Aspects of petroleum hydrocarbon metabolism in marine animals

Studies on hydrocarbon composition of Black Sea musselsMytilus galloprovincialis sampled from different habitats indicate that the quantity and composition of hydrocarbons distributed in the molluscs depend on season and sea-water quality. The data obtained under experimental conditions testify to the possibility of hydrocarbon concentration in mussel tissues after death. During filtration in sea water containing oil and oil products, these pollutants are bound into faeces and pseudofaeces which contain a greater percentage of aromatic compounds than the oil initially present in sea water. Quantitative data are presented on hydrocarbon changes in mussel excretory products during transfer from oil-polluted to clean sea water. When Black Sea crabsEriphia verrucosa are fed with mussels containing fuel-oil components accumulated from sea water, the pollutants concentrate in the whole body of the crab. This is in contrast to parenteral oil uptake, which leads to a concentration of most of the hydrocarbon in the muscles.     

Bioremediation of petroleum hydrocarbon contaminated soil: Effects of strategies and microbial community shift

Biodegradation of petroleum hydrocarbon oil (14,000 mg kg⁻¹) were investigated in six biopiles batches, differing in the remediation strategy: bioaugmentation (selected consortium and kitchen waste were introduced), biostimulation (added with rhamnolipid, high-level, or low-level nutrient), and bioaugmentation plus biostimulation (added both with rhamnolipid and bacterial consortia). After the 140-day operation, the kitchen waste (KW) and the low-level nutrient (NEL) batches achieved the highest total petroleum hydrocarbon degradation efficiency (>80%). The result of the hydrocarbon analysis revealed that the bioaugmentation approaches were the most effective ones in removing aromatic component (64% and 68%), and KW and NEL were the only two approaches that can remove the polar component with positive efficiency, 11% and 21%, respectively. The terminal-restriction fragment length polymorphism percentage (T-RFLP) abundance applied with nonmetric multidimensional scaling indicated a similarity of the bacterial communities during the early fastest remediation stage. The results of the oligonucleotide array targeting the ribosomal internal transcribed spacer (ITS) region, along with the hydrocarbon fractional analysis, indicated a successive degradation completed by the bacterial-fungi consortia. Before Day 70, the bacterial community was dominant in decomposing the saturated and partially aromatic hydrocarbons. After Day 70, the fungal community found to be dynamic and responsible for degradation of the polar hydrocarbons composing of recalcitrant metabolites.     

Hybridization in postglacial marine habitats

Within the last few million years, repeated invasions from the North Pacific have brought evolutionarily divergent lineages of Macoma balthica clams into contact in the marginal and inland seas of northern Europe (Strelkov et al. 2007). These divergent M. balthica lineages now co-occur and hybridize extensively, blurring the distinction between the lineages and with some populations best described as 'hybrid swarms'. This scenario matches the prediction that hybridization between distinct genetic entities can generate evolutionary novelty, particularly in new environments where hybrid fitness is equal to or exceeds parental types (Arnold 1997; Seehausen 2004).     

海洋石油污染物的微生物降解与生物修复

石油是海洋环境的主要污染物 ,已经对海洋及近岸环境造成了严重的危害。微生物降解是海洋石油污染去除的主要途径。海洋石油污染物的微生物降解受石油组分与理化性质、环境条件以及微生物群落组成等多方面因素的制约 ,N和P营养的缺乏是海洋石油污染物生物降解的主要限制因子。在生物降解研究基础上发展起来的生物修复技术在海洋石油污染治理中发展潜力巨大 ,并且取得了一系列成果。介绍了海洋中石油污染物的来源、转化过程、降解机理、影响生物降解因素及生物修复技术等方面内容 ,强调了生物修复技术在治理海洋石油污染环境中的优势和重要性 ,指出目前生物修复技术存在的问题。     

Accelerated biodegradation of petroleum hydrocarbon waste

Conventional landfarming approaches to bioremediation of refinery and other petroleum sludges are not acceptable environmentally and are banned in most North American jurisdictions. While initial bioreactor-based systems for treatment of these sludges required batch-cycle process-times of 1–3 months, an accelerated process has now been developed which can be completed in 10–12 days. In this process, up to 99% of total petroleum hydrocarbons are degraded and the sludges are converted from hazardous to non-hazardous according to the United States EPA's toxicity characteristic leachate procedure criteria. Understanding and exploiting mechanisms to improve hydrocarbon accession to the degrading microorganisms was a key development component of the process. Contrasting physiological mechanisms were observed for different component organisms of the mixed culture with respect to their associations with the hydrocarbon substrate; and the beneficial effects of using surfactants were demonstrated. The mixed culture used in the process exhibited a capacity for high-rate degradation of volatile organic carbons and the potential use of the culture as a liquid biofilter was demonstrated. The culture was also effective as an inoculant for the bioaugmentation of total petroleum hydrocarbon-contaminated soil and as a de-emulsifier of oilfield emulsions and could transform some other environmental contaminants which are not predominant components of crude oil.     

Bioremediation of organic and metal contaminants with dissimilatory metal reduction

PCR fingerprinting offers a practical molecular means to quickly and reliably differentiate bacteria for microbial products screening. A combination of low resolution and high resolution PCR fingerprinting provides a hirarchical system which allows the discrimination of bacteria at species and subspecies level within 7 h. DNA was extracted from cells by incubating them in water at 95°C for 30 min. A sample of 1 l of the cell-free aqueous extract then was used as a source of template DNA in the PCR. The PCR products were separated by electrophoresis on an acrylamide gel and visualized by ethidium bromide staining. The band patterns generated for each different culture were unique, reproducible, and independent of cultivation conditions. Band patterns may be compared visually or by using imaging and pattern matching software. In our laboratory, bacteria such as actinomycetes, Gram-negative and Gram-positive soil eubacteria, and photosynthetic non-sulfur bacteria have been differentiated using PCR fingerprinting.     

Bioremediation of oil by marine microbial mats

Cyanobacterial mats developing in oil-contaminated sabkhas along the African coasts of the Gulf of Suez and in the pristine Solar Lake, Sinai, were collected for laboratory studies. Samples of both mats showed efficient degradation of crude oil in the light, followed by development of an intense bloom of Phormidium spp. and Oscillatoria spp. Isolated cyanobacterial strains, however, did not degrade crude oil in axenic cultures. Strains of sulfate-reducing bacteria and aerobic heterotrophs were capable of degrading model compounds of aliphatic and aromatic hydrocarbons. Results indicate that degradation of oil was done primarily by aerobic heterotrophic bacteria. The oxygenic photosynthesis of oil-insensitive cyanobacteria supplied the molecular oxygen for the efficient aerobic metabolism of organisms, such as Marinobacter sp. The diurnal shifts in environmental conditions at the mat surface, from highly oxic conditions in the light to anaerobic sulfide-rich habitat in the dark, may allow the combined aerobic and anaerobic degradation of crude oil at the mat surface. Hence, coastal cyanobacterial mats may be used for the degradation of coastline oil spills. Oxygen microelectrodes detected a significant inhibition of photosynthetic activity subsequent to oil addition. This prevailed for a few hours and then rapidly recovered. In addition, shifts in bacterial community structure following exposure to oil were determined by denaturing gradient gel electrophoresis of PCR-amplified fractions of 16S rRNA from eubacteria, cyanobacteria and sulfate-reducing bacteria. Since the mats used for the present study were obtained from oil-contaminated environments, they were believed to be preequilibrated for petroleum remediation. The mesocosm system at Eilat provided a unique opportunity to study petroleum degradation by mats formed under different salinities (up to 21%). These mats, dominated by cyanobacteria, can serve as close analogues to the sabkhas contaminated during the Gulf War in Kuwait and Saudi Arabia. Electronic Publication     

微生物降解石油烃的功能基因研究进展

微生物对石油烃的降解在自然衰减去除土壤和地下水石油烃污染的过程中发挥了重要作用。微生物通过其产生的一系列酶来利用和降解这类有机污染物,其中,编码关键降解酶的基因称为功能基因。功能基因可作为生物标志物用于分析环境中石油烃降解基因的多样性。因此,研究石油降解功能基因是分析土著微生物群落多样性、评价自然衰减潜力与构建基因工程菌的重要基础。本文主要介绍了烷烃和芳香烃在有氧和无氧条件下的微生物降解途径,重点总结了烷烃和芳香烃降解的主要功能基因及其作用,包括参与羟化作用的单加氧酶和双加氧酶基因、延胡索酸加成反应的琥珀酸合酶基因以及中心中间产物的降解酶基因等。     

石油污染盐碱土壤棉花根际微生物与石油烃降解关系

【目的】探讨棉花(Gossypium spp.)生长对石油烃(TPH)污染盐碱土壤微生物群落结构的影响,揭示根际微生物与TPH降解的相关关系。【方法】利用磷脂脂肪酸(PLFA)方法解析根际土壤活性微生物群落随棉花生长的动态变化特征。【结果】根际土壤先后出现了21种PLFAs,包括：饱和脂肪酸(SAT),标识除放线菌之外的细菌;甲基支链末端型饱和脂肪酸(TBSAT),标识除放线菌之外的革兰氏阳性(G+)细菌;标识真菌的多不饱和脂肪酸(PUFA);标识放线菌的甲基支链中间型饱和脂肪酸(MBSAT);标识革兰氏阴性(G?)细菌的单不饱和脂肪酸(MONO)和环丙基脂肪酸(CYCLO)。棉花根际与未栽种棉花的对照(CK)相比,根际土壤微生物PLFAs种类在苗期、蕾期、吐絮期分别增加了100%、83.3%、20.0%,生物量分别增加了53.9%、6.60倍和60.7%;土壤TPH降解率分别提高13.0%、28.0%和30.6%。相关性分析表明：根际土壤TPH降解与根际土壤微生物总生物量具有低度正相关关系(|r|=0.5),但与a14:0、a16:0、i15:0标记的G+细菌生物量高度正相关(|r|≥0.8)。【结论】棉花生长对石油污染盐碱土壤活性微生物群落结构具有显著(p<0.05)的影响,且加速了土壤TPH的降解。该结果将为今后更好地开展石油污染盐碱土壤的生物修复技术研究提供理论依据。     

Environmental contaminants influencing immunefunction in marine bivalve molluscs

The increased observation of pollution induced disease conditions in marine organisms has led to a growing interest on the effects of environmental contaminants on the immune system. Most studies on modulation of the immune system in bivalves by pollutants have concentrated on the effects of heavy metals and polycyclic aromatic hydrocarbons (PAHs). The current literature on contaminant effects on specific components of the bivalve immune system is reviewed together with the effects on susceptibility to infection. Data are presented showing the effects on immune parameters of exposure to Vibrio tubiashi following pre-exposure to copper or cadmium. Mussels exposed to cadmium for 7 days followed by 7 days exposure to V. tubiashi demonstrated significantly higher numbers of circulating haemocytes compared with non-Vibrio-exposed groups. Similar experiments conducted with copper exposure for both 7 days and 7 weeks followed by V. tubiashi for 7 days demonstrated a significant decrease in the percentage of circulating eosinophils compared with basophilic cells for both short and long term exposures. The intracellular release of superoxide (NBT reduction) by haemocytes was stimulated in Vibrio-challenged mussels with no copper pre-exposure but was significantly reduced in mussels pre-exposed to 0·2 ppm of copper for 7 weeks. The mortalities for the copper experiments showed increased levels with increasing copper concentration and were consistently higher in the V. tubiashi challenged mussels which had also been exposed to copper.     

Analysis for petroleum products in marine environments

Petroleum is composed of a complex mixture of hydrocarbons that readily undergo chemical and biological conversions on entering aquatic environments. These conversions lead to the formation of a host of oxygenated products, some of which are potentially toxic to marine life and to the consumer of fishery products. State-of-the-art analytical methods, as employed in our laboratories, utilize glass-capillary gas chromatography in conjunction with mass spectrometry to analyze environmental samples containing trace amounts of aliphatic and aromatic petroleum hydrocarbons. These procedures are applied on a routine basis to the analysis of seawater, sediments and tissues of marine organisms. Despite this analytical proficiency, a need exists for analyzing oxygenated and other polar petroleum products in environmental samples. For example, techniques such as high-performance liquid chromatography (HPLC), in conjunction with on-line fluorometric assay techniques and mass spectrometry, make possible the analysis of polar oxygenated compounds resulting from both chemical and biological conversions. These methodologies are first steps toward the development of routine assay procedures for environmental samples. Current techniques for hydrocarbon analyses and new methods for analyzing polar aromatic compounds are discussed.     

低温微生物修复石油烃类污染土壤研究进展

耐冷菌、嗜冷菌等低温微生物广泛存在于极地、高山以及高纬度等土壤环境中,是石油烃类污染物在低温条件下降解与转化的重要微生物资源.利用低温微生物的独特优势,石油污染土壤的低温生物修复技术的研究成为当前热点领域.本文系统综述了低温石油烃降解菌的分类及冷适机制,低温微生物对不同类型石油烃组分的降解特征和降解机理,低温环境中接种降解菌、添加营养物质和表面活性剂等强化技术在石油污染土壤中生物修复的应用.以及微生物分子生物学技术在低温微生物降解石油烃的研究现状,为拓展我国石油污染土壤生物修复技术提供参考.     

Bacterial diversity in marine hydrocarbon seep sediments

Marine seeps introduce significant amounts of hydrocarbons into oceans and create unusual habitats for microfauna and -flora. In the vicinity of chronic seeps, microbes likely exert control on carbon quality entering the marine food chain and, in turn, hydrocarbons could influence microbial community composition and diversity. To determine the effects of seep oil on marine sediment bacterial communities, we collected sediment piston cores within an active marine hydrocarbon seep zone in the Coal Oil Point Seep Field, at a depth of 22 m in the Santa Barbara Channel, California. Cores were taken adjacent to an active seep vent in a hydrocarbon volcano, on the edge of the volcano, and at the periphery of the area of active seepage. Bacterial community profiles were determined by terminal restriction fragment length polymorphisms (TRFLPs) of 16S ribosomal genes that were polymerase chain reaction (PCR)-amplified with eubacterial primers. Sediment carbon content and C/N ratio increased with oil content. Terminal restriction fragment length polymorphisms suggested that bacterial communities varied both with depth into sediments and with oil concentration. Whereas the apparent abundance of several peaks correlated positively with hydrocarbon content, overall bacterial diversity and richness decreased with increasing sediment hydrocarbon content. Sequence analysis of a clone library generated from sediments collected at the periphery of the seep suggested that oil-sensitive species belong to the gamma Proteobacteria and Holophaga groups. These sequences were closely related to sequences previously recovered from uncontaminated marine sediments. Our results suggest that seep hydrocarbons exert a strong selective pressure on bacterial communities in marine sediments. This selective pressure could, in turn, control the effects of oil on other biota in the vicinity of marine hydrocarbon seeps.     

Psychrophilic versus psychrotolerant bacteria--occurrence and significance in polar and temperate marine habitats.

The numerical dominance and ecological role of psychrophilic bacteria in bottom sediments, sea ice, surface water and melt pools of the polar oceans were investigated using isolates, colony forming units (CFU) and metabolic activities. All sediment samples of the Southern Ocean studied showed a clear numerical dominance of cold-loving bacteria. In Arctic sediments underlying the influence of cold polar water bodies psychrophiles prevailed also but they were less dominant in sediments influenced by the warm Atlantic Water. A predominance of psychrophiles was further found in consolidated Antarctic sea ice as well as in multiyear Arctic sea ice and in melt pools on top of Arctic ice floes. A less uniform adaptation response was, however, met in polar surface waters. In the very northern part of the Fram Strait (Arctic Ocean) we found bacterial counts and activities at 1 degree C exceeding those at 22 degrees C. In surface water of the Weddell Sea (Southern Ocean) psychrophiles also dominated numerically in early autumn but the dominance declined obviously with the onset of winter-water and a decrease of chlorphyll a. Otherwise in surface water of the Southern Ocean CFUs were higher at 22 degrees C than at 1 degree C while activities were vice versa indicating at least a functional dominance of psychrophiles. Even in the temperate sediments of the German Bight true psychrophiles were present and a clear shift towards cold adapted communities in winter observed. Among the polar bacteria a more pronounced cold adaptation of Antarctic in comparison with Arctic isolates was obtained. The results and literature data indicate that stenothermic cold adapted bacteria play a significant role in the global marine environment. On the basis of the temperature response of our isolates from different habitats it is suggested to expand the definition of Morita in order to meet the cold adaptation strategies of the bacteria in the various cold habitats.     

Climate change disrupts core habitats of marine species

Driven by climate change, marine biodiversity is undergoing a phase of rapid change that has proven to be even faster than changes observed in terrestrial ecosystems. Understanding how these changes in species composition will affect future marine life is crucial for conservation management, especially due to increasing demands for marine natural resources. Here, we analyse predictions of a multiparameter habitat suitability model covering the global projected ranges of >33,500 marine species from climate model projections under three CO₂ emission scenarios (RCP2.6, RCP4.5, RCP8.5) up to the year 2100. Our results show that the core habitat area will decline for many species, resulting in a net loss of 50% of the core habitat area for almost half of all marine species in 2100 under the high-emission scenario RCP8.5. As an additional consequence of the continuing distributional reorganization of marine life, gaps around the equator will appear for 8% (RCP2.6), 24% (RCP4.5), and 88% (RCP8.5) of marine species with cross-equatorial ranges. For many more species, continuous distributional ranges will be disrupted, thus reducing effective population size. In addition, high invasion rates in higher latitudes and polar regions will lead to substantial changes in the ecosystem and food web structure, particularly regarding the introduction of new predators. Overall, our study highlights that the degree of spatial and structural reorganization of marine life with ensued consequences for ecosystem functionality and conservation efforts will critically depend on the realized greenhouse gas emission pathway.     

Microbial petroleum degradation: use of mixed hydrocarbon substrates

Methods of examining hydrocarbons to estimate the microbial degradation of petroleum are compared. Gas-liquid chromatography with a mixed hydrocarbon substrate has been shown to be useful in evaluating microbial potential for degradation of a number of hydrocarbons.     

Application of bioremediation technology in the environment contaminated with petroleum hydrocarbon

The demand for petroleum and petroleum products is increasing day by day, while oil spills and improper discharge of industrial wastes contributes to the rising contamination of the environment with petroleum hydrocarbon. Petroleum hydrocarbon spills cause various carcinogenic and neurotoxic effects, and thus effective treatment strategies are required. The various physical and chemical methods currently in use are costly and leave toxic residues in the environment. In contrast, bioremediation is a promising technology in the treatment of petroleum hydrocarbon contamination because of its high effectiveness, lower cost and environmental synergy. Here, we review the biodegradation of petroleum hydrocarbon and various factors influencing this process.     

Bioremediation of experimental petroleum spills on mineral soils in the Vestfold Hills,Antarctica

The effect of nutrient and water enhancement on the biodegradation of petroleum was tested in Antarctic mineral soils. Nitrogen, phosphorus and potassium were applied in solution, with or without gum xanthan or plastic covers, to sites artificially contaminated with distillate. The effectiveness of these procedures was assessed by measuring changes in total petroleum hydrocarbons; heptadecane/pristane and octadecane/phytane ratios; in concentrations of major hydrocarbon components and in microbial numbers and activity.Significantly lower hydrocarbon concentrations were recorded after one year in soils treated with fertilizer solutions, but only in the surface 3 cm. These soils also showed lowered heptadecane/pristane and octadecane/ phytane ratios and had the highest levels of microbial activity relative to other plots. Soils treated with gum xanthan. or covered with plastic had the highest residual hydrocarbon levels. Both treatments inhibited evaporative loss of hydrocarbon, and there were indications that gum xanthan was utilized by the microbiota as an alternative carbon source to distillate. Higher temperatures were recordecd under the plastic but no stimulation of biodegradation was detected.Estimated numbers of metabolically active bacteria were in the range 10⁷ to 10⁸ g^–1 dry weight of soil, with an estimated biomass of 0.03 to 0.26 mg g^–1 soil. Estimated numbers of amoebae were in the range 10⁶ to 10⁷ g^–1 soil (biomass of 2 to 4 mgg^–1). The highest populations were recorded in fertilized, contaminated soils, the only soils where petroleum degradation was demonstrated.