Biodegradation Of Hydrocarbons Research Articles

Biotreatment of oily sludge by a bacterial consortium: Effect of bioprocess conditions on biodegradation efficiency and bacterial community structure.

We studied the biodegradation of oily sludge generated by a petroleum plant in Bahrain by a bacterial consortium (termed as AK6) under different bioprocess conditions. Biodegradation of petroleum hydrocarbons in oily sludge (C11-C29) increased from 24% after two days to 99% after 9 days of incubation in cultures containing 5% (w/v) of oily sludge at 40°C. When the nitrogen source was excluded from the batch cultures, hydrocarbon biodegradation dropped to 45% within 7 days. The hydrocarbon biodegradation decreased also by increasing the salinity to 3% and the temperature above 40°C. AK6 tolerated up to 50% (w/v) oily sludge and degraded 60% of the dichloromethane-extractable oil fraction. Illumina-MiSeq analyses revealed that the AK6 consortium was mainly composed of Gammaproteobacteria (ca. 98% of total sequences), with most sequences belonging to Klebsiella (77.6% of total sequences), Enterobacter (16.7%) and Salmonella (5%). Prominent shifts in the bacterial composition of the consortium were observed when the temperature and initial sludge concentration increased, and the nitrogen source was excluded, favoring sequences belonging to Pseudomonas and Stenotrophomonas. The AK6 consortium is endowed with a strong oily sludge tolerance and biodegradation capability under different bioprocess conditions, where Pseudomonas spp. appear to be crucial for hydrocarbon biodegradation.

Plant-derived saponin enhances biodegradation of petroleum hydrocarbons in the rhizosphere of native wild plants

Plant-derived saponins are bioactive surfactant compounds that can solubilize organic pollutants in environmental matrices, thereby facilitating pollutant remediation. Externally applied saponin has potential to enhance total petroleum hydrocarbon (TPH) biodegradation in the root zone (rhizosphere) of wild plants, but the associated mechanisms are not well understood. For the first time, this study evaluated a triterpenoid saponin (from red ash leaves, Alphitonia excelsa) in comparison to a synthetic surfactant (Triton X-100) for their effects on plant growth and biodegradation of TPH in the rhizosphere of two native wild species (a grass, Chloris truncata, and a shrub, Hakea prostrata). The addition of Triton X-100 at the highest level (1000 mg/kg) in the polluted soil significantly hindered the plant growth (reduced plant biomass and photosynthesis) and associated rhizosphere microbial activity in both the studied plants. Therefore, TPH removal in the rhizosphere of both plant species treated with the synthetic surfactant was not enhanced (at the lower level, 500 mg/kg soil) and even slightly decreased (at the highest level) compared to that in the surfactant-free (control) treatment. By contrast, TPH removal was significantly increased with saponin application (up to 60% in C. truncata at 1000 mg/kg due to enhanced plant growth and associated rhizosphere microbial activity). No significant difference was observed between the two saponin application levels. Dehydrogenase activity positively correlated with TPH removal (p < 0.001) and thus this parameter could be used as an indicator to predict the rhizoremediation efficiency. This work indicates that saponin-amended rhizoremediation could be an environmentally friendly and effective biological approach to remediate TPH-polluted soils. It was clear that the enhanced plant growth and rhizosphere microbial activity played a crucial role in TPH rhizoremediation efficiency. The saponin-induced molecular processes that promoted plant growth and soil microbial activity in the rhizosphere warrant further studies.

Biological treatment of hydrocarbons contaminated soil by Serratia ficaria

Petroleum is one of the most important substances consumed by man at present times, a major energy source in this century, petroleum oils can cause environmental pollution during various stages of production, transportation, refining and use, petroleum hydrocarbons pollutions ranging from soil, ground water to marine environment, become an inevitable problem in the modern life, current study focused on bioremediation process of hydrocarbons contaminants that remaining in the bottom of gas cylinders and discharged to the soil. Twenty-four bacterial isolates were isolated from contaminated soils all of them gram negative bacteria, bacterial isolates screening to investigate the ability of biodegradation of hydrocarbons, these isolates inoculated with modified mineral salt media containing 1% hydrocarbons for five days in shaking incubator 150 rpm at 30oC. Then measured optical density by a spectrophotometer (UV–9200) at waves length 540nm, biomass, where three isolates appeared highest ability to growth than others isolates. These three bacterial isolates were diagnosed by morphological features, gram stain, microscopically examination, biochemical tests, as well as by using VITEK 2 Compact device. One of three isolates was selected and result of identification of this bacterium showed that belonged to Serretia ficaria.

Bioremediation of contaminated soil with hydrocarbons discharged from liquid petroleum gas filling refineries by Burkholdaria cepatia

Commercial, industrial, and military activity, largely in the 19th and 20th centuries, have led to environmental pollution that can threaten human health and ecosystem function, liquid gas petroleum (LPG) products are the major sources of energy for industry and daily life that cause environmental contamination during various stages of production, transportation, refining and use. Screening of bacterial isolate by using clear zone techniques and biomass and optical density. Results revealed that isolate Burkholdaria cepatia showed a high ability for hydrocarbons biodegradation and this isolate identified depending on morphological cultural, gram stain, microscopic features, biochemical tests, and VITEK2 compact. In this study, Burkholdaria cepatia had been examined to degrade hydrocarbons in soil. Such strain which is isolated from petroleum hydrocarbon contaminated soil has the ability to utilize a variety of hydrocarbons substrates. Optimal conditions that include (time, temperature &amp; pH) were studied for hydrocarbons biodegradation by Burkholdaria cepatia, results showed with high growth and hydrocarbons biodegredation. Biodegradation Experiments were carried out in lab scale and the growth of microorganisms was investigated directly and indirectly. Results showed an extent of biodegradation more than 80% can be achieved within 10 days using.

Review of Biological Processes in a Membrane Bioreactor (MBR): Effects of Wastewater Characteristics and Operational Parameters on Biodegradation Efficiency When Treating Industrial Oily Wastewater

Oily wastewater is generated from various sources within the petrochemical industry, including extraction, refining and processing, storage, and transportation. Over the years, large volumes of oily wastewater from this industry have made their way into the environment, negatively affecting the environment, human health, and the economy. The raw waters from the petrochemical industry can differ significantly and have complex features, making them difficult to treat. Membrane bioreactors (MBR) are a promising treatment option for complex wastewater; it is a combined physical and biological treatment. The biological component of the MBR is one of the main contributing factors to its success. It is important to know how to control the parameters within the bioreactor to promote the biodegradation of hydrocarbons to improve the treatment efficiency of the MBR. There have been many reviews on the effects of the biological factors of membrane fouling; however, none have discussed the biodegradation process in an MBR and its impact on effluent quality. This review paper investigates the hydrocarbon biodegradation process in an aerobic MBR system by gathering and analyzing the recent academic literature to determine how oily wastewater characteristics and operational parameters affect this process.

Anaerobic biodegradation of polycyclic aromatic hydrocarbons (PAHs) by fungi isolated from anaerobic coal-associated sediments at 2.5km below the seafloor.

Fungi represent the dominant eukaryotic group in the deep biosphere and well-populated in the anaerobic coal-bearing sediments up to ∼2.5km below seafloor (kmbsf). But whether fungi are able to degrade and utilize coal to sustain growth in the anaerobic sub-seafloor environment remains unknown. Based on biodegradation investigation, we found that fungi isolated from sub-seafloor sediments at depths of ∼1.3-∼2.5 kmbsf showed a broad range of polycyclic aromatic hydrocarbons (PAHs) anaerobic degradation rates (3-25%). Among them, the white-rot fungus Schizophyllium commune 20R-7-F01 exhibited the highest degradation, 25%, 18% and 13%, of phenanthrene (Phe), pyrene (Pyr) and benzo[a]pyrene (BaP); respectively, after 10 days of anaerobic incubation. Phe was utilized well and about 40.4% was degraded by the fungus, after 20 days of anaerobic incubation. Moreover, the ability of fungi to degrade PAHs was positively correlated with the anaerobic growth of fungi, indicating that fungi can use PAHs as a sole carbon source under anoxic conditions. In addition, fungal degradation of PAHs was found to be related to the activity of carboxylases, but little or nothing to do with the activity of lignin modifying enzymes such as laccase (Lac), manganese peroxidase (MnP) and lignin peroxidase (LiP). These results suggest that sub-seafloor fungi possess a special mechanism to degrade and utilize PAHs as a carbon and energy source under anaerobic conditions. Furthermore, fungi living in sub-seafloor sediments may not only play an important role in carbon cycle in the anaerobic environments of the deep biosphere, but also be able to persist in deep sediment below seafloor for millions of years by using PAHs or related compounds as carbon and energy source. This anaerobic biodegradation ability could make these fungi suitable candidates for bioremediation of toxic pollutants such as PAHs from anoxic environments.

Идентификация источников нефтяных загрязнений методом инфракрасной спектроскопии

The article demonstrates the importance of using reliable methods for identifying oil pollution in relation to accidents and incidents at hazardous production facilities of oil and gas production. Examples are given and prospects for possible negative consequences of biosocial emergencies at drilling and production facilities of the oil and gas complex and related infrastructure are shown. The processes of temporary and biodegradation of petroleum hydrocarbons in soils and aquatic environment are described. The necessity of considering the processes of transformation of oils and oil products in the environment during the production of identification eco-forensic studies in relation to them is shown. The advantages of Fourier spectrometers are revealed, which allow reliably distinguish between oil samples with a difference in optical density in the spectra at the level of 0.01 (0.3–1 % transmission), compared with diffraction infrared spectrometers. Fourier spectrometers were used to study seven oil samples from various fields of the Khanty-Mansi Autonomous Okrug. The influence was assessed related to artificial aging on the possibility of identifying the source of oil origin in relation to samples collected in the places of pollution. The results of the study of samples extracted from oil-contaminated soil were carried out and presented. The results of the research confirm the possibility of creating a reliable method for identifying oil pollution based on the method of infrared spectroscopy, as well as new methodological approaches to the problem of identifying samples of oil products in the investigation of arson. It was determined that in the case of using modern technology based on Fourier spectrometers equipped with systems for automatic processing and comparison of spectra, the method of infrared spectroscopy can be used as not only a preliminary, but also one of the basic means of identification.

Screening of Biosurfactant-producing Bacteria from Symbiotic Microbes with Gastropods in the Persian Gulf

Introduction: Biosurfactants or surface-active compounds with amphiphilic molecular structures, including a hydrophilic and a hydrophobic domain, are produced by microorganisms. These compounds increase the biodegradation of hydrocarbons in the environment due to their ability to emulsify hydrocarbon-water mixtures. This study was conducted to isolate and characterize biosurfactant-producing bacteria from the samples of Gastropods. &#x0D; Materials and Methods: The gastropod samples were collected from oil-contaminated sites in the Persian Gulf, Middle East. Biosurfactant-producing strains were isolated from these samples. The biosurfactant production ability was analyzed using Drop Collapse TEST, oil spreading test, emulsification activity test, and BATH test.&#x0D; Results: In total, 11 biosurfactant-producing strains were isolated. Two isolates with higher growth rates and biosurfactant production ability were selected for further studies. The best isolates were identified as Halomonas sp. isolate BHA16 and Vibrio alginolyticus isolate BHA 17 based on molecular analysis. Gas chromatography analysis of remaining crude oil confirmed that these strains could degrade to 51.44 % and 67.58% of crude oil, respectively.&#x0D; Conclusion: The results of this study indicated the surfactant activity of the bacterial strains isolated from Gastro pods had a good potential for the biodegradation of crude oil and could be used for the cleanup of oil-contaminated marine environments.

Insights into the syntrophic microbial electrochemical oxidation of toluene: a combined chemical, electrochemical, taxonomical, functional gene-based, and metaproteomic approach

Biodegradation of aromatic hydrocarbons in anoxic contaminated environments is typically limited by the lack of bioavailable electron acceptors. Microbial electrochemical technologies (METs) are able to provide a virtually inexhaustible electron acceptor in the form of a solid electrode.Recently, we provided first experimental evidence for the syntrophic degradation of toluene in a continuous-flow bioelectrochemical reactor known as the “bioelectric well”. Herein, we further analyzed the structure and function of the electroactive toluene-degrading microbiome using a suite of chemical, electrochemical, phylogenetic, proteomic, and functional gene-based analyses.The bioelectric well removed 83 ± 7 % of the toluene from the influent with a coulombic efficiency of 84 %. Cyclic voltammetry allowed to identify the formal potentials of four putative electron transfer sites, which ranged from −0.2 V to +0.1 V vs. SHE, consistent with outer membrane c-type cytochromes and pili of electroactive Geobacter species. The biofilm colonizing the surface of the anode was indeed highly enriched in Geobacter species. On the other hand, the planktonic communities thriving in the bulk of the reactor harbored aromatic hydrocarbons degraders and fermentative propionate-producing microorganisms, as revealed by phylogenetic and proteomic analyses. Most likely, propionate, acetate or other VFAs produced in the bulk liquid from the degradation of toluene were utilized as substrates by the electroactive biofilm. Interestingly, key-functional genes related to the degradation of toluene were found both in the biofilm and in the planktonic communities. Taken as a whole, the herein reported results highlight the importance of applying a comprehensive suite of techniques to unravel the complex cooperative metabolisms occurring in METs.

Biodegradation of polycyclic aromatic hydrocarbons by Acremonium sp. activity

Chihuahua State is the largest apple producer in Mexico. To prevent apples from freezing during the winter, petroleum-based fuels are used to heat the orchards. In this research work, a microorganism isolated from inside of a fuel plastic container was identified through morphological analysis as the fungus Acremonium sp. By cultivating the fungus in potato dextrose agar medium (PDA), we were able to study the biodegradation rates of three polycyclic aromatic hydrocarbons (PAHs). The isolated microorganism was incubated at 28 ºC in M9 mineral liquid medium using phenanthrene, anthracene, and pyrene as the only carbon source at a concentration of 50 µg/mL. Degradation of PAHs was monitored using an environmentally friendly reverse phase ultra-high-performance liquid chromatography (UHPLC) system, with a C18 column, 30% water acidified at 0.1% with trifluoroacetic acid, and 70% acetonitrile as the mobile phase, 40 ºC column temperature, and UV detection at 254 nm. After 30 days of biodegradation (optimal time), the final mean concentration for individual degradation experiments were 2.51 µg/mL phenanthrene, 3.02 µg/mL anthracene and 5.53 µg/mL pyrene. Those final concentrations indicate degradation percentile of 95%, 94%, and 89%, respectively. Biodegradation experiments combining all three PAHs showed similarly high degradation percentiles of 93%, 94%, and 85% for phenanthrene, anthracene, and pyrene, respectively. The dry weight average at day 30 in the individual and combined degradation experiments was 2.34 mg/mg PAHs degraded.

Hydrocarbons Biodegradation by Rhodococcus: Assimilation of Hexadecane in Different Aggregate States.

The aim of our study was to reveal the peculiarities of the adaptation of rhodococci to hydrophobic hydrocarbon degradation at low temperatures when the substrate was in solid states. The ability of actinobacteria Rhodococcus erythropolis (strains X5 and S67) to degrade hexadecane at 10 °C (solid hydrophobic substrate) and 26 °C (liquid hydrophobic substrate) is described. Despite the solid state of the hydrophobic substrate at 10 °C, bacteria demonstrate a high level of its degradation (30–40%) within 18 days. For the first time, we show that specialized cellular structures are formed during the degradation of solid hexadecane by Rhodococcus at low temperatures: intracellular multimembrane structures and surface vesicles connected to the cell by fibers. The formation of specialized cellular structures when Rhodococcus bacteria are grown on solid hexadecane is an important adaptive trait, thereby contributing to the enlargement of a contact area between membrane-bound enzymes and a hydrophobic substrate.

Biodegradation of high molecular weight hydrocarbons under saline condition by halotolerant Bacillussubtilis and its mixed cultures with Pseudomonas species

Biodegradation of high-molecular-weight petroleum hydrocarbons in saline conditions appears to be complicated and requires further investigation. This study used heavy crude oil to enrich petroleum-degrading bacteria from oil-contaminated saline soils. Strain HG 01, with 100% sequence similarity to Bacillussubtilis, grew at a wide range of salinities and degraded 55.5 and 77.2% of 500 mg/l pyrene and 500 mg/l tetracosane, respectively, at 5% w/v NaCl. Additionally, a mixed-culture of HG 01 with Pseudomonasputida and Pseudomonasaeruginosa, named TMC, increased the yield of pyrene, and tetracosane degradation by about 20%. Replacing minimal medium with treated seawater (C/N/P adjusted to 100/10/1) enabled TMC to degrade more than 99% of pyrene and tetracosane, but TMC had lesser degradation in untreated seawater than in minimal medium. Also, the degradation kinetics of pyrene and tetracosane were fitted to a first-order model. Compared to B.subtilis, TMC increased pyrene and tetracosane's removal rate constant (K1) from 0.063 and 0.110 per day to 0.123 and 0.246 per day. TMC also increased the maximum specific growth rate of B.subtilis, P.putida, and P.aeruginosa, respectively, 45% higher in pyrene, 24.5% in tetracosane, and 123.4% and 95.4% higher in pyrene and tetracosane.

Converging alfalfa (Medicago sativa L.) and petroleum hydrocarbon acclimated ACC-deaminase containing bacteria for phytoremediation of petroleum hydrocarbon contaminated soil

Plant assisted bioremediation of petroleum hydrocarbon contaminated soil is considered an effective green technology whereby accelerated degradation occurs due to converged effect of microorganisms and plants. However, survival and growth of microbes and plants under stress conditions is challenging task for success of the technology. In this study, plant growth promoting bacteria containing 1-aminocyclopropane-1-carboxylate (ACC)-deaminase activity and tolerance to petroleum hydrocarbon contamination were used in association with alfalfa for bioremediation of petroleum hydrocarbon contaminated soil. Eight pre-isolated bacterial isolates from soil having previous history of petroleum contamination were used in convergence with alfalfa on sand soil which was artificially contaminated (10 g crude oil per kg−1 of coarse textured soil). Combined effect of bacteria and plants on the degradation of petroleum hydrocarbons under controlled conditions of light and temperature was observed for a period of 60 days. The results of the study revealed that four bacterial isolates Bacillus subtilis strain PM32Y, Bacillus cereus strain WZ3S1, Bacillus sp. strain SM73 and Bacillus sp. strain WZ3S3 in association with alfalfa significantly degraded petroleum hydrocarbons. The most significant biodegradation (47%) of petroleum hydrocarbons was recorded in the experimental unit receiving PM32Y inoculation in association with alfalfa. Biodegradation of petroleum hydrocarbons was 33% with alone inoculation (without alfalfa) of PM32Y. The study revealed that combined use of bacteria and alfalfa plant is more efficient than alone application of either bacteria or plants for degradation of petroleum hydrocarbons.

Efficient Biodegradation of Polycyclic Aromatic Hydrocarbons in the Rhizosphere Using Plant Growth Regulators and Biological Agents

Soil contamination with Polycyclic Aromatic Hydrocarbons (PAHs) is becoming a more prevalent problem worldwide. The presented study aimed to establish a new method of an effective and cost-efficient degradation of pyrene (Py) and phenanthrene (Phe) through the combination of planting Festuca grass along with gibberellic acid (GA) supplementation, and the application of arbuscular mycorrhiza fungi (AMF). The study consisted of four experimental groups: T1: soil spiked with 200, 300, and 400 mg kg−1 Phe and Py without any vegetation, T2: cultivation of Festuca grass without any additional treatment, T3: Festuca grass with the gibberellic acid supplementation, T4: Festuca grass with the application of AMF. The results demonstrated that both: GA and AMF increased the number of rhizosphere bacteria. The activity of dehydrogenase (DHA) and peroxidase (POD) enzymes was increased in a clear concentration-dependent manner, which improved PAHs removal. The findings suggest that the use of GA and AMF with plant cultivation can be a promising strategy for the removal of PAHs from soils.

Passive electrobioremediation approaches for enhancing hydrocarbons biodegradation in contaminated soils

Electrobioremediation technologies hold considerable potential for the treatment of soils contaminated by petroleum hydrocarbons (PH), since they allow stimulating biodegradation processes with no need for subsurface chemicals injection and with little to no energy consumption. Here, a microbial electrochemical snorkel (MES) was applied for the treatment of a soil contaminated by hydrocarbons. The MES consists of direct coupling of a microbial anode with a cathode, being a single conductive, non-polarized material positioned suitably to create an electrochemical connection between the anoxic zone (the contaminated soil) and the oxic zone (the overlying oxygenated water). Soil was also supplemented with electrically conductive particles of biochar as a strategy to construct a conductive network with microbes in the soil matrix, thus extending the radius of influence of the snorkel. The results of a comprehensive suite of chemical, microbiological and ecotoxicological analyses evidenced that biochar addition, rather than the presence of a snorkel, was the determining factor in accelerating PH removal from contaminated soils, possibly accelerating syntrophic and/or cooperative metabolisms involved in the degradation of PH. The enhancement of biodegradation was mirrored by an increased abundance of anaerobic and aerobic microorganisms known to be involved in the degradation of PH and related functional genes. Plant ecotoxicity assays confirmed a reduction of soils toxicity in treatments receiving electrically conductive biochar.

Alkan Hidrokarbonları Parçalayan Enterobacter ludwigii strain D8 Suşunun Petrolle Kirlenmiş Topraklardan İzolasyonu ve Karakterizasyonu

A bacterial strain has been isolated from petroleum contaminated soil with in southeastern Turkey. This isolated strain was characterized to determine its hydrocarbon biodegradation potential. Phenotypic features and of 16 S gene sequence analysis of rRNA revealed that strain D8 belongs to the Enterobacter genus and most closely resembles Enterobacter ludwigii (100%). The optimum temperature and pH values for the growth of E. ludwigii D8 were found to be 30°C and 5.0, respectively. This bacterial strain grew in long and medium chain hydrocarbons such as 1% decane, pentadecane and squalene separately at the end of 3 day incubation in the basal medium (BM) under optimum conditions. It was shown that E. ludwigii strain D8 degrades about 27% of crude oil incubated for 5 days, while it degrades 29% of pentadecane after 3 days of incubation determined by Gas chromatography-MS analysis. The biodegradation potential of petroleum hydrocarbons of E. ludwigii strain D8 isolated and characterized in this study indicates that this strain may play a role in the bioremediation process.

Impacts of groundwater level fluctuation on soil microbial community, alkane degradation efficiency and alkane-degrading gene diversity in the critical zone: Evidence from an accelerated water table fluctuation simulation.

Petroleum hydrocarbons are hazardous to ecosystems and human health, commonly containing n-alkanes and polycyclic aromatic hydrocarbons. Previous researches have studied alkane degraders and degrading genes under aerobic or anaerobic conditions, but seldom discussed them in the intermittent saturation zone which is a connective area between the vadose zone and the groundwater aquifer with periodic alteration of oxygen and moisture. The present study investigated the difference in alkane degradation efficiency, bacterial community, and alkane degrading gene diversity in aerobic, anaerobic, and aerobic-anaerobic fluctuated treatments. All biotic treatments achieved over 90% of n-alkane removal after 120days of incubation. The removal efficiencies of n-alkanes with a carbon chain length from 16 to 25 were much higher in anaerobic scenarios than those in aerobic scenarios, explained by different dominant microbes between aerobic and anaerobic conditions. The highest removal efficiency was found in fluctuation treatments, indicating an accelerated n-alkane biodegradation under aerobic-anaerobic alternation. In addition, the copy numbers of the 16S rRNA gene and two alkB genes (alkB-P and alkB-R) declined dramatically when switched from aerobic to anaerobic scenarios and oppositely from anaerobic to aerobic conditions. This suggested that water level fluctuation could notably change the presence of aerobic alkane degrading genes. Our results suggested that alkane degradation efficiency, soil microbial community, and alkane-degrading genes were all driven by water level fluctuation in the intermittent saturation zone, helping better understand the effects of seasonal water table fluctuation on the biodegradation of petroleum hydrocarbons in the subsurface environment.

Emulating Deep-Sea Bioremediation: Oil Plume Degradation by Undisturbed Deep-Sea Microbial Communities Using a High-Pressure Sampling and Experimentation System

Hydrocarbon biodegradation rates in the deep-sea have been largely determined under atmospheric pressure, which may lead to non-representative results. In this work, we aim to study the response of deep-sea microbial communities of the Eastern Mediterranean Sea (EMS) to oil contamination at in situ environmental conditions and provide representative biodegradation rates. Seawater from a 600 to 1000 m depth was collected using a high-pressure (HP) sampling device equipped with a unidirectional check-valve, without depressurization upon retrieval. The sample was then passed into a HP-reactor via a piston pump without pressure disruption and used for a time-series oil biodegradation experiment at plume concentrations, with and without dispersant application, at 10 MPa and 14 °C. The experimental results demonstrated a high capacity of indigenous microbial communities in the deep EMS for alkane degradation regardless of dispersant application (&gt;70%), while PAHs were highly degraded when oil was dispersed (&gt;90%) and presented very low half-lives (19.4 to 2.2 days), compared to published data. To our knowledge, this is the first emulation study of deep-sea bioremediation using undisturbed deep-sea microbial communities.

Isolation and characterization of alkane hydrocarbons-degrading Delftia tsuruhatensis strain D9 from petroleum-contaminated soils

A bacterial strain from petroleum-contaminated soil in south-eastern Turkey was isolated and characterized to determine the potential of alkane hydrocarbon biodegradation. Phenotypic characteristics and the sequence analysis of the 16S rRNA gene revealed that the strain D9 is a member of the Delfitia genus and most similar to Delftia tsuruhatensis (100%). The optimum pH and temperature values for the growth of D. tsuruhatensis strain D9 were found to be 9.0-10.0 and 35°C, respectively. The strain was found to grow in some single, medium and long-chain hydrocarbons such as decane, hexadecane, and squalene, tested by short-time incubation in basal medium (BM) in the presence of 1% hydrocarbon concentrations under optimum conditions. After incubation for 3 days, 65% of the single hydrocarbon hexadecane was degraded by the D. tsuruhatensis strain D9, revealed by GC-MS analysis. The biodegradation of petroleum hydrocarbons by D. tsuruhatensis strain D9 isolated and characterized in the present study shows that it can be a good candidate in the bioremediation process.

Dose–Response Effect of Nitrogen on Microbial Community during Hydrocarbon Biodegradation in Simplified Model System

Knowledge about the influence of C:N ratio on the biodegradation process of hydrocarbon compounds is of significant importance in the development of biostimulation techniques. The purpose of this study was to assess the impact of nitrogen compounds on the environmental consortium during the process of biological decomposition of hydrocarbons. The experimental variants represented low, moderate, and excessive biostimulation with nitrogen compounds. The metabolic activity of the consortium was tested using the flow cytometry technique. The efficiency of the biodegradation of hydrocarbons of the consortium, based on the gas chromatography method, and metapopulation changes, based on the analysis of V4 16srRNA sequencing data, were assessed. The results of the research confirm the positive effect of properly optimized biostimulation with nitrogen compounds on the biological decomposition of polycyclic aromatic hydrocarbons. The negative impact of excessive biostimulation on the biodegradation efficiency and metabolic activity of microorganisms is also proven. Low resistance to changes in the supply of nitrogen compounds is demonstrated among the orders Xanthomonadales, Burkholderiales, Sphingomonadales, Flavobacteriales, and Sphingobacteriales. It is proven that quantitative analysis of the order of Rhizobiales, characterized by a high-predicted potential for the decomposition of polycyclic aromatic hydrocarbons, may be helpful during biostimulation optimization processes in areas with a high nitrogen deficiency.