Biodegradation Of Oil Research Articles

Biodegradation of crude oil in seawater by using a consortium of symbiotic bacteria

This work presents the enhancement of oil biodegradation in seawater using a mixture of oil and microorganisms. Retardation of crude oil biodegradation in seawater is hypothetically due to the inhibiting of metabolites produced by the oil bacterium which inhibit its enzymes. For this purpose, the bacteria consortium consisting of an active oil-oxidizing bacterium (AR3-Pseudomonas pseudoalcaligenes) and two oil-resistant and active heterotrophic bacteria (OG1 and OG2-Erythrobacter citreus) were formed. The heterotrophic bacteria, OG1 and OG2 were able to remove metabolites produced during oil degradation. It was found that AR3 was retarded by metabolites, while OG1 and OG2 were able to grow in the metabolites. OG1 and OG2 were applied together to enhance growth and removal of the metabolites. About 59.9% of crude oil degradation was degraded by AR3 pure culture, while 68.6% was degraded by the bacteria consortium. About 31.4% of the crude oil was found to remain in seawater due to the presence of asphaltenes and resin hydrocarbons. The bacteria consortium was able to degrade 84.1% of total hydrocarbons while 67.0% was degraded by AR3. A total of 99.8% of the aliphatic content and 38.4% of the total aromatic hydrocarbons were degraded by the bacteria consortium, while a lower 79.4% of total aliphatic and 31.0% of total aromatic were degraded by AR3 under the same experimental conditions. The results which were obtained from this study support the hypothesis that the retardation of oil degradation by AR3 is due to the inhibition of metabolites on the growth.

Crude Oil Biodegradation Potential using Acinetobacter baumannii CYA20 and Bacillus subtilis CYA27 from the Bekasi Coast, Indonesia

The pollution of coastal areas caused by oil spills is an environmental issue that needs further attention. Crude oil contains persistent organic pollutants (POPs) that are difficult to degrade. This study aimed to isolate bacterial strains capable of degrading crude oil from the Bekasi coast through bacterial isolate characterization and crude oil biodegradation tests using a crude oil-enriched microcosm model. Two strains with higher TPH degradation values were selected among the isolated bacteria, namely CYA20 and CYA27, which specifically showed values of 46% and 66%, respectively. These strains were tolerant to NaCl concentrations of up to 4% and 12%, respectively, and they were also tolerant to pH values ranging from 5 to 9 and temperatures between 10°C and 50°C. Both strains were shown to utilize POPs, such as phenanthrene and fluorene, produce biosurfactants, and exhibited an emulsification activity in paraffin ranging from 0.373 to 0.533. Phylogenetic analyses identified these bacterial strains as Acinetobacter baumannii CYA20 and Bacillus subtilis CYA27, respectively. The results of this study indicate that these isolates could be developed as biodegradation agents for the bioremediation of crude oil-contaminated environments.

Experimental investigations to enhance the tribological behaviour of biodegradable oil by using manganese doped ZnO/FMWCNTs nanomaterials as lubricant additive

A novel binary hybrid nanomaterial of functionalized multi-walled carbon nanotubes (FMWCNTs) anchored on the surface of manganese doped zinc oxide nanosheets Mn0.10ZnO0.90 (MnZnO) were synthesized by using simple hydrothermal method. Further, the nanomaterials such as zinc oxide (ZnO), functionalized multiwalled carbon nanotubes (FMWCNTs) and ZnO/FMWCNTs hybrid nanomaterials have also been considered to evaluate the influence of doping of manganese in ZnO nanosheets on the tribological properties. The individual nanomaterials and synthesized hybrid nanomaterials were characterized by employing X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), Thermo gravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS) techniques. The tribological performances of ZnO nanoparticles, FMWCNTs, ZnO/FMWCNTs and MnZnO/FMWCNTs hybrid nanomaterials dispersed in castor oil were investigated by a reciprocating ball on disk tribo tester. The castor oil with optimum concentration of 0.10 wt% MnZnO/FMWCNTs hybrid nanomaterials exhibited the superior tribological performance than the castor oil, ZnO, FMWCNTs and ZnO/FMWCNTs hybrid nanomaterial additives and reduced the coefficient of friction and wear volume by 26.21 % and 89.09 % respectively. The outstanding lubricating behaviour of MnZnO/FMWCNTs hybrid nanomaterial are corresponds to the synergistic mechanism of Mn doped ZnO nanosheets and FMWCNTs and formation of boundary film on the frictional surface. The surface characteristics and chemical composition of the worn bronze specimen lubricated with various nanomaterial additives have been examined using FESEM, EDS, optical profilometer and X-ray photoelectron spectroscopy.

Potential Application of Biosurfactant-Producing Bacteria for Bioremediation of Oil Polluted Marine Intertidal Sediments

The removal of oil contaminants in marine intertidal sediments under cold climate is an urgent issue. Although the bioavailability of petroleum hydrocarbons decreases at low temperatures, biosurfactants can promote oil biodegradation. In this study, characteristics of biosurfactants produced by cold-adapted oil-degrading bacteria Planococcus sp. XW-1 were studied. Adding the XW-1 biosurfactant could effectively facilitate the solubility of phenanthrene, pyrene, diesel oil, and crude oil. The solubilization was limited by the number of rings and the molecular weight (WSRphenanthrene = 0.0234; WSRpyrene = 0.0165; WSRdiesel oil = 0.0027; WSRcrude oil = 0.0015). Additional biosurfactants significantly washed out crude oil adsorbed to the sand (reduction from 17.1%, 22.7% to 87.9% and 94.28% in 24 h). With the increase in particle size, the removal efficiency increased from 87.9% to 94.28%. After the addition of biosurfactant, the effect of degradation increased by 20% in 20 days. The results suggest that the biosurfactant-producing bacteria Planococcus sp. XW-1 is a promising candidate used in the in situ bioremediation of petroleum-contaminated intertidal sediment.

Oil biodegradation in permeable marine sediments: Effects of benthic pore-water advection and solute exchange

Oil spills have been recognized as among the worst kinds of environmental disasters, causing severe coastal ecological and economic damages. Although benthic flow and solute fluxes are known to have strong impacts on fate and transport of oil deposited within marine sediments, their endogenous mechanisms still remain to be uncovered. In this paper, simulations of flow and solute transport processes along with hydrocarbon biodegradation were conducted in a cylindrical benthic chamber system to investigate influences of benthic hydrodynamics on oil biodegradation in permeable marine sediments. Results show that ripple-flow interactions create subsurface recirculation cells whereby seawater infiltrates into the benthic sediments at ripple troughs while groundwater discharges near the crests. It results in a spatially varied oil biodegradation rate in marine sediments. Significant oil biodegradation occurs near sediment ripple troughs due to direct oxygen recharge, while biodegradation of oil deposited uphill becomes slow due to limited oxygen replenishment. Oil biodegradation decreases subsurface oxygen content, and consequently impedes discharge of oxygen from benthic sediments. Our results reveal a dynamic interaction between oil biodegradation and benthic flow and solute transport processes, which has strong implications for predicting oil persistence and biodegradation within marine sediments and its associated impacts on benthic biogeochemical processes.

Oil Absorbent Polypropylene Particles Stimulate Biodegradation of Crude Oil by Microbial Consortia.

Oil absorbent particles made from surface-modified polypropylene can be used to facilitate the removal of oil from the environment. In this study, we investigated to what extent absorbed oil was biodegraded and how this compared to the biodegradation of oil in water. To do so, we incubated two bacterial communities originating from the Niger Delta, an area subject to frequent oil spills, in the presence and absence of polypropylene particles. One community evolved from untreated soil whereas the second evolved from soil pre-exposed to oil. We observed that the polypropylene particles stimulated the growth of biofilms and enriched species from genera Mycobacterium, Sphingomonas and Parvibaculum. Cultures with polypropylene particles degraded more crude oil than those where the oil was present in suspension regardless of whether they were pre-exposed or not. Moreover, the community pre-exposed to crude oil had a different community structure and degraded more oil than the one from untreated soil. We conclude that the biodegradation rate of crude oil was enhanced by the pre-exposure of the bacterial communities to crude oil and by the use of oil-absorbing polypropylene materials. The data show that bacterial communities in the biofilms growing on the particles have an enhanced degradation capacity for oil.

Microplastic and oil pollution in oceans: Interactions and environmental impacts

Microplastics (MPs) have been found in oil-polluted oceans, but studies on MPs and oil were still focused on their respective transport, biodegradation, and bioaccumulation. The interactions between MPs and oil in the marine environment remain unknown. MPs would incorporate with oil to form MP-oil agglomerate (MOA), the behaviors of MOA were thus discussed in this study. It was found that the MOA formation resulted in the decreased oil dispersion efficacy and affect marine oil spill response operations. Moreover, oil biodegradation rate would be changed when oil existed as the form of MOA. The slow vertical transport of MOA might lead to wider ocean contamination. MOA would cause much worse impacts on phytoplankton, zooplankton, and high trophic species in the marine environment than MPs or oil individually. MOA assembling with phytoplankton in oceans may reduce carbon dioxide (CO2) transport to deep seas. Exploring the interactions between MPs and oil in the marine environment opened a door for understanding MPs and oil as co-contaminants.

Enzymatic bioprospecting of endophytic Aspergillus niger isolated from Albizia lebbeck (L.) Benth

Endophytic fungi reside inside plants in a mutualistic relationship with the host and produce numerous bioactive compounds, including extracellular enzymes. A rich diversity of endophytic fungi associated with the medicinal plant Albizia lebbeck (L.) Benth was bio-prospected in the present study. Thirty-three isolates obtained from the plant were assessed for secretion of six different extracellular hydrolytic enzymes. The results showed that 38%, 9%, 69%, 16%, 38%, and 13% of the endophytic isolates could produce amylase, protease, lipase, laccase, cellulase, and gelatinase enzymes, respectively. Overall, 78% of the isolates showed positive results for one or the other enzyme. Aspergillus niger (Isolate 8) isolated from the bark proved to be most efficient in producing all the enzymes and was further exploited for various applications. The crude fungal amylase of the isolate helped in 39.08% reduction in biochemical oxidation demand (BOD) of municipal wastewater. Effective blood stain removal from the white cotton cloth was achieved when crude protease was used in combination with detergent. 13.29% biodegradation of vegetable oil was observed using fungal lipase. Dye decolorization of methylene blue (71.65%) and methyl orange (56.53%) was observed by fungal laccase. Saccharification of bagasse (83.94%) and paper (64.93%) was achieved by using fungal cellulase. Complete extraction of silver from waste X-ray films was achieved by crude gelatinase. The results obtained in the present study can further be strengthened using purified enzymes.

Bioremediation of Petroleum Hydrocarbons in the Upper Parts of Sandy Beaches.

The biodegradation of dispersed crude oil in the ocean is relatively rapid (a half-life of a few weeks). However, it is often much slower on shorelines, usually attributed to low moisture content, nutrient limitation, and higher oil concentrations in beaches than in dispersed plumes. Another factor may be the increased salinity of the upper intertidal and supratidal zones because these parts of the beach are potentially subject to prolonged evaporation and only intermittent inundation. We have investigated whether such an increase in salinity has inhibitory effects on oil biodegradation in seashores. Lightly weathered Hibernia crude oil was added to beach sand at 1 or 10 mL/kg, and fresh seawater, at salinities of 30, 90, and 160 g/L, was added to 20% saturation. The biodegradation of oil was slower at higher salinities, where the half-life increased from 40 days at 30 g/L salts to 58 and 76 days at 90 and 160 g/L salts, respectively, and adding fertilizers somewhat enhanced oil biodegradation. Increased oil concentration in the sand, from 1 to 10 mL/kg, slowed the half-life by about 10-fold. Consequently, occasional irrigation with fertilization could be a suitable bioremediation strategy for the upper parts of contaminated beaches. However, dispersing oil at sea is probably the most suitable option for the optimal removal of spilled crude oil from the marine environment.

Biodegradation of Spent Automobile Engine Oil in Soil Microcosms Amended with Cow Dung

The discharge of spent engine oil in terrestrial and aquatic environments constitutes public health and socio-economic hazards. In this study, the potentials of organic waste (cow dung) amendments as biostimulating agents of the indigenous microflora for hydrocarbon biodegradation in soil microcosms deliberately contaminated with spent engine oil (5%v/w) was investigated for a period of 6 weeks. Physico-chemical and microbiological analysis of soil samples was determined using standard methods. A microcosm constructed consists of 8 trays containing 1kg of soil, artificially contaminated with 50ml of spent engine oil and treated with 50g, 100g and 150g of cow dung. Spent engine oil degradation was assessed gravimetrically at weekly interval and chromatographically after 6 weeks of biodegradation treatment. Results of the physico-chemical analysis showed that the pH of soil was 6.56 while nitrate, moisture content, phosphate and total organic content were 0.82mg/kg, 9.28%, 0.73mg/kg and 3.60mg/kg respectively. Microbiological analysis of the soil sample showed that the total heterotrophic bacteria were 3.6x106cfu/g, while total heterotrophic fungal and hydrocarbon utilizing bacteria (HUB) were 2.2x104cfu/g and 7.9 x104cfu/g respectively. The mean value of the total viable counts (TVC) population of hydrocarbon-utilizers was higher in biostimulated soil which ranged from (2.10x105-5.30x109cfu/g) compared with that of control (1.20x105-3.10x108cfu/g). Residual oil concentration showed a more remarkable decrease throughout the incubation period (0.400-0.259mg/g, 0.420-0.218mg/g and 0.410-0.220mg/g for treatments 1, 2 and 3 respectively) when compared to that of control which ranged from 0.400-0.304mg/g. At the end of 6 weeks of microcosms biodegradation studies, percentage degradations of the spent engine oil were 23.81%, 35.29%, 45.45% and 44.94% for CON, T1, T2 and T3 respectively. The result obtained from this study showed that cow dung can be effectively used as a biostimulant during bioremediation of spent engine oil polluted site to enhance biodegradation ability of the indigenous microbial population.

Hydrolysis of Methylumbeliferyl Substrate Proxies for Esterase Activities as Indicator for Microbial Oil Degradation in the Ocean: Evidence from Observations in the Aftermath of the Deepwater Horizon Oil Spill (Gulf of Mexico)

Biological oil weathering facilitated by specialized heterotrophic microbial communities plays a key role in the fate of petroleum hydrocarbon in the ocean. The most common methods of assessing oil biodegradation involve (i) measuring changes in the composition and concentration of oil over time and/or (ii) biological incubations with stable or radio-labelled substrates. Both methods provide robust and invaluable information on hydrocarbon biodegradation pathways; however, they also require extensive sample processing and are expensive in nature. More convenient ways to assess activities within microbial oil degradation networks involve measuring extracellular enzyme activity. This perspective article synthesizes previously published results from studies conducted in the aftermath of the 2010 Deepwater Horizon (DwH) oil spill in the northern Gulf of Mexico (nGoM), to test the hypothesis that fluorescence assays of esterases, including lipase activity, are sensitive indicators for microbial oil degradation in the ocean. In agreement with the rates and patterns of enzyme activity in oil-contaminated seawater and sediments in the nGoM, we found close correlations between esterase activity measured by means of methylumbeliferyl (MUF) oleate and MUF butyrate hydrolysis, and the concentration of petroleum hydrocarbons in two separate laboratory incubations using surface (<1 m) and deep nGoM waters (>1200 m). Correlations between esterase activities and oil were driven by the presence of chemical dispersants, suggesting a connection to the degree of oil dissolution in the medium. Our results clearly show that esterase activities measured with fluorogenic substrate proxies are a good indicator for oil biodegradation in the ocean; however, there are certain factors as discussed in this study that need to be taken into consideration while utilizing this approach.

Mahua oil as an alternative biodegradable collector for the flotation of low-rank high-ash oxidized coals based on kinetic studies

ABSTRACT Flotation of low-rank-oxidized coals is a challenging task for the recovery of carbonaceous material using conventional collectors. The presence of polar hydroxyl, carbonyl, phenols, and other oxygenated functional groups on the surface of such colas influence the hydrophobicity of coals. The present paper summarizes the results of in-depth studies on the analysis of the flotation response of low-volatile-medium coking coal using two types of collectors viz., the conventional Diesel oil and a biodegradable Mahua oil. The performance and response of the flotation to these two reagents have been analyzed through kinetic studies. Further, the presence of oxygenated functional groups and fatty acids in the biodegradable collector markedly enhances the flotation of low-rank-oxidized coals (also called LVMC coal) are compared with the conventional collector diesel oil. The paper recommends that, since biodegradable oil is a natural, renewable, environmentally friendly, nontoxic oil, which has no chemical additives or harmful chemicals, it can be used as an alternative collector for the flotation of low-rank-oxidized coals.

Using structured laser illumination planar imaging (SLIPI) as a new technique to monitor the degradation of biodegradable oils in electrical power transformers

The aging process of the insulating oils of an electrical transformer is initiated as soon as the transformer is put into service. The quality of these oils must therefore be rigorously evaluated to have reliable and exploitable data for decision-making. In general, the decision is to continue monitoring, reclaiming/regenerating, or replacing the oil in extreme cases. Thus, early diagnosis of power transformer oils helps prevent potential breakdowns that could considerably impact the electrical energy transmission and distribution network. This research used an imaging technique called SLIPI (Structured Laser Illumination Planar Imaging) to accurately determine the extinction coefficient in different samples of optically dense biodegradable oils (natural and synthetic esters). The variation in the extinction coefficient as a function of the aging of these biodegradable oils under test has been investigated. The results indicate that the SLIPI is reliable as a diagnostic tool for biodegradable oils in power transformers. This technique could therefore be an alternative solution to the conventional monitoring methods.

Effect of dispersants on bacterial colonization of oil droplets: A microfluidic approach

Bacteria biodegradation of immiscible oil requires cell-droplet encounters, surface attachment, and hydrocarbon metabolism. Chemical dispersants are applied to oil spills to reduce the mean dispersed droplet size, thereby increasing the available surface area for attachment, in attempts to facilitate bacterial biodegradation. However, their effectiveness remains contentious as studies have shown that dispersants can inhibit, enhance, or have no effect on biodegradation. Therefore, questions remain on whether dispersants affect surface attachment or cell viability. Here, using microfluidics and time-lapse microscopy, we directly observe the attachment and growth of the marine bacterium, Alcanivorax borkumensis, on stationary crude oil droplets (5 μm <R < 150 μm) in the presence of Corexit 9500. We show that the average colonization time, or the time comprised of encounters, attachment, and growth, is dependent on droplet size and primarily driven by diffusive encounters. Our results suggest that dispersants do not inhibit or enhance these biophysical processes.

Transcriptome Profiling Reveals Differential Gene Expression of Laccase Genes in Aspergillus terreus KC462061 during Biodegradation of Crude Oil.

Simple SummaryThe Kingdom of Fungi is one of the most significant microorganism kingdoms, especially for soil fungi, which are still unexplored. Soil fungi play an extremely crucial role in the biodegradation of pollutants, mainly hydrocarbons. In this paper, molecular analysis delivers insights into laccase production by Aspergillus terreus KC462061 in the existence of crude oil, which is supported by the presence of five inducers, including aromatic compounds and metal ions. This paper established that the laccase of A. terreus KC462061 plays an essential function in the biodegradation of crude oil, and the synergistic effect of the Cu-ABTS compound caused an increase in laccase yields up to 22-fold after 10 days. This study confirmed that gas chromatography–mass spectrometry was a very accurate tool to demonstrate the biodegradation efficiency of A. terreus KC462061 for crude oil. The synergistic effect of the Cu-ABTS compound has the highest induction level of the transcription profile. Lcc11 and 12 were the main Lcc genes in transcription profiles throughout the life cycle of A. terreus KC462061, and their transcript abundance was correlated with the Cu-ABTS compound. A quantitative real-time polymerase chain reaction (qPCR) was used for the analysis of the transcription profile of eight laccase genes in A. terreus KC462061. Cu-ABTS was highly effective for efficient laccase expression profiling, mainly via Lcc11 and 12 transcription induction.Fungal laccases have high catalytic efficiency and are utilized for the removal of crude oil because they oxidize various aliphatic and aromatic hydrocarbons and convert them into harmless compounds or less toxic compounds, thus accelerating the biodegradation potential of crude oil. Laccases are important gene families and the function of laccases genes varied widely based on transcription and function. Biodegradation of crude oil using Aspergillus terreus KC462061 was studied in the current study beside the transcription level of eight laccase (Lcc) genes have participated in biodegradation in the presence of aromatic compounds, and metal ions. Time-course profiles of laccase activity in the presence of crude oil indicated that the five inducers individual or combined have a very positive on laccase activity. In the status of the existence of crude oil, the synergistic effect of Cu-ABTS compound caused an increase in laccase yields up to 22-fold after 10 days than control. The biodegradation efficiencies of A. terreus KC462061 for aliphatic and aromatic hydrocarbons of crude oil were 82.1 ± 0.2% and 77.4 ± 0.6%, respectively. The crude oil biodegradation efficiency was improved by the supplemented Cu-ABTS compound in A. terreus KC462061. Gas chromatography–mass spectrometry was a very accurate tool to demonstrate the biodegradation efficiencies of A. terreus KC462061 for crude oil. Significant differences were observed in the SDS-PAGE of A. terreus KC462061 band intensities of laccase proteins after the addition of five inducers, but the Cu-ABTS compound highly affects very particular laccase electrophoresis. Quantitative real-time polymerase chain reaction (qPCR) was used for the analysis of transcription profile of eight laccase genes in A. terreus KC462061 with a verified reference gene. Cu2+ ions and Cu-ABTS were highly effective for efficient laccase expression profiling, mainly via Lcc11 and 12 transcription induction. The current study will explain the theoretical foundation for laccase transcription in A. terreus KC462061, paving the road for commercialization and usage.

Cellulosic paper-based membrane for oil-water separation enabled by papermaking and in-situ gelation

Cellulosic paper-based membranes reveal incalculable application values for oil–water separation owing to their renewability and biodegradability. In this work, a cellulosic paper-based membrane was prepared via papermaking and in-situ gelation. The porosity of the membrane can be tailored by pulp refining in papermaking to further adjust the flux of membranes. The as-prepared membrane can separate oil–water emulsion efficiently with separation efficiency > 98.5%. The membranes also showed good underwater oil repellency due to the hydration layer. Besides, the wet strength of the paper-based membranes was enhanced by micro-dissolved and in-situ gelation to suit the underwater separation process. The membrane is expected to be a low-cost, highly-efficient material for oily wastewater purification. This work demonstrates a new idea for the development of oil–water separation and papermaking, which provides a feasible strategy for large scale production of fully biodegradable oil–water separation membranes.

Characterization of two novel strains of Pseudomonas aeruginosa on biodegradation of crude oil and its enzyme activities

Crude oil contaminant is one of the major problem to environment and its removal process considered as most challenging tool currently across the world. In this degradation study, crude oil hydrocarbons are degraded on various pH optimization conditions (pH 2, 4,6,7,8 and 10) by using two biosurfactant producing bacterial strains Pseudomonas aeruginosa PP3 and Pseudomonas aeruginosa PP4. During crude oil biodegradation, degradative enzymes alkane hydroxylase and alcohol dehydrogenase were examined and found to be higher in PP4 than PP3. Biodegradation efficiency (BE) of crude oil by both PP3 and PP4 were analysed by gas chromatography mass spectroscopy (GCMS). Based on strain PP3, the highest BE was observed in pH 2 and pH 4 were found to be 62% and 69% than pH 6, 7, 8 and 10 (47%, 47%, 49% and 45%). It reveals that PP3 was survived effectively in acidic condition and utilized the crude oil hydrocarbons. In contrast, the highest BE of PP4 was observed in pH 7 (78%) than pH4 (68%) and pH's 2, 6, 8 and 10 (52%, 52%, 43% and 53%) respectively. FTIR spectra results revealed that the presence of different functional group of hydrocarbons (OH, –CH3, CO, C–H) in crude oil. GCMS results confirmed that both strains PP3 and PP4 were survived in acidic condition and utilized the crude oil hydrocarbons as sole carbon sources. This is the first observation on biodegradation of crude oil by the novel strains of Pseudomonas aeruginosa in acidic condition with higher BE. Overall, the extracellular enzymes and surface active compounds (biosurfactant) produced by bacterial strains were played a key role in crude oil biodegradation process.

Lab-scale bioremediation technology: Ex-situ bio-removal and biodegradation of waste cooking oil by Aspergillus flavus USM-AR1

Large amounts of waste cooking oil from residential areas can cause adverse effect on the environment if not disposed properly. Fungi have a higher tolerance to hydrocarbon toxicity due to their physiology and adaptation to the environment. Consequently, they can be employed in bioremediation to reduce waste oils release to the environment. This work aims to bio-remove and biodegrade the waste cooking oil using a newly isolated strain Aspergillus flavus USM-AR1, in stirred tank reactor (STR). The strain showed remarkable removal activity of waste cooking oil. The removal efficiency of waste cooking oil reached 97% on day 3 of cultivation. This was attained when the culture was agitated at 400 rpm, maintaining the Reynold’s number of that obtained in the shake flask culture. Fortuitously, the best dispersion of waste cooking oil was also obtained at 400 rpm. The highest cell surface hydrophobicity (MATH) at 76.42% was observed at day 3 of cultivation. The maximum biosurfactant and emulsification activity occurred at day 2 of cultivation, which were 43 mm and 44%, respectively. Cell surface hydrophobicity and biosurfactant produced by strain Aspergillus flavus USM-AR1 played an important role in bio-removal of waste cooking oil, making this strain a prospective candidate for treating waste cooking oil.

Isolation and Characterization of Three New Crude Oil Degrading Yeast Strains, Candida parapsilosis SK1, Rhodotorula mucilaginosa SK2 and SK3

Bioremediation using yeasts is an alternative way to minimize the effects of oil spillage on soil. This paper aims to establish a bioremediation protocol involving the optimization of physicochemical parameters. In this regard, three new yeast strains, SK1, SK2 and SK3, were isolated from hydrocarbon-contaminated samples from the Fez-Meknes region, Morocco. These isolates were identified as new species of Candida parapsilosis (SK1) and Rhodotorula mucilaginosa (SK2 and SK3), respectively, based on the similarity of their ITS region. The kinetic analysis of the process of degradation of petroleum oils are highlighted. These analyses were based on the degradation kinetics, and biomass formation using gravimetric analysis and gas chromatography coupled with mass spectrometry techniques. The strains were able to degrade 68% of the total petroleum hydrocarbon in 21 days, as the sole carbon source. The addition of glucose increased the rate at which crude oil was consumed by the isolates. Our results suggest that inoculants based on Candida parapsilosis (SK1) and Rhodotorula mucilaginosa (SK2 and SK3) cells have potential application in the biodegradation of crude oil and possibly in the degradation of other related aromatic compounds.

From Surface Water to the Deep Sea: A Review on Factors Affecting the Biodegradation of Spilled Oil in Marine Environment

Over the past century, the demand for petroleum products has increased rapidly, leading to higher oil extraction, processing and transportation, which result in numerous oil spills in coastal-marine environments. As the spilled oil can negatively affect the coastal-marine ecosystems, its transport and fates captured a significant interest of the scientific community and regulatory agencies. Typically, the environment has natural mechanisms (e.g., photooxidation, biodegradation, evaporation) to weather/degrade and remove the spilled oil from the environment. Among various oil weathering mechanisms, biodegradation by naturally occurring bacterial populations removes a majority of spilled oil, thus the focus on bioremediation has increased significantly. Helping in the marginal recognition of this promising technique for oil-spill degradation, this paper reviews recently published articles that will help broaden the understanding of the factors affecting biodegradation of spilled oil in coastal-marine environments. The goal of this review is to examine the effects of various environmental variables that contribute to oil degradation in the coastal-marine environments, as well as the factors that influence these processes. Physico-chemical parameters such as temperature, oxygen level, pressure, shoreline energy, salinity, and pH are taken into account. In general, increase in temperature, exposure to sunlight (photooxidation), dissolved oxygen (DO), nutrients (nitrogen, phosphorous and potassium), shoreline energy (physical advection—waves) and diverse hydrocarbon-degrading microorganisms consortium were found to increase spilled oil degradation in marine environments. In contrast, higher initial oil concentration and seawater pressure can lower oil degradation rates. There is limited information on the influences of seawater pH and salinity on oil degradation, thus warranting additional research. This comprehensive review can be used as a guide for bioremediation modeling and mitigating future oil spill pollution in the marine environment by utilizing the bacteria adapted to certain conditions.