Crude Oil Pollution Research Articles

Production of Biofuel from Cassava

An experiment was conducted to produce ethanol/biofuel from cassava flour which reduce both consumption of crude oil and environmental pollution. Cassava flour hydrolysate with standard glucose and sucrose solutions were used as controls. The effects of yeast concentrations (5, 15 and 20%) and fermentation time (24, 48, 72, 96 and 120 h) on alcohol yield from CFH were also studied. The maximum carbon-dioxide evolved during fermentation was 8.57 g recorded by cassava flour hydrolysate while the conversion efficiency of sugars to alcohol was 247.6, 97.14 and 92.51% for cassava flour hydrolysate, standard glucose and sucrose solutions, respectively. Alcohol produced was mostly ethanol with traces of methanol. However, yeast concentrations did not showed any significant effect but fermentation time had significant impact on alcohol yield which suggests that the high yield of alcohol could be obtained from cassava flour hydrolysate.
 Environ. Sci. & Natural Resources, 12(1&2): 171-174, 2019

Combined Effects of Elevated Temperature and Crude Oil Pollution on Oxidative Stress and Apoptosis in Sea Cucumber (Apostichopus japonicus, Selenka).

Currently, global climate change and oil pollution are two main environmental concerns for sea cucumber (Apostichopus japonicus) aquaculture. However, no study has been conducted on the combined effects of elevated temperature and oil pollution on sea cucumber. Therefore, in the present study, we treated sea cucumber with elevated temperature (26 °C) alone, water-accommodated fractions (WAF) of Oman crude oil at an optimal temperature of 16 °C, and Oman crude oil WAF at an elevated temperature of 26 °C for 24 h. Results showed that reactive oxygen species (ROS) level and total antioxidant capacity in WAF at 26 °C treatment were higher than that in WAF at 16 °C treatment, as evidenced by 6.03- and 1.31-fold-higher values, respectively. Oxidative damage assessments manifested that WAF at 26 °C treatment caused much severer oxidative damage of the biomacromolecules (including DNA, proteins, and lipids) than 26 °C or WAF at 16 °C treatments did. Moreover, compared to 26 °C or WAF at 16 °C treatments, WAF at 26 °C treatment induced a significant increase in cellular apoptosis by detecting the caspase-3 activity. Our results revealed that co-exposure to elevated temperature and crude oil could simulate higher ROS levels and subsequently cause much severer oxidative damage and cellular apoptosis than crude oil alone on sea cucumber.

Negative impacts of mining on Neotropical freshwater fishes

Abstract Mining activities have significantly affected the Neotropical freshwater ichthyofauna, the most diverse in the world. However, no study has systematized knowledge on the subject. In this review, we assembled information on the main impacts of mining of crude oil, gold, iron, copper, and bauxite on aquatic ecosystems, emphasizing Neotropical freshwater fishes. The information obtained shows that mining activities generate several different disturbances, mainly via input of crude oil, metals and other pollutants, erosion and siltation, deforestation, and road construction. Mining has resulted in direct and indirect losses of fish diversity in several Neotropical waterbodies. The negative impacts on the ichthyofauna may change the structure of communities, compromise entire food chains, and erode ecosystem services provided by freshwater fishes. Particularly noteworthy is that mining activities (legal and illegal) are widespread in the Neotropics, and often located within or near protected areas. Actions to prevent and mitigate impacts, such as inspection, monitoring, management, and restoration plans, have been cursory or absent. In addition, there is strong political pressure to expand mining; if – or when – this happens, it will increase the potential of the activity to further diminish the diversity of Neotropical freshwater fishes.

Biodegradation of buried crude oil in soil microcosm by fungal co-culture

Crude oil pollution in soil is a major environmental problem over the world. After long-term contamination, crude oil can be buried in the soil and leaving the toxic and persistence compounds. Treatment of buried crude oil in soil is a major challenge. In this study, buried crude oil in soil (20 cm-depth) was treated by the co-culture of three fungal strains (Pestalotiopsis sp. NG007/Polyporus sp. S133/Trametes hirsuta D7 with composition 1/1/1 and pre-grown in wood meal) placed on the top or bottom layer of the soil. Biodegradation behavior of crude oils were analyzed at different depth interval (0–5 cm, 5–15 cm, and 15–20 cm) with constant oxygen diffusion. The results showed that both position of fungal co-culture could degrade crude oil 63 – 92% after 30 days. Placing the co-culture in the bottom layer position of the soil demonstrated more effective degradation for all the depth interval than that of the top layer position. During the biodegradation, the co-culture produced oxidative enzymes such as catechol 1,2-dioxygenase, catechol 2,3-dioxygenase, laccase, manganese peroxidase, and lignin peroxidase with significant activities. This study offers an important strategy to remediate crude oil contaminated soil, specifically buried crude oil.

Response of oligotrophic coastal microbial populations in the SE Mediterranean Sea to crude oil pollution; lessons from mesocosm studies

Anthropogenically-induced oil spills release large amounts of organic pollutants into the marine environment. To date, little is known about the response of microbial populations (biomass, activity and diversity) to crude oil pollution in Low Nutrients Low Chlorophyll and warm systems. Here, we investigated the daily dynamics of phytoplankton and heterotrophic bacteria in response to an oil spill (500 μm thick layer) in the coastal waters of the SE Mediterranean Sea (SEMS), using mesocosms during winter and summer. Crude oil addition caused a marked decrease in phytoplankton biomass (40–76%) and production rates (22–96%), whereas heterotrophic bacterial abundance and production increased (4–68% and 17–165%, respectively). Concurrently, amplicon sequencing of the 16S rRNA gene revealed that oil-degrading bacteria became abundant 48–96 h post-oil addition, while the cosmopolitan Synechococcus and SAR11 lineages were significantly reduced (by 78–98% and 59–98%, respectively). Fertilization with inorganic nutrients (NO3 and PO4) reduced the deleterious effects of the oil, resulting in a less distinct reduction in phytoplankton biomass/abundance. Our results highlight the potential of intrinsic microbial communities to degrade oil-derived pollutants in oligotrophic coastal waters.

Histopathological effects and biomarker response of earthworms, Eisenia fetida, after exposure to crude oil contaminated soils.

Earthworms are the most abundant invertebrates in the soils and are permanently in close contact with soil particles. Therefore, they are significantly affected by the pollutants that reach the soil system. The study was aimed at evaluating the effect of exposure to crude oil contaminated soil on Eisenia fetida using cellular antioxidant enzymes and tissue organization as biomarkers. E. fetida were exposed to different concentrations of crude oil contamination of 1 mL, 2 mL. and 3 mL (0.25, 0.50 and 0.75%) for 14 days. The antioxidant/oxidant parameters were analysed in the muscle and liver tissues. The results showed that only the reduced glutathione (GSH) of earthworms exposed to 1 mL were not significant (p>0.05) from the control, while the other concentrations (2 mL – 0.50% and 3 mL – 0.75%) were significantly different (p<0.05) from the control. The activity of catalase (CAT) with respect to the total protein content was highest in the liver of earthworms exposed to 1 mL (0.25% conc.) on day 7 (51.84 μmol/mg pro) while the least CAT activity with respect to the total protein content was reported in the liver of control earthworms after 14 days (19.51 μmol/mL/min). A significant increase in the activity of superoxide dismutase at all the concentrations (0.25, 0.50 and 0.75%) after 14 days were also observed. Significant histopathological alterations were observed in E. fetida from the three concentrations. Severe disruptions in the arrangement of their body wall muscle layers, distorted internal viscera, as well as cellular degeneration, pigments, moderate to severe areas of lesion, and distortion of the shape of circular and longitudinal muscles, eroding of internal and external tissues leading to total destruction of body wall were observed. In conclusion, the study revealed that crude oil even at lower concentration induced biomarker responses in E. fetida such as higher levels of Malondialdehyde in E. fetida after exposure crude oil due its toxicity. Histopathological alterations such as cellular degeneration, moderate to severe areas of necrosis, areas of inflammation, inclusion bodies, pigments, and distortion of the shapes of circular and longitudinal muscles also showed the adverse impacts of crude oil pollution in the soils.

Biochemical Studies Reveal Remarkable Influence of Bioremediation Treatments on Health Status of Crude Oil Polluted Soil and Oxidative Stress in Selected Plants

Oil spillage is a challenging global problem which requires urgent search for effective clean-up strategies to conserve the ecosystem. In this study, effects of crude oil pollution and bioremediation treatments on soil health and plant growth were investigated. Agricultural soil was polluted with crude oil ranging from 5.0 to 25.0 mL per kg soil. Three food crops, maize (Zea mays), soybean (Glycine max) and amaranth (Amaranthus cruentus) were planted and grown in three groups; Group I comprised plants on polluted soils without any treatment. Group II were plants on polluted soils exposed to bioremediation treatments using biostimulation and bioaugmentation methods. Group III comprised plants on clean soil which served as control. Experiments were carried out in triplicates. Soil enzyme activities and physicochemical parameters were determined using standard assay and evaluation procedures. Growth parameters, proximate composition and oxidative stress indicators of maize, soybean and amaranth plants were monitored over 120 d experimental period. Results indicated significant inhibition (p &amp;lt 0.05) of activity of soil enzymes (dehydrogenase, β-glucosidase, acid phosphatase, arylsulphatase, amidase and protease) by crude oil pollution. The trend was significantly reversed in bioremediated soils with significant enhancement of enzyme activity. Height of plant and number of leaves significantly decreased (p &amp;lt 0.05) with increasing concentration of crude oil polluted soil. Improvement in plant growth parameters was recorded in soils bioremediated with inorganic and organic fertilizers. Levels of oxidative stress indicators (superoxide dismutase, catalase and peroxidase) and malondialdehyde from stem of plants grown on bioremediated soils significantly reduced compared with polluted soil. GC-MS analysis revealed more significant level of crude oil degradation in soil bioremediated with inorganic fertilizer (NPK). Results established the efficacy of bioremediation treatments in alleviating toxicity of crude oil pollution in agricultural soils and revealed biostimulation using NPK and cow dung (organic fertilizer) as a more effective strategy.

Crude oil pollution and biodegradation at the Persian Gulf: A comprehensive and review study.

The Persian Gulf consider as the fundamental biological marine condition between the seas. There is a different assortment of marine life forms including corals, wipes, and fish in this marine condition. Mangrove timberlands are found all through this sea-going biological system. Sullying of the Persian Gulf to oil-based goods is the principle of danger to this marine condition and this contamination can effectively affect this differing marine condition. Numerous specialists examined the result of oil contamination on Persian Gulf marine creatures including corals sponges, bivalves, and fishes. These analysts affirmed this oil contamination on the Persian Gulf significantly diminished biodiversity. Diverse microorganisms fit to consume oil-based commodities detailed by various scientists from the Persian Gulf and their capacity to the debasement of unrefined petroleum has been examined. There has additionally been little exploration of cyanobacteria, yeast, and unrefined petroleum debasing organisms in this sea-going environment. Biosurfactants are amphipathic molecules that upgrade the disintegration of oil and increment their bioavailability to corrupt microscopic organisms. Additionally, biosurfactant-producing bacteria were discovered from the Persian Gulf, and the capability to degradation of crude oil in microscale was evaluated. The current review article aims to collect the finding of various researches performed in the Persian Gulf on oil pollution and crude-oil biodegradation. It is expected that by applying biological methods in combination with mechanical and chemical methods, the hazard consequences of crude-oil contamination on this important aquatic ecosystem at the world will be mitigated and a step towards preserving this diverse marine environment.

The potential use of Cordia myxa in the remediation of crude oil pollution

This study investigated the effects of hydrocarbon-degrading bacteria and organic matter on a crude oil-polluted soil by Cordia myxa. The treatments consisted of crude oil at two levels (3 and 6% w/w), municipal waste compost at two levels (5 and 10% v/v), and two different bacterial strains (Pseudomonas sp.141 and Pseudomonas sp. 27ps). At the end of the growth period, the plants were harvested and prepared for the laboratory analyses. The greatest population of oil degrading-bacteria (4.6 × 106 CFU/g soil) was observed in the treatment containing 10% compost, 6% crude oil, and Pseudomonas sp.141. The highest crude oil degradation (76.49%) was recorded in the soil polluted with 6% crude oil, amended with 10% compost, and inoculated with Pseudomonas sp.141. The investigation on the degradation of the chains of C10–C35 compounds indicated that, in various treatments, the most abundant compound was among those with fewer carbon atoms (C12–C25), so the application of organic matter boosted the degradation of crude oil. In conclusion, C. myxa seedlings has an acceptable efficiency in the remediation of the oil-contaminated soil affected by biological factors (compost and Pseudomonas bacteria), which is because of their high tolerance to the pollution and their ability to penetrate deeper soil layers.

Characterization of Autochthonous Bacterial Isolates with The Potentiality to Degrade Spent Engine Oil from Contaminated Soil Area Enriched with Glycine max

This study was conducted to identify and characterize bacteria capable of degrading spent oil contaminated soil. The physicochemical parameters of used engine oil were analyzed according to existing standards, while the total heterotrophic plate counts (HBC) and hydrocarbon utilizing bacteria counts were ascertained with the pour plate methods using nutrient agar and minimal salt agar (MSA) media respectively. The results indicated a mean total HBC ranging from 2.86 ± 0.08 to 5.76 log10 CFU/g and mean hydrocarbon utilizing bacterial counts from 1.32 ± 0.09 to 3.82 ± 0.25 log10 CFU/g, with samples enriched with Glycine max (Soybean) recorded to have the highest bacterial counts. The phenotypic identification of the hydrocarbon utilizing bacteria as sources of carbon and energy showed the presence of two primary bacterial genera: Bacillus and Micrococcus.However, from the overall 50 counted colonies, the frequency of occurrence for Bacillus was 41 (82 %) whereas, the Micrococcus was (9) 18%. The obtained data, confirmed the breakdown capacity of autochthonous (indigenous) organisms notably; Bacillus in the reduction of pollutants linked with oil spillage. This provides for reliable and promising approach of ameliorating crude oil pollutants and its inherent threats. &#x0D; Keywords: Soil, spent oil, Glycine max, degrading bacteria, isolation and bioremediation

The effect of cassava effluent and empty oil palm fruit bunch on remediation of petroleum polluted soil and crop production in the tropics: A review

Purpose There is an increased demand for proper utilization of wastes to benefit humans especially as it relates to generation of economic gains. Although the agro-based industry and the petroleum industry contribute to high levels of waste generation, it is possible that the wastes from the agro industry could be used for management of petroleum hazards and pollution. This review focuses on the identification of potential benefits of two highly ignored agro wastes: cassava effluent and empty oil palm bunch, which contribute to the emission of greenhouse gases and increasing the disease causing potentials of these wastes for people living where they are disposed. Methods In this review, we utilized available literature to reveal the importance of agro wastes as well as their different beneficial applications especially as they concern the remediation of crude oil pollution. Results Evidence from previous research indicates that cassava effluent contains some beneficial nutrient components that negatively affect soil chemistry and plant growth. The use of empty oil palm bunch, on the other hand, has been reported to contribute to the improvement of soil nutrient properties and crop production. Conclusion We postulate that the chemical constituent of these two agricultural wastes may significantly complement their ability to improve crop production when combined, as well as mediate cleanup of soils exposed to crude oil pollution over time.

Functional Gene Diversity of Selected Indigenous Hydrocarbon-Degrading Bacteria in Aged Crude Oil.

Crude oil pollution has consistently deteriorated all environmental compartments through the cycle of activities of the oil and gas industries. However, there is a growing need to identify microbes with catabolic potentials to degrade these pollutants. This research was conducted to identify bacteria with functional degradative genes. A crude oil-polluted soil sample was obtained from an aged spill site at Imo River, Ebubu, Komkom community, Nigeria. Bacteria isolates were obtained and screened for hydrocarbon degradation potential by turbidometry assay. Plasmid and chromosomal DNA of the potential degraders were further screened for the presence of selected catabolic genes (C230, Alma, Alkb, nahAC, and PAHRHD(GP)) and identified by molecular typing. Sixteen (16) out of the fifty (50) isolates obtained showed biodegradation activity in a liquid broth medium at varying levels. Bacillus cereus showed highest potential for this assay with an optical density of 2.450 @ 600 nm wavelength. Diverse catabolic genes resident in plasmids and chromosomes of the isolates and, in some cases, both plasmid and chromosomes of the same organism were observed. The C230 gene was resident in >50% of the microbial population tested, while other genes occurred in lower proportions with the least observed in nahAC and PAHRHD. These organisms can serve as potential bioremediation agents.

Hazard quotient, microbial diversity, and plant composition of spent crude oil-polluted soil

BackgroundThe present work assesses the concentration of some heavy metal, plant species composition, and microbial diversity of spent crude oil-polluted soil from electric generator plant house, auto mechanic workshop, bakery, and auto spare part shops in four local governments areas (Egor, Ikpoba-Okha, Oredo, and Ovia North) in Edo State, Southern Nigeria.ResultsHazard quotient (HQ) of heavy metals varied in all the spent crude oil-polluted soil evaluated in the study. The HQ of heavy metals from auto mechanic workshop had the highest values for Cr (2.19), Mn (0.0965), Zn (4.1108), Fe (9.32015), and Cd (0.0155). The most frequent bacterial and fungal species found in all 16 sites were Bacillus subtilis (93.75%) and Aspergillus niger (100.0%) respectively. Auto spare part shops in Oredo had a bacterial count of 1.0 × 105 CFU/g while the bacteria count around power generator plants in Egor had a bacteria count of 1.71 × 105 CFU/g. Some of the plant species identified around all the sites include Acanthospermum hispidum, Alternanthera repens, Axonopus compressus, Cyperus esculentus, Eleusine indica, Paspalum scrobiculatum, and Tridax procumbens.ConclusionSpent crude oil pollution of the soil led to high amounts of heavy metal in the soil. However, the presence of higher plants and variable diversity and richness of microorganisms found in the soil are likely contributing to the remediation of the polluted soil.

Microbiological and Physicochemical Assessment of Sediment in Bodo Community, Rivers State, Niger Delta

Crude oil pollution is common place in the Niger Delta despite well known adverse effects on aquatic and terrestrial biodiversities. Triplicate sediment samples were obtained from Bodo community in Ogoni Land, Niger Delta and made into a composite sample. The sample was then evaluated for physicochemical parameters, heavy metals, total petroleum hydrocarbon (TPH), polyaromatic aromatic hydrocarbon (PAH), total heterotrophic bacteria (THBC), and fungi (THFC) using standards methodologies. Concentration profile of heavy metals was iron (Fe) &gt; chromium (Cr) &gt; zinc (Zn) &gt; nickel (Ni) &gt; vanadium (V) in decreasing order. Furthermore, the concentrations of total nitrogen, total phosphorus, nitrate, sulphate were 884.53, 12.32, 34.45, and 26.76 mg/kg, respectively. TPH and PAH concentrations were 30,797 and 52.12 mg/kg, respectively. Nitrate, iron, chromium, nickel, TPH, and PAH all failed to meet regulatory standards. TPH failed to meet Environmental Guidelines and Standards for the Petroleum Industry in Nigeria (EGASPIN) target and intervention values of 50 and 5,000 mg/kg, respectively. Total heterotrophic bacteria and fungi counts were observed to decrease with days of incubation in crude oil. The findings in the study reveal worrisome levels of TPH, PAH, iron, chromium, and nickel, and impact on microbial diversity. Thus, there is a need for periodic monitoring of sediments and water bodies in the Niger Delta.

Isolation and Characterization of Crude Oil Degrading Bacteria in Association with Microalgae in Saver Pit from Egbaoma Flow Station, Niger Delta, Nigeria

The capability of indigenous bacteria and microalgae in crude oil effluents to grow in and utilize crude oil as their sole source of carbon and energy provides an environmentally friendly and economical process for dealing with crude oil pollution and its inherent hazards. In view of the toxicity of crude oil spillages to indwellers of the affected ecosystems and the entire affected environment, the isolation of pure bacterial and microalgae cultures from crude effluents is a step in the right direction, particularly for bio-augmentation or bioremediation purposes. The total heterotrophic bacteria count and hydrocarbon utilizing bacteria count, as well as the microalgae count, were determined with the pour plate technique. The physicochemical properties of the effluent samples were also analyzed. Identification of the hydrocarbon utilizing bacteria was performed with phenotypic techniques. The result shows a mean total heterotrophic bacterium count of 5.91 log CFU/ml and a mean microalga count of 4.77 log cells/ml. When crude oil and polycyclic aromatic hydrocarbon (PAH) were used as sole carbon sources, total hydrocarbon utilizing bacteria counts were respectively estimated at 3.89 and 2.89 log CFU/ml. Phenotypic identification of hydrocarbon utilizing bacteria in the crude oil effluents revealed the presence of two main bacterial genera: Streptococcus and Pseudomonas. Data obtained from this study confirmed the biodegradative abilities of indigenous bacterial species, thus, ultimately resulting in the amelioration of the toxicity associated with the crude oil effluents.

Influence of a mycorrhizal fungus and mineral fertilizer on the performance of Costus lucanusianus under crude oil contaminated soil

Considering the detrimental effects of crude oil pollution on plants, and its implications on food security and environmental safety, it becomes imperative to screen for plants with strong tolerance to crude oil contaminated soil. This study was conducted to assess the influence of arbuscular mycorrhizal fungus (AM) and a mineral fertilizer (NPK 15 15 15 grade), on the performance of African spiral ginger (Costus lucanusianus) plant, under crude oil contaminated soil. About 10 kg of sterilized soil was contaminated with Bonny light crude oil at different concentrations of; 0, 200, 300 and 500 ml/ pot. Moreover, a fertilizer (i.e. NPK) was applied at three different levels (0, 0.7 and 1.2 g/ pot) to the crude oil contaminated soil in the pots, and then inoculated with arbuscular mycorrhizal (AM) fungus; consisting of 20 g of Glomus clarum. After that, Costus lucanusianus was planted in the pot soil by stem cuttings. Results of this greenhouse assay involving; the residual total petroleum hydrocarbon (TPH) content of the soil, plant height, number of leaves, fresh and dry weights, percent of mycorrhizal root colonization, and fungal total colony count, were collected at 4, 8 and 12 weeks after planting (WAP). Current results showed that mycorrhizal inoculation and fertilizer application enhanced the tolerance and growth of C. lucanusianus plant to the crude oil contaminated soil. Mycorrhizal inoculation and NPK fertilizer application at 1.2 g/ pot recorded higher and significantly (p < 0.05) different plant height, number of leaves, fresh and dry weights of C. lucanusianus. The TPH degradation and removal was higher in soil inoculated with AM, compared to non AM inoculated control treatments. Similarly, NPK fertilizer application also resulted in lower residual TPH content in the crude oil contaminated soil, compared to the control. Combined AM colonization and NPK fertilizer application resulted in improved physiological parameters of the C. lucanusianus plant.

Highlighting the Crude Oil Bioremediation Potential of Marine Fungi Isolated from the Port of Oran (Algeria)

While over hundreds of terrestrial fungal genera have been shown to play important roles in the biodegradation of hydrocarbons, few studies have so far focused on the fungal bioremediation potential of petroleum in the marine environment. In this study, the culturable fungal communities occurring in the port of Oran in Algeria, considered here as a chronically-contaminated site, have been mainly analyzed in terms of species richness. A collection of 84 filamentous fungi has been established from seawater samples and then the fungi were screened for their ability to utilize and degrade crude oil. A total of 12 isolates were able to utilize crude oil as a unique carbon source, from which 4 were defined as the most promising biodegrading isolates based on a screening test using 2,6-dichlorophenol indophenol as a proxy to highlight their ability to metabolize crude oil. The biosurfactant production capability was also tested and, interestingly, the oil spreading and drop-collapse tests highlighted that the 4 most promising isolates were also those able to produce the highest quantity of biosurfactants. The results generated in this study demonstrate that the most promising fungal isolates, namely Penicillium polonicum AMF16, P. chrysogenum AMF47 and 2 isolates (AMF40 and AMF74) affiliated to P. cyclopium, appear to be interesting candidates for bioremediation of crude oil pollution in the marine environment within the frame of bioaugmentation or biostimulation processes.

Acute toxicity and hematological indices and biochemical parameters of giant sturgeon, Huso huso after acute exposure to crude oil

This study was conducted to assess the effect of crude oil on some immunophysiological variables of Huso huso weighing 8.5±1g at 22°C. The 96h-LC50 value was first measured under static conditions and hematological and biochemical parameters were then assessed in treated fish exposed to 96h-LC50. The LC50- 96h of 17.4 mg L-1 was obtained. The leucocyte and erythrocyte counts were declined in the treatments compared to the control, while the mean corpuscular volume and hematocrit were significantly higher than those in the fish exposed to crude oil LC50 concentration. An increase in serum glucose was seen in sera samples of the treatments while levels of alanine aminotransferase, alkaline phosphatase and lactate dehydrogenase were lower than those the control. The alterations of the hemato-biochemical parameters can be used as suitable biomarkers in monitoring of crude oil pollution in the aquatic environment and to protect aquatic organisms such as great sturgeon.

Bioremediation treatment improves water quality for Nile tilapia (Oreochromis niloticus) under crude oil pollution.

Despite favorable publicity of bioremediation as an affordable technology for cleanup of crude oil, public concerns on ecological safety in the presence of residual oil remain a global challenge. In this study, effects of crude oil exposure at sublethal concentration (0.25% v/v) and bioremediation treatment were investigated on histology and biochemical parameters of organs (gills, liver, kidney, and brain) of juvenile Nile tilapia (Oreochromis niloticus). Ten percent (10%) of mixed bacterial culture was used for bioaugmentation treatment. Ninety juvenile fish were used for study, and experiments were carried out in triplicates for three different groups. Malondialdehyde (MDA), an index of lipid peroxidation, was assayed as biomarker for oxidative stress. Activities of antioxidant enzymes (superoxide dismutase (SOD) and catalase (CAT)), level of non-enzymatic antioxidant (reduced glutathione (GSH)), and activity of brain acetylcholinesterase (AChE) were assayed in selected fish organs as markers for environmental stressor. Histological examination of fish organs was done for all groups. Results of treated groups were compared with those of the control. Levels of MDA significantly increased with significant inhibition of antioxidant enzyme activities in the polluted group. Activities of SOD, CAT, and AChE and levels of GSH in fish organs in the bioaugmentation group were similar to results obtained in the control. Remarkably, the bioaugmentation group showed minimal or no lesions which suggested the efficacy of bioremediation technique in alleviating crude oil toxicity and preserving normal physiology of fish. This study provides deeper insights into the ecosafety of bioremediation treatment and can be extrapolated to other species of fish.

Remediation of Crude Oil-Polluted Soil by the Bacterial Rhizosphere Community of Suaeda salsa Revealed by 16S rRNA Genes.

Crude oil pollution of soil is a serious environmental issue, and bioremediation using plants and microorganisms is a natural and sustainable method for its restoration. Pot incubation of a two-factor randomized block (plants with two levels, and crude oil with three levels) was designed to investigate the rhizosphere bacterial community of Suaeda salsa (L.) Pall. Crude oil contamination of soil was studied at different levels: 2 g/kg (low), 4 g/kg (medium), and 6 g/kg (high) levels. In this study, the physicochemical properties of the collected rhizosphere soil were analyzed. Moreover, the soil bacteria were further identified using the 16S rRNA gene. The effects of S. salsa and crude oil and their interaction on the physiochemical properties of the soil and crude oil degradation were found to be significant. Crude oil significantly influenced the diversity and evenness of bacteria, while the effects of S. salsa and interaction with crude oil were not significant. Proteobacteria were found to be dominant at the phylum level. Meanwhile, at the genera level, Saccharibacteria and Alcanivorax increased significantly in the low and medium contamination treatment groups with S. salsa, whereas Saccharibacteria and Desulfuromonas were prevalent in the high contamination treatment group. High crude oil contamination led to a significant decrease in the bacterial diversity in soil, while the effects of S. salsa and its interaction were not significant. Despite the highest abundance of crude oil degradation bacteria, S. salsa reduced crude oil degradation bacteria and increased bacteria related to sulfur, phosphorus, and nitrogen cycling in the low and high contamination group, whereas the opposite effect was observed for the medium contamination treatment group. The abundance of most crude oil degradation bacteria is negatively correlated with crude oil content. Nitrogen cycling bacteria are sensitive to the total nitrogen, total phosphorus, ammonia nitrogen, and nitrate nitrogen, and pH of the soil. Sulfur cycling bacteria are sensitive to aromatic hydrocarbons, saturated hydrocarbons, and asphaltene in soil. This research is helpful for further studying the mechanism of synergistic degradation by S. salsa and bacteria.