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Background: This research aimed to investigate the correlation between students’ physical fitness and campus-built environment, which could put forward some suggestions for the construction of a campus environment. Method: Four colleges in Xi’an were regarded as special “semi-closed” spaces. Combined with ArcGIS and SPSS, the correlation between the built environment of colleges and the students’ physical fitness test results in 2019 was analyzed (n = 1498). Results: regarding the men questioned in this research, there was a significant correlation between street connectivity and vital capacity, grip strength, 50 m running, 1000 m running, a significant correlation between land use mix and vital capacity, sit-and-reach, pull-up, grip strength, a significant correlation between green space per capita and vital capacity, grip strength, 50 m running, and a significant correlation between walk score and vital capacity, pull-up, grip strength, and 50 m running. Regarding the women questioned in this research, there was a significant correlation between street connectivity and vital capacity, grip strength, 50 m running, 800 m running, curl-up, a significant correlation between land use mix and vital capacity, sit-and-reach, curl-up, grip strength, 800 m running, a significant correlation between green space per capita and vital capacity, grip strength, curl-up, sit-and-reach, and a significant correlation between walk score and vital capacity, curl-up, grip strength, and 800 m running. Conclusion: the built environment on campus can indirectly affect the physical fitness of college students. Increasing the number of intersections and short connections of campus streets, ensuring that the green space of the campus meets the standards, and reasonably arranging the site selection of buildings are conducive to improving the physical fitness of students.

Red soils are acid soils which occupy about one fifth of the total area of tropical and subtropical soils in China. Peanut (Arachis hypogaea L.) is regarded as the main oil and cash crop in the red soil region. However, yields of peanut have gradually but significantly declined under continuous cropping. We conducted a field experiment in Jiangxi province, south China from 1996 to investigate the mitigation of the peanut continuous cropping constraint. Three types of fertilizer (chemical, organic, and organic fertilizer with effective microbes) were applied in the field. After 20 years of cropping the continuous cropping constraint was found to be more severe where chemical fertilizers were applied and was mitigated where the fields were amended with organic fertilizer or organic fertilizer with effective microbes. Soil properties and the rhizosphere bacterial community structure were determined in 2016. Long-term application (20 years) of organic fertilizer increased the plant available phosphorus in the rhizosphere soil. Phosphorus is known to be one of the most limiting factors for peanut growth in red soils and peanut yield was promoted as the soil phosphorus status increased. Organic fertilizer and effective microbes also optimized the rhizobacteria of peanut to mitigate the continuous cropping obstacle. The bacterial wilt pathogen (Ralstonia) decreased in abundance in the rhizosphere and bacterial wilt disease of peanut declined significantly. Moreover, beneficial bacteria in the rhizosphere capable of promoting peanut growth increased in abundance.

The role of symbiotic rhizobia in the alleviation of polychlorinated biphenyl (PCB)-induced phytotoxicity in alfalfa and the brassinosteroid (BR) hormone signaling involved were investigated during phytoremediation. The association between alfalfa and Sinorhizobium meliloti was adopted as a remediation model. Phytotoxicity due to PCB 77 (3,3',4,4'-tetrachlorobiphenyl) exerted adverse impacts on plant performance (biomass accumulation and photosynthesis) and elicited cellular oxidative stress (overproduction of reactive oxygen species, lipid peroxidation, and cell necrosis) which was largely attenuated by pre-inoculation with S. meliloti strain NM. The protective role may have been achieved as a result of strengthening of basic antioxidant defense before stress as evidenced by the augmented activity and gene expression of antioxidative enzymes (peroxidase, glutathione reductase, superoxide dismutase, catalase, and ascorbate peroxidase) of both leaves and roots. In nodulated seedlings peroxidase showed additive increased activity following PCB exposure but the activities of the other four enzymes tended to remain stable after stress. Furthermore, application of strain NM and brassinolide both triggered the accumulation of endogenous BRs and the antioxidant network, while pre-treatment of seedlings with a biosynthetic inhibitor of BRs, brassinazole, abolished the rhizobia-induced activation of detoxification responses towards PCB. These observations indicate that association with S. meliloti NM enhanced the systemic antioxidant defenses of alfalfa to detoxify PCB, at least in part, via BR-dependent signaling pathways. These results contribute to our knowledge of the 'logistic role' played by rhizobia in assisting the phytoremediation of PCB-contaminated soils and suggest an optimum manipulation strategy for bioremediation.

Pentachloronitrobenzene (PCNB) is a toxic chlorinated nitroaromatic compound. However, only a few bacteria have been reported to be able to utilize PCNB. In the present study, one pentachloronitrobenzene (PCNB)-degrading bacterium, Cupriavidus sp. YNS-85, was isolated from a contaminated Panax notoginseng plantation. The strain co-metabolized 200 mg L−1 PCNB in aqueous solution with a removal rate of 73.8% after 5 days. The bacterium also degraded PCNB effectively under acid conditions (pH 4–6) and showed resistance to toxic trace elements (arsenic, copper, and cadmium). Its ability to utilize proposed PCNB intermediates as sole carbon sources was also confirmed. The soil microcosm experiment further demonstrated that bacterial bioaugmentation enhanced the removal of PCNB (37.8%) from soil and the accumulation of pentachloroaniline (89.3%) after 30 days. Soil enzyme activity and microbial community functional diversity were positively influenced after bioremediation. These findings indicate that Cupriavidus sp. YNS-85 may be a suitable inoculant for in situ bioremediation of PCNB-polluted sites, especially those with acid soils co-contaminated with heavy metal(loid)s.

Understanding the relationship between polycyclic aromatic hydrocarbon (PAH) dissipation potential in different soils and the bacterial community changes is of great importance for bioremediation and ecological evaluation. Soil microcosms were constructed with four different types of soils, including Anthrosol (Ant), Black soil (Black), Fluvo-aquic soil (Flu), and Red soil (Red), by spiking with pyrene at three concentrations (5, 30, and 70 mg kg−1). Real-time PCR and Illumina sequencing were employed to examine the bacterial community changes. The results showed that the pyrene dissipation rate differed with soil type. The fastest pyrene dissipation was observed in Ant soil: greater than 90% reduction was achieved by day 14 at higher pyrene dosages (30 and 70 mg kg−1) and no lag time existed before onset of pyrene dissipation at all spiked dosages. A 7-day and 14-day lag time was needed in Black and Flu soils, respectively before pyrene dissipation at pyrene concentration of 70 mg kg−1, more than 90% reduction of pyrene could still be achieved by day 21 for the Black soil and by day 42 for the Flu soil at all pyrene dosages. The evident reduction of pyrene in Ant, Black, and Flu soils was significantly correlated (r = 0.847–0.914; P

The widespread and increasing application of chlorothalonil (CTN) raises concerns about its non-target impacts, but little information is available on the effect of CTN on the key functional genes related to soil nitrogen (N) cycling, especially in the case of repeated applications. In the present study, a microcosm incubation was conducted to determine CTN residues and the impacts on the abundances of key functional genes related to N cycling after repeated CTN applications. The results demonstrated that repeated CTN applications at the recommended application rate and five times the recommended rate led to the accumulation of CTN residue in soil at concentrations of 5.59 and 78.79 mg kg − 1 , respectively, by the end of incubation. Real time PCR (RT-PCR) revealed that repeated CTN applications had negative effects on the chi A and apr A gene abundances. There were significantly negative correlations between CTN residues and abundances of AOA and AOB genes. In addition, the abundances of key functional genes involved in soil denitrification were declined by repeated CTN applications with the sole exception of the nos Z gene. This study suggests that repeated CTN applications could lead to the accumulation of CTN residue and generate somewhat inconsistent and erratic effects on the abundances of key functional genes related to soil N cycling.

A bacterial strain ZY1 capable of utilizing PCBs as its carbon source was isolated from the root nodules of Chinese milk vetch (Astragalus sinicus L.). The strain was identified as Mesorhizobium sp. according to its physiological-biochemical properties and the analysis of its 16S rRNA gene sequence. When the initial OD600 was 0.15, 62.7% of 15 mg L(-1) 3,3',4,4'-TCB in a liquid culture was degraded by Mesorhizobium sp. ZY1 within 10 days. Mesorhizobium sp. ZY1 also greatly increased the biotransformation of soil PCBs. Pot experiments indicated that the soil PCB concentrations of a single incubation of strain ZY1 (R) and a single planting of A. sinicus (P) decreased by 20.5% and 23.0%, respectively, and the concentration of PCBs in soil treated with A. sinicus and strain ZY1 decreased by 53.1%. We also observed that A. sinicus-Mesorhizobium sp. ZY1 treatment (PR) improved plant biomass and the concentration of PCBs in plants compared with a single A. sinicus planting treatment (P). The results suggest that the synergistic association between A. sinicus and PCBs-degrading Mesorhizobium sp. ZY1 can stimulate the phytoextraction of PCBs and the rhizosphere microflora to degrade PCBs, and might be a promising bioremediation strategy for PCB-contaminated soil.

Peanut yield and quality are seriously compromised by continuous monoculturing in the red soil region of southern China. Monoculturing can cause soil degradation and an increase in soil-borne diseases. This research aimed to investigate the influence of long-term peanut monocropping and different fertilization treatments on peanut growth, soil physical and chemical properties and soil microbial community. A long-term fertilization experiment established in 1996 was utilized to examine the effect of various fertilization treatments including chemical and organic fertilizers treatments. Deep 16S rRNA gene pyrosequencing highlighted changes in the abundance and structure of bacterial communities, especially of the pathogenic and beneficial bacterial communities in long term chemical fertilizer treatment in comparison to the organic manure treatment. Chemical fertilizer treatment causes a shift in bacterial community structure and decrease in diversity under the long-term monocropping in comparison to organic fertilizer. The abundance of the bacterial pathogen Ralstonia solanacearum, a causative agent of peanut wilt, was found to be associated with a loss of community diversity and loss of the peanut yield. The organic fertilizers more effectively increase microbial diversity in the soil and changed the community structure. Long-term use of the chemical fertilizer leads to a decrease in microbial diversity of the soil and an increase in R. solanacearum with associated increase of peanut wilt. The potential decrease in diversity and competition between the bacterial community and the pathogen may be a contributing factor to increased disease during long-term chemical fertilizer use.

Legume–rhizobium symbioses have the potential to remediate soils contaminated with chlorinated organic compounds. Here, the model symbiosis between Medicago sativa and Sinorhizobium meliloti was used to explore the relationships between symbiotic nitrogen fixation and transformation of tetrachlorobiphenyl PCB 77 within this association. 45-day-old seedlings in vermiculite were pretreated with 5 mg L–1 PCB 77 for 5 days. In PCB-supplemented nodules, addition of the nitrogenase enhancer molybdate significantly stimulated dechlorination by 7.2-fold and reduced tissue accumulation of PCB 77 (roots by 96% and nodules by 93%). Conversely, dechlorination decreased in plants exposed to a nitrogenase inhibitor (nitrate) or harboring nitrogenase-deficient symbionts (nifA mutant) by 29% and 72%, respectively. A range of dechlorinated products (biphenyl, methylbiphenyls, hydroxylbiphenyls, and trichlorobiphenyl derivatives) were detected within nodules and roots under nitrogen-fixing conditions. Levels of nitrogenase...

The co-metabolism of benzo[a]pyrene (B[a]P) and the capacity of the fungus Trichoderma reesei FS10-C to bioremediate an aged polycyclic aromatic hydrocarbon (PAH)-contaminated soil were investigated. The fungal isolate removed about 54% of B[a]P (20mg L-1) after 12days of incubation with glucose (10g L-1) supplementation as a co-metabolic substrate. Bioaugmented microcosms showed a 25% decrease in total PAH concentrations in soil after 28days, and the degradation percentages of 3-, 4-, and 5(+6)-ring PAHs were 36%, 35%, and 25%, respectively. In addition, bioaugmented microcosms exhibited higher dehydrogenase (DHA) and fluorescein diacetate hydrolysis (FDAH) activities and increased average well-color development (AWCD), Shannon-Weaver index (H), and Simpson index (D) significantly. Principal component analysis (PCA) also distinguished clear differentiation between treatments, indicating that bioaugmentation restored the microbiological function of the PAH-contaminated soil. The results suggest that bioaugmentation by T. reesei FS10-C might be a promising bioremediation strategy for aged PAH-contaminated soils.

The concentrations of six priority phthalic acid esters (PAEs) in intensively managed suburban vegetable soils in Nanjing, east China, were analyzed using gas chromatography-mass spectrometry (GC-MS). The total PAE concentrations in the soils ranged widely from 0.15 to 9.68 mg kg(-1) with a median value of 1.70 mg kg(-1), and di-n-butyl phthalate (DnBP), bis-(2-ethylhexyl) phthalate (DEHP) and di-n-octyl phthalate (DnOP) were the most abundant phthalate esters. Soil PAR concentrations depended on the mode of use of plastic film in which PAEs were incorporated as plasticizing agents and both the plastic film and poultry manure appeared to be important sources of soil PAEs. Vegetables in rotation with flooded rice led to lower concentrations of PAEs in soil. The results indicate that agricultural plastic film can be an important source of soil PAE contamination and further research is required to fully elucidate the mechanisms of PAE contamination of intensive agricultural soils with different use modes of use of plastic film. Crown Copyright (C) 2013 Published by Elsevier Ltd. All rights reserved.

Polycyclic aromatic hydrocarbon (PAH) and metal-polluted sites caused by abandoned coking plants are receiving wide attention. To address the associated environmental concerns, innovative remediation technologies are urgently needed. This study was initiated to investigate the feasibility of a cleanup strategy that employed an initial phase, using methyl-β-cyclodextrin (MCD) solution to enhance ex situ soil washing for extracting PAHs and metals simultaneously, followed by the addition of PAH-degrading bacteria (Paracoccus sp. strain HPD-2) and supplemental nutrients to treat the residual soil-bound PAHs. Elevated temperature (50 °C) in combination with ultrasonication (35 kHz, 30 min) at 100 g MCD L(-1) was effective in extracting PAHs and metals to assist soil washing; 93 % of total PAHs, 72 % of Cd, 78 % of Ni, 93 % of Zn, 84 % of Cr, and 68 % of Pb were removed from soil after three successive washing cycles. Treating the residual soil-bound PAHs for 20 weeks led to maximum biodegradation rates of 34, 45, 36, and 32 % of the remaining total PAHs, 3-ring PAHs, 4-ring PAHs, and 5(+6)-ring PAHs after washing procedure, respectively. Based on BIOLOG Ecoplate assay, the combined treatment at least partially restored microbiological functions in the contaminated soil. The ex situ cleanup strategy through MCD-enhanced soil washing followed by microbial augmentation can be effective in remediating PAH and metal-contaminated soil.

The contamination of soils by polycyclic aromatic hydrocarbons (PAHs) is a widespread environmental problem and the remediation of PAHs from these areas has been a major concern. The effectiveness of many in situ bioremediation systems may be constrained by low contaminant bioavailability due to limited aqueous solubility or a large magnitude of sorption. The objective of this research was to evaluate the effect of methyl-beta-cyclodextrin (MCD) on bioaugmentation by Paracoccus sp. strain HPD-2 of an aged PAH-contaminated soil. When 10% (W/W) MCD amendment was combined with bioaugmentation by the PAH-degrading bacterium Paracoccus sp. strain HPD-2, the percentage degradation of total PAHs was significantly enhanced up to 34.8%. Higher counts of culturable PAH-degrading bacteria and higher soil dehydrogenase and soil polyphenol oxidase activities were observed in 10% (W/W) MCD-assisted bioaugmentation soil. This MCD-assisted bioaugmentation strategy showed significant increases (p0.05) in the average well color development (AWCD) obtained by the BIOLOG Eco plate assay, Shannon-Weaver index (H) and Simpson index (lambda) compared with the controls, implying that this strategy at least partially restored the microbiological functioning of the PAH-contaminated soil. The results suggest that MCD-aided bioaugmentation by Paracoccus sp. strain HPD-2 may be a promising practical bioremediation strategy for aged PAH-contaminated soils.

Dissipation and plant uptake of polycyclic aromatic hydrocarbons (PAHs) in contaminated agricultural soil planted with perennial ryegrass were investigated in a field experiment. After two seasons of grass cultivation the mean concentration of 12 PAHs in soil decreased by 23.4% compared with the initial soil. The 3-, 4-, 5-, and 6-ring PAHs were dissipated by 30.9%, 25.5%, 21.2%, and 16.3% from the soil, respectively. Ryegrass shoots accumulated about 280 μg·kg−1, shoot dry matter biomass reached 2.48 × 104 kg·ha−1, and plant uptake accounted for about 0.99% of the decrease in PAHs in the soil. Significantly higher soil enzyme activities and microbial community functional diversity were observed in planted soil than that in the unplanted control. The results suggest that planting ryegrass may promote the dissipation of PAHs in long-term contaminated agricultural soil, and plant-promoted microbial degradation may be a main mechanism of phytoremediation.

An in situ phytoremediation trial was developed in order to investigate the function of alfalfa during a 2-year bioremediation of an agricultural soil contaminated with polychlorinated biphenyls (PCBs). The study was conducted with the aim to better understand the application potential of PCB phytoremediation at field scale. Two treatments were set up in this field study: (1) soil without planting as a control (CK), and (2) soil planted with alfalfa (P). Kinetics of soil PCB removal during the bioremediation treatment was determined using gas chromatography. Soil enzyme activities including dehydrogenase and fluorescein diacetate (FDA) esterase were detected by spectrophotometry. In addition, soil microbial community structures were investigated by using denaturing gradient gel electrophoresis (DGGE). After the first and second years of remediation, planting alfalfa significantly decreased the initial soil PCB concentrations by 31.4% and 78.4%, respectively. Moreover, the presence of alfalfa significantly increased soil dehydrogenase and FDA esterase activities during the remediation. Changes in soil bacterial community structure and diversity were observed by PCR–DGGE fingerprinting. Planting alfalfa significantly increased soil bacterial diversity. Some well-known PCB-degrading bacteria such as Chloroflexi sp. may have contributed to the rhizoremediation of PCBs. Results of this field study suggest that alfalfa is a promising candidate for phytoremediation of PCB-contaminated agricultural soil.

Microbe-assisted phytoremediation is emerging as one of the most effective means by which plants and their associated rhizosphere microbes degrade organic contaminants in soils. A pot study was conducted to examine the effects of inoculation with Rhizobium meliloti on phytoremediation by alfalfa grown for 90 days in an agricultural soil contaminated with weathered polycyclic aromatic hydrocarbons (PAHs). Planting with uninoculated alfalfa (P) and alfalfa inoculated with R. meliloti (PR) significantly lowered the initial soil PAH concentrations by 37.2 and 51.4% respectively compared with unplanted control soil. Inoculation with R. meliloti significantly increased the counts of culturable PAH-degrading bacteria, soil microbial activity and the carbon utilization ability of the soil microbial community. The results suggest that the symbiotic association between alfalfa and Rhizobium can stimulate the rhizosphere microflora to degrade PAHs and its application may be a promising bioremediation strategy for aged PAH-contaminated soils.

A field experiment was conducted to study the effects of inoculation with the arbuscular mycorrhizal fungus Glomus caledonium and/or Rhizobium meliloti on phytoremediation of an agricultural soil contaminated with weathered PCBs by alfalfa grown for 180 days. Planting alfalfa (P), alfalfa inoculated with G. caledonium (P + AM), alfalfa inoculated with R. meliloti (P + R), and alfalfa co-inoculated with R. meliloti and G. caledonium (P+AM+R) decreased significantly initial soil PCB concentrations by 8.1, 12.0, 33.8, and 43.5%, respectively. Inoculation with R. meliloti and/or G. caledonium (P+AM+R) increased the yield of alfalfa, and the accumulation of PCBs in the shoots. Soil microbial counts and the carbon utilization ability of the soil microbial community increased when alfalfa was inoculated with R. meliloti and/or G. caledonium. Results of this field study suggest that synergistic interactions between AMF and Rhizobium may have great potential to enhance phytoremediation by alfalfa of an agricultural soil contaminated with weathered PCBs.

A field-scale experiment was carried out to compare the effectiveness of five plant species in the remediation of oily sludge. Alfalfa, tall fescue, and soybean substantially increased the removal rate of oil and grease (O&G) after 120 days of remediation. Of these, soybean treatment showed the highest removal rate of 34.2% compared with only 13.7% in the unplanted control plot. In addition to assisting with phytoremediation, soybean can also be used for energy production, for example in the production of biodiesel. Furthermore, microbial counts and community level physiological profiling using Biolog sole carbon source utilization tests were used to investigate the effect of plants on the microbial community of oily sludge. Plants selectively increased microbial counts in the rhizosphere and O&G concentrations of the sludge were negatively correlated with counts of TPH (total petroleum hydrocarbon) degraders. The acute biotoxicity of the sludge was also tested by the bacterial luminescence method and alfalfa treatments decreased the biological toxicity of the sludge compared with the unplanted control.

In situ bioremediation of oily sludge-contaminated soil by biostimulation of indigenous microbes through adding manure was conducted at the Shengli oilfield in northern China. After bioremediation for 360 days, total petroleum hydrocarbon (TPH) content was reduced by 58.2% in the treated plots compared with only 15.6% in the control plot. Moreover, bioremediation significantly improved the physicochemical properties of the soil in the treated plot. Soil microbial counts and community-level physiological profiling were also examined. Manure addition increased TPH degraders and polycyclic aromatic hydrocarbon (PAH) degraders in the contaminated soil by one to two orders of magnitude. The activity and biodiversity of soil microbial communities also increased markedly in the treated plot compared with that of the control. Finally, biotoxicity was used to evaluate the soils and a sharp increase in the EC50 of the soil after bioremediation was observed, indicating that bioremediation had reduced the toxicity of the soil.

The transformation of PAHs by fungal laccases has been reported but there are no published studies on the direct application of free laccase in the remediation of PAHs-contaminated soil. Here we report a study in which the transformation of PAHs by a fungal laccase was studied both in reaction mixtures and in soil. Anthracene and benzo(a)pyrene were the most degradable of the 15 US Environmental Protection Agency (EPA) priority PAHs tested. Use of a redox mediator greatly enhanced the oxidation of several PAHs in reaction mixtures and the main intermediates were identified as anthraquinone for anthracene and benzo(a)pyrenyl acetate for benzo(a)pyrene as determined by GC–MS analysis. No significant correlation was found between oxidation and ionization potentials of individual PAHs. Soil microcosms were set up to test the potential of laccase to remediate an aged PAHs-contaminated soil. The laccase transformed the PAHs immediately after it was added to the soil and significant dissimilation of benzo(a)pyrene and toxic-equivalent concentration based on benzo(a)pyrene was observed after incubation for 14 days, indicating the potential of laccase to detoxify the soil. Moreover, extractable laccase activity was completely lost and the biomass of the indigenous microorganisms remained constant in the microcosms at the end of the incubation period, suggesting that the enzyme may have potential as an agent for the efficient and safe cleanup of soil contaminated with PAHs.

Microcosms were set up with a PAHs-contaminated soil using biostimulation (addition of ground corn cob) and bioaugmentation (inoculated with Monilinia sp. W5-2). Degradation of polycyclic aromatic hydrocarbons and microbial community were examined at the end of incubation period. After 30 days, bioaugmented microcosms showed a 35+/-0% decrease in total PAHs, while biostimulated and control microcosms showed 16+/-9% and 3+/-0% decrease in total PAHs, respectively. Bioaugmented microcosms also revealed 70+/-8% and 72+/-2% decreases in benzo[a]pyrene and anthracene, respectively, while the values for biostimulated and control microcosms were much lower. Detoxification of soils in bioaugmented microcosms was confirmed by genetic toxicity assay, suggesting important role of fungal remediation. Molecular fingerprint profiles and selective enumeration showed biostimulation with ground corn cob increased both number and abundance of indigenous aromatic hydrocarbons degraders and changed microbial community composition in soil, which is beneficial to natural attenuation of PAHs. At the same time, bioaugmentation with Monilinia strain W5-2 imposed negligible effect on indigenous microbial community. This study suggests that fungal remediation is promising in eliminating PAHs, especially the part of recalcitrant and highly toxic benzo[a]pyrene, in contaminated soil. It is also the first description of soil bioremediation with Monilinia sp.

This study aimed to explore the effects of Trichoderma reesei FS10-C on the phytoremediation of Cd-contaminated soil by Sedum plumbizincicola as well as soil fertility. After characterizing the Cd tolerance of T. reesei FS10-C, a pot experiment was carried out to investigate the plant growth and Cd uptake of S. plumbizincicola with the addition of inoculation agents with/without T. reesei FS10-C. The soil samples in pots were analyzed for pH, available phosphorus (P), microbial biomass C, enzyme activities, microbial community functional diversity and Trichoderma colonization ability. The results indicated that FS10-C possessed high Cd resistance up to 300 mg L-1. All inoculation agents enhanced the biomass of plant shoots by 6-53% fresh weight and 16-61% dry weight as well as Cd uptake in plant shoots by 10-53% compared with the control. In addition, soil biomass C, enzyme activities and microbial community evenness were all increased to varying degrees by all inoculation agents, indicating that soil microbial biomass and activities were both enhanced. It was also found that the two inoculation agents accompanied by FS10-C were better compared with the inoculation agents without FS10-C on all accounts, from which it could be concluded that T. reesei FS10-C was effective in improving Cd phytoremediation of S. plumbizincicola and soil fertility. Furthermore, among all the inoculation agents, solid fermentation powder of FS10-C demonstrated the greatest capacity to enhance plant growth, Cd uptake, nutrient release, and microbial biomass and activities, as indicated by its superior ability to colonize Trichoderma. Thus, we could also conclude that solid fermentation powder of FS10-C was a good candidate for use as an inoculation agent for T. reesei FS10-C to improve the phytoremediation of Cd-contaminated soil and soil fertility.

The increased application of graphene raises concerns about its environmental impact, but little information is available on the effect of graphene on the soil microbial community. This study evaluated the impact of graphene on the structure, abundance and function of the soil bacterial community based on quantitative real-time polymerase chain reaction (qPCR), pyrosequencing and soil enzyme activities. The results show that the enzyme activities of dehydrogenase and fluorescein diacetate (FDA) esterase and the biomass of the bacterial populations were transiently promoted by the presence of graphene after 4 days of exposure, but these parameters recovered completely after 21 days. Pyrosequencing analysis suggested a significant shift in some bacterial populations after 4 days, and the shift became weaker or disappeared as the exposure time increased to 60 days. During the entire exposure process, the majority of bacterial phylotypes remained unaffected. Some bacterial populations involved in nitrogen biogeochemical cycles and the degradation of organic compounds can be affected by the presence of graphene.

Environmental pollutants have received considerable attention due to their serious effects on human health. There are physical, chemical, and biological means to remediate pollution; among them, bioremediation has become increasingly popular. The nitrogen-fixing rhizobia are widely distributed in the soil and root ecosystems and can increase legume growth and production by supplying nitrogen, resulting in the reduced need for fertilizer applications. Rhizobia also possess the biochemical and ecological capacity to degrade organic pollutants and are resistant to heavy metals, making them useful for rehabilitating contaminated soils. Moreover, rhizobia stimulate the survival and action of other biodegrading bacteria, thereby lowering the concentration of pollutants. The synergistic action of multiple rhizobial strains enhances both plant growth and the availability of pollutants ranging from heavy metals to persistent organic pollutants. Because phytoremediation has some restrictions, the beneficial interaction between plants and rhizobia provides a promising option for remediation. This review describes recent advances in the exploitation of rhizobia for the rehabilitation of contaminated soil and the biochemical and molecular mechanisms involved, thereby promoting further development of this novel bioremediation strategy into a widely accepted technique.

Understanding the potential for Polycyclic aromatic hydrocarbons (PAH) degradation by indigenous microbiota and the influence of PAHs on native microbial communities is of great importance for bioremediation and ecological evaluation. Various studies have focused on the bacterial communities in the environment where obvious PAH degradation was observed, little is known about the microbiota in the soil where poor degradation was observed. Soil microcosms were constructed with a red soil by supplementation with a high-molecular-weight PAH (pyrene) at three dosages (5, 30, and 70 mg ⋅ kg(-1)). Real-time PCR was used to evaluate the changes in bacterial abundance and pyrene dioxygenase gene (nidA) quantity. Illumina sequencing was used to investigate changes in diversity, structure, and composition of bacterial communities. After 42 days of incubation, no evident degradation was observed. The poor degradation ability was associated with the stability or significant decrease of abundance of the nidA gene. Although the abundance of the bacterial 16S rRNA gene was not affected by pyrene, the bacterial richness and diversity were decreased with increasing dosage of pyrene and the community structure was changed. Phylotypes affected by pyrene were comprehensively surveyed: (1) at the high taxonomic level, seven of the abundant phyla/classes (relative abundance1.0%) including Chloroflexi, AD3, WPS-2, GAL5, Alphaproteobacteria, Actinobacteria, and Deltaproteobacteria and one rare phylum Crenarchaeota were significantly decreased by at least one dosage of pyrene, while three phyla/classes (Acidobacteria, Betaproteobacteria, and Gammaproteobacteria) were significantly increased; and (2) at the lower taxonomic level, the relative abundances of twelve orders were significantly depressed, whereas those of nine orders were significantly increased. This work enhanced our understanding of the biodegradation potential of pyrene in red soil and the effect of pyrene on soil ecosystems at the microbial community level.

Summary This paper summarizes the conception and development of microbial fertilizers and inoculants in China that are used to improve soil quality and the growth, yield and protection of crops. The results presented show the relative effects of these microbial products applied singly or with chemical fertilizers on soil fertility, crop yield and protection. The paper discusses current trends in the development and use of microbial fertilizers in China and suggests areas of high priority research.

The effectiveness of many bioremediation systems for PAH-contaminated soil may be constrained by low contaminant bioaccessibility due to limited aqueous solubility or large sorption capacity. Information on the extent to which PAHs can be readily biodegraded is of vital importance in the decision whether or not to remediate a contaminated soil. In the present study the rate-limiting factors in methyl-β-cyclodextrin (MCD)-enhanced bioremediation of PAH-contaminated soil were evaluated. MCD amendment at 10 % (w/w) combined with inoculation with the PAH-degrading bacterium Paracoccus sp. strain HPD-2 produced maximum removal of total PAHs of up to 35 %. The desorption of PAHs from contaminated soil was determined before and after 32 weeks of bioremediation. 10 % (w/w) MCD amendment (M2) increased the Tenax extraction of total PAHs from 12 to 30 % and promoted degradation by up to 26 % compared to 6 % in the control. However, the percentage of Tenax extraction for total PAHs was much larger than that of degradation. Thus, in the control and M2 treatment it is likely that during the initial phase the bioaccessibility of PAHs is high and biodegradation rates may be limited by microbial processes. On the other hand, when the soil was inoculated with the PAH-degrading bacterium (CKB and MB2), the slowly and very slowly desorbing fractions (F sl and F vl ) became larger and the rate constants of slow and very slow desorption (k sl and k vl ) became extremely small after bioremediation, suggesting that desorption is likely rate limiting during the second, slow phase of biotransformation. These results have practical implications for site risk assessment and cleanup strategies.

Purpose A 7-month field experiment was conducted to investigate the polycyclic aromatic hydrocarbon (PAH) remediation potential of two plant species and changes in counts of soil PAH-degrading bacteria and microbial activity.

A microcosm study was conducted to test the bioremediation potential of Paracoccus sp. strain HPD-2 on an aged PAH-contaminated soil. Bioaugmented microcosms showed a 23.2% decrease in soil total PAH concentrations after 28days, with a decline in average concentration from 9942 to 7638microg kg(-1) dry soil. The percentage degradation of 3-, 4- and 5(+6)-ring PAHs was 35.1%, 20.7% and 24.3%, respectively. Higher counts of culturable PAH-degrading bacteria, microbial biomass and enzyme activities were observed in bioaugmented soil. The bioaugmented microcosms showed significant increases (p0.05) in the average well-color development (AWCD) obtained by the BIOLOG ecoplate assay and Shannon-Weaver index (H) compared to the controls. Principal component analysis of BIOLOG data clearly differentiated between the bioaugmented and control microcosms, implying that bioaugmentation restored the microbiological functioning of the PAH-contaminated soil. The results suggest that bioaugmentation by Paracoccus sp. strain HPD-2 may be a promising bioremediation strategy for aged PAH-contaminated soils.

Carbon supplementation, soil moisture and soil aeration are believed to enhance in situ bioremediation of PAH-contaminated soils by stimulating the growth of indigenous microorganisms. However, the effects of added carbon and nitrogen together with soil moisture and soil aeration on the dissipation of PAHs and on associated microbial counts have yet to be fully assessed. In this study the effects on bioremediation of carbon source, carbon-to-nitrogen ratio, soil moisture and aeration on an aged PAH-contaminated agricultural soil were studied in microcosms over a 90-day period. Additions of starch, glucose and sodium succinate increased soil bacterial and fungal counts and accelerated the dissipation of phenanthrene and benzo(a)pyrene in soil. Decreases in phenanthrene and benzo(a)pyrene concentrations were effective in soil supplemented with glucose and sodium succinate (both 0.2 g C kg(-1) dry soil) and starch (1.0 g C kg(-1) dry soil). The bioremediation effect at a C/N ratio of 10:1 was significantly higher (P < 0.05) than at a C/N of either 25:1 or 40:1. Soil microbial counts and PAH dissipation were lower in the submerged soil but soil aeration increased bacterial and fungal counts, enhanced indigenous microbial metabolic activities, and accelerated the natural degradation of phenanthrene and benzo(a)pyrene. The results suggest that optimizing carbon source, C/N ratio, soil moisture and aeration conditions may be a feasible remediation strategy in certain PAH contaminated soils with large active microbial populations.

Polychlorinated biphenyls (PCB) are persistent pollutants in soil environments where they continue to present considerable human health risks. Successful strategies to remediate contaminated soils are needed that are effective and of low cost. Bioremediation approaches that include the use of plants and microbial communities to promote degradation of PCB have significant potential but need further assessment under field conditions. The effects of growth of alfalfa (Medicago sativa L.) and inoculation with a symbiotic nitrogen fixing bacterium (Rhizobium meliloti) on the removal of polychlorinated biphenyls (PCB) from rhizosphere soil were evaluated in a field experiment. The initial PCB content of the soil ranged from 414 to 498 microg kg(-)(1). PCB removal for the rhizosphere soil was enhanced in the planted treatments, an average of 36% decrease in PCB levels compared to a 5.4% decrease in the unplanted soil, and further enhanced when plants were inoculated with the symbiotic Rhizobium (an average of 43% decrease) when evaluated at 90 days after planting. Plant biomass production was higher in the inoculated treatment. The total PCB content was increased from 3.30 microg kg(-)(1) to 26.72 microg kg(-)(1) in plant shoots, and from 115.07 microg kg(-)(1) to 142.23 microg kg(-)(1) in roots in the inoculated treatment compared to the planted treatment. Increased colony forming units (cfu) of total heterotrophic bacteria, biphenyl-degrading bacteria and fungi were observed in the rhizosphere of inoculated plants. PCB removal from the rhizosphere soil was not significantly correlated with the direct PCB uptake by the plants in any of the treatments but was significantly correlated with the stimulation of rhizosphere microflora. Changes in the soil microbial community structure in the planted and inoculated treatment were observed by profiling of bacterial ribosomal sequences. Some bacteria, such as Flavobacterium sp., may have contributed to the effective degradation of PCB and deserve further investigation.

Field-scale bioremediation of oily sludge in prepared beds was studied at Shengli oilfield in northern China. The influence of manure, coarse sand, sawdust, a specialized microbial preparation and greenhouse conditions on the efficiency of removal of oil and grease was evaluated. After bioremediation for 230d, oil and grease content fell by 32-42gkg(-1)dry sludge in treated plots, indicating removal of 27-46% compared with only 15% in the control plot. Addition of manure, coarse sand, sawdust and greenhouse conditions significantly (p0.05) increased the amount removed. Moreover, the physico-chemical properties of the sludge in all treated plots improved significantly after bioremediation. Microbial biomass in sludge and community-level physiological profiling examined using BIOLOG microplates was also studied. Total petroleum hydrocarbon degraders and polycyclic aromatic hydrocarbon degraders increased in all treated oily sludge. The activity of sludge microbial communities increased markedly in the treated plots compared with the control. Canonical correspondence analysis showed that differences in substrate utilization patterns were highly correlated (p0.05) with sludge hydrolyzable N and oil and grease content. The biological toxicity of the oily sludge was lower following bioremediation in most of the treated plots as evaluated using Photobacterium phosphoreum T3.

Background A climate-controlled pot experiment was conducted to investigate the effects of planting alfalfa and applying organic fertilizer on the dissipation of benzo[a]pyrene from an aged contaminated agricultural soil. Results Short-term planting of alfalfa inhibited the dissipation of benzo[a]pyrene from the soil by 8.9%, and organic fertilizer enhanced benzo[a]pyrene removal from the soil by 11.6% compared with the unplanted and unfertilized treatments, respectively. No significant interaction was observed between alfalfa and organic fertilizer on benzo[a]pyrene dissipation. Sterilization completely inhibited the removal of benzo[a]pyrene from the soil indicating that its degradation by indigenous microorganisms may have been the main mechanism of dissipation. Furthermore, significant positive relationships were observed between benzo[a]pyrene removal and the contents of soil ammonium nitrogen, nitrate nitrogen, and total mineral nitrogen at the end of the experiment, suggesting that competition between plants and microorganisms for nitrogen may have inhibited benzo[a]pyrene dissipation in the rhizosphere of alfalfa and the addition of organic fertilizer may facilitate microbial degradation of benzo[a]pyrene in the soil.