Assessing the potential for Crude Oil degradation by Biosurfactant-producing Bacteria isolated from Marine Ecosystems in Nigeria

Background: Soil remediation is one the important problem in environmental studies. Thus, this research was conducted to evaluate the effect of organic chelates and gibberellic acid (GA3 ) on the degradation of crude oil in the soil co-contaminated with Ni and crude oil under canola cultivation. Methods: For treatments, HEDTA and NTA chelates at rates of 0 and 2.5 mmol/kg soil and foliar GA3 (0 (GA3 (-) and 0.05 (GA3 (+) mM) were used. In addition, the soil was polluted with Ni (0 and 100 mg Ni/kg soil) and crude oil at rates of 0, 2, and 4% (W/W). The plant used in this experiment was canola. The concentration of Ni in soil and plant was measured using atomic absorption spectroscopy (AAS). The concentration of total petroleum hydrocarbon (TPH) was measured using GC-mass. The mean differences were calculated according to the least significant difference (LSD) test. Results: The greatest degradation of crude oil belonged to the non-Ni-polluted soil under cultivation of GA3 -treated plant, while the lowest one was observed in the soil received the greatest level of HEDTA and NTA chelates. Applying 0.05 mM GA3 foliar significantly increased the degradation of crude oil in soil and Ni in plant shoot by 12.1 and 8.3%, respectively. In addition, soil microbial respiration was also increased by 11.3%. Conclusion: HEDTA, NTA, and GA3 had a significant effect on the Ni phytoremediation efficiency and degradation of crude oil in soil that is a positive point in environmental pollution. However, the role of soil physico-chemical properties on the phytoremediation efficiency cannot be ignored.

Biosurfactants are amphiphilic molecules with effective surface-active and biological properties applicable to replace synthetic surfactant in petroleum industry. Interest in microbial surfactants has been steadily increasing in recent years, as they have numerous advantages compared to chemical surfactants including a lower toxicity, better environmental compatibility and effective properties at extreme temperature, pH levels and salinity. A crude oil-degrading yeast strain (C. 1214-BK14) was selected among the isolated strains as a potential biosurfactant-producer from producing oil wells at White Tiger oilfield because of its ability to produce biosurfactant using crude oil as a sole carbon source. An emulsification index (E24%) of 57% was obtained initially by Candida tropicalis 1214-BK14 in previous study. Therefore, the optimization of biosurfactant production of this strain for enhanced crude oil degradation was carried out based on central composite design and analyzed using response surface methodology (RSM). The biosurfactant production process was investigated as function of three independent variables: crude oil (2.5-5 % w/v), (NH4)2SO4 (0.35-0.45% w/v), and solution pH (5-8). RSM analysis showed that the optimum condition for the biosurfactant production by C. tropicalis 1214-BK14 were 6.1, 3.97% (w/v) and 0.37% (w/v) for pH, concentration of carbon (crude oil) and nitrogen substrate ((NH4)2SO4), respectively, with the emulsification index measured in the conditions was 80.2%. The total crude oil and C10-C43 alkanes degradation efficiency by this strain estimated using GC/MS were 89.8% and 80.47-98.58%, respectively. These results revealed that the strain Candida tropicalis 1214-BK14 exhibited a tremendous potential for contaminated-crude oil degradation and microbial enhanced oil recovery (MEOR).

Effects of salinization and crude oil contamination on soil bacterial community structure in the Yellow River Delta region, China

Isolation and identification of biosurfactant producing and crude oil degrading Pseudomonas aeruginosa strains

Petroleum and its byproducts are one group of universal environmental pollutants. Microorganisms have over time played significant roles in the clean-up exercise of unwanted substances in the environment. This research was aimed at studying the degradative potentials of biosurfactantproducing bacterial isolates (Bacillus sp.) from palm oil mill effluent (POME) in crude oil degradation. Standard microbiological and analytical methods were applied to ascertain biosurfactant production and degradation of crude oil by Bacillus sp. isolated from palm oil mill effluent discharged points and logging area of effluent bunk at Nigerian Institute for Oil-Palm Research (NIFOR) in Edo State. The bacteria were isolated and subjected to screening for hydrocarbon degradation and biosurfactant production. Biosurfactants characterization by Fourier Transform Infra-Red (FTIR) technique. total viable heterotrophic bacterial count of POME and Bonny light crude oil ranged from 6.6 x106 – 8.2 x106 cfu/ml and 4.2 x106 – 5.8 x106 cfu/ml respectively. Bacillus sp. that had the highest biodegradative potential and biosurfactant production was identified molecularly as Bacillus circulans. It could be used as bio-stimulants to ameliorate crude oil polluted areas as an efficient and cost- effective technology.

The spillage of petroleum hydrocarbons into our environment causes a lot of disastrous environmental pollution. The employment of biosurfactant-producing and hydrocarbon-utilizing microorganisms enhances the effectiveness of bioremediation of these toxic pollutants. This study was aimed at isolating biosurfactant-producing and crude oil degradingbacteria from hydrocarbon-polluted soils and characterization of the biosurfactant produced. The biosurfactant screening techniques employed were haemolysis assay, drop collapse test, oil displacement test, tilting glass test and emulsification index (E24) test. The degradation rate of the most potent crude oil degrader was determined using gravimetric method and Gas Chromatography – Mass Spectroscopy (GC-MS) analysis. The bacterium was identified based on phenotypic, biochemical and molecular analyses. Fourier Transform Infra-Red (FTIR) and GC-MS analyses were used to characterize the biosurfactant produced. A potent bacterium, Enterococcus hirae (identified by 16s rDNA sequencing) was isolated from hydrocarbon contaminated soil and it could degrade 77.2% of total petroleum hydrocarbons after two weeks of culture when grown in mineral salt medium (MSM) supplemented with 2% (v/v) crude oil as the sole carbon source. Chromatogram of the treated crude revealed that E. hirae could potentially degrade various hydrocarbon contents (C21 – C35) present in the crude oil. The biosurfactant produced was characterized as Glycolipids (Rhamnolipids) using FTIR and GC-MS analyses. This study demonstrates E. hirae as an efficient biosurfactant producer and crude oil degrader. To the best of the researchers’ knowledge, this is the first time E. hirae is reported as both biosurfactant producers and crude oil degrader.

Biodegradation of oily waste sludge using vermiremediation and composting process bioaugmentated with isolated hydrocarbon-degrading bacteria: Performance and ecotoxicity assessment

Studies on reclamation of crude oil polluted soil by biosurfactant producing Pseudomonas aeruginosa (DKB1)

Microbial remediation has been regarded as one of the most promising decontamination techniques for crude oil pollution. However, there are few studies on the interaction of bacteria in the microbial community during bioremediation. The aim of this work was to research the promotion of defined co-culture of Bacillus subtilis SL and Pseudomonas aeruginosa WJ-1 for biodegradation of crude oil. After 7 days of incubation, the analysis of residual oil, saturated and aromatic fraction in the samples showed that the degradation efficiency of them was significantly improved. The degradation efficiency of crude oil was enhanced from 32.61% and 54.35% in individual culture to 63.05% by the defined co-culture of strains SL and WJ-1. Furthermore, it was found that the defined co-culture system represented relatively excellent performance in bacterial growth, cell surface hydrophobicity (CSH) and emulsification activity. These results indicated that the combination of Bacillus subtilis and Pseudomonas aeruginosa can effectively promote the degradation and utilization of crude oil, which may provide a new idea for the improvement of bioremediation strategies. GRAPHICAL ABSTRACT.

Characterization of two biosurfactant producing strains in crude oil degradation

There are several physical, chemical, and biological methods to remove petroleum hydrocarbons from contaminated environments. Biological processes are considered the most exciting, cost-effective, and environmentally friendly approaches for removing petroleum hydrocarbons compared to chemical or physical processes. Biosurfactants enhance the bioavailability of hydrophobic organic compounds, making them effective agents for environmental cleanup. Hence, this study aimed to isolate biosurfactant-producing bacteria from the estuarine sediment of the crude oil-contaminated Iko River estuary capable of degrading petroleum hydrocarbons using appropriate methods. The results revealed that Pseudomonas aeruginosa, Bacillus subtilis, Micrococcus spp. and Bacillus spp. exhibited haemolytic activity. All organisms except Bacillus cereus were positive for the emulsification, drop collapse, and oil spread tests. However, Pseudomonas aeruginosa demonstrated the highest emulsification capacity, followed by Bacillus subtilis, Micrococcus spp., Bacillus spp., and Bacillus cereus, respectively. Degradation of crude oil and its components was faster when enhanced with a mixed culture of Bacillus subtilis and Pseudomonas aeruginosa than with individual bacterial isolates. Bacillus subtilis reduced the crude oil component from 257.27 mg/l to 120.42 mg/l. Pseudomonas aeruginosa reduced crude oil component 257.27 mg/l to 48.41 mg/l, whereas the mixed culture of Bacillus subtilis and Pseudomonas aeruginosa reduced crude oil components from 257.27 mg/l to 7.82 mg/l. Biosurfactant-producing bacteria with hydrocarbon-utilising capacity have the potential to enhance the biodegradation of total petroleum hydrocarbons. The key to increasing hydrocarbon degradation rates is bioaugmentation with a biosurfactant-producing bacterial consortium that can act synergistically to degrade hydrocarbons more effectively.

Background and Objectives: Petroleum hydrocarbons are harmful to the environment, human health, and all other living creatures. Oil and its byproducts in contact with water block sunshine to phytoplanktons and thus break the food chain and damage the marine food source. This study aims to isolate the crude oil degrading and biosurfactant producing bacteria from the oil contaminated soils of Gachsaran, Iran. Materials and Methods: Isolation was performed in peptone-water medium with yeast extract. Oil displacement area, emulsification index and bacterial phylogeny using 16S rRNA analysis were studied. Results and Conclusion: Three isolates were able to degrade the crude oil. In the first day, there were two phases in the medium; after a few days, these three bacteria degraded the crude oil until there was only one phase left in the medium. One strain was selected as a superior strain by homogenizing until the medium became clear and transparent. This method confirmed that the strain produces biosurfactant. According to the morphological and biochemical tests, the strain isolated from the oil contaminated soils is a member of Bacillus subtilis, so to study the bacterial phylogeny and taxonomy of the strain, an analysis of 16S rRNA was carried out, and the phylogenic tree confirmed them. The results verified that oil contaminated soils are good source for isolation of the biosurfactant producing bacteria.

Crude oil degradation has been carried out using biopile reactor in total petroleum hydrocarbon (TPH) concentration of 5%, 10% and 15%. The thermophilic microorganisms used from isolation result and identification are Aeromonas salmonicida, Bacillus pantothenticus, and Stenotrophomonas maltophilia. The biodegradation of biopile reactor is done by various concentrations of TPH, total plate count (TPC), and volatile suspended solid (VSS) per day for 30 days. The biodegradation of kinetic parameter calculated consists of μ, μm, Y, Yt, Yobs, Kd, Ks from TPH concentration decision, and TPC and VSS in every microorganism with t (observation time) of 0 hour to 168 hours. The crude oil separation efficiency in a biople reactor shows that the largest separation occurs in a starting TPH concentration of 15%, which becomes 61.8% later on, followed by a starting TPH concentration of 10% and 5%, which is as much as 61% and 48.4%.

This study investigated the impacts of crude oil, diesel, and gasoline on the diversity of indigenous microbial communities as well as culturable microorganisms in the studied soil. Oil contamination led to shifts in thediversityofthesoil'smicrobialcommunities, regardless of the contaminant applied. Unpolluted soils were more diverse and evenly distributed than contaminated samples. The domain Bacteria accounted for 65.15% of the whole microbial community. The bacterial phylum Proteobacteria dominated in all samples, followed by Actinobacteria and Acidobacteria. Pseudomonas with 28.15% of reads dominated in Proteobacteria, while Rhodococcus (3.07%) dominated in Actinobacteria, and Blastocatella (2.53%) dominated in Acidobacteria. The dominant fungal phyla across all samples were Ascomycota dominated by Penicillium (50.48% of sequences), and Zygomycota dominated by Mortierella (16.87%). Sequences similar to the archaeal phyla, Euryarchaeota and Thaumarchaeota, were also detected. The number of culturable microorganisms increased following the contamination and was higher in contaminated samples than in clean samples. Oil contamination also resulted in the enrichment of oil-degrading strains. Two bacteria, Serratia marcescens strain PL and Raoultella ornithinolytica PS, which were isolated from crude oil-contaminated soil, exhibited strong crude oil degradation ability. Strain PL was the most efficient strain and degraded 75.10% of crude oil, while strain PL degraded 65.48%, after 20days of incubation. However, the mixed culture of the two strains was more effective than single strain and could achieve up to 96.83% of crude oil degradation, with a complete abatement of straight-chain hydrocarbons (from C12 to C25), and more than 91% removal of highly branched hydrocarbons, phytane and pristane, which are known to be more recalcitrant to biodegradation. Strains PS and PL are two newly isolated crude oil degraders that are not among the most prominent crude oil-degrading strains referenced in the literature. Therefore, their high degradation capacity makes them perfect candidates for the bioremediation of petroleum hydrocarbon contaminated environments.

A major hindrance to the effective use of fungi in bioremediation is their inherent slow growth. Despite this, Aspergillus spp. may be used effectively. Our experiments demonstrate that bacteria, although inefficient in hydrocarbon degradation, may be effectively used in a consortium to overcome the lag in fungal utilization of petroleum hydrocarbons. Crude petroleum oil (160mg; at 8g/L) in minimal medium was inoculated with a previously isolated biofilm-forming consortium (Aspergillus sp. MM1 and Bacillus sp. MM1) as well as monocultures of each organism and incubated at 30 ℃ under static conditions. Residual oil was analyzed by GC-MS. Crude oil utilization of Aspergillus-Bacillus biofilm was 24 ± 1.4% in 3days, increased to 66 ± 7% by day 5 and reached 99 ± 0.2% in 7days. Aspergillus sp. MM1 monoculture degraded only 14 ± 6% in 5days. However, at the end of 7days, it was able to utilize 98 ± 2%. Bacillus sp. MM1 monoculture utilized 20 ± 4% in 7days. This study indicates that there is a reduction of the fungal lag in bioremediation when it is in association with the bacterium. Although in monoculture, Bacillus sp. MM1 is inefficient in crude oil degradation, it synergistically enhances the initial rate of crude petroleum oil degradation of the fungus in the consortium. The rapid initial removal of as much crude oil as possible from contaminated sites is vital to minimize detrimental impacts on biodiversity.