Hydrocarbon-utilizing Bacteria Research Articles

From Killer to Solution: Evaluating Bioremediation Strategies on Microbial Diversity in Crude Oil-Contaminated Soil over Three to Six Months in Port Harcourt, Nigeria

The study aimed to evaluate the efficacy of various bioremediation approaches on microbial diversity in crude oil-contaminated soil over three to six months in Port Harcourt, Nigeria. The objective was to assess the impact of different bioremediation strategies on microbial populations, particularly focusing on hydrocarbon-utilizing bacteria and fungi. Microbial populations were quantified using serial dilution and microbial count techniques. The vapor phase transfer mechanism was employed to estimate hydrocarbon-utilizing bacteria and fungi. Bacterial and fungal colonies were incubated for five days, followed by biochemical tests for isolate identification. Fungal pure cultures were observed under a microscope. The study observed a significant increase in microbial populations in soil free of crude oil pollution when bioremediators such as mushrooms and earthworms were introduced. Mushrooms exhibited a 50% increase in hydrocarbon-utilizing bacteria (HUB), while earthworms showed a 55% increase in HUB over the three to six-month period. The longer lifespan and nutrient absorption capabilities of earthworms facilitated faster growth. Furthermore, significant growth in the microbial population of hydrocarbon-utilizing bacteria and fungi was observed in crude oil-polluted soil after employing bioremediation, with the highest growth observed in soil treated with mushrooms at six months, followed by earthworms at six months. Conversely, the lowest microbial population was recorded in soil polluted with 10% crude oil and remediated with earthworms at three months. The results suggest that mushrooms and earthworms effectively increase microbial populations in crude oil-polluted soil. However, mushrooms demonstrated a higher microbial population increase compared to earthworms, especially in terms of promoting the growth of hydrocarbon-utilizing bacteria (HUB) and hydrocarbon-utilizing fungi (HUF). Based on the findings, it is recommended to prioritize using mushrooms as bioremediation agents in similar environmental restoration efforts due to their superior efficacy in increasing microbial populations, particularly HUB and HUF. This study underscores the potential of mushrooms and earthworms as effective bioremediation agents for restoring microbial diversity in crude oil-contaminated soil, offering insights for sustainable environmental restoration practices in oil-affected regions like Port Harcourt, Nigeria.

Culture-Dependent Characterization of Hydrocarbon Utilizing Bacteria and Fungi from an Artisanal Crude Oil Refining Site

Crude oil refining is a global insert responsible for the production of a wide array of petroleum based products crucial for various sectors including energy, transportation, and manufacturing. However, the artisanal form of crude oil refining, often characterized by its small scale and limited technological infrastructure, has emerged as a major environmental concern in several regions around the world. Illegal refining of crude oil has led to oil spillages which in turn lead to a disruption of the microbial population of the soil. Hence, the aim of this study was to isolate and characterize the heterotrophic and hydrocarbon utilizing bacteria and fungi from an artisanal crude oil refining site. A total of thirty six (36) soil samples were collected from three (3) artisanal crude oil refining sites at iwofe, ogbogoro and ibaa community all in Rivers State, Nigeria. The samples were collected using soil auger and subjected to standard microbiological procedures such as culturing, isolation and identification. The results revealed significantly elevated levels of heterotrophic and hydrocarbon utilizing bacteria and fungi in the soil samples, with notable variations (p≤0.05) across the different artisanal crude oil refining sites. Total Heterotrophic Bacteria (THB) counts ranged from 3.75x105CFU/g in Iwofe to 2.70x105CFU/g in Ibaa, Total heterotrophic Fungal (THF) counts ranged from 2.80x104CFU/g recorded in Ogbogoro to 1.45x104CFU/g recorded in Iwofe, Hydrocarbon Utilizing Bacteria (HUB) counts ranged from 2.25x103CFU/g in Ibaa to 1.30x103CFU/g in Iwofe and Hydrocarbon Utilizing Fungi (HUF) counts ranged from 2.50x102CFU/g recorded in Ogbogoro to 1.40x102CFU/g recorded in Ibaa community with significant differences (p≤0.05). Bacteria isolated and characterized from the soil include Enterobacter, Pseudomonas putida, Serratia and Bacillus amyloliquefaciens while fungi include Fusarium, Aspergillus, Penicillium and Mucor. The microorganisms identified in this study have been reported to play key roles in the utilization of crude oil. Pseudomonas and Bacillus were the most dominant bacterial isolates and their dominance could imply that the soil could support the growth of crops. Thus, while they utilize the hydrocarbons, they also serve as plant-growth promoting microorganisms. Although some of the microorganisms in the present study have been reported to promote the growth of plant, the dumping of crude oil products legal or illegal should be minimized to avoid the extinction of plant-promoting microorganisms.

Identification of Catabolic Genes Involved in the Degradation of Used Engine Lubricant- Contaminated Soil by Lysinibacillus odysseyi and Bacillus sp. (in: firmicutes)

This study aimed to identify selected catabolic genes in two indigenous hydrocarbon-degrading bacteria involved in the biodegradation of used engine lubricant-contaminated soil. Used engine lubricant-contaminated and uncontaminated soil samples were collected, and their physicochemical characteristics were evaluated. The results indicated that water holding capacity, potassium, nitrogen, and phosphate were higher in used lubricant-uncontaminated soil than in used lubricant-contaminated soil but vice versa for pH, total carbon, cation exchange, organic carbon, nickel, and lead levels. Culturable heterotrophic and hydrocarbon-utilizing bacterial counts were carried out on both Nutrient agar and Mineral Salt Medium (MSM) amended with used engine lubricant. The counts for heterotrophic bacteria (3.8×108±0.21 cfu/gm) were higher than that of hydrocarbon-utilizing bacteria (2.2×108±0.15 cfu/gm). All isolated bacteria (16) underwent screening for hydrocarbon degradation potential. Lysinibacillus odysseyi and Bacillus sp (in: firmicutes) emerged as the best oil degraders. Further screening of the chromosomal and plasmid DNA of the two bacteria was done to determine the presence and location of some selected catabolic genes (NidA, AlkB, NahH, NahAC, and Alma). The presence of Alkane monooxygenase (AlkB) and Naphthalene dioxygenase (NahAC) genes was confirmed in both isolates, while Pyrene dioxygenase (NidA) was confirmed in Bacillus sp. (in: firmicutes) only. The location of AlkB was confirmed to be both plasmid and chromosome, while NidA and NahAC genes were confirmed to be the plasmid. In conclusion, the soil contaminated with used engine lubricant contained indigenous bacteria, Lysinibacillus odysseyi, and Bacillus sp. (in: firmicutes), the two bacteria with the highest degradation potential, contained catabolic genes, monooxygenase (AlkB), NidA, and dioxygenase (NahAC). Therefore, they are effectively used as engine lubricant degraders, and the possibility of horizontal gene transfer can be used in important industrial applications and is recommended for the bioremediation of petroleum compounds.

Optimization of Bioremediation of Crude Oil Polluted Soil through Variation in Moisture Content and Proportion of Augmenting Bacterium and Fungus

Aim: The aim of this study was to enhance bioremediation of crude-oil polluted soil through optimization procedures. Study Design: The Box-Benkhen coded values format and experimental design were used in the design of the study. Place and Duration of Study: The study was carried out in the Microbiology laboratory of the Department of Microbiology, Rivers State University, Nigeria, between February 2024 and July 2024. Methodology: Hydrocarbon utilizing bacteria (HUB) & fungi (HUF) were isolated from crude-oil polluted soil, and screened for hydrocarbon degrading ability (HCDA). HUB and HUF with the highest HCDA were identified and used for bioremediation optimization experiment. In the experiment, different combination of moisture content (MC), and proportion of HUB (pHUB) & HUF (pHUF) were investigated for their effect on extent of hydrocarbon reduction (EoHR). EoHR obtained from the different combinations were fitted using a generalized polynomial model so as to obtain a polynomial equation for predicting EoHR. The equation was used in generating prediction profiles from which the combined values of the 3 parameters that will lead to the highest EoHR was determined. The predicted combined values were implemented in a new setup. A control and a setup enhanced with fertilizer were also prepared. The setups were maintained for 3 weeks. On day 0, 14, and 21 samples were collected and analyzed for total hydrocarbon concentration (THC). Results: The results obtained showed that among the coded isolated HUB and HUF, HB5 and HF1 had the highest HCDA; 36.4% and 4.1% respectively, and were identified phenotypically as Klebsiella ornithinolytica and Aspergillus flavus respectively. The results of the optimization experiment and prediction profiles showed that the highest (68.6%) EoHR was achievable at MC = 20%, pHUB = 10%, and pHUF = 1%. The actual EoHR on day 21 in the optimized, enhanced optimized, and control setups were 60.3, 58.9, and 39.9% respectively. Conclusion: Bioremediation optimization studies is advantageous and should be carried out on crude-oil polluted sites before carrying out bioremediation.

The potential of Serratia marcescens in Bioremediation of Crude-oil Polluted Soil

Bioremediation, which involves the use of microorganisms, is an environmentally friendly approach in restoring crude-oil polluted environments. The use of Serratia marcescens (SM) in bioremediation of crude-oil polluted soil was investigated in this study. Soil from a farm was inoculated in nutrient broth for bacterial enrichment. The broth culture was inoculated on nutrient agar and incubated at ambient temperatures (27 – 32 °C). Bacterial isolates with red colonies were selected and identified. Identified SM was used in preparing bacterial-mineral-salts suspension. The bioremediation experiment consisted of two setups: Control (CT) and setup treated with SM (TSM). Both setups contained crude-oil polluted soil. Mineral-salt solution and the bacterial-mineral-salt suspension were added to setup CT and TSM, respectively. Total hydrocarbon concentration (THC), total heterotrophic bacteria (THB), hydrocarbon utilizing bacteria (HUB), total fungi (TF), and hydrocarbon utilizing fungi (HUF) in the setups were determined at various times. About 38.3 % and 46.5 % THC reduction were achieved in setup CT and TSM, respectively. The percentage of THB that are HUB was higher in setup TSM on day 7 (8.8 %) and day 28 (4.4 %) but higher in setup CT on day 14 (1.7 %) and day 21 (6.6 %). The percentage of TF that are HUF was higher in setup TSM on day 14 (98.0 %) and on day 28 (41.6 %) but higher in setup CT on day 21 (85.3 %). It is concluded that SM has a potential for use in bioremediation of crude-oil polluted soil

Molecular Characterization and Tolerance Potential of Culturable Crude Oil-Degrading Microbes in Santa-Barbara River, Bayelsa State, Nigeria

There has been chronic contamination of the surrounding aquatic and terrestrial environments in the Niger Delta region of Nigeria due to the enormous activities of crude oil exploration. This study aimed to characterize and assess the crude oil tolerance potential of indigenous microbes from crude oil spills in Santa Barbara River, Bayelsa State, Nigeria, that could serve as potential consortia for bioremediation of the crude oil spills. Total crude oil hydrocarbon-utilizing bacteria count (THUBC) and total crude oil hydrocarbon-utilizing fungi count (THUFC) in the samples were determined with a culture-dependent spread plate technique. Bacterial and fungal isolates were characterised using standard phenotypic and 16S/Internal Transcribed Spacer region rRNA gene sequencing techniques, respectively. The tolerance of autochthonous bacterial isolates to different concentrations of crude oil was subsequently determined. THUBC and THUFC in crude oil-polluted water samples ranged from 1.88 log10 CFU/ml to 2.74 log10 CFU/ml and from 0.00 log10 CFU/ml to 1.70 log10 CFU/ml, respectively. Representative strains of Proteus mirabilis, Bacillus subtilis, Pseudomonas aeruginosa, Micrococcus luteus and Aspergillus flavus isolates obtained from crude oil-polluted water samples were deposited in the GenBank (NCBI) under accession numbers OQ969924, OQ969951, OQ969987, OQ970009 and OQ975908. Proteus mirabilis, Pseudomonas aeruginosa and Aspergillus flavus demonstrated the most significant tolerance to crude oil pollutants (minimum crude oil inhibitory concentrations (MIC) = 80%) followed by Bacillus subtilis and Micrococcus luteus (MIC= 40%). The findings from this study are pointers to the potential role of the microbial isolates as bioremediation consortia to remediate the polluted Santa Barbara River.

Compositional Profiles and Spatial Distribution of Microplastics Across Three Selected Rivers in Rivers State, Nigeria

Microplastics (MP) are ubiquitous and persistent contaminants in waterbodies and a pervasive and preventable threat to the health of marine ecosystems. These particles are defined as <5 mm in size and can be introduced into the environment via primary sources such as the use and disposal of microbeads in cosmetic, cleaning products and sandblasting, as well as secondary sources which include the fragmentation of litter by mechanical or UV light-induced degradation. This study was conducted to investigate the concentrations of microplastic contaminants in Imo River, Ntawogba River and New Calabar River as well as the physicochemical and microbial characteristics of the water bodies. Composite sampling technique was used in this study. The physicochemical analysis of the water samples was carried out both in-situ and ex-situ while the microbiological analysis was performed ex-situ to determine the load using APHA 9215B/9610B and ASTM D 5465-93 (Pour plate) test methods. The total heterotrophic bacteria were more predominant than the other microbial groups in samples obtained from the three rivers. The relatively higher hydrocarbon-utilizing bacteria counts obtained in samples collected from Ntwawogba River is suggestive of benign hydrocarbon contamination of the river. Two techniques (Fourier Transform Infrared Spectroscopy, FTIR and Gas Chromatography-Mass Spectrometry, GC-MS) were used to identify the microplastics and their concentrations. The reference spectra for the FTIR results were in the spectral range stretching from 4000–650cm-1 where the prominent absorption peak at 2920 cm-1 corresponded to aliphatic C-H (Hydrocarbon) stretching, indicating the presence of CH2 (Alkene) and CH3 (Alkane) groups in the microplastic samples, at 1725 cm-1 associated with carbonyl (C=O). The band at 1600 cm-1 is characteristic of aromatic C=C stretching, at 1200-1000 cm-1 range suggesting C-O stretching vibrations. The region between 800 and 700 cm-1 corresponded to out-of-plane bending vibrations commonly seen in aromatic groups while the GC-MS polymer identification library produced results of both qualitative and quantitative assessment of the microplastics. The eight (8) priority MP polymers found in the water samples were polyethylene (PE), polyethylene terephthalate, dioctyl terephthalate, polybrominated diphenyl ether, tetrabromobisphenol A, polypropylene, acrylic fibre, and polystyrene. SEM images of the MPs were acquired at various magnifications to capture their surface features, shapes, and sizes. PE was found to be the most ubiquitous MP (45.74%, 45.84% and 47.76%) across Imo, Ntawogba and New Calabar River, respectively.
 Results obtained indicate the pervasiveness of MPs in the studied rivers and signify threat to aquatic organisms and man via their biomagnification through the food chain.

Enhancing Bioremediation of Crude Oil Contaminated Soil from Kokori, Delta State, Nigeria Using Cow Dung as Biostimulant

This study was aimed at assessing the bioremediation of crude oil contaminated soil from kokori, Delta state, Nigeria by indigenous bacteria flora using cow dung as biostimulants. The activities of commercial agricultural investors, small-scale farmers, and the indigenous people of the Nigerian Niger Delta, whose livelihood has been heavily dependent on agriculture, have all been severely impeded and even destroyed by the crude oil spill. Therefore, a solution to the issue of oil spills in these places is required. Hydrocarbon contaminated soil was collected from a crude oil polluted sites and a non-contaminated soil was collected from Agricultural cultivable farmland in kokori, Delta state and its physicochemical properties were determined before the bioremediation period. The nutrients composition of cow dung used for the study was determined. After adding different amounts of cow dung to 200g of soil, the mixture was left to incubate at room temperature for six (6) weeks. Throughout the course of the experiment, measurements of the total petroleum hydrocarbon eliminated and the hydrocarbon-utilizing bacteria count (HUB) were made at one-week intervals. Increased in the HUB counts with corresponding decrease in the amount of hydrocarbons were observed. While highest HUB count was observed for the various amendment at week six, 5g/kg cow dung treatments had the highest count (3.35 x103cfu/g) with residual hydrocarbon (519.56mg/kg) while treatments 2.5g/kg cow dung had 2.91x103cfu/g with residual hydrocarbon of 541.06mg/kg. The result further revealed the degree of degradation likewise the bioremediation efficiency with C having the highest degree of degradation of (49.04%) at week six and bioremediation efficiency of (75.26%) at the first week of study. The introduction of cow dung into soil that has been contaminated with hydrocarbons promotes the growth of naturally occurring bacteria that break down hydrocarbons, leading to a greater amount of hydrocarbon degradation.

Remediation of hydrocarbons and metals by hydrocarbon utilizing Pseudomonas taiwanensis YSA-17 isolated from soil contaminated with petroleum.

Careless handling of petroleum in petrochemical industries releases toxic hydrocarbons and metals to soil and water. The aim of the present study was to isolate hydrocarbon-utilizing and metal-tolerant bacteria. Hydrocarbon-utilizing bacteria from petroleum-contaminated soils were isolated on the Bushnell Hass medium. Hydrocarbon degradation by Pseudomonas taiwanensis strain YSA-17 was observed by gas chromatography-mass spectrometry. Bioaccumulation of metals by strain YSA-17 was assessed in nutrient broth. Among different strains, YSA-17 showed the highest potential for hydrocarbon utilization. After 20 days of incubation, YSA-17 completely degraded one compound and during its degradation, there was the formation of 13 new compounds which were absent in uninoculated control. Results of scanning electron microscope and Fourier transmission infrared (FTIR) indicated degradation of hydrocarbons. FTIR showed the formation of new functional groups in YSA-17 inoculated medium. Expression of the total quantity of hydrocarbon-degrading gene (AlkB and NehAc) in petroleum-amended nutrient broth inoculated with strain YSA-17 enhanced significantly during 20 days of incubation compared to control. YSA-17 also significantly removed metals. This study concluded that bioinoculant can be utilized for the bioremediation of pollutants cocontaminated with hydrocarbons and metals. Petroleum-contaminated soil will be remediated for pollutants.

Seasonal Influence on the Microbiology and Physicochemistry of Crude Oil Polluted Wetlands

Pollutants such as crude oil spills in an environment, affect the physical, chemical and biological properties of that environment. This study was conducted to determine the effect of seasonal variations on the microbiological and physicochemical characteristics of three crude oil-polluted wetlands in Rivers State, Nigeria. Soil samples were collected at 3 depths (0-15cm, 15-30cm and 30-45cm) with the aid of a hand auger, sampling was done for a period of twelve months covering the rainy (March to August) and dry seasons (September to February). Samples were analyzed for physicochemical characteristics, using standard analytical and microbiological methods. The data obtained was analyzed using the statistical package for social science (SPSS) version 22 and Duncan’s multiple range test was used to separate means where differences occurred. Microbiological analyses showed that significantly higher microbial counts were observed in the dry season than in the rainy season in the wetland samples which could be due to favourable environmental conditions during the period of study. Wetland soil total heterotrophic bacterial (THB) count in the wet season ranged from 1.09x107cfu/g to 10.45x107cfu/g and from 2.43x107cfu/g to 18.56x107cfu/g in the dry season. Total heterotrophic bacteria had the highest population in all soil depths (0-15cm, 15-30cm and 30-45cm) in both seasons. Hydrocarbon-utilizing bacteria such as Bacillus subtilllis, B. rigui, B. flexus, Lysinibacillus macrolides, Staphylococcus aureus, Proteus penneri and fungi such as Aspergillus species, Fusarium species, Mucor species and Rhizopus species were genetically identified in this study. Temperature and other physicochemical parameters in the wetlands were altered due to the variation in season. Higher temperature ranges were observed in the dry season than in the rainy season as seen in Iwofe, temperature ranged from 26.500C (0-15cm) to 28.500C (30-45cm) in the rainy season while in the dry season it ranged from 31.500C (0-15cm) to 33.500C (30-45cm) which was above FEPA permissible limit of 300C for soil temperature. The study showed that season of study as well as crude oil spillage have significant effects on the microbiology and physicochemical characteristics of wetlands and therefore, contribute to microbiological degradation in wetlands.

Use of Wastewater from Legume Cooking in Bioremediation of Crude-Oil Polluted Soil

Wastewaters generated from the cooking of foods contain nutrients. Such wastewaters may have the potential to be used as nutrients in bioremediation of hydrocarbon polluted environments. In this study, use of wastewaters generated from the cooking of two legumes as nutrient source during bioremediation of hydrocarbon polluted soil was investigated. Crudeoil polluted soils were treated with wastewater from cooking of cowpea (setup B), wastewater from cooking of groundnut-pods (setup G), a mixture of the wastewaters (setup B+G), and tap-water (control setup: setup C). Selected microbial group and physicochemical parameters were determined at seven days interval. The results obtained showed that the extent of hydrocarbon degradation in setup B, G, B+G, and C were 45.5, 23.2, 1.3, and 37.9 % respectively. There was decrease in total organic carbon (TOC), phosphorus, and nitrogen in the setups. However, in setup G there was increase in TOC. Setup C and B had the highest decrease in phosphorus, and setup B had the highest decrease in nitrogen. There was decrease and subsequent increase in percent hydrocarbon-utilizing bacteria in all the setups; the subsequent increase was highest in setup B. There was generally a decrease in percent hydrocarbon-utilizing fungi, except in setup C. The hydrocarbon utilizing microorganisms isolated from the treated soils include Bacillus, Micrococcus, Acinetobacter, Staphylococcus, Pseudomonas, Penicillium, Aspergillus, Candida and Fusarium. Their presence indicates that hydrocarbon degradation was due to biodegradation. It is concluded that wastewater from cooking of cowpeas can be applied in bioremediation of crude-oil polluted soil.

Effect of glucose on biodegradation of hydrocarbons in crude-oil polluted soil undergoing bioremediation

Bioremediation of crude oil polluted soil can be enhanced by addition of easily assimilated carbon sources such as glucose. The aim of this study was to determine the effect of increasing concentration of glucose on biodegradation of hydrocarbons in crude-oil polluted soil undergoing bioremediation. Some hydrocarbon utilizing bacteria and fungi were used as bioremediation agents in the study. Soil artificially polluted with crude-oil was divided into 5 setups: CT (control), S1, S2, S4, and S8. Suspension of the bioremediation agents and nutrients were added to the setups. About 5, 10, 20, and 40 g glucose were added to S1, S2, S4, and S8 respectively: equivalent to 1, 2, 4, and 8 % glucose concentration. Soil moisture in the setups was maintained at 10-20 % during the experimental period. Total hydrocarbon concentration (THC), and population of total heterotrophic bacteria (THB), hydrocarbon utilizing bacteria (HUB), total fungi (TF), & hydrocarbon utilizing fungi (HUF) were determined on day 1 and 21. Results obtained showed that increase in HUB occurred only in setup S1, and setup S1 had the highest extent of hydrocarbon degradation (18.93 %). Setup S8 had the lowest extent of hydrocarbon degradation (0.79 %). It is concluded that glucose concentration of 1 % and below will enhance biodegradation of hydrocarbons in crude-oil polluted soils, whereas high glucose concentration will retard hydrocarbon biodegradation. Also, the study indicates the possibility of fungi not partaking in hydrocarbon degradation when glucose is made available.

Enhanced Phytoremediation of Crude Oil Polluted Soil Using Pseudomonas fluorescens

Environmental pollution in the Niger Delta has been a huge concern. Bacteria have proven to be of great benefit in the degradation of petroleum hydrocarbons. This research is aimed at enhanced phytoremediation of crude oil polluted soil using Pseudomonas fluorescens. Soil was collected from oil spill polluted site at B-dere, Rivers State. Six (6) treatments consisting of contaminated soil (CS), uncontaminated soil (US), augmenting organisms Pseudomonas fluorescens (Pse), and phytoremediation grasses (Elbow buffalo grass (Panicum subalbidum) (PAN-G) and Sedge plant Schoenoplectus senegalensis (SCH-G)) were evaluated during a period of 28 days. Total Heterotrophic Bacteria (THB) and Hydrocarbon Utilizing Bacteria (HUB) were monitored. Physicochemical parameters monitored were pH, Temperature, Nitrogen, Phosphorus, Potassium and Total Hydrocarbon Content (THC). Baseline results of physicochemical parameters carried out in the uncontaminated soil were pH, temperature (oC), Moisture content (%), Electrical conductivity (uS/cm), Total Organic Carbon (TOC), Soil Organic Matter, Total Hydrocarbon Content (THC), Nitrogen, Phosphorus and Potassium (mg/kg). The amount of hydrocarbon remediated and percentage bioremediation in the soil after 28 days were: CS+PSE+SCH (3454mg/kg; 85.28%) > CS + BAC + SCH-G (3264mg/kg; 80.59%) > CS +PSE + BAC + SCH-G (3210mg/kg; 79.26%) and CS + SCH-G had the lowest (434mg/kg: 62%). This research revealed that Schoenoplectus senegalensis (sedge plant) is a suitable plant species for phytoremediation of crude oil polluted soil than Panicum subalbidum. Moreso, Schoenoplectus senegalensis (sedge plant) has a higher phytoremediation potential when augmented with Psuedomonas. it is therefore recommended that Schoenoplectus senegalensis (sedge plant) in combination with augmenting organism (Psuedomonas) is best option for remediation of crude oil polluted.

Microbiological Status, Physico-chemistry and Plant Performance in Spent Lubricating Oil (SLO) Polluted Soils Amended with Spiked Organic Fertilizer

Soil contaminations by spent lubricating oil (SLO) have been reported to be threatening as it can negatively impact soil macro/micro-flora, destroy the food chains, disrupt biogeochemical cycling of elements, thus reducing soil fertility/productivity, with attendant economic implications. This study evaluated the changes in microbial population and performance of plant in SLO polluted soils amended with different organic fertilizers. The fertilizers were produced from organic waste materials using aerobic composting technique; pollution was simulated in potted soils; soil toxicity were determined using Zea mays L. as test crop; microbial counts and physicochemical properties of the test soils were determined using standard microbiological and chemical protocols respectively. Apart from significant (P˂0.05) decrease in population of total heterotrophic bacteria (THB) and total fungal counts (TFC) (2.6×108 to 6.1×107 cfu/g and 2.3×105 to 1.7×105 cfu/g respectively), and increase in populations of hydrocarbon utilizing bacteria (HUB) and hydrocarbon utilizing fungi (HUF) (7.3×103 to 4.6×104 cfu/g and 8.0×103 to 1.7×104 cfu/g respectively) following contamination of soil with SLO at pollution level., results also revealed increase (improvements) in counts of all microbial groups at the end of remediation treatments. Mean microbial count in soils amended with different levels of fertilizer treatments (5%, 10%, and 15%) reflected a dose-dependent increase as follows: Ft2 ˃ Ft0 ˃ Ft4 for the 5% (3.7×108 cfu/g), 10% (9.2×107 cfu/g) and 15% (6.9×107 cfu/g) respectively. At 5% application, post remediation pH increased following the order: Ft0 ˃ Ft2 ˃ Ft4 (6.00, 5.34, and 4.90 respectively). The test crop, Zea mays L. recorded 100% and 62.5% germination in amended and unamended soils respectively. Leave length and chlorophyll index of Z. mays L. grown on remediated soils ranged between 35.10±0.40 – 52.85±0.05 (at 5% treatments); 32.60±0.10 – 56.55±0.35 (at 10% treatments); and 35.35±0.15 – 42.45±0.25 (at 15% treatments), compared with 30.30±0.80 – 50.55±0.75 (for PS) and 18.05±0.85 – 25.50±0.70 (for unamended CS). All test crops yielded except those grown on unamended soils. Conclusively, application of organic fertilizers to SLO polluted soils increased population of different groups of soil microbes, leading to increased breakdown of the pollutant and reduced soil toxicity.

Antimicrobial and Metal Tolerance of Bacteria Isolated from Underground Water Sample of Aged Crude Oil Contaminated Site

The study was aimed at evaluating metal tolerant and antibiotic resistant bacteria isolated from underground water around aged crude oil polluted site. Samples were collected from different locations around aged crude oil polluted site and control sample from an uncontaminated site of Bodo community, Gokana Local Government, Rivers state, Nigeria. The samples were cultured on nutrient agar, Bushnell Hass and MacConkay agar using standard microbial technique. Antibiogram of the isolated and identified bacteria were determined by Kirby-Bauer disc diffusion method. The bacterial tolerance of different concentrations of the heavy metals, Chromium, Vanadium, Arsenic, Cadmium and Lead was determined. The total heterotrophic bacterial count (THBC) of the samples ranged from 1.26×104 CFU/ml to 3.6×105 CFU/ml. Count of hydrocarbon utilizing bacteria (HUB) ranged from 1.02×103 to 3.2×103 CFU/ml and the coliform count of the sample ranged from 4.2×103 CFU/ml to 4.0×103ml. The predominant bacteria identified were Bacillus sp, Micrococcus sp, and Staphylococcus sp, Enterobacter sp and Proteus sp. All (100%) the Gram-positive bacteria were resistant to the antibiotic, Ceftazidime, Cefprozil and Cloxacin, 92% were resistant to Gentamycin and Erythromycin while 80% were resistant to Augmentin. All (100%) of the Gram-negative bacteria isolates were resistant to cefluroxime, 66% were resistant to Augmentin and Ceftazidim, and 33% were observed to be resistant to Nitrofurantin and Gentamicin. It was observed that all the isolates were tolerant to 50 µg/ml concentration, 70 to 100% of the isolates were tolerant to 100 µg/ml concentration, 17 to 100% were tolerant to 200 µg/ml concentration while 11 to 41% were tolerant to 300 µg/ml concentration of all the heavy metals studied. From this study, it was revealed that petroleum aged contamination could be a source of heavy-metal tolerance and antibiotic resistance in bacteria.

Study on Amendment of Rapeseed Meal, Soybean Meal, and NPK Fertilizer as Biostimulants in Bioremediation of Diesel-Contaminated Soil by Autochthonous Microorganisms

ABSTRACT The adverse impact of total petroleum hydrocarbons (TPH) can be mitigated through bioremediation. However, the efficiency of bioremediation is often compromised due to its slow speed. Therefore, this study aimed to evaluate the promoting effect of organic and inorganic biostimulants on the bioremediation rate of autochthonous microorganisms. The study examined the impact of rapeseed meal (biostimulation-BS1), soybean meal (BS2), and NPK fertilizer (BS3), as biostimulants on pH, bacterial and fungal count, enzymatic activities, and also TPH values of diesel-contaminated soil. The results revealed that amending the soil with rapeseed meal, soybean meal, and NPK fertilizer resulted in a significant increase in dehydrogenase and catalase activities, with 9.96, 7.7, and 6.75-fold and 2.52, 2.4, and 2.52-fold enhancement, respectively, compared to natural attenuation (NA-as control) which contains diesel-contaminated soil without any organic or inorganic amendments. Moreover, the pH value of the BS1 (6.4) and BS2 (6.77) groups was almost neutral. The growth of heterotrophic and hydrocarbon-utilizing bacteria and fungi was significantly improved with organic matter amendment (P < .05). The TPH removal efficiencies in natural attenuation, BS1, BS2, BS3, and rapeseed meal+ soybean meal+ NPK fertilizer (BS4) groups were 49.22%, 71.65%, 90.55%, 65.77%, and 55.25%, respectively. Molecular identification revealed that three hydrocarbon-utilizing bacteria belonged to various genera, including Nocardiopsis, Streptomyces, and Mammaliicoccus. Overall, this study suggests that amending organic compounds to contaminated soil is an effective, cost-effective, and eco-friendly strategy to improve the bioremediation rate of autochthonous microorganisms.

Modelling and Optimizing the Effect of pH on Remediation of Crude Oil Polluted Soil with Biochar Blend: RSM Approach

This research modelled the effect of pH on the remediation of crude oil-polluted soil using biochar blend. The biochar blends, PL-500, pW-500, and RS-400, were made by pyrolyzing poultry litter, pine wood, and rice straw at varied temperatures and times. The pH of the crude oil polluted soil was 4.72. Response surface experimental design mixed biochar to remediate total petroleum hydrocarbons (TPH). Following 30 days of bioremediation, 15g PL-500, 3g PW-500 and 6g RS-400, removed a maximum of 46% TPH. The experimental data were statistically modelled and optimized using design expert software and response surface methods. Analysis of variance (ANOVA) was used to determine the significance of each regression coefficient. Biochar blend improved soil pH to 6.9 following remediation. ANOVA indicated that PL-500 was significant for predicting TPH % degradation at p =0.0290, suggesting that its high pH, nutrient, and soil water conservation values made it more effective in remediating TPH. The quadratic model predicts with R2 =0.8567. A model fit statistics were used to examine soil pH influence on TPH remediation. RSM study indicated a good positive association between statistical model and experiment with R2 = 0.7612. The model fits experimental data and predicts that . Remediation requires soil pH and biochar's alkalinity raised soil pH to 6.9, which promoted hydrocarbon-utilizing bacteria.

MICROBIOLOGICAL PROPERTIES OF SOIL SAMPLES IMPACTED BY HYDROCARBONS FROM SELECTED SITES IN THE NIGER DELTA REGION OF NIGERIA

This study determined the microbiological properties of soil samples from selected hydrocarbon impacted sites in the Niger Delta region. Standard sampling and analytical methods were employed. The following microbial properties were analyzed; Heterotrophic bacteria counts (cfu/g), Hydrocarbon Utilization Bacteria (cfu/g), Heterotrophic fungi counts (cfu/g) and Hydrocarbon Utilization Fungi (cfu/g). Findings revealed that the microbial properties of soil samples across selected impacted sites of the Niger Delta showed a significant difference in the surface and sub-surface levels with values for Total Heterotrophic Bacteria (THB) ranging from (1.04 × 103 to 2.45 × 103 cfu/g) and Hydrocarbon Utilizing Bacteria (HUB) ranging from (3.96 × 103 to 9.99 × 103 cfu/g) for surface and sub-surface respectively with p-values &lt;0.05 across all the sampled stations. Hydrocarbon Utilizing bacteria and fungi genera isolated were Clostridium, Bacillus, Acinetobacter, Pseudomonas, Flavobacterium, Vibrio, Achromobacter, Arthrobacter, Corynebacterium, Citrobacter, penicillium, Trichoderma, Geochrichum, Candida, Fusarium, Aspergillus niger, Aspergillus sp., Cladosporium, Condiva, and Rhodotorula. Based on these findings, it is concluded that, the higher the concentration of pollutants in the soil, the more the number of microorganisms. Hence, it is recommended that the relevant agencies should constantly check the levels of microbial properties as per WHO guidelines.

Occurrence of Heavy Metal and Antibiotic Resistant Bacteria in Soils from Selected Mechanic Workshops in Ibadan Metropolis, Nigeria

Aim: This study investigated the occurrence of antibiotic and heavy metal co - resistance in bacteria indigenous to mechanic workshops.&#x0D; Study Design: The study is an experimental study.&#x0D; Place: Samples were collected at mechanic workshop.&#x0D; Methodology: Soil samples were collected from three mechanic workshops and tested for the presence of heavy metals. Hydrocarbon-utilizing bacteria was also isolated from the soils using Bushnell Haas medium supplemented with 1% engine oil or petrol. Isolates obtained were subjected to antibiotic resistance test and those that showed extensive drug resistance to the tested antibiotics were further tested for heavy metal resistance. Selected isolates were then identified using 16S rRNA gene sequence.&#x0D; Results: The soil samples contained excessive amounts of Lead, Iron, Copper and Zinc, while the concentrations of Nickel, Cobalt, Cadmium and Chromium were within WHO permissible limit. A total of 10 hydrocarbon-degrading isolates were obtained from the soil samples, seven of which were gram negative and three were gram positive. Three of the isolates showed extensive drug resistance to 14 of the tested antibiotics. Three isolates were then subjected to heavy metal resistance test and all of them showed resistance to the tested heavy metals. They were identified and given ascension numbers as Stenotrophomonas maltophilia MW392903, Achromobacter xylosoxidans MW392904 and Pseudomonas aeruginosa MW392905.&#x0D; Conclusion: It was observed that heavy metal resistance and antibiotic resistance can be selected for simultaneously as organisms adapt ways to cope with man’s activities in the environment, and while traits like hydrocarbon utilization and heavy metal resistance make the organisms promising in bioremediation, the inadvertent possession of antibiotic resistance by these environmental isolates poses a challenge to the health sector.

Use of natural sorbents for accelerated bioremediation of grey forest soil contaminated with crude oil

Due to the extensive oil extraction and transportation that occurs in oil-producing countries, many lands remain contaminated because of accidental leakages. Despite its low cost and environmentally safe nature, bioremediation technology is not always successful, mainly because of the soil toxicity to the degrading microbial populations and plants. Here we report a three-year microfield experiment on the influence of natural sorbents of mineral (zeolite, kaolinite, vermiculite, diatomite), organic (peat), carbonaceous (biochar) origin, and a mixed sorbent ACD (composed of granular activated carbon and diatomite) on the bioremediation of grey forest soil contaminated with weathered crude oil (40.1 g total petroleum hydrocarbons (TPH) kg−1). Optimal doses of the sorbents significantly accelerated bioremediation of petroleum-contaminated soil through bioaugmentation followed by phytoremediation. The main reason for the influence of the sorbent amendments relied upon the creation of optimal conditions for the activation of hydrocarbon-utilizing bacteria and plant growth due to the reduction of soil toxicity, as well as maintaining an optimal pH and water-air regime in the soil. That happened because of reducing the soil hydrophobicity, increasing porosity and water holding capacity. The content of the TPH in the best samples (2% biochar or ACD) reduced to their local permissible concentration accepted for remediated soils in the Russian Federation (≤5 g kg−1) after two warm seasons compared to that after three warm seasons in the other samples. Although some sorbents decelerated biodegradation of highly condensed polycyclic aromatic hydrocarbons (PAHs, including benzo(a)pyrene) in the soil, the overall risk from the residual contaminants present in the remediated soil and plants was minimized. The final total content of the main PAHs in the sorbent-amended soils did not exceed the maximal permissible levels that are accepted in most EU countries (1000–40,000 μg kg−1), and they did not accumulate in the aboveground phytomass of grasses in dangerous concentrations.