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© 2017 Parajuli et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Long-term exposure to polyaromatic hydrocarbons (PAHs) has been connected to chronic human health disorders. It is also well-known that i) PAH contamination alters soil bacterial communities, ii) human microbiome is associated with environmental microbiome, and iii) alteration in the abundance of members in several bacterial phyla is associated with adverse or beneficial human health effects. We hypothesized that soil pollution by PAHs altered soil bacterial communities that had known associations with human health. The rationale behind our study was to increase understanding and potentially facilitate reconsidering factors that lead to health disorders in areas characterized by PAH contamination. Large containers filled with either spruce forest soil, pine forest soil, peat, or glacial sand were left to incubate or contaminated with creosote. Biological degradation of PAHs was monitored using GC-MS, and the bacterial community composition was analyzed using 454 pyrosequencing. Proteobacteria had higher and Actinobacteria and Bacteroidetes had lower relative abundance in creosote contaminated soils than in non-contaminated soils. Earlier studies have demonstrated that an increase in the abundance of Proteobacteria and decreased abundance of the phyla Actinobacteria and Bacteroidetes are particularly associated with adverse health outcomes and immunological disorders. Therefore, we propose that pollution-induced shifts in natural soil bacterial community, like in PAH-polluted areas, can contribute to the prevalence of chronic diseases. We encourage studies that simultaneously address the classic “adverse toxin effect” paradigm and our novel “altered environmental microbiome” hypothesis.

© 2017 The Author(s)Purpose: Soil restoration is still mainly carried out ex situ by excavating and replacing the contaminated soil. In situ remediation would reduce the costs of soil transportation and this way, the problem is not merely transferred elsewhere. The present study introduces a field case where the aged, oil-contaminated soil in a former fuel station in Finland was treated in situ sequentially with different methods. Materials and methods: Several approaches, including soil vapor extraction and biostimulation with electrokinetic pumping, were performed in the field. After these treatments, the dense original portion of the soil beneath the gasoline pump location, ca 100 m3, was still contaminated with petroleum-derived volatile organic compounds (VOCs), with concentrations of nearly 10,000 mg kg−1 measured at some hotspots. After a period of electroosmotic water circulation, the electrical field (0.5 V cm−1, DC) was kept connected for 6 months without addition of water, leading to dewatering and warming of the soil. Results and discussion: In contrast to the situation with the original wet soil, VOCs, in lab conditions, were found to volatilize very efficiently from the dewatered soil. When the soil vapor extraction treatment was renewed using perforated tubing installed horizontally at ca 1 m depth in the dewatered soil at the contaminated site, the treatment was efficient and the soil was decontaminated in 5 months. The final VOC concentrations were on average 190 mg kg−1 (n = 13) with the highest value of 700 mg kg−1 at one hotspot. After a risk evaluation, the site was concluded to be sufficiently clean for industrial use. Conclusions: Since with many former fuel stations, the contamination consists of both volatile fractions that are difficult to degrade by biological means and heavier compounds for which biostimulation is often suitable, a combination of different methods may be worth pursuing.

© 2017, The Author(s).A traditional sand filter for treatment of household wastewater was constructed in the fall of 2012 at Biolinja 12, Turku, Finland. Construction work was led and monitored by an authorized wastewater treatment consultant. The filter was placed on a field bordered by open ditches from all sides in order to collect excess rain and snowmelt waters. The filter was constructed and insulated from the environment so that all outflowing water was accounted for. Untreated, mainly municipal, wastewater from Varissuo suburb was pumped from a sewer separately via three septic tanks (volume = 1 m3 each) into the filters. Normally, wastewater was distributed to ground filters automatically according to pre-programmed schedule. Initially, the daily flow was 1200 L day−1 to reflect the average organic load of a household of five persons (load: ca 237 g day−1 BOD; 73 g day−1 total N; and 10.4 g day−1 total P). Later in the test, the flow rate was decreased first to 900 and then to 600 L day−1 to better reflect the average volume produced by five persons. Volumes of inlet wastewater as well as treated water were monitored by magnetic flow meters. Samples were withdrawn from the inlet water, from the water entering the filters after the third septic tank, and from the outflowing water. After an initial adaption time, the reductions in BOD and chemical oxygen demand were constantly between 92 and 98%, showing that the biological degradation process in the filters functioned optimally and clearly comply with the national and EU standards. The reduction in total nitrogen and total phosphorus, however, reached required levels only during the first months of testing, apparently when buildup of microbial biomass was still ongoing. After this initial period of 3 months showing satisfactory reduction levels, the reduction of total nitrogen varied between 5 and 25% and total phosphorus mostly between 50 and 65%. Nitrification was efficient in the filter, but as indicated by high nitrate levels and poor nitrogen reductions, denitrification was inefficient or absent. During the winter period, the temperature in the filter dropped to near freezing, but at all time points, the flow of water was unaffected by freezing. During snowmelt and heavy rain, occasional flooding was observed. Such situations may lead to dilution rather than purification of the wastewater. In conclusion, the sand filter tested worked well for reduction of the organic load in municipal wastewater but failed to sufficiently reduce nitrogen and phosphorus levels.

© 2017 The AuthorsGrowth and fatty acid production of microalga Selenastrum sp. with associated bacteria was studied in lab-scale experiments in three composting leachate liquids. Nutrient reduction in cultures was measured at different initial substrate strengths. A small, pilot-scale photobioreactor (PBR) was used to verify lab-scale results. Similar growth conditions supported growth of both Selenastrum and bacteria. CO2 feed enhanced the production of biomass and lipids in PBR (2.4 g L−1 and 17% DW) compared to lab-scale (0.1–1.6 g L−1 and 4.0–6.5% DW) experiments. Also prolonged cultivation time increased lipid content in PBR. At both scales, NH4-N with an initial concentration of ca. 40 mg L−1 was completely removed from the biowaste leachate. In lab-scale, maximal COD reduction was over 2000 mg L−1, indicating mixotrophic growth of Selenastrum. Co-cultures are efficient in composting leachate liquid treatment, and conversion of waste to biomass is a promising approach to improve the bioeconomy of composting plants.

© 2017 Society for Applied Microbiology and John Wiley & Sons LtdSoil microbes play a key role in controlling ecosystem functions and providing ecosystem services. Yet, microbial communities in urban green space soils remain poorly characterized. Here we compared soil microbial communities in 41 urban parks of (i) divergent plant functional types (evergreen trees, deciduous trees and lawn) and (ii) different ages (constructed 10, ∼50 and >100 years ago). These microbial communities were also compared to those in 5 control forests in southern Finland. Our results indicate that, despite frequent disturbances in urban parks, urban soil microbes still followed the classic patterns typical of plant-microbe associations in natural environments: both bacterial and fungal communities in urban parks responded to plant functional groups, but fungi were under tighter control of plants than bacteria. We show that park age shaped the composition of microbial communities, possibly because vegetation in old parks have had a longer time to modify soil properties and microbial communities than in young parks. Furthermore, control forests harboured distinct but less diverse soil microbial communities than urban parks that are under continuous anthropogenic disturbance. Our results highlight the importance of maintaining a diverse portfolio of urban green spaces and plant communities therein to facilitate complex microbial communities and functions in urban systems.

© 2015 Elsevier B.V. The Grain for Green (GFG) Project in China is currently the largest environmental rehabilitation project aimed at turning low-yielding farm land to forests and pastures. Such conversion of land use type also promotes remediation of the polluted environment. Soil microbes reflect soil function and are therefore considered an essential component of ecosystem restoration. To evaluate the environmental effects of converting atrazine polluted farmland to secondary forest, we determined soil chemical properties, soil bacterial communities and their responses to three types of land use (primary forest, PF; secondary forest, SF; farm land, FL) in Wuying, China. Our results showed that soil organic matter significantly decreases in the order PF > SF > FL. Bacterial 16S rRNA gene 454 pyrosequencing revealed that the soil bacterial diversity level remained unchanged. However between FL and the two forested sites, we observed an increase of Actinobacteria, β-proteobacteria and Firmicutes; and a decrease of Acidobacteria and Verrucomicrobia, while in SF the bacterial community structure was similar to PF. We conclude that reforestation permits bacterial community, resetting from FL back to a state that resembles natural conditions. In addition, 20 years of natural attenuation degraded soil atrazine residues in SF but traces remained in the soil. Reforestation generally resulted in favorable ecological impacts on soil quality and the bacterial community compared with active farm fields.

© 2015 Elsevier Ltd. We investigated the bioremediation of 16 polycyclic aromatic hydrocarbons (PAH) in historically creosote contaminated soil using both laboratory and field scale experiments. We found that nutrient amendments and circulation of methyl-β-cyclodextrin (CD) solution enhanced soil microbial degradation capacity. In the laboratory experiment, the degradation of lower molecular weight, 2-3 ringed PAHs was achieved already by circulating nutrient solution and the use of CD mainly increased the desorption and removal of larger, 4-5 aromatic ringed PAH compounds. The 1% CD concentration was most feasible for bioremediation as most of the extracted PAH compounds were degraded. In the 5% CD treatment, the PAH desorption from soil was too fast compared to the degradation capacity and 25% of the total PAH amount remained in the circulated solution. Similar lab-scale results have been generated earlier, but very little has been done in full field scale, and none in freezing conditions. Although freezing stopped circulation and degradation completely during the winter, PAH degradation returned during the warm period in the field test. Circulation effectiveness was lower than in the laboratory but the improved nutrient and moisture content seemed to be the main reason for decreasing soil PAH concentrations. It also appeared that PAH extraction yield in chemical analysis was increased by the CD treatment in field conditions and the results of CD-treated and non-treated soil may therefore not be directly comparable. Therefore, a positive effect of CD on PAH degradation velocity could not be statistically confirmed in the field test. Based on our results, we recommend initiating the bioremediation of PAH contaminated soil by enhancing the microbial degradation with nutrient amendments. The CD seems to be useful only at the later stage when it increases the solubilisation of strongly absorbed contaminants to some extent. More investigation is also needed of the CD effect on the PAH yield in the chemical analysis.

© 2016 Taylor and Francis Group, LLC. The present study aimed to investigate microbial communities in seven Indian composts and their potential for biocontrol of Fusarium oxysporum f. sp. lycopersici. In addition, identification of bioactive substances in disease suppressive composts was also attempted. Composts were chosen based on disease suppressiveness and subjected to molecular microbial analyses. Total genomic DNA from the composts was extracted and amplified with polymerase chain reaction using primers targeting the 18S rRNA and 16S rRNA genes of fungi and bacteria, respectively. Denaturing gradient gel electrophoresis (DGGE) fingerprinting and DNA sequencing were used to identify the fungal and bacterial targets. Phylogenetic analysis of the fungal 18S rRNA ITS gene sequences showed that phylum Ascomycota was dominant in all composts, while in the bacterial 16S rRNA gene sequences, the phylum Proteobacteria was dominant. Some fungi in disease suppressive composts grouped phylogenetically close to F. oxysporum. Bacterial sequences with close similarity (>95% identity) with Actinobacterium showed a strong presence only in disease suppressive composts. Disease suppressive composts formed a separate group in the cluster analysis of 18S rRNA ITS and 16S rRNA gene sequences. Gas chromatography-time of flight-mass spectrometry was performed with compost extracts to determine if bioactive substances were present in disease suppressive composts. The analysis of compost organic matter showed a negative association of disease suppressiveness with phloroglucinol, sitosterol, and monoenoic fatty acid, while cholesterol and certain organic acids were positively associated with suppressiveness.

© 2016, Płociniczak, Sinkkonen, Romantschuk, Sułowicz and Piotrowska-Seget.Environmental pollution by heavy metals has become a serious problem in the world. Phytoextraction, which is one of the plant-based technologies, has attracted the most attention for the bioremediation of soils polluted with these contaminants. The aim of this study was to determine whether the multiple-tolerant bacterium, Brevibacterium casei MH8a isolated from the heavy metal-contaminated rhizosphere soil of Sinapis alba L., is able to promote plant growth and enhance Cd, Zn, and Cu uptake by white mustard under laboratory conditions. Additionally, the ability of the rifampicin-resistant spontaneous mutant of MH8a to colonize plant tissues and its mechanisms of plant growth promotion were also examined. In order to assess the ecological consequences of bioaugmentation on autochthonous bacteria, the phospholipid fatty acid (PLFA) analysis was used. The MH8a strain exhibited the ability to produce ammonia, 1-amino-cyclopropane-1-carboxylic acid deaminase, indole 3-acetic acid and HCN but was not able to solubilize inorganic phosphate and produce siderophores. Introduction of MH8a into soil sigNificantly increaSed S. alba biomass and the accumulation of Cd (208%), Zn (86%), and Cu (39%) in plant shoots in comparison with those grown in non-inoculated soil. Introduced into the soil, MH8a was able to enter the plant and was found in the roots and leaves of inoculated plants thus indicating its endophytic features. PLFA analysis revealed that the MH8a that was introduced into soil had a temporary influence on the structure of the autochthonous bacterial communities. The plant growth-promoting features of the MH8a strain and its ability to enhance the metal uptake by white mustard and its long-term survival in soil as well as its temporary impact on autochthonous microorganisms make the strain a suitable candidate for the promotion of plant growth and the efficiency of phytoextraction.

Details of biogas quality are in a decisive role when determining the biogas utilization and the purification requirements and equipments. Comprehensive measurements of the biogas composition together with knowledge of the actuating factors could offer a potential tool for on-line process control and troubleshooting. In the present work, the effects of process changes related to reactor loading variations on concentrations of selected trace compounds in biogas were studied. The results showed that the process was well under control up to the load of 8 kgVS/m3d. Gaseous concentrations of siloxanes, hydrogen sulfide as well as most VOCs remained quite constant. However, the formation of gaseous ethanol was found to accelerate at the load-increasing points. Furthermore, a significant temporary increase in N2O formation was occasionally found due to some oxygen penetration in the reactor.