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Remediation strategies for metal(loid)-polluted soils vary among the wide range of approaches, including physical, chemical, and biological remediation, or combinations of these. In this study, we assessed the effectiveness of a set of soil remediation treatments based on the combined application of inorganic (marble sludge) and organic amendments (vermicompost, and dry olive residue [DOR] biotransformed by the saprobic fungi Coriolopsis rigida and Coprinellus radians) and inoculation with arbuscular mycorrhizal fungi (AMFs) (Rhizophagus irregularis and Rhizoglomus custos). The treatments were applied under greenhouse conditions to soil residually polluted by potentially toxic elements (PTEs) (Pb, As, Zn, Cu, Cd, and Sb), and wheat was grown in the amended soils to test the effectiveness of the treatments in reducing soil toxicity and improving soil conditions and plant performance. Therefore, we evaluated the influence of the treatments on the main soil properties and microbial activities, as well as on PTE availability and bioaccumulation in wheat plants. Overall, the results showed a positive influence of all treatments on the main soil properties. Treatments consisting of a combination of marble and organic amendments, especially biotransformed DOR amendments, showed the greatest effectiveness in improving the soil biological status, promoting plant growth and survival, and reducing PTE availability and plant uptake. Furthermore, AMF inoculation further enhanced the efficacy of DOR amendments by promoting the immobilization of PTEs in soil and stimulating the phytostabilization mechanisms induced by AMFs, thus playing an important bioprotective role in plants. Therefore, our results highlight that biotransformed DOR may represent an efficient product for use as a soil organic amendment when remediating metal(loid)-polluted soils, and that its application in combination with AMFs may represent a promising sustainable bioremediation strategy for recovering soil functions and reducing toxicity in polluted areas., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Drought is a major threat to plant growth in many parts of the world. During periods of drought, multiple aspects of plant physiology are negatively affected. For instance, water shortages induce osmotic imbalance, inhibit photosynthesis, decrease nutrient uptake, and increases the production of reactive oxygen species (ROS). In this context, it is necessary to develop sustainable strategies for crops that would help mitigate these conditions. In previous studies, endophytic Zopfiella erostrata strains were found to extensively colonize plant roots, forming a profuse melanized mycelium in the rhizosphere, which could be involved in improving water uptake and nutrient mineralization in plants. The aim of this study is to evaluate the effect of different strains of Z. erostrata on stress mitigation in wheat and tomato plants grown under water deficit conditions. General plant growth variables, as well as physiological and biochemical parameters, related to oxidative status were determined. Our data demonstrate that inoculation with both Zopfiella strains had a very significant effect on plant growth, even under water deficit conditions. However, we observed an even more pronounced impact, depending on the plant and strain involved, suggesting a certain degree of plant/strain compatibility. The biochemical aspects, the accumulation of proline, the oxidative damage to lipids, and the activity of antioxidant enzymes varied considerably depending on the endophyte and the plant evaluated.

Symbiotic associations with arbuscular mycorrhizal fungi (AMF) offer an effective indirect mechanism to reduce heavy metal (HM) stress; however, it is still not clear which AMF species are more efficient as bioremediating agents. We selected different species of AMF: Rhizoglomus custos (Custos); Rhizoglomus sp. (Aznalcollar); and Rhizophagus irregularis (Intraradices), in order to study their inoculation in wheat grown in two soils contaminated with two levels of HMs; we tested the phytoprotection potential of the different AMF symbioses, as well as the physiological responses of the plants to HM stress. Plants inoculated with indigenous Aznalcollar fungus exhibited higher levels of accumulation, mainly in the shoots of most of the HM analyzed in heavily contaminated soil. However, the plants inoculated with the non-indigenous Custos and Intraradices showed depletion of some of the HM. In the less-contaminated soil, the Custos and Intraradices fungi exhibited the greatest bioaccumulation capacity. Interestingly, soil enzymatic activity and the enzymatic antioxidant systems of the plant increased in all AMF treatments tested in the soils with both degrees of contamination. Our results highlight the different AMF strategies with similar effectiveness, whereby Aznalcollar improves phytoremediation, while both Custos and Intraradices enhance the bioprotection of wheat in HM-contaminated environments.

The objective of this study was the development and design of a treatment system at a pilot-plant scale for the remediation of hydrocarbons in industrial wastewater. The treatment consists of a combined approach of absorption and biodegradation to obtain treated water with sufficient quality to be reused in fire defense systems (FDSs). The plant consists of four vertical flow columns (bioreactors) made of stainless steel (ATEX Standard) with dimensions of 1.65 × 0.5 m and water volumes of 192.4 L. Each bioreactor includes a holder to contain the absorbent material (Pad Sentec polypropylene). The effectiveness of the treatment system has been studied in wastewater with high and low pollutant loads (concentrations higher than 60,000 mg L -1 of total petroleum hydrocarbons (TPH) and lower than 500 mg L -1 of TPHs, respectively). The pilot-plant design can function at two different flow rates, Q1 (180 L h -1 ) and Q2 (780 L h -1 ), with or without additional aeration. The results obtained for strongly polluted wastewaters showed that, at low flow rates, additional aeration enhanced hydrocarbon removal, while aeration was unnecessary at high flow rates. For wastewater with a low pollutant load, we selected a flow rate of 780 L h -1 without aeration. Different recirculation times were also tested along with the application of a post-treatment lasting 7 days inside the bioreactor without recirculation. The microbial diversity studies showed similar populations of bacteria and fungi in the inlet and outlet wastewater. Likewise, high similarity indices were observed between the adhered and suspended biomass within the bioreactors. The results showed that the setup and optimization of the reactor represent a step forward in the application of bioremediation processes at an industrial/large scale.

The addition of compost from sewage sludge to soils represents a sustainable option from an environmental and economic point of view, which involves the valorisation of these wastes. However, before their use as a soil amendment, compost has to reach the quality levels according to the normative, including microbial parameters. Viruses are not included in this regulation and they can produce agricultural problems and human diseases if the compost is not well sanitised. In this study, we carried out the analysis of the viral populations during a composting process with sewage sludge at an industrial scale, using semipermeable cover technology. Viral community was characterised by the presence of plant viruses and bacteriophages of enteric bacteria. The phytopathogen viruses were the group with the highest relative abundance in the sewage sludge sample and at 70 days of the composting process. The diversity of bacterial viruses and their specificity, with respect to the more abundant bacterial taxa throughout the process, highlights the importance of the interrelations between viral and bacterial communities in the control of pathogenic communities. These results suggest the possibility of using them as a tool to predict the effectiveness of the process.

The disposal of reject brine, a highly concentrated waste by-product generated by various industrial processes, represents a major economic and environmental challenge. The common practice in dealing with the large amounts of brine generated is to dispose of it in a pond and allow it to evaporate. The rate of evaporation is therefore a key factor in the effectiveness of the management of these ponds. The addition of various dyes has previously been used as a method to increase the evaporation rate. In this study, a biological approach, using pigmented halophilic bacteria (as opposed to chemical dyes), was assessed. Two bacteria, an Arthrobacter sp. and a Planococcus sp. were selected due to their ability to increase the evaporation of synthetic brine. When using industrial brine, supplementation of the brine with an iron source was required to maintain the pigment production. Under these conditions, the Planococcus sp. CP5-4 produced a carotenoid-like pigment, which resulted in a 20% increase in the evaporation rate of the brine. Thus, the pigment production capability of halophilic bacteria could potentially be exploited as an effective step in the management of industrial reject brines, analogous to the crystallizer ponds used to mine salt from sea water., (© 2018 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.)

Sewage sludge composting is a profitable process economically viable and environmentally friendly. In despite of there are several kind of composting types, the use of combined system of semipermeable cover film and aeration air-floor is widely developed at industrial scale. However, the knowledge of the linkages between microbial communities structure, enzyme activities and physico-chemical factors under these conditions it has been poorly explored. Thus, the aim of this study was to investigate the bacterial dynamic and community structure using next generation sequencing coupled to analyses of microbial enzymatic activity and culturable dependent techniques in a full-scale real composting plant. Sewage sludge composting process was conducted using a semi-permeable Gore-tex cover, in combination with an air-insufflation system. The highest values of enzymatic activities such as dehydrogenase, protease and arylsulphatase were detected in the first 5 days of composting; suggesting that during this period of time a greater degrading activity of organic matter took place. Culturable bacteria identified were in agreement with the bacteria found by massive sequencing technologies. The greatest bacterial diversity was detected between days 15 and 30, with Actinomycetales and Bacillales being the predominant orders at the beginning and end of the process. Bacillus was the most representative genus during all the process. A strong correlation between abiotic factors as total organic content and organic matter and enzymatic activities such as dehydrogenase, alkaline phosphatase, and ß-glucosidase activity was found. Bacterial diversity was strongly influenced by the stage of the process, community-structure change was concomitant with a temperature rise, rendering favorable conditions to stimulate microbial activity and facilitate the change in the microbial community linked to the degradation process. Moreover, results obtained confirmed that the use of semipermeable cover in the composting of sewage sludge allow a noticeable reduction in the process-time comparing to conventional open windrows., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

This study investigated the response of autochthonous microorganisms of diesel polluted soils to land-farming treatments. Inorganic NPK (nitrogen, phosphorous, and potassium) fertilizer and Ivey surfactant were applied alone or in combination as biostimulating agents. The study was carried out in experimental separated land-farming plots performed with two soils: a sandy clay soil with low biological activity and a sandy clay soil with higher biological activity, contaminated with two concentrations of diesel: 10,000 and 20,000mgkg(-1). Bacterial growth, dehydrogenase activity and CO2 production were the biological parameters evaluated. Non-metric multidimensional scaling analysis proved that moisture content showed a tendency related to microbial growth and that heterotrophic and degrading microorganisms had the best relationship. Initial biological activity of soil influenced the response with 11.1% of variability attributed to this parameter. Soils with low activity had higher degree of response to nutrient addition., (Copyright © 2014 Elsevier Inc. All rights reserved.)

The precipitation of calcium carbonate and calcium sulphate by isolated bacteria from seawater and real brine obtained in a desalination plant growth in culture media containing seawater and brine as mineral sources has been studied. However, only bioprecipitation was detected when the bacteria were grown in media with added organic matter. Biomineralization process started rapidly, crystal formation taking place in the beginning a few days after inoculation of media; roughly 90% of total cultivated bacteria showed. Six major colonies with carbonate precipitation capacity dominated bacterial community structure cultivated in heterotrophic platable bacteria medium. Taxonomic identification of these six strains through partial 16S rRNA gene sequences showed their affiliation with Gram-positive Bacillus and Virgibacillus genera. These strains were able to form calcium carbonate minerals, which precipitated as calcite and aragonite crystals and showed bacterial fingerprints or bacteria calcification. Also, carbonic anhydrase activity was observed in three of these isolated bacteria. The results of this research suggest that microbiota isolated from sea water and brine is capable of precipitation of carbonate biominerals, which can occur in situ with mediation of organic matter concentrations. Moreover, calcium carbonate precipitation ability of this microbiota could be of importance in bioremediation of CO2 and calcium in certain environments.

We report the first genome sequence for Arthrobacter siccitolerans 4J27, a newly described desiccation-tolerant species. The complete genome of A. siccitolerans 4J27 has been sequenced and is estimated to be around 5.3 Mb in size, with an average GC content of 65.13%. We predict 4,480 protein-coding sequences (CDSs)., (Copyright © 2014 Manzanera et al.)

The present study focuses on the remediation of diesel-polluted soil using modified Fenton treatment coupled with inorganic NPK fertilizer ("Fenton+NPK"). Studies were carried out in a pilot plant containing 1 m(3) of sandy soil contaminated with 20,000 mg kg(-1) of diesel, placed outdoors at a temperature ranging between 5 and 10 °C. Results showed that NPK-fertilizer as post-treatment stimulated culturable degrading bacteria and enhanced dehydrogenase activity. Fenton+NPK treatment increased total petroleum hydrocarbon (TPH) removal efficacy. Natural attenuation removed 49% of TPH in the surface layer, 23% of TPH in the non-saturated layer and 4% of the TPH in the saturated layer, while the percentage removed of TPH after Fenton+NPK treatment was 58%, 57% and 32% respectively. The results from our study showed that, immediately after soil contamination, occurred a specialization and differentiation of the bacterial community, but after this initial modification, no significant changes of bacterial diversity was observed under natural attenuation conditions. In contrast, when the Fenton's reagent was applied a reduction of the bacterial biodiversity was observed. However, the post-biostimulation did enhance the degrading microbiota and stimulated their degrading biological activity. In conclusion, biostimulation, as a post-treatment step in chemical oxidation, is an effective solution to remediate hydrocarbon-polluted sites., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Biodegradation is one of the primary mechanisms for elimination of petroleum and other hydrocarbon pollutants from the environment. It is considered an environmentally acceptable way of eliminating oils and fuel because the majority of hydrocarbons in crude oils and refined products are biodegradable. Petroleum hydrocarbon compounds bind to soil components and are difficult to remove and degrade. Bioemulsifiers can emulsify hydrocarbons enhancing their water solubility and increasing the displacement of oily substances from soil particles. For these reasons, inclusion of bioemulsifiers in a bioremediation treatment of a hydrocarbon polluted environment could be really advantageous. There is a useful diversity of bioemulsifiers due to the wide variety of producer microorganisms. Also their chemical compositions and functional properties can be strongly influenced by environmental conditions. The effectiveness of the bioemulsifiers as biostimulating agent in oil bioremediation processes has been demonstrated by several authors in different experimental assays. For example, they have shown to be really efficient in combination with other products frequently used in oil bioremediation such as they are inorganic fertilizer (NPK) and oleophilic fertilizer (i.e. S200C). On the other hand, the bioemulsifiers have shown to be more efficient in the treatment of soil with high percentage of clay. Finally, it has been proved their efficacy in other biotechnological processes such as in situ treatment and biopiles. This paper reviews literature concerning the application of bioemulsifiers in the bioremediation of soil polluted with hydrocarbons, and summarizes aspects of the current knowledge about their industrial application in bioremediation processes.

Ochrobactrum anthropi strain AD2 was isolated from the waste water treatment plant of an oil refinery and was identified by analysis of the sequence of the gene encoding 16S rDNA. This bacterium produced exopolysaccharides in glucose nutrient broth media supplemented with various hydrocarbons (n-octane, mineral light and heavy oils and crude oils). The exopolysaccharide AD2 (EPS emulsifier) synthesized showed a wide range of emulsifying activity but none of them had surfactant activity. Yield production varied from 0.47 to 0.94 g of EPS l(-1) depending on the hydrocarbon added. In the same way, chemical composition and emulsification activity of EPS emulsifier varied with the culture conditions. Efficiency of the EPS emulsifier as biostimulating agent was assayed in soil microcosms and experimental biopiles. The AD2 biopolymer was added alone or combined with commercial products frequently used in oil bioremediation such as inorganic NPK fertilizer and oleophilic fertilizer (S200 C). Also, its efficiency was tested in mixture with activated sludge from an oil refinery. In soil microcosms supplemented with S200 C+EPS emulsifier as combined treatment, indigenous microbial populations as well as hydrocarbon degradation was enhanced when compared with microcosms treated with NPK fertilizer or EPS emulsifier alone. In the same way EPS emulsifier stimulated the bioremediation effect of S200 C product, increasing the number of bacteria and decreasing the amount of hydrocarbon remained. Finally, similar effects were obtained in biopile assays amended with EPS emulsifier plus activated sludge. Our results suggest that the bioemulsifier EPS emulsifier has interesting properties for its application in environment polluted with oil hydrocarbon compounds and may be useful for bioremediation purposes.