Bioremediation Of Hydrocarbon-contaminated Soil Research Articles

Phylogenomic analysis of the genus Delftia reveals distinct major lineages with ecological specializations.

Delftia is a diverse betaproteobacterial genus with many strains having agricultural and industrial relevance, including plant-growth promotion, bioremediation of hydrocarbon-contaminated soils, and heavy metal immobilization. Delftia spp. are broadly distributed in the environment, and have been isolated from plant hosts as well as healthy and diseased animal hosts, yet the genetic basis of this ecological versatility has not been characterized. Here, we present a phylogenomic comparison of published Delftia genomes and show that the genus is divided into two well-supported clades: one 'Delftia acidovorans' clade with isolates from soils and plant rhizospheres, and a second 'Delftia lacustris and Delftia tsuruhatensis' clade with isolates from humans and sludge. The pan-genome inferred from 61 Delftia genomes contained over 28 000 genes, of which only 884 were found in all genomes. Analysis of industrially relevant functions highlighted the ecological versatility of Delftia and supported their role as generalists.

Evaluation of the lipase from castor bean (Ricinus Communis L.) as a potential agent for the remediation of used lubricating oil contaminated soils.

Bioremediation of hydrocarbons-contaminated soils, using enzymes, is considered an alternative technology for soil remediation, obtaining shorter remediation times, greater removal efficiencies, and less waste generation. The lipases from invasive plants such as castor bean (Ricinus Communis L.) could represent an opportunity for its application in this purpose. This paper reports the results of evaluating enzymatic treatment at different conditions for the remediation of used lubricating oil-contaminated soils. Four assays were performed for the removal of the contaminant in a soil sample: (1) natural attenuation and (2) biostimulation with urea (10% w/v), both used as blanks, (3) enzymatic treatment with lipases at ambient conditions (room temperature, soil pH) and (4) enzymatic treatment with lipases at ideal conditions (temperature 37°C, pH 4.5). After seven weeks of treatment, removal percentages of 14.23 ± 1.92%, 35.71 ± 5.17%, 14.11 ± 6.71%, and 94.26 ± 1.91%, respectively, were obtained. The degradation of the contaminant was analyzed by Fourier-transform Infrared spectroscopy (FTIR) for each assay. Results show the potential of the lipases for catalyzing the degradation of this contaminant in the soil at ideal conditions, representing an alternative technology to be applied as treatment ex-situ. This paper is the first study known to show the utilization of castor bean lipase for the remediation of hydrocarbons-contaminated soils.

Advances in bioremediation of hydrocarbon-contaminated soil

With continuous improvement of people's living standards, great efforts have been paid to environmental protection. Among those environmental issues, soil contamination by petroleum hydrocarbons has received widespread concerns due to the persistence and the degradation difficulty of the pollutants. Among the various remediation technologies, in-situ microbial remediation enhancement technologies have become the current hotspot because of its low cost, environmental friendliness, and in-situ availability. This review summarizes several in-situ microbial remediation technologies such as bioaugmentation, biostimulation, and integrated remediation, as well as their engineering applications, providing references for the selection of in-situ bioremediation technologies in engineering applications. Moreover, this review discusses future research directions in this area.

Bioremediation of hydrocarbon-contaminated soil from Carlini Station, Antarctica: effectiveness of different nutrient sources as biostimulation agents

Logistics and scientific activities carried out in Antarctic stations entail the risk of contamination by fuels. Among remediation strategies, biostimulation significantly improves the efficiency of hydrocarbons (HCs) removal. A 1-year-long field trial was performed in mesocosms filled with soil chronically contaminated with HCs. Three nutrient sources were evaluated as biostimulation agents: inorganic salts (with and without aeration by mixing), a slow-release granular fertilizer (Nitrofoska®) and a commercial bioremediation product (OSEII®). Their performance was assessed considering the number of culturable bacteria, the changes induced in the structure of bacterial communities, the HCs removal efficiencies and the estimation of the abiotic and biodegradative losses of HCs. The soil indigenous microbiota reduced the concentration of hydrocarbons by up to 50% in 50 days and 87% in 365 days depending on the biostimulation agent used. OSEII® (a mixture of surfactants, nutrients, and enzymes) performed better in the medium term, promoting bacterial growth and rapidly inducing changes in the structure of bacterial community, and Nitrofoska® proved to be more efficient for long-term processes, less affecting the size and structure of the microbiota. A mixed strategy combining the fastest action of commercial products acting during summer with slow-release fertilizers acting throughout the year is proposed as a long-term bioremediation treatment for Antarctic areas where the temperature rises above the freezing point and the ground is free of snow shortly during summer. This study highlights the importance of conducting research to develop remediation processes compatible with the Antarctic Treaty, exploiting the metabolic potential of the indigenous microbiota.

Surfactant addition in diesel oil degradation \u2013 how can it help the microbes?

PurposeDespite wide research on bioremediation of hydrocarbon-contaminated soil, the mechanisms of surfactant-enhanced bioavailability of the contaminants are still unclear. The presented study was focused on the in-depth description of relationships between hydrocarbons, bacteria, and surfactants. In order to that, the biodegradation experiments and cell viability measurements were conducted, and the properties of cell surface were characterized.MethodsMTT assay was employed to measure plant extracts toxicity to microbes. Then, membrane permeability changes were evaluated, followed by diesel oil biodegradation in the presence of surfactants measurements by GCxGC-TOFMS and PCR-RAPD analysis.ResultsOur study undoubtedly proves that different surfactants promote assimilation of different groups of hydrocarbons and modify cell surface properties in different ways. Increased biodegradation of diesel oil was observed when cultures with Acinetobacter calcoaceticus M1B were supplemented with Saponaria officinalis and Verbascum nigrum extracts. Interestingly, these surfactants exhibit different influences on cell surface properties and their viability in contrast to the other surfactants. Moreover, the preliminary analyses have shown changes in the genome caused by exposure to surfactants.ConclusionsThe results indicated that the benefits of surfactant use may be related to deep modification at the omics level, not only that of cell surface properties and confirms the complexity of the interactions between bacterial cells, pollutants and surfactants.

Eco-Friendly Bioemulsifier Production by Mucor circinelloides UCP0001 Isolated from Mangrove Sediments Using Renewable Substrates for Environmental Applications.

The successful production of a biosurfactant is dependent on the development of processes using low cost raw materials. In the present work, an economically attractive medium composed of corn steep liquor and waste cooking oil was formulated to maximize the production of bioemulsifier by Mucor circinelloides UCP0001. A central rotational composite design was applied to statistical validation of the production. The emulsifying properties, stability under extreme conditions, its toxicity character, and the characterization of the bioemulsifier were determined. The best condition for biomolecule synthesis occurred in the assay 2 containing 4% of corn steep liquor and 3% waste soybean oil and exhibited 100% emulsification index for canola oil and petroleum, as well as excellent emulsifying activity for canola oil and burned engine oil. The nutritional factors studied showed statistical relevance, since all linear, quadratic effects and their interactions were significant. The bioemulsifier showed 2.69 g/L yield and the chemical character of the molecule structure was identified by FT-IR (Fourier Transform Infrared) spectroscopy. The bioemulsifier showed no toxicity to Artemia salina and Chlorella vulgaris. Stable emulsions were obtained under extreme conditions of temperature, pH, and salinity. These findings contribute to understanding of the relationship between production, physical properties, chemical composition, and stability of bioemulsifier for their potential applications in biotechnology, such as bioremediation of hydrocarbon-contaminated soil and water.

Rhamnolipid production using Shewanella seohaensis BS18 and evaluation of its efficiency along with phytoremediation and bioaugmentation for bioremediation of hydrocarbon contaminated soils

This study reports the combined use of a rhamnolipid type biosurfactant (BS) along with phytoremediation and bioaugmentation (BA) for bioremediation of hydrocarbon-contaminated soils. Bacterial isolates obtained from hydrocarbon contaminated soil were screened for rhamnolipid production and isolate BS18, identified as Shewanella seohaensis, was selected for bioremediation experiments. Growth of BS18 in mineral salt medium (MSM) with diesel oil as the carbon source showed a maximum biomass of 8.2 g L−1, rhamnolipid production of 2.2 mg g−1 cell dry weight, surface tension reduction of 28.6 mN/m and emulsification potential (EI24%) of 65.6. Characterization of rhamnolipid based on Fourier transmittance infrared (FTIR) analysis confirmed the presence of OH, CH2/CH3, C=O, and COO stretching vibrations, respectively, which are distinctive features of rhamnolipid type BSs. In bioremediation experiments, the lowest hydrocarbon concentration of 2.1 mg g−1 of soil for non-sterilized soil and 4.3 mg g−1 of soil for sterilized soil was recorded in the combined application of rhamnolipid, phytoremediation, and BA. This treatment also yielded the highest hydrocarbon degrading bacterial population (6.4 Log Cfu g−1 of soil), highest plant biomass (8.3 g dry weight plant−1), and the highest hydrocarbon uptake (512.3 mg Kg−1 of plant).

Stable bioemulsifiers are produced by Acinetobacter bouvetii UAM25 growing in different carbon sources.

Acinetobacter species are identified as producing surface-active and emulsifying molecules known as bioemulsifiers. Production, characterization and stability of bioemulsifiers produced by Acinetobacter bouvetii UAM25 were studied. A. bouvetii UAM25 grew in three different carbon and energy sources: ethanol, a glycerol-hexadecane mixture and waste cooking oil in an airlift bioreactor, showing that bioemulsifier production was growth associated. The three purified bioemulsifiers were lipo-heteropolysaccharides of high molecular weight (4866 ± 533 and 462 ± 101kDa). The best carbon source and energy for bioemulsifier production was wasted cooking oil, with a highest emulsifying capacity (76.2 ± 3.5EUmg-1) as compared with ethanol (46.6 ± 7.1EUmg-1) and the glycerol-hexadecane mixture (49.5 ± 4.2EUmg-1). The three bioemulsifiers in our study displayed similar macromolecular structures, regardless of the nature (hydrophobic or hydrophilic) of the carbon and energy source. Bioemulsifiers did not decrease surface tension, but the emulsifying capacity of all of them was retained under extreme variation in salinity (0-50gNaClL-1), pH (3-10) and temperature (25-121°C), indicative of remarkable stability. These findings contribute to understanding of the relationship between: production, physical properties, chemical composition and stability of bioemulsifiers for their potential applications in biotechnology, such as bioremediation of hydrocarbon-contaminated soil and water.

Bioremediation of hydrocarbon-contaminated soils in cold regions: Development of a pre-optimized biostimulation biopile-scale field assay in Antarctica

Bioremediation proved to be an effective approach to deal with soil contamination, especially in isolated, cold environments such as Antarctica. Biostimulation, involving the addition of macronutrients -mainly nitrogen and phosphorous- is considered the simplest and cheapest bioremediation process. Optimizing the levels of these nutrients is a key step prior to the application of a biostimulation strategy. In this work, N and P levels, optimized by Response Surface Methodology (RSM) at lab-scale, were applied to an Antarctic hydrocarbon contaminated soil. The process was performed on-site, using high density polyethylene geomembranes (800μm) to isolate treated soil from the surroundings and under environmental conditions at Carlini station (Antarctica) during 50days. Two 0.5ton biopiles were used as experimental units; a control biopile (CC), and a biostimulated system (BS), amended with N and P. At the end of the assay, hydrocarbon removal was significantly higher in BS system compared to CC (75.79% and 49.54% respectively), showing that the applied strategy was effective enough to perform a field-assay in Antarctica that significantly reduce soil contamination levels; and proving that RSM represents a fundamental tool for the optimization of nutrient levels to apply during bioremediation of fuel contaminated cold soils.

R-strategist versus K-strategist for the application in bioremediation of hydrocarbon-contaminated soils

A laboratory study was undertaken to determine the degradative potentials of the pure bacterial strains Mycobacterium frederiksbergense IN53 (Actinobacteria, a K-strategist) and Acinetobacter sp. IN47 (Gammaproteobacteria, an r-strategist) as well as a combination of these strains under harsh environmental conditions (high hydrocarbon load: 50,883 and 46,682 mg kg−1 dry weight of soil for non-sterile and sterile soil samples, respectively; moisture content lower than 20%). A decrease in total petroleum hydrocarbons (TPH) and the activity of soil enzymes (dehydrogenase and lipase) indicated that the effects of M. frederiksbergense IN53 and the consortium were equivalent. However, these two microbial treatments showed significantly better degradative actions than Acinetobacter sp. IN47. Similar biodegradation yields were observed in sterile and non-sterile soil samples. These results suggest that bioaugmentation with M. frederiksbergense IN53 (K-strategist) provides a better approach for the treatment of hydrocarbon-contaminated sites in which the optimum remediation bioprocess conditions are difficult to maintain.

Optimization of Fermentation Medium and Culture Conditions of Hydrocarbon-Degrading Bacterium <i>Brevibacillus panacihumi</i> W25

Members belonging to the genus Brevibacillus had potentials in the bioremediation of hydrocarbon-contaminated soils. However, little is known about the fermentation medium and culture conditions of Brevibacillus panacihumi. The effect of concentrations of glucose and (NH4)2SO4, initial pH value and culture temperature on the biomass of B. panacihumi W25 was measured with single factor experiments, which was a hydrocarbon-degrading bacterium. Polynomial regression analysis showed optimal concentration of glucose and (NH4)2SO4, initial pH value and culture temperature were 45.2 g/L, 0.6 g/L, pH 7.3 and 30.3°C, respectively. The optimization of fermentation of B. panacihumi was reported for the first time.

A feasibility study on the bioremediation of hydrocarbon-contaminated soil from an Alpine former military site: Effects of temperature and biostimulation

A laboratory feasibility study on the bioremediation of hydrocarbon-contaminated soil from an Alpine former military site was conducted over a period of 30weeks. We determined the effects of temperature (10°C and 20°C) and of various biostimulation treatments (inorganic nitrogen–phosphorus–potassium fertilization and the two commercial products Inipol EAP22 and Terramend) versus natural attenuation on the loss of total petroleum hydrocarbons (TPH), microbial activity (soil respiration) and community composition (phospholipid fatty acids, PLFA). The hydrocarbon contamination was removed almost completely (up to 92.7%) at 20°C, while at 10°C losses up to 69% were obtained. Biostimulation by the addition of nutrients had a significantly stimulating effect on the biodegradation activity of the indigenous soil microorganisms; however, a considerable amount of hydrocarbon loss could be attributed to natural attenuation. Shifts in microbial community composition during bioremediation included the significant increase of soil fungi at 10°C and of Gram-negative soil bacteria at 20°C. Significantly positive correlations between hydrocarbon loss, soil respiration and patterns of phospholipid fatty acids demonstrated the involvement of a wide range of soil microorganisms (Gram-positive and Gram-negative bacteria, fungi) in the bioremediation of the investigated soil.

Persistence and degrading activity of free and immobilised allochthonous bacteria during bioremediation of hydrocarbon-contaminated soils

Rhodococcus sp. and Pseudomonas sp. bioremediation experiments were carried out using free and immobilized cells on natural carrier material (corncob powder) in order to evaluate the feasibility of its use in the bioremediation of hydrocarbon-contaminated soils. Terminal restriction fragment length polymorphism analysis was performed on the 16S rRNA gene as molecular fingerprinting method in order to assess the persistence of inoculated strains in the soil over time. Immobilized Pseudomonas cells degraded hydrocarbons more efficiently in the short term compared to the free ones. Immobilization seemed also to increase cell growth and stability in the soil. Free and immobilized Rhodococcus cells showed comparable degradation percentages, probably due to the peculiarity of Rhodococcus cells to aggregate into irregular clusters in the presence of hydrocarbons as sole carbon source. It is likely that the cells were not properly adsorbed on the porous matrix as a result of the small size of its pores. When Rhodococcus and Pseudomonas cells were co-immobilized on the matrix, a competition established between the two strains, that probably ended in the exclusion of Pseudomonas cells from the pores. The organic matrix might act as protective agent, but it also possibly limited cell density. Nevertheless, when the cells were properly adsorbed on the porous matrix, the immobilization became a suitable bioremediation strategy.

DETECTION OF HYDROCARBON DEGRADING THERMOPHILIC BACTERIA USING MOLECULAR BIOLOGY TECHNIQUES AND POSSIBLE USES IN ACCELERATED HYDROCARBON BIOREMEDIATION

ABSTRACT During the past two years we have established that thermophilic bacteria belonging to the genus Geobacillus exist in large numbers in otherwise cool soil environments. These thermophiles have a growth range of 40–80°C and can be found in soils in high numbers (104 colony forming units (CFU)/g). These thermophilic geobacilli have a rapid growth rate with doubling times between 20–30 minutes at 65–70°C on nutrient broth and most have a wide rang ability to degrade hydrocarbons including aromatic molecules. This suggested that they could play a role in the attenuation of hydrocarbon-contaminated soils. To assess their activity in situ, molecular biology techniques were employed firstly though designing a taxon specific forward PCR primer (THERM) to detect the geobacilli and secondly through targeting the alkane monooxygenase (alkB) gene expression. A reverse transcriptase PCR experiment established that the alkane monooxygenase activity in pure cultures of Geobacillus are only inducible when they are grown at temperatures >40°C in the presence of alkane. Similarly soil microcosms spiked with alkane only gave the alkB RT PCR product when incubated at temperatures above 40°C. Mixed sequences of the alkB gene fragment were detected in soil and appear to belong to numerous thermophilic rather than mesophilic bacteria. We believe these thermophilic geobacilli may have a significant role in hydrocarbon biodegradation at elevated temperatures and may be utilized for bioremediation of hydrocarbon-contaminated soils.

The use of biological activities to monitor the removal of fuel contaminants—perspective for monitoring hydrocarbon contamination: a review

Soil biological activities are vital for the restoration of soil contaminated with hydrocarbons. Their role includes the biotransformation of petroleum compounds into harmless compounds. In this paper, the use of biological activities as potential monitoring tools or bioindicators during bioremediation of hydrocarbon-contaminated soil are reviewed. The use of biological activities as bioindicators of hydrocarbon removal in soil has been reported with variable success. This variability can be attributed partially to the spatial variability of soil properties, which undoubtedly plays a role in the exposure of organisms to contaminants. Widely used bioindicators have been enzyme activities, seed germination, earthworm survival and microorganisms or microbial bioluminescence. A mixture of some successful utilization of biological activities and several failures, and inconsistencies reported, show that at this stage there is no general guarantee of successful utilization of biological activities as monitoring tools. Wherever possible, the use of biological activities as bioindicators of hydrocarbon removal must be used to complement existing traditional monitoring tools.

Identification and assessment of contaminated sites at Casey Station, Wilkes Land, Antarctica

AbstractIn December 1993 a study of contaminated sites at Casey Station, Wilkes Land, Antarctica, was undertaken. The preliminary assessment of these contaminated sites is presented here. A register of contaminated sites for Casey Station was developed, based on a survey of past Antarctic expeditioners, relevant literature, and in-house reports relating to site usage and history. On this basis a sampling strategy was devised for the highest priority, potentially contaminated sites at Casey Station. Samples were collected from the refuse disposal site (tip site) at Thala Valley and the mechanical workshop/powerhouse areas of ‘Old’ Casey. The results indicated that copper, lead, and zinc were leaching from the tip site into adjacent Brown Bay, with ‘hot spots’ of high petroleum hydrocarbon levels. The mechanical workshop/powerhouse area was also shown to be contaminated with petroleum hydrocarbons, polycyclic aromatic hydrocarbons, and metals such as copper, lead, and zinc. Several recommendations were made, including the removal of rubbish mixed with soil at the bottom end of Thala Valley in such a manner as to prevent any further release of contaminants, with subsequent site monitoring to verify effective removal of contaminants to acceptable environmental levels. It was also recommended that further investigations be carried out on the ecosystem of Brown Bay, the large fuel spill site, the upper and lower fuel-storage areas, and the area around the incinerator. There is scope for monitoring the natural breakdown and migration of contaminants at the mechanical workshop/powerhouse site. This should include studies on bioremediation of hydrocarbon-contaminated soils. Mechanisms for arresting surface migration should be investigated in those sites identified. In addition to meeting some of the international obligations of the Protocol on Environmental Protection to the Antarctic Treaty, this work also contributes towards the development of an approach to assessment and management of contaminated sites that is uniquely adapted to the Antarctic environment and could be applied at other Antarctic stations. to the assessment and management of contaminated sites that is uniquely adapted to the Antarctic environment. This approach could be utilised for site assessments at other Antarctic stations.

Enhancing Biodegradation of Petroleum Hydrocarbons with Guanidinium Fatty Acids

Bioremediation of hydrocarbon-contaminated soils is an attractive process for treating contaminated soils because it converts contaminants into harmless byproducts at low cost. However, the process is slow and typically requires months to years to reach regulated end points. In laboratory studies, we have been able to improve the process by adding selected guanidinium fatty acids to the contaminated soils. One of these materials, guanidinium cocoate, was synthesized from coconut acid and guanidine carbonate in a facile one-step process. Rates of biodegradation enhancement of nonvolatile hydrocarbons were evaluated using either oxygen and carbon dioxide respirometry in soil slurries or periodic measurements of extractable hydrocarbon residues in unsaturated soil microcosms. Results show rate enhancements in both soil slurries and unsaturated soil microcosms when these systems were treated with 500−1500 ppm of the surfactant. Adding small amounts of CGS to a silty clay soil containing aged lubricant-type hydrocarbons increased rates of hydrocarbon disappearance, mineralization, and oxygen utilization in unsaturated soil and soil slurry systems. Based on these initial investigations, doses of approximately 2 lb of CGS/t of soil appear effective at increasing rates of biodegradation.