Migration,clogging, and carbon source release of nano emulsified vegetable oil in porous media,evaluated by column experiments

To effectively solve the problem of aquifer clogging in the process of in situ bioremediation of groundwater pollution by micron emulsified vegetable oil (Micron EVO), Nano emulsified vegetable oil (Nano EVO) was prepared to replace conventional micron EVO, and three one-dimensional laboratory columns packed with medium or fine sands were conducted to simulate migration, clogging, and carbon source release of EVO in porous media. Column experiment results show that micron and nano EVO resulted in a 20.40% and 3.20% reduction in permeability of medium sand, respectively. Correspondingly, the interception of micron and nano EVO in medium sand were 28.51% and 20.15%, respectively. Obviously, EVO interception is an important reason for permeability loss, and reducing EVO droplet size can effectively alleviate permeability loss in porous media. The COD ratios (dissolved COD/total COD) of micron and nano EVO in medium sand were 87.61% and 61.95%, respectively. The release effect of nano EVO was better than that of micron EVO. Effective longevity of micron and nano EVO were 243.17 d and 98.80 d, respectively. The effect of fine sand media on EVO indicated nano EVO can be used in a finer granular media, and its longevity can also be extended in this media.     

石油污染生态系统中细菌群落结构及其代谢机制研究进展

石油化工产品的不合理处置与泄漏导致石油及其衍生物大量释放到环境中,由此造成的环境污染问题日益严重,石油污染已成为全球性公害之一。微生物修复技术凭借其成本低、环境友好等优势,广泛应用于石油污染的治理。大量研究表明功能微生物群落在石油污染生态系统的修复体系中发挥了重要的作用。其中,细菌是最主要、最活跃的石油降解微生物。然而,在原位/异位生物修复过程中,存在功能菌群在污染体系中难维持、易失调及石油烃降解途径不明晰等问题。因此,本文总结了石油污染自然生态系统和微宇宙实验体系中的细菌群落结构、石油烃代谢机制及相关功能基因,并对微生物法处理石油污染的未来研究方向提出展望,为石油污染场地生物修复方案的制定提供理论参考。     

Comparative hydrocarbon utilization by hydrophobic and hydrophilic variants of Pseudomonas aeruginosa

Aims: To investigate hydrocarbon degradation by hydrophobic, hydrophilic and parental strains of Pseudomonas aeruginosa. Methods and Results: Partitioning of hydrocarbon‐degrading P. aeruginosa strain in a solvent/aqueous system yielded hydrophobic and hydrophilic fractions. Exhaustive partitioning of aqueous‐phase cells yielded the hydrophilic variants (L), while sequential fractionation of the hydrophobic phase cells yielded successive fractions exhibiting increasing cell‐surface hydrophobicity (CSH). In hydrocarbon adherence assays (bacterial attachment to hydrocarbon), L had a value of 20%, which increased from 61·7% in first hydrophobic fraction (H₁) to 72·2% in the third (H₃). Crude oil degradation by L was 70%, but increased from 82% in H₁ to 93% in H₃. L variant produced most exopolysaccharides and reduced surface tension from about 73 to 49 mN m^?1. Rhamnolipid production was highest in L, but was not detected in all crude oil cultures. Conclusions: Hydrophobic subpopulations of hydrocarbon‐degrading P. aeruginosa exhibited greater hydrocarbon‐utilizing ability than hydrophilic ones, or the parental strain. Significance and Impact of the Study: Results demonstrate that a population of P. aeruginosa consists of cells with different CSH which affect hydrocarbon utilization. This potentially provides the population with the capacity to utilize different hydrophobic substrates found in petroleum. Judicious selection of such hydrophobic subpopulations can enhance hydrocarbon pollution bioremediation.     

Removing of Crude Oil From Polluted Areas Using the Isolated Fungi From Tehran Oil Refinery

The pollution of soil and the subsurface environment by crude oil spill and petroleum products spill is a major concern around the world. The aim of this research was to investigate the ability of fungi isolated from Tehran oil refinery area in removing crude oil and to evaluate their enzymatic activities. Plant root samples were collected from the polluted and control areas, and rhizospheral fungi were isolated and determined using the laboratory methods and taxonomic keys. Seven fungal species were isolated and then cultured in potato dextrose agar (PDA) media containing 0–15% (v/v) crude oil. Oil removal was determined after a one-month growth of fungal colonies and then compared with the control media. The results showed that the studied fungi were able to remove crude oil from the media. The highest removal efficiency was observed in Aspergillus sp. Total protein content and enzymatic activity (of peroxidase and catalase) increased with increasing crude oil pollution. The highest enzymatic activity was evaluated in Aspergillus sp. growing in media containing 15% petroleum and the lowest activity was found in non-polluted groups. Results showed that there is a direct correlation between oil-removing potency and enzymatic activity. Aspergillus sp. showed the highest enzyme activity and also the highest petroleum removal efficiency.     

Effectiveness of the cleaning performance of the bacterial strain <Emphasis Type="Italic">Acinetobacter</Emphasis> sp. SG06-02 in the petroleum hydrocarbon-polluted intestine of clams

Summary A petroleum-degrading bacterial strain Acinetobacter sp. SG06-02 in the oil-polluted intestine of shellfish clam was previously isolated in our laboratory. In this study, the effectiveness of using its cleaning performance on petroleum pollution was investigated. The accumulation of petroleum in the intestine of Ruditapes philippinarum was determined by a UV spectrophotometer. The survival and growth of the SG06-02 strain in the intestine of Ruditapes philippinarum after oil pollution were examined. The concentration of oil accumulated in the Ruditapes philippinarum intestine quickly rises to 254.97 mg/kg within 12 h after placing the clam in the petroleum-polluted seawater tank. After decontaminating using Acinetaobacter we found that the concentration of petroleum inside the Ruditapes philippinarum declined significantly. The results of the cleaning experiments showed that the degradation activity by using bioremediation method of the strain SG06-02 increased 12.8∼30.2% compared to using clean seawater in 4 days. This research indicated that the petroleum degrading bacteria could survive and was effective in cleaning oily pollutants in the seashell.     

Susceptibilities of Yeasts to Yeast Cell Wall Lytic Enzyme of Arthrobacter luteus

The susceptibilities of various strains of yeast to a yeast cell wall lytic enzyme produced by Arthrobacter lutens were examined. Twenty six strains of yeasts, mainly in the genera Saccharomyces and Candida were tested. They were tested after growth attained to the logarithmic or to the resting stage in different media (malt extract medium or n-paraffin medium) and various culture conditions (shaking or stationary liquid cultures or agar slopes).

The effects of various treatments, such as heating, or treatment with 2-mercaptoethanol or sodium dodecylsulfate on their susceptibility were also examined.

These various conditions and treatments greatly influenced the susceptibilities of the yeast cells, suggesting that they affected the composition and/or structure of the yeast cell walls.     

Identification and Kinetic Characteristics of an Indigenous Diesel-degrading Gordonia alkanivorans Strain

Summary An indigenous strain Gordonia alkanivorans CC-JG39 was isolated from oil-contaminated sludge of a local gas station located in central Taiwan. The bacterial isolate was able to grow on diesel-containing Bushnell–Haas medium and also tolerate various chemical additives frequently used in petroleum products (e.g. BETX, methyl-tert-butyl ether, and naphthalene). Kinetics of diesel-limited cell growth and biodegradation of diesel followed a Monod-type model. The kinetic constants for cell growth (μ_max and K_S,G) were 0.158 h⁻¹ and 3196 mg/l, respectively, while those for biodegradation of diesel (v_{max, diesel} and K_S,D) were 3.59 mg/h/mg cell and 2874 mg/l, respectively. G. alkanivorans CC-JG39 produced extracellular surface-active material, leading to a low surface tension of nearly 33 mN/m. The CC-JG39 strain also possessed the ability to float towards the oil/water interface. These features might play some roles in enhancing the mass transfer efficiency between oil substrate and the bacterial cells. Therefore, G. alkanivorans CC-JG39 may have potential applications in bioremediation of oil pollution sites.     

Lysinibacillus sphaericus proved to have potential for the remediation of petroleum hydrocarbons

In this study, the ability of Lysinibacillus sphaericus to degrade aromatic hydrocarbons as well as complex hydrocarbon mixtures, such as diesel oil and oily sludge, was evaluated. L. sphaericus was able to grow when toluene, naphthalene, or phenanthrene were used as a sole carbon source in minimal salt medium. Removal efficiencies of up to 95% were found for C₁₀-C₂₈ hydrocarbons in the biodegradation assays of diesel oil. The biodegradation of oily sludge was evaluated in landfarming-like experiments in the open air and in completely covered containers in the field. After 50 days of treatment, the removal efficiency of total petroleum hydrocarbons in open-air and closed assays was of 84.1% and 60.1%, respectively. Furthermore, L. sphaericus was able to degrade volatile hydrocarbons (benzene, toluene, ethylbenzene, and phenol) in the headspace of closed containers, preventing the emission of these compounds to the atmosphere. L. sphaericus was herein proposed as a promising candidate to be used in bioremediation strategies of petroleum hydrocarbons.     

石油污染环境中固氮和寡氮营养细菌的分离鉴定及其特性

[背景]石油污染治理中的生物修复因无二次污染、处理成本低等优点受到人们的广泛关注,但由于石油烃向环境中大量输入,导致环境中氮源的相对不足成为制约生物修复效率的关键因素之一,因此筛选能够适应寡氮环境的微生物具有重要的生态意义.[目的]从辽河油田油藏水中筛选在不添加氮源培养基中生长的微生物,为石油污染环境生物修复提供候选菌...     

一株石油烃降解菌的细胞疏水性及其乳化性质

【目的】从新疆油田石油污染土壤中分离到一株在25 °C条件下利用烃类产生生物表面活性剂的菌株红球菌(Rhodococcus sp.) HL-6, 对其菌体细胞疏水性及所产表面活性剂进行研究。【方法】通过细胞粘附性、表面张力及乳化活性测定对菌株所产表面活性剂进行性质研究。【结果】菌株HL-6在亲水性和疏水性基质中均能产生生物表面活性剂, 在疏水性基质中可以将培养液表面张力由初始的62.487 mN/m降到30.667 mN/m, 培养液在pH 6?9及NaCl浓度1%?5%范围内乳化效果良好, 在4 °C到55 °C范围内乳化效果均为100%, 菌株对柴油的耐受能力很高, 在30%柴油浓度下依然生长良好并且有44%的乳化活性。【结论】HL-6菌株的细胞表面具有很强的疏水性, 这有助于菌体细胞对烃类的摄取。该菌株能够利用烃类基质生产生物表面活性剂, 可以明显降低培养液表面张力并且对石油烃具有良好的乳化作用。说明菌株HL-6能够适应海洋滩涂石油污染的环境, 并可用于严重石油污染区域的生物修复。     

A halotolerant Alcanivorax sp. strain with potential application in saline soil remediation

Biodegradation of petroleum compounds in saline environments seems intricate and needs more attention. In this study, tetracosane was used to enrich alkane-degrading bacteria from oil-contaminated saline soils. Among the isolates, strain Qtet3, with the highest 16s rRNA gene sequence similarity to Alcanivorax dieselolei B-5^T, was able to grow at a wide range of NaCl concentrations and was shown by GC analysis to degrade more than 90% of tetracosane in 10 days. This strain has at least two alkB genes and could grow on crude oil and diesel fuel, and utilize various pure aliphatic hydrocarbon substrates (from C₁₂ to C₃₄). Highly hydrophobic cell surfaces and lack of significant surface tension reduction in the media suggest that the main mechanism of the cells for accessing substrate is to attach directly to hydrocarbon particles. Application of this strain for remediating crude oil-contaminated soils irrigated with defined saline water demonstrated that this halotolerant bacterium could survive and grow in saline soils irrigated with NaCl solutions up to 5% w/v, with the highest hydrocarbon degradation of 26.1% observed at 2.5% NaCl. This strain is promising for future industrial applications especially in bioremediation of saline soils and wastes.     

Use of Rice Husk as Bulking Agent in Bioremediation of Automobile Gas Oil Impinged Agricultural Soil

Evaluation of rice husk (RH) as bulking agent in bioremediation of automobile gas oil (AGO) hydrocarbon polluted agricultural soil using renewal by enhanced natural attenuation (RENA) as control was the subject of the present investigation. The effect of different parameters such as total petroleum hydrocarbon (TPH), dehydrogenase activity (DHA), optical density and pH on bioremediation performance were evaluated. The studied parameters such as microbial dynamics, percentage degradation and DHA were found to be higher in RH-amended system and differed significantly with control at P < 0.05. RH resulted in high removal efficiency of 97.85 ± 0.93% under a two-month incubation period, while RENA had lesser removal efficiency of 53.15 ± 3.81%. Overall hydrocarbon biodegradation proceeded very slowly in the RENA particularly from week 0 to 4. Experimental data perfectly fitted into the first-order kinetic and generated high r² values (0.945), first-order degradation constant (0.47 day^?1), and shorter degradation half-life (1.50 d)—t_1/2 = Ln2/K and Ln2 numerically equals to 0.693 and hence written as 0.693/K. Micrococcus luteus and Rhizopus arrhizus were isolated in the present study, which displayed extreme AGO hydrocarbon biodegradative abilities. The use of RH in hydrocarbon-polluted soil significantly increased biodegradation rate and resulted in effective AGO cleanup within 2 months period. Therefore, RH provides an alternative source of bioremediation material in field application for abundant petroleum hydrocarbon soil pollution.     

Effects of carbon and nitrogen sources on rhamnolipid biosurfactant production by <Emphasis Type="Italic">Pseudomonas nitroreducens</Emphasis> isolated from soil

Rhamnolipid biosurfactant production by Pseudomonas nitroreducens isolated from petroleum-contaminated soil was investigated. The effects of carbon, nitrogen and carbon to nitrogen ratio on biosurfactant production were examined using mineral salts medium as the growth medium. The tenso-active properties (surface activity and critical micelle concentrations of the produced biosurfactant were also evaluated. The best carbon source, nitrogen source were glucose and sodium nitrate giving rhamnolipid yields of 5.28 and 4.38 g l⁻¹, respectively. The maximum rhamnolipid production of 5.46 g l⁻¹ was at C/N (glucose/sodium nitrate) of 22. The rhamnolipid biosurfactant reduced the surface tension of water from 72 to ~37 mN/m. It also has critical micelle concentration of ~28 mg l⁻¹. Thus, the results presented in our reports show that the produced rhamnolipid can find wide applications in various bioremediation activities such as enhanced oil recovery and petroleum degradation.     

Inhibition of Virulence Factors of <Emphasis Type="Italic">Candida</Emphasis> spp. by Different Surfactants

Candida yeasts are opportunistic pathogens responsible for infections in immunocompromised individuals. Among the virulence factors present in these yeasts we can mention the ability to adhere to host cells, exoenzyme production and germ tube formation. Several compounds, such as antifungal agents, plants extracts, protein inhibitors and surfactants, have been tested regarding their capacity in inhibit Candida spp. virulence factors. Among these compounds, a significant lower number of works are focused on the inhibition action caused by different types of surfactant. The present work aimed to evaluate the effect generated by the surfactants cetyltrimethylammonium chloride (CTAC), sodium dodecyl sulfate (SDS), N-hexadecyl-N–N′-dimethyl-3-ammonio-1-propane-sulfonate (HPS) and octylphenoxypolyethoxyethanol (Triton X-100) on the viability, adhesion ability and exoenzyme production by Candida species. CTAC and HPS were capable to inhibit Candida spp. growth at very low concentrations. All surfactants demonstrated to be capable to inhibit the adhesion of Candida species to buccal epithelial cells (BEC) and the proteinase production. On the other hand, the phospholipase production remained unaltered after the treatment with these compounds. The present data denote that cationic and zwitterionic surfactants are interesting prototypes of inhibitory agents against Candida spp., which is probably associated with the cationic punctual charge of both surfactants. The results are discussed in details in agreement with recent reports from literature.     

Biomaterial-Associated Infection with Candida albicans in Mice

Candida yeasts are frequently isolated from patients with continuous ambulatory peritoneal dialysis peritonitis or other biomaterial-associated infections. The mouse model of candidal peritonitis was used to study the interaction of Candida cells with end-point attached heparinized polyethylene (H-PE) and with polymorphonuclear leukocytes (PMNs) or macrophages (Mφ). Two Candida strains differing in cell surface hydrophobicity and in expression of fibronectin (Fn) binding were used for the study. Cells of both Candida strains adhered at higher numbers to H-PE surfaces preadsorbed with Fn or with human dialysis fluid (HDF) than to non-modified H-PE, supporting a role of Fn in mediating adhesion. C. albicans 4016 cells expressing low hydrophobicity and low binding of soluble Fn demonstrated stronger adhesion to PMNs than the more hydrophobic C. albicans 3248 yeasts, which express high binding of soluble Fn. However, C. albicans 4016 cells were more resistant to phagocytic killing and were hardly eradicated in intraperitoneally infected mice. The animals depleted in PMNs by treatment with CY were neither able to eradicate C. albicans 3248 (rapidly eliminated by normal mice) nor C. albicans 4016 yeasts (with a tendency to persist in the tissues of normal mice).     

Magnesium-induced biofilm development in Arthrobacter sp. SUK 1201 and removal of hexavalent chromium

This study reports the influence of Mg ions on the development and architecture of biofilms by a chromium resistant and reducing bacterium Arthrobacter sp. SUK 1201 and their utilization in the removal of toxic hexavalent chromium. Among the different metal ions tested, Mg(II) greatly influenced the biofilm growth in peptone yeast extract glucose medium. Both Scanning and Confocal Laser Scanning Microscopy revealed that biofilms formed under the induction of Mg(II) had characteristic higher cell densities. The cells remain embedded in thick porous layers of extracellular polymeric substances as evident from the fluorescein isothiocyanate labeled lectin concanavalin A and 4, 6- diamino-2-phenylindole staining. COMSTAT analysis also indicated maximum thickness and roughness coefficient of the biofilm grown in presence of Mg(II). Biofilms of Arthrobacter sp. SUK 1201 developed under such Mg (II) influenced condition showed complete removal of 0.5 mM Cr(VI) in mineral salts medium. The biofilm of this isolate grown in presence of Mg(II) was also able to remove 60µM Cr(VI) from mine seepage water suggesting its possible implication in effective bioremediation of chromium polluted environments.     

氧化胁迫诱导苍白杆菌JP1形成VBNC状态及其特征

石油降解菌在各种有害环境因素作用下会进入活的非可培养(viable but non-culturable, VBNC)状态，从而影响其生长及石油降解率。为了研究有害环境因素对石油降解菌生长及石油降解率的影响，采用分光光度法、荧光染色-激光共聚焦显微镜观测H₂O₂胁迫下苍白杆菌(Ochrobactrum sp.)JP1细胞的生长及VBNC状态形成情况。结果表明，不同浓度H₂O₂对其生长有一定抑制作用，当培养液中H₂O₂浓度为75.0 mmol/L时，可有效抑制苍白杆菌JP1生长，处理12 h后苍白杆菌JP1进入VBNC状态。VBNC状态的苍白杆菌JP1细胞缩小变成球体，周质间隙增大；在适宜条件下，VBNC状态苍白杆菌JP1能够复苏为可培养状态，添加丙酮酸钠能够促进VBNC状态细菌细胞的复苏。复苏后的苍白杆菌RJP1具有良好的环境适应性和石油降解能力，为石油污染生物修复的菌种筛选及应用提供了新的策略。     

Use of microorganism-immobilized polyurethane foams to absorb and degrade oil on water surface

Highly oil-absorbent polyurethane foam (PUF) materials were obtained by polymerizing polyether polyol mixture and carbodiimide-modified d-methyl diisocyanate in a weight ratio of 10:2. The foam materials were prepared to contain inorganic nutrients (slow-release fertilizer; SRF) and oil-degrading yeast cells, Yarrowia lipolytica 180, to be applied for removal of oil films on surface waters through absorption and biodegradation after oil spills. PUFs absorbed 7–9 times their own weight of Arabian light crude oil and the oil absorbency appeared to improve as the ratio of surface area to foam weight increased. PUFs showed excellent floatability which was maintained for more than 6 months in sea water, and less than 5% of the absorbed oil was released when the foams were left on water for more than 10 days. For immobilization of yeast cells into PUFs, various immobilization techniques were tested to compare their oil degrading ability and the maintenance thereof. All immobilized cells showed oil degrading abilities as good as those of free cells immediately after the preparation of PUFs, however, the activity of chitin-immobilized cells remained at a high level for the longest period of preservation. The high efficiency of oil absorption and oil degradation by PUF-immobilized yeast cells suggested that PUF-immobilized cells have a high potential as a bioremediation technique for the treatment of oil films on surface waters. Received: 27 September 1999 / Received revision: 6 March 2000 / Accepted: 17 March 2000     

Multiple mechanisms may contribute to the adherence ofCandida yeasts to living cells

The adherence ofCandida yeasts to monolayers of human intestinal epithelium was studied in order to determine the specific and nonspecific mechanisms that might contribute to yeast adherence. Multiple factors were shown to significantly affect the adherence of yeasts to intestinal cells. It was demonstrated that hydrophobic yeasts adhered two times greater than normal yeasts, and positively charged yeasts adhered ten times greater than normal yeasts to monolayers of intestinal epithelium. The binding of yeasts to the intestinal cells was saturable and was most effectively blocked by mucin, which caused an 83% reduction in adherence, whereas the addition ofd-glucose caused a 41% reduction in adherence. Aggregation or coadherence of yeasts occurred as the yeast inocula were increased.Candida appears to possess the ability to adhere to living tissue by several mechanisms, such as adhesin-receptor interactions, nonspecific hydrophobic and ionic bonding, and aggregation or coadherence. This is the first demonstration of multiple forces that may act simultaneously in the process of adherence of yeasts to living cells.     

Phytoremediation of Light Crude Oil by Maize (Zea mays L.) Bio-Augmented with Plant Growth Promoting Bacteria

The aim of this study was to evaluate the converged effect of maize and plant growth promoting bacteria on degradation of petroleum hydrocarbons under axenic conditions. Artificially spiked sand with 10 g kg^?1 light crude oil was planted with maize alone and in combination with eight bacterial isolates having plant growth promotion and bioremediation potential to observe the dissipation of petroleum hydrocarbons. Results showed remarkable suppression of maize growth and biomass production due to phytotoxicity of the crude oil contamination. However, bio-augmentation of plants with bacteria having ACC-deaminase activity significantly compensated the reduction in plant growth compared to uninoculated plants. The results revealed that plants bio-augmented with PM32Y exhibited significant increase in root length (75%), plant height (74%), and biomass (67%) as compared to uninoculated plants after 60 days of planting. The same bacterium in convergence with maize caused 43% degradation of petroleum hydrocarbons as compared to the unplanted and uninoculated control. Amplification, sequencing and phylogenetic analysis of 16S rRNA gene sequence identified PM32Y bacterium as Bacillus subtilis strain. It is concluded that bio-augmentation of plants with plant growth promoting bacteria having bioremediation potential and ACC-deaminase activity can successfully be used in phytoremediation of petroleum hydrocarbons.