), while the abundance was increased by PAH exposure. The results clearly indicated that the exposure of plants to PAHs would be beneficial for improving the effectiveness of phytoremediation of PAHs.

Biodegradation of Mixed PAHs by PAH-Degrading Endophytic Bacteria.

Endophytic bacteria can promote plant growth, induce plant defence mechanisms, and increase plant resistance to organic contaminants. The aims of the present study were to isolate highly PAH-degrading endophytic bacteria from plants growing at PAH-contaminated sites and to evaluate the capabilities of these bacteria to degrade polycyclic aromatic hydrocarbons (PAHs) in vitro, which will be beneficial for re-colonizing target plants and reducing plant PAH residues through the inoculation of plants with endophytic bacteria. Two endophytic bacterial strains P1 (Stenotrophomonas sp.) and P3 (Pseudomonas sp.), which degraded more than 90% of phenanthrene (PHE) within 7 days, were isolated from Conyza canadensis and Trifolium pretense L., respectively. Both strains could use naphthalene (NAP), PHE, fluorene (FLR), pyrene (PYR), and benzo(a)pyrene (B(a)P) as the sole sources of carbon and energy. Moreover, these bacteria reduced the contamination of mixed PAHs at high levels after inoculation for 7 days; strain P1 degraded 98.0% NAP, 83.1% FLR, 87.8% PHE, 14.4% PYR, and 1.6% B(a)P, and strain P3 degraded 95.3% NAP, 87.9% FLR, 90.4% PHE, 6.9% PYR, and negligible B(a)P. Notably, the biodegradation of PAHs could be promoted through additional carbon and nitrogen nutrients; therein, beef extract was suggested as the optimal co-substrate for the degradation of PAHs by these two strains (99.1% PHE was degraded within 7 days). Compared with strain P1, strain P3 has more potential for the use in the removal of PAHs from plant tissues. These results provide a novel perspective in the reduction of plant PAH residues in PAH-contaminated sites through inoculating plants with highly PAH-degrading endophytic bacteria.

Potential of Endophytic Bacterium Paenibacillus sp. PHE-3 Isolated from Plantago asiatica L. for Reduction of PAH Contamination in Plant Tissues.

Endophytes are ubiquitous in plants, and they may have a natural capacity to biodegrade polycyclic aromatic hydrocarbons (PAHs). In our study, a phenanthrene-degrading endophytic Paenibacillus sp. PHE-3 was isolated from P. asiatica L. grown in a PAH-contaminated site. The effects of environmental variables on phenanthrene biodegradation by strain PHE-3 were studied, and the ability of strain PHE-3 to use high molecular weight PAH (HMW-PAH) as a sole carbon source was also evaluated. Our results indicated that pH value of 4.0-8.0, temperature of 30 °C-42 °C, initial phenanthrene concentration less than 100 mg·L(-1), and some additional nutrients are favorable for the biodegradation of phenanthrene by strain PHE-3. The maximum biodegradation efficiency of phenanthrene was achieved at 99.9% after 84 h cultivation with additional glutamate. Moreover, the phenanthrene biodegradation by strain PHE-3 was positively correlated with the catechol 2,3-dioxygenase activity (ρ = 0.981, p < 0.05), suggesting that strain PHE-3 had the capability of degrading HMW-PAHs. In the presence of other 2-, 3-ringed PAHs, strain PHE-3 effectively degraded HMW-PAHs through co-metabolism. The results of this study are beneficial in that the re-colonization potential and PAH degradation performance of endophytic Paenibacillus sp. PHE-3 may be applied towards reducing PAH contamination in plants.

[Isolation, identification and characterization of a diethylstilbestrol-degrading bacterial strain Serratia sp].

Utilizing the diethylstilbestrol (DES)-degrading bacteria to biodegrade DES is a most reliable technique for cleanup of DES pollutants from the environment. However, little information is available heretofore on the isolation of DES-degrading bacteria and their DES removal performance in the environment. A novel bacterium capable of degrading DES was isolated from the activated sludge of a wastewater treatment plant. According to its morphology, physiochemical characteristics, and 16S rDNA sequence analysis, this strain was identified as Serratia sp.. The strain was an aerobic bacterium, and it could degrade 68.3% of DES (50 mg x L(-1)) after culturing for 7 days at 30 degrees C, 150 r x min(-1) in shaking flasks. The optimal conditions for DES biodegradation by the obtained strain were 30 degrees C, 40-60 mg x L(-1) DES, pH 7.0, 5% of inoculation volume, 0 g x L(-1) of added NaCl, and 10 mL of liquid medium volume in 100 mL flask.

[Isolation of two endophytic phenanthrene-degrading strains and their degradation capacity].

Two endophytic bacterial strains, which could degrade high concentration (up to 200 mg.L-1) of phenanthrene in liquid, were isolated from plants grown in PAHs-contaminated soils by the selective. enrichment culture. According to the results of morphology, physiology and the phylogenetic analyses of 16S rDNA sequence, stain P1 was identified as Stenotrophomonas sp. , and strain P3 was identified as Pseudomonas sp.. Two strains were aerobic bacteria, the degradation rates of phenanthrene (100 mg.L-1) by strain P1 and strain P3 were all greater than 90% at 28 degrees C on the rotation shaker at 150 r.min-1 for 7 days. The degradation rates of phenanthrene by two strains were greater than 70% when cultivated under the conditions as: 20-30 degrees C , pH 6-8, 0%-4% NaCl, 10-30 mL/100 mL inventory. It suggested that the optimum culture condition was: 30 degrees C, pH 7.0, NaCl< or =4% , inventory < or = 30 mL/100 mL flask. Through comprehensive comparison analyses on the degradation capacity of two strains, it showed that the tolerance of strain P1 to high temperature was higher than that of str ain P3, while the tolerance of strain P3 to pH change and anoxic condition was higher than that of strain P1.

Low concentrations of polycyclic aromatic hydrocarbons promote the growth of Microcystis aeruginosa.

There is an increasing need to describe the growth characteristics of cyanobacteria exposed to polycyclic aromatic hydrocarbons (PAHs) because the presence of PAHs in lakes is known to affect the growth of this kind of microorganisms. In this work, the effects of low concentrations of PAHs on Microcystis aeruginosa (M. aeruginosa) were investigated. M. aeruginosa were cultivated in the medium with a mixture of PAHs (0.486 mg L(-1) naphthalene, 0.049 mg L(-1) phenanthrene, and 0.0015 mg L(-1) pyrene) and different concentrations of nitrogen and phosphorus. During 31 d of incubation, profiles of cell number and chlorophyll-a content were determined. The results indicated that when the concentration of an individual PAH was below its no observed effect concentration (NOEC), the exposure of M. aeruginosa to a mixture of PAHs markedly promoted cell density after 7d of culture. Low concentrations of nutrients in the medium improved the growth of M. aeruginosa in the presence of PAHs. When concentrations of both phosphorus and nitrogen were 50% lower than those of the control, the specific growth rate of M. aeruginosa increased by 100% when exposed to PAHs, and the generation time decreased from 10.5 to 5.3d. The chlorophyll-a content in medium also increased from 2.23 to 3.18 µg mL(-1), which was attributed to an increase in cell numbers.

Removal of polycyclic aromatic hydrocarbons from aqueous solution on soybean stalk-based carbon.

Soybean [ (L.) Merr.] stalk-based carbons were prepared by phosphoric acid activation at different carbonization temperatures. Characteristics of the prepared carbon, including specific surface area, iodine number, and amount of methylene blue sorption, were determined. Experiments on phenanthrene, naphthalene, and acenaphthene, as representatives of polycyclic aromatic hydrocarbons (PAHs), removal from aqueous solution by the prepared carbon were conducted at different levels of carbon addition. The results indicated that the specific surface area, iodine number, and amount of methylene blue sorption increased with an increase of carbonization temperature. The maximum values were observed at 700°C and were 287.63 m g, 508.99 mg g, and 90.14 mg g, respectively. The removal efficiencies of phenanthrene, naphthalene, and acenaphthene tended to increase with increasing carbon amounts and carbonization temperature. The optimal removal performance was obtained under the experimental conditions of carbon concentrations of 0.04 g 32 mL and carbonization temperature of 700°C, and the removal efficiencies of phenanthrene, naphthalene, and acenaphthene were 99.89, 100, and 95.64%, respectively. The performance of the prepared carbon was superior to that of commercial activated carbon. Additionally, for the same carbon concentrations, the removal efficiency of PAHs on prepared carbons followed the order: phenanthrene > naphthalene > acenaphthene. Results obtained from this work provide some insight into the reuse of an agricultural residue, and also provide a new application for the treatment of PAHs in contaminated water utilizing activated carbon prepared from agricultural residues.

Cosorption of phenanthrene and mercury(II) from aqueous solution by soybean stalk-based biochar.

Soybean [Glycine max (L.) Merr.] stalk-based biochar was prepared using oxygen-limited pyrolysis. We evaluated phenanthrene (PHE) and Hg(II) sorption, from single and binary component solutions, onto prepared biochar. We found that the prepared biochar efficiently removed PHE and Hg(II) from aqueous solutions. The isotherms for PHE and Hg(II) sorption could be described using linear and Tóth models, respectively, both with high regression coefficients (R(2) > 0.995). When PHE and Hg(II) coexisted in an aqueous solution, we observed direct competitive sorption, each one suppressing another. Our results provide insight into the recycling of agricultural residues, and also a new application for removal of polycyclic aromatic hydrocarbons and heavy metals from contaminated water utilizing biochar from agricultural residue.