Oil-degrading Bacteria Research Articles

Biodiversity and oil degradation capacity of oil-degrading bacteria isolated from deep-sea hydrothermal sediments of the South Mid-Atlantic Ridge

Studies have reported that various hydrocarbons and hydrocarbon-degrading bacteria are found in global deep-sea hydrothermal regions. However, little is known about degradation characteristics of culturable hydrocarbon-degrading bacteria from these regions. We speculate that these bacteria can be used as resources for the bioremediation of oil pollution. In this study, six oil-degrading consortia were obtained from the hydrothermal region of the Southern Mid-Atlantic Ridge through room-temperature enrichment experiments. The dominant oil-degrading bacteria belonged to Nitratireductor, Pseudonocardia, Brevundimonas and Acinetobacter. More varieties of hydrocarbon-degrading bacteria were obtained from sediments (preserved at 4 °C) near hydrothermal vents. Most strains had the ability to degrade high molecular weight petroleum components. In addition, Pseudonocardia was shown to exhibit a high degradation ability for phytane and pristine for the first time. This study may provide new insights into the community structure and biodiversity of culturable oil-degrading bacteria in deep-sea hydrothermal regions.

Biodegradation of weathered crude oil by microbial communities in solid and melted sea ice

Oil spilled in the Arctic may drift into ice-covered areas and become trapped until the ice melts. To determine if exposure to oil during freezing may have a priming effect on degradation of the oil, weathered dispersed oil (2-3 mg/L) was frozen into solid ice for 200 days at -10 °C, then melted and incubated for 64 days at 4 °C.No degradation was measured in oil frozen into ice prior to melting. Both total amount of oil and target compounds were biotransformed by the microbial community from the melted ice. However, oil released from melted ice was degraded at a slower rate than oil incubated in fresh seawater at the same temperature (4 °C), and by a different microbial community. These data suggest negligible biodegradation of oil frozen in sea ice, while oil-degrading bacteria surviving in the ice may contribute to biodegradation when the ice melts.

Aerobic degradation of oil-based mud drilling fluid by in situ bacteria in the Hawizeh Marshes

The increasing global demand for hydrocarbon has brought new challenges in the petroleum reservoir's drilling process. Non-biodegradable chemical additives are used in drilling fluid and it leads to endangering the environment and personnel safety. Thus, there is a great need for new biodegradable drilling fluid additives that can protect the environment and personal safety while drilling is done well. This study with help of microbial analysis investigates the effects of in situ bacteria to degenerate the gasoline inside the oil-based mud, in the returned lubricant from one of the oil wells next to the Hawizeh Marshes. Four types of bacteria inside the oil-based mud were observed. According to the high growth and degradation of crude oil, one strain was selected. Determination of the coagulase and clumping test shows that the isolated strain belongs to staphylococcus. We investigate the performance of the staphylococcus bacterium on the lubricant from biological degradation aspects, using a gas chromatography technique. It was observed that the exposure of a small amount of the bacteria against 10 mL of lubricant indicates a considerable degree of degeneration, only in a few days. The residual crude oil in the culture medium was analyzed by gas chromatography (GC) and SARA. The results confirmed that the strain can degrade crude oil and produce lighter hydrocarbon. The saturate fraction increased about 23%, while the Resin and Asphaltene fractions decreased about 11% and 12%, respectively. This research is the first report on the characterization of crude oil-degrading bacteria from in situ bacteria at Hawizeh Marsh and by using this bacterium in the field the effect of oil pollution can be reduced on this marsh environment in a few days.

Analyses of community structure and role of immobilized bacteria system in the bioremediation process of diesel pollution seawater

Immobilized bacteria system plays an important role during degradation process in oil contaminated seawater. Although the immobilized bacteria system can be recycled to avoid pollution after remediation, it remains an open question on whether or not the secondary pollution occurs during the degradation process. Additionally, the research on the role of immobilized bacteria system in the process of oil removal is not clear enough. In this study, both the diesel degradation rate of diesel by immobilized bacteria system and changes in marine microbial community structure were determined to explore the role of immobilized bacteria system. The immobilized bacteria system was added to the diesel polluted seawater (1% diesel) for 30 days. The degradation performance was investigated during the process, and the microbial community structure was analyzed simultaneously. The results illustrated that the degradation rate of diesel by immobilized bacteria system reached 78.39% after 30 days, and Alcanivorax (59.09%), Achromobacter (24.34%) and Thalassospira (9.84%) were the dominant genera in the immobilized bacteria system. The addition of immobilized bacteria system increased the content of nitrogen and phosphorus, and then promoted the growth of oil-degrading bacteria. Thus, functional genes related to oil degradation increased. Additionally, there was little difference in the microbial composition between the treated seawater and the unpolluted seawater. Based on all results, it can be inferred that immobilized bacteria system triggered and stimulated diesel degradation process. This study provides a promising way to improve the removal of oil, and provides theoretical support for the wide application of immobilized microorganism technology.

RETRACTED ARTICLE: Management of offshore oil pollution and logistics transportation based on decision tree

Decision tree algorithm is one of the most widely used inductive thinking algorithms in data mining. Its construction does not require any domain knowledge or parameter settings, and it is widely suitable for exploratory knowledge discovery. The decision tree algorithm has clear structure, fast calculation speed, high precision, and higher flexibility and reliability. It can be used to process multidimensional data, and the acquired knowledge is intuitive and easy to understand. Decision tree algorithms are now widely used in medicine, manufacturing, financial analysis, astronomy, molecular biology, and remote sensing image classification. For example, in the field of marine oil pollution, the influence of bacterial flora has been studied through experiments with simulated bar graphs and bio-enhanced seawater oil pollution remediation, environmental parameters, and microbial metabolism have been found to affect the oil diffusion rate at the same time. In the early days, due to the high concentration of microorganisms, the established bacterial colonies that degraded petroleum had a certain degrading ability. As the abundance of microbial communities increases, the benefits of TCOB-4 and TCOB-5 gradually decrease. The oil of TCOB-5 is highly degradable, and may continue to function during the test period, and is compatible with other oil-degrading bacteria. The dominant position. With the rapid development of third-party logistics, logistics profits, the third source of profits, have become a black hole in the entire supply chain. If transportation costs can be reduced, the efficiency of the logistics system can be improved and profits can be maximized. Therefore, studying the decisions of third-party logistics transportation providers has undoubtedly become the top priority of ensuring fast transportation, reducing transportation costs, and conducting effective logistics management research.

Detection of hydrocarbon-degrading bacteria on deepwater corals of the northeast Atlantic using CARD-FISH

Recently, studies have begun to identify oil-degrading bacteria and host-taxon specific bacterial assemblages associated with the coral holobiont, including deep-sea cold-water corals, which are thought to provide metabolic functions and additional carbon sources to their coral hosts. Here, we describe the identification of Marinobacter on the soft tissue of Lophelia pertusa coral polyps by Catalyzed Reporter Deposition Fluorescence in situ Hybridization (CARD-FISH). L. pertusa samples from three reef sites in the northeast Atlantic (Logachev, Mingulay and Pisces) were collected at depth by vacuum seal to eliminate contamination issues. After decalcification, histological processing and sagittal sectioning of the soft coral polyp tissues, the 16S rRNA-targeted oligonucleotide HRP-labelled probe Mrb-0625-a, and Cyanine 3 (Cy3)-labelled tyramides, were used to identify members of the hydrocarbon-degrading genus Marinobacter. Mrb-0625-a-hybridized bacterial cell signals were detected in different anatomical sites of all polyps collected from each of the three reef sites, suggesting a close, possibly intimate, association between them, but the purpose of which remains unknown. We posit that Marinobacter, and possibly other hydrocarbon-degrading bacteria associated with Lophelia, may confer the coral with the ability to cope with toxic levels of hydrocarbons in regions of natural oil seepage and where there is an active oil and gas industry presence.

Rapid capturing of oil-degrading bacteria by engineered attapulgite and their synergistic remediation for oil spill

HypothesisHigh-efficiency dispersion and enhanced biodegradation play important roles in the treatment of oily wastewater. Due to the flaws of chemical surfactants, it is necessary to study the alternative dispersants that are eco-friendly and sustainable. Therefore, applying natural attapulgite (ATP) to coat Brevibacillus parabrevis for dispersion and biodegradation was studied. ExperimentsTo capture negatively charged bacteria in water, ATP was modified by positively charged Poly (allylamine hydrochloride) (PAH). The capturing capability of Poly (allylamine hydrochloride)-attapulgite (PAH-ATP) particles for bacterial cells, emulsification of PAH-ATP particles and bacteria on oil, toxicity of PAH-ATP to bacteria, biodegradation of oil, etc., were comprehensively investigated. FindingsPAH-ATP modified bacteria show a highly effective emulsification for oil due to the synergism of PAH-ATP and bacteria. The emulsion stabilized by (PAH-ATP)@bacteria presents small and stable oil droplets in one month, which is benefit for the following biodegradation. Compared with bare bacteria and PAH-ATP, PAH-ATP can capture bacteria to the surface of the oil droplets which can greatly improve the degradation of oil pollution. Importantly, the presence of PAH-ATP does not inhibit the reproduction and activity of bacteria. Treatment of oily wastewater by combining natural nanoparticles and oil-degrading bacteria has the advantages of economy, environmental protection, and sustainability.

Biodegradation Potential of Oil-degrading Bacteria Related to the Genus Thalassospira Isolated from Polluted Coastal Area in Mediterranean Sea

ABSTRACT Three bacterial species related to the genus Thalassospira (T. lucentensis, T. xianhensis and T. profundimaris), isolated from polluted sediment and seawater samples collected from Priolo Bay (eastern coast of Sicily, Ionian Sea), were analyzed for their biotechnological potential. For this purpose, the presence of specific catabolic genes associated to aliphatic and aromatic hydrocarbon metabolism, the production of biosurfactants and emulsification activity, the capability to degrade oil-derived linear, branched, cyclic alkanes, and polycyclic aromatic hydrocarbons (PAHs) were evaluated. Alkane hydroxylase gene (alkano-monoxygenase alkb and citocrome P450) were present in genome of all strains, confirming their hydrocarbons degrading capability. All strains of Thalassospira produced biosurfactants and showed emulsification activity. The two-dimensional gas chromatography analysis (GC×GC) showed that they were able to degrade oil fractions with the capacity ranging between 77% and 91%. The data obtained in this study demonstrated the biodegradation ability of Thalassospira and suggest that these strains play an important role in marine contaminated ecosystems

Metagenomics and Quantitative Stable Isotope Probing Offer Insights into Metabolism of Polycyclic Aromatic Hydrocarbon Degraders in Chronically Polluted Seawater.

Bacterial biodegradation is a significant contributor to remineralization of polycyclic aromatic hydrocarbons (PAHs)-toxic and recalcitrant components of crude oil as well as by-products of partial combustion chronically introduced into seawater via atmospheric deposition. The Deepwater Horizon oil spill demonstrated the speed at which a seed PAH-degrading community maintained by chronic inputs responds to acute pollution. We investigated the diversity and functional potential of a similar seed community in the chronically polluted Port of Los Angeles (POLA), using stable isotope probing with naphthalene, deep-sequenced metagenomes, and carbon incorporation rate measurements at the port and in two sites in the San Pedro Channel. We demonstrate the ability of the community of degraders at the POLA to incorporate carbon from naphthalene, leading to a quick shift in microbial community composition to be dominated by the normally rare Colwellia and Cycloclasticus We show that metagenome-assembled genomes (MAGs) belonged to these naphthalene degraders by matching their 16S-rRNA gene with experimental stable isotope probing data. Surprisingly, we did not find a full PAH degradation pathway in those genomes, even when combining genes from the entire microbial community, leading us to hypothesize that promiscuous dehydrogenases replace canonical naphthalene degradation enzymes in this site. We compared metabolic pathways identified in 29 genomes whose abundance increased in the presence of naphthalene to generate genomic-based recommendations for future optimization of PAH bioremediation at the POLA, e.g., ammonium as opposed to urea, heme or hemoproteins as an iron source, and polar amino acids.IMPORTANCE Oil spills in the marine environment have a devastating effect on marine life and biogeochemical cycles through bioaccumulation of toxic hydrocarbons and oxygen depletion by hydrocarbon-degrading bacteria. Oil-degrading bacteria occur naturally in the ocean, especially where they are supported by chronic inputs of oil or other organic carbon sources, and have a significant role in degradation of oil spills. Polycyclic aromatic hydrocarbons are the most persistent and toxic component of crude oil. Therefore, the bacteria that can break those molecules down are of particular importance. We identified such bacteria at the Port of Los Angeles (POLA), one of the busiest ports worldwide, and characterized their metabolic capabilities. We propose chemical targets based on those analyses to stimulate the activity of these bacteria in case of an oil spill in the Port POLA.

Characterization of the Microbial Community Structure and Function During the Natural Attenuation of Oil in Marine Environments Using In Situ Microcosms

ABSTRACT Climate change, the opening of the northwest passage, the production and transportation of oil reserves in addition to the large size and number of ocean-going vessels, are putting all Canada's oceans at an elevated risk for an oil spill. Responses to marine oil spills include physical (skimming and recovery), chemical (dispersants, herders) and biological processes (biodegradation). Natural attenuation, a weathering process that includes physical, chemical and biological action on spilled oil, is a potential remediation strategy that needs to be explored and exploited. In the Canadian context, we are using genomics approaches to better understand the natural populations of oil degrading microorganisms in our oceans, their diversity, spatial and temporal dynamics, and locations that may be more vulnerable to oil spills. The purpose of this study was to perform an evaluation of the effectiveness of an in situ microcosm experimental system to study indigenous microbial communities that have oil degrading potential and to determine whether this experimental system could have an impact on acute toxicity to various marine organisms. In situ microcosms are slitted columns that contain support matrices such as clay beads or river rocks, with or without an oil coating. Columns can be incubated in different locations, at different depths and different time periods, during which microbial biofilm develops on the support materials. By using oil coated and uncoated matrices, comparative microbial community data that demonstrates the response of the microbial community to the presence of oil can be obtained. Long-term incubations (1 year) conducted at CFS-Alert showed that known oil-degrading bacteria (Colwellia, Oleibacter, Thalassolituus, Cycloclasticus, Oceanobacter and Alcanivorax) became dominant only on the oil coated matrices, confirming their presence in the local seawater. Acute toxicity tests were performed in aquaria on a variety of test organisms to evaluate the possible effects of oil components leaching into the water from the in situ microcosms. Limited and transient toxicity to only two tested organisms (green sea urchin fertilization and green algal growth). Considering the analyses were conducted in a closed circulation system, it is highly likely that in an open ocean environment, toxicity would be negligible. Data from these studies will be valuable to support guidelines for the exploitation of natural attenuation as an alternative response measure (ARM) to address oil spills in Canadian waters.

Preliminary Study of Crude Oil Degradation by Microorganisms Isolated from Polluted Soil in Okarki, River State, Nigeria

Pollution of the environment by hydrocarbon compounds has become a significant management challenge in oil-producing countries. Presently, the use of biological means for the reclamation of polluted sites is the most acceptable technique owing to its eco-friendliness. This study was carried out to assess the crude oil degradation potential of indigenous microorganisms in polluted soil. The polluted soil was obtained from a crude oil-ladened site in Okarki, River State, Nigeria. Bacterial and fungal organisms present in the polluted soil were isolated on Nutrient agar and Saboraud dextrose agar plates respectively. The isolates were identified based on their morphological, microscopic and biochemical characteristics. Gravimetric analysis of the crude oil degradation by the isolates was done in Bushnell Hass medium supplemented with 5% crude oil as the only carbon source. A total of 6 bacterial genera namely, Staphylococcus, Citrobacter, Micrococcus, Pseudomonas, Bacillus and Corynebacterium were identified while the fungal isolates were Aspergillus niger, Aspergillus flavus and Penicillium sp. Bacterial and fungal counts were 2.57±0.01 Log cfu/g and 2.08±0.07 Log cfu/g respectively. Bacillus sp. had the highest relative abundance (27.3%), while Micrococcus sp. and Corynebacterium sp. had the least occurrence (9.1%). Among the fungal group, A. niger showed the highest percentage occurrence in the polluted soil. All the indigenous organisms isolated from the polluted soil showed varying potentials for crude oil degradation. Bacillus sp. and Penicillium sp. were the highest crude oil-degrading bacterium and fungus respectively. The degradation potential of the bacterial consortium was significantly higher (P < 0.05) than the other consortia tested. This study has shown that indigenous organisms possess the potential for crude oil degradation.

Molecular identification of crude oil-degrading bacteria isolated from polluted sites in Algeria

The petroleum industry in Algeria takes a predominant place in the econo-my. This industry amplifies the environmental contamination and affects microbial diversity of soils. Bioremediation is a cost-effective and efficient process for removing hydrocarbon pollutants. The aim of the study was to isolate cultivable telluric bacteria and to assess their potential as bioremedi-ation agents against the contamination of petroleum hydrocarbons. Crude oil polluted soil samples were taken from different oil refinery in Algeria. Elemental analysis was determined by inductively coupled plasma optical emission spectrometry (ECP-OES). The screening of bacteria degrading hy-drocarbons was studied with oil spreading technique on mineral salt medium (MSM agar) supplemented with crude oil as the only carbon source and en-ergy for direct visualization of clear zones on agar plates. Among the isolates, ten were selected for their degradation potential based on their large clear zone (from 0.5 to 3.2 Cm) for phenotypic and genotypic characterization. Molecular identification was performed by sequencing the gene encoding 16s rRNA. The comparison of sequences with GenBank database showed similarity with different strains Aeromonas hydrophila, Stenotrophomonas maltophilia, Enterobacter xiangfangensis, Pseudomonas aeruginosa, Serratia marcescens, and Raoultella sp. These results are significant for the applica-tion of these isolates at the environmental scale in bioremediation of pollut-ed soils.

The influence of the association of barley plants with petroleum degrading bacteria on the hormone content, growth and photosynthesis of barley plants grown in the oil-contaminated soil

Maintenance of active plant growth is important for successful phytoremediation of soil contaminated with petroleum oil products. Strains of oil-degrading bacteria introduced into rhizosphere were found to reduce the extent of plant growth inhibition resulting from petroleum stress. The effect was due to combining the capacity for petroleum degradation with promotion of plant growth by bacterial phytohormones. The purpose of this work was to compare the relative importance of these mechanisms in supporting the growth of barley plants against the background of oil pollution of the soil. Plants were treated with bacterial suspensions of four strains capable of petroleum degradation and production of indole acetic acid (IAA, plant hormone of the auxin class). The strains were shown to differ in their ability to support plant growth under conditions of oil pollution. Introduction of bacteria into soil accelerated petroleum degradation. Nevertheless, oil degradation was not the only mechanism behind promotion of plant growth, since the strain with the lowest ability to degrade oil was characterized by a relatively high growth-stimulating activity. The highest ability to stimulate plant growth was detected in the case of strains, which were the most effective in increasing the concentration of IAA in plants and decreasing the stress-induced accumulation of abscisic acid (ABA).

Inter- and Intra-Annual Bacterioplankton Community Patterns in a Deepwater Sub-Arctic Region: Persistent High Background Abundance of Putative Oil Degraders.

Hydrocarbon-degrading bacteria naturally degrade and remove petroleum pollutants, yet baselines do not currently exist for these critical microorganisms in many regions where the oil and gas industry is active. Furthermore, understanding how a baseline community changes across the seasons and its potential to respond to an oil spill event are prerequisites for predicting their response to elevated hydrocarbon exposures. In this study, 16S rRNA gene-based profiling was used to assess the spatiotemporal variability of baseline bacterioplankton community composition in the Faroe-Shetland Channel (FSC), a deepwater sub-Arctic region where the oil and gas industry has been active for the last 40 years. Over a period of 2 years, we captured the diversity of the bacterioplankton community within distinct water masses (defined by their temperature and salinity) that have a distinct geographic origin (Atlantic or Nordic), depth, and direction of flow. We demonstrate that bacterioplankton communities were significantly different across water samples of contrasting origin and depth. Taxa of known hydrocarbon-degrading bacteria were observed at higher-than-anticipated abundances in water masses originating in the Nordic Seas, suggesting these organisms are sustained by an unconfirmed source of oil input in that region. In the event of an oil spill, our results suggest that the response of these organisms is severely hindered by the low temperatures and nutrient levels that are typical for the FSC.IMPORTANCE Oil spills at sea are one of the most disastrous anthropogenic pollution events, with the Deepwater Horizon spill providing a testament to how profoundly the health of marine ecosystems and the livelihood of its coastal inhabitants can be severely impacted by spilled oil. The fate of oil in the environment is largely dictated by the presence and activities of natural communities of oil-degrading bacteria. While a significant effort was made to monitor and track the microbial response and degradation of the oil in the water column in the wake of the Deepwater Horizon spill, the lack of baseline data on the microbiology of the Gulf of Mexico confounded scientists' abilities to provide an accurate assessment of how the system responded relative to prespill conditions. This data gap highlights the need for long-term microbial ocean observatories in regions at high risk of oil spills. Here, we provide the first microbiological baseline established for a subarctic region experiencing high oil and gas industry activity, the northeast Atlantic, but with no apparent oil seepage or spillage. We also explore the presence, relative abundances, and seasonal dynamics of indigenous hydrocarbon-degrading communities. These data will advance the development of models to predict the behavior of such organisms in the event of a major oil spill in this region and potentially impact bioremediation strategies by enhancing the activities of these organisms in breaking down the oil.

Bioremediation of marine oil spills by immobilized oil-degrading bacteria and nutrition emulsion.

The combination of bioaugmentation and biostimulation was used to speed up the bioremediation of marine oil spills. A novel carrier material that consisted of puffed panicum miliaceum (PPM), calcium alginate and chitosan was prepared. The porous structure and low density of PPM ensured this carrier material not only had appropriate physical and biological properties for the aggregation of microorganisms but also was biodegradable and floating on the seawater surface for bioremediation of oil pollution. An oil-degrading bacterial consortium was immobilized via adsorption on the carrier material. The immobilized bacteria were observed with scanning electron microscopy. The number of viable cells immobilized on the material was approximately 1.12 × 108CFU/g. To solve the problem of nutrients supplementation in seawater, an emulsion formed with urea solution, soybean lecithin, alcohol and oleic acid was prepared as oleophilic fertilizer. The results from laboratory and field mesocosm experiments showed that the combination of immobilized bacteria and the emulsion achieved a higher oil removal efficiency compared with the use of them separately. The results of field mesocosm experiments conducted in the coastal seawater showed that most of the petroleum pollutant (> 98%) was removed from the surface of seawater in 24h. GC-MS analysis showed that most components of petroleum pollutants had been removed. This formula with immobilized bacteria and emulsion can be exploited further for the bioremediation of marine oil spills.

Study on the Treatment Effect of the Oily Wastewater by the Biological Soil Aquifer Treatment System

Soil aquifer treatment with physical, chemical and biological functions for oily wastewater treatment was put forward and strain identification, best growth conditions was studied in this paper, including temperature, pH, diesel oil content and inorganic salt concentrations. Firstly, the oily wastewater treatment effect and the influence factors of the SAT was investigated. Then, the oil degradation bacteria were domesticated, screened and purified and its degradation characteristics were studied and build a biological SAT(bioSAT). Thirdly, the oily wastewater was treated by the bioSAT and the effect was investigated. At last, to confirm the optimal treatment conditions. The research results showed that: 5 bacteria strains were identified as following: Enterococcus faecalis-L1, Lysiniibacillus-L2, Bacillus sp-L3, Rhodococcus equi-L4 and Ochrobactrum-L5. Based on their ability to degrade oil, L-2 and L-4 were selected and their growth conditions majorized. Optimum bacteria growth was recorded at 2% substrate (diesel) concentration, pH 7-8, temperature range between 25°C and 30°C and inorganic salt concentration range from 1 g/L to 3 g/L for the bacteria strains L2 and L4. The equilibrium concentration was reached on the 30th day, and the highest removal rates of 84.63% and 99.23% were reached on the 36th day.

Reconstruction and evaluation of oil-degrading consortia isolated from sediments of hydrothermal vents in the South Mid-Atlantic Ridge

In this study, sediments were collected from two different sites in the deep-sea hydrothermal region of the South Atlantic Ocean. Two microbial enrichment cultures (H7S and H11S), which were enriched from the sediments collected at two sample sites, could effectively degrade petroleum hydrocarbons. The bacterial diversity was analyzed by high-throughput sequencing method. The petroleum degradation ability were evaluated by gas chromatography–mass spectrometry and gravimetric analysis. We found that the dominant oil-degrading bacteria of enrichment cultures from the deep-sea hydrothermal area belonged to the genera Pseudomonas, Nitratireductor, Acinetobacter, and Brevundimonas. After a 14-day degradation experiment, the enrichment culture H11S, which was obtained near a hydrothermal vent, exhibited a higher degradation efficiency for alkanes (95%) and polycyclic aromatic hydrocarbons (88%) than the enrichment culture H7S. Interestingly, pristane and phytane as biomarkers were degraded up to 90% and 91% respectively by the enrichment culture H11S, and six culturable oil-degrading bacterial strains were isolated. Acinetobacter junii strain H11S-25, Nitratireductor sp. strain H11S-31 and Pseudomonas sp. strain H11S-28 were used at a density ratio of 95:4:1 to construct high-efficiency oil-degrading consortium H. After a three-day biodegradation experiment, consortium H showed high degradation efficiencies of 74.2% and 65.7% for total alkanes and PAHs, respectively. The degradation efficiency of biomarkers such as pristane and high-molecular-weight polycyclic aromatic hydrocarbons (such as CHR) reached 84.5% and 80.48%, respectively. The findings of this study indicate that the microorganisms in the deep-sea hydrothermal area are potential resources for degrading petroleum hydrocarbons. Consortium H, which was artificially constructed, showed a highly efficient oil-degrading capacity and has significant application prospects in oil pollution bioremediation.

Response of bacterial and fungal communities to high petroleum pollution in different soils

Petroleum pollution of soils is a major environmental problem. Soil microorganisms can decompose a significant fraction of petroleum hydrocarbons in soil at low concentrations (1–5%). This characteristic can be used for soil remediation after oil pollution. Microbial community dynamics and functions are well studied in cases of moderate petroleum pollution, while cases with heavy soil pollution have received much less attention. We studied bacterial and fungal successions in three different soils with high petroleum contents (6 and 25%) in a laboratory experiment. The proportion of aliphatic and aromatic compounds decreased by 4–7% in samples with 6% pollution after 120 days of incubation but remained unchanged in samples with 25% hydrocarbons. The composition of the microbial community changed significantly in all cases. Oil pollution led to an increase in the relative abundance of bacteria such as Actinobacteria and the candidate TM7 phylum (Saccaribacteria) and to a decrease in that of Bacteroidetes. The gene abundance (number of OTUs) of oil-degrading bacteria (Rhodococcus sp., candidate class TM7-3 representative) became dominant in all soil samples, irrespective of the petroleum pollution level and soil type. The fungal communities in unpolluted soil samples differed more significantly than the bacterial communities. Nonmetric multidimensional scaling revealed that in the polluted soil, successions of fungal communities differed between soils, in contrast to bacterial communities. However, these successions showed similar trends: fungi capable of lignin and cellulose decomposition, e.g., from the genera Fusarium and Mortierella, were dominant during the incubation period.

Isolation and characterization of a high-efficiency marine diesel oil-degrading bacterium

In the recent 50 years, marine oil spills had resulted in severe environmental pollution problems worldwide. In this study, 12 petroleum-degrading strains named MJ1 to MJ12, which can use diesel oil as the sole carbon source for growth, were isolated from the seawater in Jiaozhou Bay, China. Strain MJ4 has the highest diesel-degrading rate which is up to 26.54% in 5 days with the diesel oil concentration of 10 g/L. According to the BLAST research, 16SrRNA sequence of MJ4 showed 99% similarity to Bacillus megaterium strain. Single-factor experiments and response surface methodology were carried out to optimize the environmental factors and their reciprocal action for affecting the diesel oil degradation process of Bacillus sp. MJ4. Results of single-factor experiments revealed that the highest degradation rate was obtained with temperature of 28 °C, pH of 8.8, diesel oil concentration of 25 g/L, P/N ratio of 0.56, nitrogen and phosphorus dosage quantity of 0.35 g/L and 0.18 g/L, respectively. A nonlinear regression equation of diesel oil degradation rate and pH, temperature, P/N ratio was obtained. The model predicted the maximum degradation rate of 72.21% with temperature of 28 °C, pH of 8.88, P/N ratio of 0.31, respectively.

Effect of rhizospheric oil-degrading bacteria on the biological state of oil-polluted soil

Effect of rhizospheric oil-degrading bacteria on the biological state of oil-polluted soil