Oil-degrading Bacteria Research Articles

Biodegradation kinetics of petroleum hydrocarbons by composite microbial agents combined with slow release agents in groundwater

Bioremediation of oil-polluted groundwater is often limited by the properties of oil and oligotrophic conditions in the groundwater environment, sometimes causing long biodegradation times and low biodegradation efficiencies. To clarify this issue, dominant oil-degrading bacteria and slow release agents (SRAs) were prepared and mixed to enhance the biodegradation of different oil samples and hydrocarbons in the groundwater environment. The biodegradation efficiencies of diesel oil, Venezuelan crude oil, and Jibei heavy crude oil by the consortia of bacteria increased from 33.66 %–52.21 % to 34.90 %–63.43 % when optimal nitrogen (N) and phosphorus (P) nutrients were added with SRAs. The release kinetics of N and P SRAs (NP-SRAs) followed Fickian diffusion, and the biodegradation processes of the five petroleum hydrocarbons and three oil products were all well approximated by a second-order kinetic model. The half-lives of the five hydrocarbons in the groundwater were shortened from 0.01 to 7.46 d with the NP salt directly added to 0.002–6.67 d when the NP-SRAs and oxygen SRAs were added, and they decreased from 4.85 to 34.00 d to 2.80–28.90 d for the three oil samples. This study provides insights into the biodegradation kinetics of different hydrocarbons, facilitating the development of effective microbial remediation technologies for the oil contaminated groundwater environment.

Chronic Exposure to Petroleum-Derived Hydrocarbons Alters Human Skin Microbiome and Metabolome Profiles: A Pilot Study.

Petroleum-derived substances, like industrial oils and grease, are ubiquitous in our daily lives. Comprised of petroleum hydrocarbons (PH), these substances can come into contact with our skin, potentially causing molecular disruptions and contributing to the development of chronic disease. In this pilot study, we employed mass spectrometry-based untargeted metabolomics and 16S rRNA gene sequencing analyses to explore these effects. Superficial skin samples were collected from subjects with and without chronic dermal exposure to PH at two anatomical sites: the fingers (referred to as the hand) and arms (serving as an intersubject variability control). Exposed hands exhibited higher bacterial diversity (Shannon and Simpson indices) and an enrichment of oil-degrading bacteria (ODB), including Dietzia, Paracoccus, and Kocuria. Functional prediction suggested enriched pathways associated with PH degradation in exposed hands vs non-exposed hands, while no differences were observed when comparing the arms. Furthermore, carboxylic acids, glycerophospholipids, organooxygen compounds, phenol ethers, among others, were found to be more abundant in exposed hands. We observed positive correlations among multiple ODB and xenobiotics, suggesting a chemical remodeling of the skin favorable for ODB thriving. Overall, our study offers insights into the complex dysregulation of bacterial communities and the chemical milieu induced by chronic dermal exposure to PH.

Enhanced degradation of crude oil by immobilized bacterial consortium through eliminating microbial flocculation towards crude oil

Microbial degradation is considered an effective and sustainable technique for the remediation of oily sludge; thus, the acquisition of crude oil-degrading bacteria is crucial for effective bioremediation. This study introduces a novel domestication-enrichment-isolation (DEI) strategy to isolate crude oil-degrading bacteria from oily sludge. Two strains, Rhodococcus rhodochrous JS-24 (R.rh) and Gordonia cholesterolivorans JS-13 (G.ch), demonstrated the highest degradation rates of 53.7% and 34.6%, respectively, within 7 days. While no synergistic effect was observed with their combined use in free bacterial consortia, and the overall degradation rate decreased to 51.9 %, which was weaker than that of R. rh treatment alone. The decrease in degradation rate is attributed to microbial flocculation towards crude oil: most droplets of crude oil were encapsulated into spherical aggregations by G. ch, thereby hindering the contact and degradation of droplets by R. rh. In contrast, immobilization technology significantly enhanced crude oil degradation by eliminating this flocculation effect. The immobilized bacterial consortium achieved a 95.5% degradation rate, representing the highest degradation rate reported for bacterial consortia. This study reveals for the first time that the side effects of bioflocculation on crude oil degradation and provides guidance for the construction of bacterial consortium.

The effects of high-precision scale dispersant concentrations on microbial community and new implications for dispersant application after marine oil spills

The usage of dispersant presents a difficult choice: the uncertainty of beneficial biodegradation of spilled oil against what could be a greater environmental impact from the finely dispersed oil. Here, we evaluated the effect of dispersant on the microbial community at a high-precision concentration (0.1–20 % (v/v), 10 gradients) to elucidate the uncertainty of beneficial biodegradation and proposed the associated mechanism. Results at the phylum, class, and genus level revealed no significant changes in microbial diversity and structure at low-concentration dispersants (0.1–3 %), but significant changes at high-concentration dispersants (5–20 %). For beneficial biodegradation, 4 oil-degrading bacteria and 3 non-oil-degrading bacteria exhibited strong positive (R2 > 0.72) and negative (R2 > 0.73) correlations at 0.1–3 % low-concentrations. More importantly, oil-degrading bacteria abundance exceeded 75.9 % in the total abundance proportion (70.1 %) of them. This indicated low-concentration dispersants can promote biodegradation. In the high-concentrations, similar but opposite results were shown. Therefore, dispersant concentration dominates biodegradation of spilled oil. Finally, we proposed the associated “bacterial peaking” mechanism and clarified that biodegradation increases under the drive of the affected bacteria and reach a peak at low-concentration dispersants, but decline rapidly at high-concentrations. This study provided a new insight to understand the usage of dispersant on biodegradation of spilled oil in the sea.

Isolation of biosurfactant-producing and crude oil-degrading bacterium, Enterococcus hirae, from hydrocarbon-polluted soils and characterization of the biosurfactant produced

Isolation of biosurfactant-producing and crude oil-degrading bacterium, Enterococcus hirae, from hydrocarbon-polluted soils and characterization of the biosurfactant produced

Molecular identification of rhamnolipids produced by Pseudomonas oryzihabitans during biodegradation of crude oil.

The ability to produce biosurfactants plays a meaningful role in the bioavailability of crude oil hydrocarbons and the bioremediation efficiency of crude oil-degrading bacteria. This study aimed to characterize the produced biosurfactants by Pseudomonas oryzihabitans during the biodegradation of crude oil hydrocarbons. The biosurfactants were isolated and then characterized by Fourier transform infrared (FTIR), liquid chromatography-mass-spectrometry (LC-MS), and nuclear magnetic resonance spectroscopy (NMR) analyses. The FTIR results revealed the existence of hydroxyl, carboxyl, and methoxyl groups in the isolated biosurfactants. Also, the LC-MS analysis demonstrated a main di-rhamnolipid (l-rhamnopyranosyll-rhamnopyranosyl-3-hydroxydecanoyl-3-hydroxydecanoate, Rha-Rha-C10-C10) along with a mono-rhamnolipid (l-rhamnopyranosyl-b-hydroxydecanoylb-hydroxydecanoate, Rha-C10-C10). In agreement with these findings, the NMR analysis confirmed the aromatic, carboxylic, methyl, sulfate moieties, and hexose sugar in the biosurfactants. The emulsion capacity of the biosurfactants decreased the surface tension of the aqueous system from 73.4 mN m-1 to around 33 mN m-1 at 200 mg L-1 as the critical micelle concentration. The emulsification capacity of the biosurfactants in the formation of a stable microemulsion for the diesel-water system at a wide range of pH (2-12), temperature (0-80°C), and salinity (2-20 g L-1 of NaCl) showed their potential use in oil recovery and bioremediation through the use of microbial enhancement. This work showed the ability of Pseudomonas oryzihabitans NC392 cells to produce rhamnolipid molecules during the biodegradation process of crude oil hydrocarbons. These biosurfactants have potential in bioremediation studies as eco-friendly and biodegradable products, and their stability makes them optimal for areas with extreme conditions.

Compositional change of bacterial communities in oil-polluted seawater amid varying degrees of nanoplankton bacterivory

Petroleum hydrocarbons are being released into the marine environment continuously. They will undergo weathering and may eventually be biodegraded by bacteria and other microbes. While nanoplankton (2–20 μm) are the major consumers of marine bacteria, their effect on the process of biodegradation of oil hydrocarbons is still debated. A 14-day microcosm experiment was conducted to investigate the effects of crude oil hydrocarbons on nanoplankton bacterivory and bacterial community in coastal waters. The coefficients of population growth (0.56–1.80 d−1 for all treatments considered) and grazing mortality (0.38–1.65 d−1 for all treatment considered) of bacteria estimated with the dilution method did not differ among the treatments of control (Ctrl), low dose chemically dispersed oil (LDOil, 2 μL L−1 of crude oil), and high dose chemically dispersed oil (HDOil, 8 μL L−1 of crude oil). Bacterial abundance ranged between 0.21–0.86 × 106 cells mL−1 on average for all treatments. The lack of drastic increases in the cell density of bacterial cells in the oil-loaded treatments was observed throughout the experiment period. Sequencing analysis of the 16S rRNA gene revealed the progressive changes in the community compositions of bacteria in all treatments. The relatively high abundance of oil-degrading bacteria, including Cycloclasticus and Alcanivorax on Days 3–14 of the experiment reflected the presence of biodegradation of oil in the LDOil and HDOil treatments. Throughout the 14 days, the community composition of bacteria in the LDOil and HDOil treatments became more similar and they both differed from that in the Ctrl treatment. This study concluded that, in oil-polluted seawater, the changes in the bacterial community composition were mainly resulting from the addition of chemically dispersed crude oil.

Mechanism of Crude Oil Biodegradation in Bioreactors: A Model Approach

Oil-degrading bacteria have the ability to degrade alkanes present in crude oil because of a special enzymatic system, the alkane hydroxylase complex (AlkH). The mechanism for the transport and degradation of alkanes present in crude oil remains unclear, especially related to the first step in hydrocarbons oxidation. In this work, we present a novel model of the crude oil biodegradation mechanism by considering the contact between the oil drop and the cell and calculating the mass transfer coefficients in three oleophilic bacteria (B. licheniformis, P. putida and P. glucanolyticus). The mass transfer coefficients are evaluated under critical time conditions, when the kinetics and mass transport are in balance, and the difference in the values obtained (kL α = 1.60 × 10−3, 5.25 × 10−4 and 6.19 × 10−4 m/d, respectively) shows the higher value of the mass transfer coefficient and higher biodegradation potential for B. licheniformis. Because the morphology of the cells has been analyzed by optical and electron microscopy, in the proposed model, the increase in the size of the cells in P. glucanolyticus compared to P. putida exhibits higher values of the mass transfer coefficients and this is attributed, as a novel statement, to a bigger window for alkanes transport (contact area) when the external area of the cell is bigger.

Effects of biochar immobilization of Serratia sp. F4 OR414381 on bioremediation of petroleum contamination and bacterial community composition in loess soil

Petroleum hydrocarbons pose a significant threat to human health and the environment. Biochar has increasingly been utilized for soil remediation. This study investigated the potential of biochar immobilization using Serratia sp. F4 OR414381 for the remediation of petroleum-contaminated soil through a pot experiment conducted over 90 days. The treatments in this study, denoted as IMs (maize straw biochar-immobilized Serratia sp. F4), degraded 82.5% of the total petroleum hydrocarbons (TPH), 59.23% of the aromatic, and 90.1% of the saturated hydrocarbon fractions in the loess soils. During remediation, the soil pH values decreased from 8.76 to 7.33, and the oxidation-reduction potential (ORP) increased from 156 to 229 mV. The treatment-maintained soil nutrients of the IMs were 138.94 mg/kg of NO3- -N and 92.47 mg/kg of available phosphorus (AP), as well as 11.29% of moisture content. The activities of soil dehydrogenase (SDHA) and catalase (CAT) respectively increased by 14% and 15 times compared to the CK treatment. Three key petroleum hydrocarbon degradation genes, including CYP450, AJ025, and xylX were upregulated following IMs treatment. Microbial community analysis revealed that a substantial microbial population of 1.01E+ 09 cells/g soil and oil-degrading bacteria such as Salinimicrobium, Saccharibacteria_genera_incertae_sedis, and Brevundimonas were the dominant genera in IMs treatment. This suggests that the biochar immobilized on Serratia sp. F4 OR414381 improves soil physicochemical properties and enhances interactions among microbial populations, presenting a promising and environmentally friendly approach for the stable and efficient remediation of petroleum-contaminated loess soil.

Microbial community response to biostimulation and bioaugmentation in crude oil-polluted sediments of the Persian Gulf

The Persian Gulf is a transit point for a lot of crude oil at the international level. The purpose of this research is to compare two methods of biostimulation and bioaugmentation for degradation of sediments contaminated with crude oil in the Persian Gulf. In this research, six types of microcosms were designed (Sediments from Khark Island). Some indicators such as: the quantity of marine bacteria, enzyme activity (Catalase, Polyphenol oxidase, Dehydrogenase), biodiversity indices and the percentage of crude oil degradation were analyzed during different days (0, 20, 40, 60, 80, 100 and 120). The results of this research showed that the highest quantity of heterotrophic and crude oil-degrading bacteria was found in the sixth microcosm (SB). This microcosm represents a combination of two methods: bioaugmentation and biostimulation (3.9 × 106 CFU g−1). Following crude oil pollution, the activity of catalase and polyphenol oxidase increased and the dehydrogenase enzyme decreased. The bioaugmentation microcosm exhibited the highest activity of enzymes among all the microcosms studied. Predominant bacteria in each microcosm belonged to: Cellulosimicrobium, Shewanella, Alcanivorax and Cobetia. The highest degradation of crude oil is related to the Stimulation-Bioaugmentation microcosm (SB). The statistical results of this research proved that there is a significant relationship between the type of method chosen for biodegradation with the sampling time and the quantity of marine bacteria. The results of this research confirm that crude oil pollution in the Persian Gulf sediments can be reduced by choosing the proper bioremediation method.

An industrially potent rhamnolipid-like biosurfactant produced from a novel oil-degrading bacterium, Bacillus velezensis S2.

Surfactants can reduce the interfacial surface tension between two immiscible liquids making them a desirable component for various industrial applications. However, the toxic nature of chemical surfactants brought immense attention towards biosurfactants. Being biodegradable, biosurfactants are eco-friendly and considered safer for different commercial uses. This study focused on the production of biosurfactant from an oil-degrading bacteria and its functional efficacy for prospective industrial applications. Here, a promising oil-tolerant strain, Bacillus velezensis S2 was isolated from oil contaminated sites which showed >50% degradation of convoluted crude oil within 28 days in comparison to a control. The isolate was then found to produce an excellent surface-active compound with an emulsification index of 67.30 ± 0.8% and could reduce the surface tension up to 36.86 ± 0.36 mN m-1. It also manifested a critical micelle concentration of 45 mg L-1 while reducing the surface tension from 72 to 30 mN m-1. When extracting biosurfactant from isolated bacteria, ethyl acetate extraction showed 1.5 times greater efficacy than chloroform : methanol extraction. The purified biosurfactant was characterized using TLC, 1H NMR, 13C NMR, FTIR, elemental analyses and spectrophotometric techniques leading to its identification as a rhamnolipid. The stability of produced biosurfactant at higher temperature (up to 180 °C) was determined by thermal analysis, endorsing its application in high temperature reservoir conditions. Additionally, the extracted biosurfactant showed excellent foaming efficacy with insignificant antibacterial and cytotoxic responses, which indicates their potential application in cleaning and cosmetics industries. Thus, the present study outlines a bi-functional novel isolate Bacillus velezensis S2 which could play a significant role in oil remediation from the environment as well as serve as a potential source of non-toxic and eco-friendly biosurfactants for various industrial applications.

Synergistic dispersion and biodegradation of oil in seawater based on Janus nanosheets and oil-degrading bacteria

Janus nanosheets synergistically interact with oil-degrading bacteria for marine oil spill remediation.

Assessment of Biostimulation and Bioaugmentation on Crude Oil-Polluted Sediments Microbial Community of Persian Gulf: A Microcosm Simulation Study

The Persian Gulf is a transit point for a lot of crude oil at the international level. The purpose of this research is to compare two methods of biostimulation and bioaugmentation for degradation of sediments contaminated with crude oil in the Persian Gulf. In this research, six types of microcosms were designed (sediments of Khark Island). Some indicators, such as the quantity of marine bacteria, enzyme activity (catalase, polyphenol oxidase, and dehydrogenase), biodiversity indices, and the percentage of crude oil degradation were analyzed during different days (0, 20, 40, 60, 80, 100 and 120). The results of this research showed that the highest quantity of heterotrophic and crude oil-degrading bacteria to the sixth microcosm (stimulation–bioaugmentation), a combination of two methods bioaugmentation and biostimulation (3.9 × 106 CFU g−1). After crude oil pollution, the activity of catalase and polyphenol oxidase increased, and the dehydrogenase enzyme decreased. Bioaugmentation microcosm has the highest activity of enzymes among all studied microcosms. Predominant bacteria in each microcosm belonged to Cellulosimicrobium, Shewanella, Alcanivorax, and Cobetia. The highest degradation of crude oil is related to the stimulation–bioaugmentation microcosm. The statistical results of this research proved that there is a significant relationship between the type of method chosen for biodegradation with the sampling time and the quantity of marine bacteria. The results of this research confirm that crude oil pollution in the Persian Gulf sediments can be reduced by choosing the proper bioremediation method.

Petroleum hydrocarbon degradation of husk biochar product carrying biofilm-forming bacteria

Environmental pollution problems caused by petroleum and its derivatives such as polycyclic aromatic hydrocarbons (PAHs) has remarkably increased and become a major global threat to human health and ecological equilibrium, resulting in a crucial need for remediation. Recently, in order to solve this problem, biofilm is one of the biodegradation approaches which could degrade and transform oil components effectively. Moreover, to enhance the petroleum hydrocarbons removal efficiency and easy to apply in any place bio-carriers, biochar was used to attach biofilm-forming microorganisms. Biochar is not only used as a carrier for microorganisms but also a source of substrates to help absorb a part of aromatic compounds. Therefore, in this investigation, we used the mixture of multiple petroleum-degrading and biofilm-forming bacterial strains immobilized on husk biochar to create an oil-degrading product. The ability of oil-degrading bacteria immobilized on biochar, planktonic bacteria and biochar without bacteria on the elimination of total petroleum hydrocarbons and several aromatic hydrocarbons was investigated. The results indicated that using husk biochar as a carrier for biofilm-forming bacteria to attach on could considerably enhance the removal efficiency of oil components. At 50 kg/batch scale, the formed product could remove 99% of total petroleum hydrocarbons with the initial amount of 4.786 mg/l and over 96% of aromatic hydrocarbons including anthracene, naphthalene, phenanthrene and pyrene with the initial amount of 250 mg/l. The obtained product is porous, black, with particle size of 1-3 mm, cell density of ≥ 109 CFU/g(ml), stable for use ≥ 6 months and safe for the environment. In general, the obtained results highpoint the great possible of applying this product in the treatment of oil contaminated soil and water.

Distribution and abundance of oil-degrading bacteria in seawater of the Yellow Sea and Bohai Sea, China

Petroleum hydrocarbons are widespread in seawater. As an important sea area in northern China, the content and distribution of petroleum hydrocarbons in seawater need our attention because of the high toxicity and lasting polluting effects on the ecological environment of the Yellow Sea and Bohai Sea. In addition, there are few reports comparing the diversity of oil-degrading bacteria before and after enrichment. Therefore, we collected surface seawater from 10 sites in the Yellow Sea and Bohai Sea in the autumn of 2020 to study the distribution characteristics of total petroleum hydrocarbons (TPH) and the diversity of oil-degrading bacteria. The concentration of TPH was 81.65 μg/L-139.55 μg/L at ten sites in the Bohai Sea and the Yellow Sea, which conformed to the China Grade II water quality standard (GB3097–1997). Moreover, the pristine/phytane (PR/PH) value of most sites was close to 1, indicating that the area was obviously polluted by exogenous petroleum hydrocarbons. We found that oil-degrading bacteria in the seawater of the Yellow Sea and the Bohai Sea had a good degradation effect on C11-C14 short chain alkanes (degradation rate of 59.19–73.22 %) and C1-C4 phenanthrene (degradation rate of 48.19–60.74 %). In terms of the diversity of oil-degrading bacteria, Gammaproteobacteria and Alphaproteobacteria dominated the enriched bacterial communities. Notably, the relative abundance of Alcanivorax changed significantly before and after enrichment. We proposed that surface seawater in the Bohai Sea and Yellow Sea could form oil-degrading bacteria mainly composed of Alcanivorax, which had great potential for oil pollution remediation.

Remediation of Petroleum-contaminated Soil by Highly Efficient Oil-degrading Bacteria and Analysis of Its Enhancement Mechanism

A 120-day in situ remediation of oil-contaminated soil was carried out by using highly efficient oil-degrading bacteria. The effects of bio-enhanced remediation and changes in soil physicochemical properties and enzyme activities were investigated. Combined with metagenomic sequencing and bioinformatics analysis, the strengthening mechanism was revealed. The results showed that compared with the blank control group (Ctrl), the degradation rate of total petroleum hydrocarbons in the bioremediation group (Exp-BT) was significantly increased, reaching 81.23%. During enhanced bioremediation by highly efficient oil-degrading bacteria, the pH of the soil was stable, the oxidation capacity of the system was improved, and the electrical conductivity was in the range suitable for agricultural activities. Lipase and dehydrogenase maintained high activity during repair. In addition, the analysis of the initial contaminated soil (B0), the highly efficient oil-degrading bacteria obtained from domestication (GZ), and the soil samples after bioremediation (BT) in the obtained samples showed that, at the phylum level, the total proportion of Proteobacteria and Actinobacteria increased by 17.1%. At the genus level, the abundance of Nocardioides, Achromobacter, Gordonia, and Rhodococcus increased significantly. The species and function contribution analysis of COG and KEGG proved that the above bacterial genera had important contributions to the degradation of petroleum hydrocarbons. A high abundance of petroleum hydrocarbon-related metabolic enzymes and five petroleum hydrocarbon-related degradation genes was found in the soil after remediation:alkM, tamA, rubB, ladA, and alkB. The analysis showed that the introduction of the exogenous petroleum hydrocarbon-degrading bacteria group enhanced the metabolic activity of microorganism-related enzymes and the expression of corresponding functional genes.

Genome analysis of a coral-associated bacterial consortium highlights complementary hydrocarbon degradation ability and other beneficial mechanisms for the host

Here we report the oil degradation genetic potential of six oil-degrading bacteria (ODB), previously used as a bioremediation consortium, isolated from the hydrocoral Millepora alcicornis and seawater. The strains were identified as Halomonas sp. (LC_1), Cobetia sp. (LC_6), Pseudoalteromonas shioyasakiensis (LC_2), Halopseudomonas aestusnigri (LC_3), Shewanella algae (LC_4), and Brucella intermedia (LC_5). The taxonomic identification differed from that of the original paper when we used whole genome gene markers instead of just 16S rRNA gene. Genes responsible for the degradation of aromatic hydrocarbons and n-alkanes were found in all genomes, although different (and complementary) steps of the metabolic pathways were unique to each strain. Genes for naphthalene and toluene degradation were found in various strains. We annotated quinate degradation genes in LC_6, while LC_3 and LC_5 presented genes for biosurfactant and rhamnolipid biosynthesis. We also annotated genes related to beneficial mechanisms for corals, such as genes involved in nitrogen and DMSP metabolism, cobalamin biosynthesis and antimicrobial compounds production. Our findings reinforce the importance of using bacterial consortia for bioremediation approaches instead of single strains, due to their complementary genomic arsenals. We also propose a genome-based framework to select complementary ODB that can provide additional benefits to coral health.

Correlating the succession of microbial communities from Nigerian soils to petroleum biodegradation

Whilst biodegradation of different hydrocarbon components has been widely demonstrated to occur by specialist oil-degrading bacteria, less is known about the impact on microbial communities as a function of oil composition by comparing the biodegradation of chemically complex fuels to synthetic products. The objectives of this study were (i) to assess the biodegradation capacity and succession of microbial communities isolated from Nigerian soils in media with crude oil or synthetic oil as sole sources of carbon and energy, and (ii) to assess the temporal variability of the microbial community size. Community profiling was done using 16 S rRNA gene amplicon sequencing (Illumina), and oil profiling using gas chromatography. The biodegradation of natural and synthetic oil differed probably due to the content of sulfur that may interfere with the biodegradation of hydrocarbons. Both alkanes and PAHs in the natural oil were biodegraded faster than in the synthetic oil. Variable community responses were observed during the degradation of alkanes and more simple aromatic compounds, but at later phases of growth they became more homogeneous. The degradation capacity and the size of the community from the more-contaminated soil were higher than those from the less-contaminated soil. Six abundant organisms isolated from the cultures were found to biodegrade oil molecules in pure cultures. Ultimately, this knowledge may contribute to a better understanding of how to improve the biodegradation of crude oil by optimizing culturing conditions through inoculation or bioaugmentation of specific bacteria during ex-situ biodegradation such as biodigesters or landfarming.

In English

The main task and relevance of this work are to develop the most effective sorbents for cleaning oil pollution or accidental oil spills. A generalized criterion for evaluating the effectiveness of a sorbent is the local availability and fast renewability of raw materials for biochar. The features of obtaining biochar from cellulose-containing plant raw materials of corn cobs are described. The effect was studied of the pyrolysis conditions of the selected plant material on the physicochemical properties of biochar, which are responsible for the intermolecular interaction of the sorbent with the adsorbed substance and for immobilization and viability of oil degrading bacteria, which indicates the possibility to control the properties of oil destructive sorbent at the production stage. The optimal mode of carbonization of such raw materials has been worked out to obtain a sorbent with porosity and chemical compatibility with oil-degrading bacteria. Cultural cultivation for immobilization of oil-degrading bacteria was carried out in a nutrient medium and a concentrate was prepared. It is shown that biochar with oil-oxidizing microorganisms fixed on its surface has significant sorption and destructive properties.

Long-term biodegradation of crude oil in high-arctic backshore sediments: The Baffin Island Oil Spill (BIOS) after nearly four decades

With an on-going disproportional warming of the Arctic Ocean and the reduction of the sea ice cover, the risk of an accidental oil spill from ships or future oil exploration is increasing. It is hence important to know how crude oil weathers in this environment and what factors affect oil biodegradation in the Arctic. However, this topic is currently poorly studied. In the 1980s, the Baffin Island Oil Spill (BIOS) project carried out a series of simulated oil spills in the backshore zone of beaches located on Baffin Island in the Canadian High Arctic. In this study two BIOS sites were re-visited, offering the unique opportunity to study the long-term weathering of crude oil under Arctic conditions. Here we show that residual oil remains present at these sites even after almost four decades since the original oiling. Oil at both BIOS sites appears to have attenuated very slowly with estimated loss rates of 1.8–2.7% per year. The presence of residual oil continues to significantly affect sediment microbial communities at the sites as manifested by a significantly decreased diversity, differences in the abundance of microorganisms and an enrichment of putative oil-degrading bacteria in oiled sediments. Reconstructed genomes of putative oil degraders suggest that only a subset is specifically adapted for growth under psychrothermic conditions, further reducing the time for biodegradation during the already short Arctic summers. Altogether, this study shows that crude oil spilled in the Arctic can persist and significantly affect the Arctic ecosystem for a long time, in the order of several decades.