Hydrocarbon-degrading Microorganisms Research Articles

Characterization the microbial diversity and functional genes in the multi-component contaminated groundwater in a petrochemical site.

Microorganisms in groundwater at petroleum hydrocarbon (PHC)-contaminated sites are crucial for PHC natural attenuation. Studies mainly focused on the microbial communities and functions in groundwater contaminated by PHC only. However, due to diverse raw and auxiliary materials and the complex production processes, in some petrochemical sites, groundwater suffered multi-component contamination, but the microbial structure remains unclear. To solve the problem, in the study, a petrochemical enterprise site, where the groundwater suffered multi-component pollution by PHC and sulfates, was selected. Using hydrochemistry, 16S rRNA gene, and metagenomic sequencing analyses, the relationships among electron acceptors, microbial diversity, functional genes, and their interactions were investigated. Results showed that different production processes led to different microbial structures. Overall, pollution reduced species richness but increased the abundance of specific species. The multi-component contamination multiplied a considerable number of hydrocarbon-degrading and sulfate-reducing microorganisms, and the introduced sulfates might have promoted the biodegradation of PHC. PRACTITIONER POINTS: The compound pollution of the site changed the microbial community structure. Sulfate can promote the degradation of petroleum hydrocarbons by hydrocarbon-degrading microorganisms. The combined contamination of petroleum hydrocarbons and sulfates will decrease the species richness but increase the abundance of endemic species.

Structure and composition of microbial communities in the water column from Southern Gulf of Mexico and detection of putative hydrocarbon-degrading microorganisms.

This study assessed the bacterioplankton community and its relationship with environmental variables, including total petroleum hydrocarbon (TPH) concentration, in the Yucatan shelf area of the Southern Gulf of Mexico. Beta diversity analyses based on 16S rRNA sequences indicated variations in the bacterioplankton community structure among sampling sites. PERMANOVA indicated that these variations could be mainly related to changes in depth (5 to 180 m), dissolved oxygen concentration (2.06 to 5.93 mg L-1), and chlorophyll-a concentration (0.184 to 7.65 mg m3). Moreover, SIMPER and one-way ANOVA analyses showed that the shifts in the relative abundances of Synechococcus and Prochlorococcus were related to changes in microbial community composition and chlorophyll-a values. Despite the low TPH content measured in the studied sites (0.01 to 0.86 μL L-1), putative hydrocarbon-degrading bacteria such as Alteromonas, Acinetobacter, Balneola, Erythrobacter, Oleibacter, Roseibacillus, and the MWH-UniP1 aquatic group were detected. The relatively high copy number of the alkB gene detected in the water column by qPCR and the enrichment of hydrocarbon-degrading bacteria obtained during lab crude oil tests exhibited the potential of bacterioplankton communities from the Yucatan shelf to respond to potential hydrocarbon impacts in this important area of the Gulf Mexico.

Nutrients, surfactants, and aeration in constructed wetlands affect bacterial persistence and metabolic activity during the remediation of crude oil-contaminated water

The use of constructed wetlands (CWs) is one of the best options to treat wastewater. In CWs, microorganisms play a major role in the degradation of organic pollutants but the concentration of nutrients, surfactant, and aeration (NSA) in oil-contaminated water is one of the factors that affect the persistence and metabolic functioning of hydrocarbon-degrading microorganisms. In the present investigation, the influence of the addition of NSA on the persistence of the augmented bacteria, copy of (alkane hydroxylase gene) alkB gene, and its expression level in the water, soil, and plants of CWs were evaluated. The CWs mesocosms were developed by the vegetation of Typha latifolia and Cyperus laevigatus and inoculated with the bacterial consortium (Pseudomonas putida TYRI39, Acinetobacter junii TYRH47, Acinetobacter sp. CYRH17, Pseudomonas sp. CYSI27, and Pseudomonas sp. TYRH42). The mesocosms were provided with nutrients (20 mg l− 1 N, 2.6 mg l− 1 P, and 16.4 mg l− 1 K) in liquid form, surfactant Tween-20 (0.2%, v/v) in liquid form, and aeration (≥ 7.0 ± 1 mg l− 1 DO) using aeration pump. The addition of NSA in CWs enhanced the persistence and metabolic functioning of the inoculated bacteria in the water, rhizospheric soil, and plants. The maximum hydrocarbon removal (97%) was observed in the water treated by CWs having C. laevigatus, bacteria, and NSA, and it is correlated with the copy numbers of alkB and its expression level. The application of NSA in CWs not only improved bacterial persistence and catabolic gene expression but also increased plant development and hydrocarbon removal.

Broad-spectrum hydrocarbon-degrading microbes in the global ocean metagenomes

Understanding the diversity and functions of hydrocarbon-degrading microorganisms in marine environments is crucial for both advancing knowledge of biogeochemical processes and improving bioremediation methods. In this study, we leveraged nearly 20,000 metagenome-assembled genomes (MAGs), recovered from a wide array of marine samples across the global oceans, to map the diversity of aerobic hydrocarbon-degrading microorganisms. A broad bacterial diversity was uncovered, with a notable preference for degrading aliphatic hydrocarbons over aromatic ones, primarily within Proteobacteria and Actinobacteriota. Three types of broad-spectrum hydrocarbon-degrading bacteria were identified for their ability to degrade various hydrocarbons and possession of multiple copies of hydrocarbon biodegradation genes. These bacteria demonstrate extensive metabolic versatility, aiding their survival and adaptability in diverse environmental conditions. Evidence of gene duplication and horizontal gene transfer in these microbes suggested a potential enhancement in the diversity of hydrocarbon-degrading bacteria. Positive correlations were observed between the abundances of hydrocarbon-degrading genes and environmental parameters such as temperature (−5 to 35 °C) and salinity (20 to 42 PSU). Overall, our findings offer valuable insights into marine hydrocarbon-degrading microorganisms and suggest considerations for selecting microbial strains for oil pollution remediation.

Characterization of hydrocarbon degraders from Northwest Passage beach sediments and assessment of their ability for bioremediation.

Global warming-induced sea ice loss in the Canadian Northwest Passage (NWP) will result in more shipping traffic, increasing the risk of oil spills. Microorganisms inhabiting NWP beach sediments may degrade hydrocarbons, offering a potential bioremediation strategy. In this study, the characterization and genomic analyses of 22 hydrocarbon-biodegradative bacterial isolates revealed that they contained a diverse range of key alkane and aromatic hydrocarbon-degradative genes, as well as cold and salt tolerance genes indicating they are highly adapted to the extreme Arctic environment. Some isolates successfully degraded Ultra Low Sulfur Fuel Oil (ULSFO) at temperatures as low as -5°C and high salinities (3%-10%). Three isolates were grown in liquid medium containing ULSFO as sole carbon source over 3 months and variation of hydrocarbon concentration was measured at three time points to determine their rate of hydrocarbon biodegradation. Our results demonstrate that two isolates (Rhodococcus sp. R1B_2T and Pseudarthrobacter sp. R2D_1T) possess complete degradation pathways and can grow on alkane and aromatic components of ULSFO under Arctic conditions. Overall, these results demonstrate that diverse hydrocarbon-degrading microorganisms exist in the NWP beach sediments, offering a potential bioremediation strategy in the events of a marine fuel spill reaching the shores of the NWP.

Green remediation and enhanced metal accumulation using moringa oleifera leaf extracts and hydrocarbon-degrading microorganisms in crude oil-impacted soils of the niger delta, nigeria

This emerging technology called “Phytoremediation” which uses plants to remove pollutants from the environment is preferred over traditional methods, because it offers site restoration, partial decontamination, and maintenance of biological activity and physical structure whilst being potentially cheap, visually unobtrusive and with a possibility of bio-recovery of metals. Because of these advantages, phytoremediation is considered as a 'green', sustainable pollution removal process. The present study was designed to evaluate Phytoremediation potential of Moringa oleifera leaf extract on soil contaminated with Spent Engine Oil. Top soil (0-15cm depth) was randomly collected and 5kg each of the composite samples were transferred into fifty (50) plastic buckets with drainage holes at the base, plugged with cotton wool to retain the soil. The Plastic buckets were arranged into five treatment groups with Ten (10) replicates each. The polythene bags were arranged in a completely randomized block design. Spent Engine oil obtained from mechanic shops in Bedwell Calabar, Cross River State, was applied as the pollutant. The Spent engine oil was introduced at different concentration levels (0.3, 0.5, 0.7, and 1.0 l/5kg) into the treatment groups apart from the control (0.0 l/5kg).The results across the various treatment levels where subjected to statistical analysis, using Analysis of variance (ANOVA) and the results showed that physicochemical parameters (soil pH and organic carbon), Heavy Metals present, Total Petroleum Hydrocarbon and Microbial Counts were significantly higher (P<0.05) in treatment groups than the control. The result also showed a significant reduction (P<0.05) of the Total petroleum hydrocarbon after treatment.

Physicochemical and microbial alterations in crude oil-contaminated soil samples

Environmental pollution is becoming an issue of concern due to its negative impact on the living and non-living components of the environment. Crude oil and its products are the major sources of environmental pollution that renders negative impact on the soil mineral components and microorganism. This study was thus carried out to determine the effect of crude oil on soil physicochemical properties, bacterial and fungal population. The experiment lasted for 42 days and the analysis were carried out at days 0, 14, 28 and 42 using standard protocols. Results obtained show significant changes (P ≤ 0.05) in hydrocarbons and other physicochemical parameters such as pH, nitrate, electrical conductivity, sodium ion, calcium ion, phosphate and magnesium ion, when the control was compared with crude oil contaminated soil. Also, soil bacterial and fungal count decreased significantly (P ≤ 0.05) with increasing concentrations of crude oil indicating its toxicity to soil microbial consortium. However, results also showed that hydrocarbon-degrading microorganisms strived at higher concentrations but insignificantly (P ≤ 0.05) in comparison with the control. Owing to the result obtained in this study, crude oil exploration should be properly managed to prevent spillages that negatively impact on the environment.

Microbial responses to increased salinity in oiled upper tidal shorelines

The microbial degradation of crude oil stranded on seashores is usually much slower than that of dispersed oil at sea. This is usually attributed to nutrient limitation and higher oil concentrations on beaches than in dispersed plumes, in addition to the low moisture content and transient hypersaline conditions of the upper intertidal and supratidal zones. Here, we investigated the effect of hypersaline conditions, oil concentration, and nutrient limitation on the hydrocarbonoclastic activity. Beach sand, with oil concentrations of 1 and 10 mL/kg, was infiltrated with seawater at salinities of 30, 90, and 160 g/L to 20% saturation, with and without the addition of nutrients. Oil chemistry, 16 S rRNA gene amplicon, and metagenomic sequencing analyses were conducted every 30 days for 180 days. The biodegradation of aromatic hydrocarbons was much slower at higher salinities, while that of alkanes was not noticeably affected, and the addition of nutrients only marginally enhanced the biodegradation of hydrocarbons. The relative abundance and diversity of genera varied substantially with the increase in pore water salinity, whereby halophilic hydrocarbon-degrading microorganisms, particularly in the Marinobacter genus, were significantly abundant only under hypersaline conditions. The enzymes were considerably less abundant at high salinities, mainly for those associated to aromatic hydrocarbon degradation pathways. Consequently, occasional inundation of the upper parts of oiled sandy beaches with seawater to decrease the pore water salinity and reseed the contaminated region with indigenous hydrocarbon degraders, along with the concomitant addition of fertilizers, could be a suitable, non-destructive, and inexpensive response tool for enhancing the biodegradation of beached crude oil, particularly that of the aromatic fraction.

From rivers to marine environments: A constantly evolving microbial community within the plastisphere

Plastics accumulate in the environment and the Mediterranean Sea is one of the most polluted sea in the world. The plastic surface is rapidly colonized by microorganisms, forming the plastisphere. Our unique sampling supplied 107 plastic pieces from 22 geographical sites from four aquatic ecosystems (river, estuary, harbor and inshore) in the south of France in order to better understand the parameters which influence biofilm composition. In parallel, 48 enrichment cultures were performed to investigate the presence of plastic degrading-bacteria in the plastisphere. In this context, we showed that the most important drivers of microbial community structure were the sampling site followed by the polymer chemical composition. The study of pathogenic genus distribution highlighted that only 11% of our plastic samples contained higher proportions of Vibrio compared to the natural environment. Finally, results of the enrichment cultures showed a selection of hydrocarbon-degrading microorganisms suggesting their potential role in the plastic degradation.

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

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

Bioremediation of river sediment polluted with polychlorinated biphenyls: A laboratory study

Persistent organic pollutants (POPs) are lipophilic, constant and bioaccumulative toxic compounds. In general, they are considered resistant to biological, photolytic, and chemical degradation with polychlorinated biphenyls (PCBs) belonging to these chemicals. PCBs were never produced in Serbia, but they were imported and mainly used in electrical equipment, transformers, and capacitors. Our study aimed to analyse sequential multi-stage aerobic/anaerobic microbial biodegradation of PCBs present in the river sediment from the area known for long-term pollution with these chemicals. The study with an autochthonous natural microbial community (NMC model system) and NMC augmented with allochthonous hydrocarbon-degrading (AHD) microorganisms (isolated from location contaminated with petroleum products) (NMC-AHD model system) was performed in order to estimate the potential of these microorganisms for possible use in future bioremediation treatment of these sites. The laboratory biodegradation study lasted 70 days, after which an overall >33 % reduction in the concentration of total PCBs was observed. This study confirmed the strong potential of the NMC for the reduction of the level of PCBs in the river sediment under alternating multi-stage aerobic/anaerobic conditions.

Trace Metal Contamination Impacts Predicted Functions More Than Structure of Marine Prokaryotic Biofilm Communities in an Anthropized Coastal Area.

Trace metal (TM) contamination in marine coastal areas is a worldwide threat for aquatic communities. However, little is known about the influence of a multi-chemical contamination on both marine biofilm communities’ structure and functioning. To determine how TM contamination potentially impacted microbial biofilms’ structure and their functions, polycarbonate (PC) plates were immerged in both surface and bottom of the seawater column, at five sites, along strong TM contamination gradients, in Toulon Bay. The PC plates were incubated during 4 weeks to enable colonization by biofilm-forming microorganisms on artificial surfaces. Biofilms from the PC plates, as well as surrounding seawaters, were collected and analyzed by 16S rRNA amplicon gene sequencing to describe prokaryotic community diversity, structure and functions, and to determine the relationships between bacterioplankton and biofilm communities. Our results showed that prokaryotic biofilm structure was not significantly affected by the measured environmental variables, while the functional profiles of biofilms were significantly impacted by Cu, Mn, Zn, and salinity. Biofilms from the contaminated sites were dominated by tolerant taxa to contaminants and specialized hydrocarbon-degrading microorganisms. Functions related to major xenobiotics biodegradation and metabolism, such as methane metabolism, degradation of aromatic compounds, and benzoate degradation, as well as functions involved in quorum sensing signaling, extracellular polymeric substances (EPS) matrix, and biofilm formation were significantly over-represented in the contaminated site relative to the uncontaminated one. Taken together, our results suggest that biofilms may be able to survive to strong multi-chemical contamination because of the presence of tolerant taxa in biofilms, as well as the functional responses of biofilm communities. Moreover, biofilm communities exhibited significant variations of structure and functional profiles along the seawater column, potentially explained by the contribution of taxa from surrounding sediments. Finally, we found that both structure and functions were significantly distinct between the biofilm and bacterioplankton, highlighting major differences between the both lifestyles, and the divergence of their responses facing to a multi-chemical contamination.

Plant-Soil-Microbiota Combination for the Removal of Total Petroleum Hydrocarbons (TPH): An In-Field Experiment.

The contamination of soil with total petroleum hydrocarbons (TPH) may result in dramatic consequences and needs great attention, as soil rehabilitation would need more effort from a sustainability perspective. However, there is still no known general method since the remediation technology is strictly site-specific. Adaptive biological system dynamics can play a key role in understanding and addressing the potential of situ-specific biological combinations for soil pollutants removal. The potential worst-case of TPH contamination reflects soil affected by heavy industrial activities, such as oil refineries. Therefore, the experimental trial was conducted on a 2,000 m2 area from a contaminated site located in northern Italy. We evaluated the remediation potential over time (270 days) assessing (i) the phytoremediation efficiency of two species of Poaceae (Festuca arundinacea Schreb. and Dactylis glomerata L.) and two species of Fabaceae (Medicago sativa L. and Lotus corniculatus L.) and (ii) the role of the indigenous bacteria flora and endo-mycorrhizae consortium addition in plant growth promotion. We also induced resistance to contamination stress in a field experiment. Thirty-three indigenous bacteria selected from the contaminated soils showed marked plant growth promotion. Moreover, functional metagenomics confirmed the metabolic capability of hydrocarbon-degrading microorganisms living in the polluted soil. Our data showed that soil enzymatic activities increased with hydrocarbon degradation rate after 60 days. Both Poaceae and Fabaceae resulted in remarkable remediation potential. Stress markers and antioxidant activity indicated that the selected plant species generally need some time to adapt to TPH stress. In conclusion, our evaluation implied both the rhizosphere effects and functional features of the plant and suggested that plants should (i) have marked tolerance to specific contaminants, (ii) be characterized by an extensive root system, and (iii) be susceptible to arbuscular mycorrhizal fungi (AMF) infection.

The Effect of an Adsorbent Matrix on Recovery of Microorganisms from Hydrocarbon-Contaminated Groundwater.

The microbial degradation of recalcitrant hydrocarbons is an important process that can contribute to the remediation of oil and gas-contaminated environments. Due to the complex structure of subsurface terrestrial environments, it is important to identify the microbial communities that may be contributing to biodegradation processes, along with their abilities to metabolize different hydrocarbons in situ. In this study, a variety of adsorbent materials were assessed for their ability to trap both hydrocarbons and microorganisms in contaminated groundwater. Of the materials tested, a porous polymer resin (Tenax-TA) recovered the highest diversity of microbial taxa in preliminary experiments and was selected for additional (microcosm-based) testing. Oxic and anoxic experiments were prepared with groundwater collected from a contaminated aquifer to assess the ability of Tenax-TA to adsorb two environmental hydrocarbon contaminants of interest (toluene and benzene) while simultaneously providing a surface for microbial growth and hydrocarbon biodegradation. Microorganisms in oxic microcosms completely degraded both targets within 14 days of incubation, while anoxically-incubated microorganisms metabolized toluene but not benzene in less than 80 days. Community analysis of Tenax-TA-associated microorganisms revealed taxa highly enriched in sessile hydrocarbon-degrading treatments, including Saprospiraceae, Azoarcus, and Desulfoprunum, which may facilitate hydrocarbon degradation. This study showed that Tenax-TA can be used as a matrix to effectively trap both microorganisms and hydrocarbons in contaminated environmental systems for assessing and studying hydrocarbon-degrading microorganisms of interest.

ПОВЫШЕНИЕ ЭФФЕКТИВНОСТИ РЕМЕДИАЦИИ НЕФТЕЗАГРЯЗНЕННЫХ ПОЧВ В ПРИРОДНО-КЛИМАТИЧЕСКИХ УСЛОВИЯХ СЕВЕРА ТОМСКОЙ ОБЛАСТИ И СОПРЕДЕЛЬНЫХ РЕГИОНОВ С ПРИМЕНЕНИЕМ АБОРИГЕННЫХ МИКРООРГАНИЗМОВ

Актуальность исследования. Наибольшая антропогенная нагрузка, связанная с эксплуатацией природных ресурсов в Томской области, приходится на нефтегазодобывающую промышленность. Геоэкологический анализ территории показал, что наиболее уязвимыми участками являются северные административные районы, при этом основной фактор нефтяного загрязнения почв – аварии на трубопроводах. Биоремедиация является низкозатратным и экологичным методом восстановления нарушенных территорий. Эффективный подход к биоремедиации нефтезагрязненных почв заключается в выделении аборигенных микроорганизмов-деструкторов углеводородов и создании биопрепаратов на их основе. Цель: разработать промышленный консорциум на основе аборигенных углеводородокисляющих бактерий из почв Севера Томской области и оценить его эффективность для биоремедиации нефтезагрязненных почв. Объекты и методы. Культуры аборигенных углеводородокисляющих микроорганизмов получены в селективных условиях из образца почвы Советского месторождения нефти Томской области, загрязненной сырой нефтью. Выделенные штаммы идентифицировали с использованием молекулярно-генетических методов на основе анализа последовательностей гена 16SрРНК. Изучение физиологических и биохимических свойств изолятов выполняли стандартными методами, морфологию клеток изучали микроскопически. Для оценки эффективности биопрепарата на основе выделенного штамма проводили полевые испытания на нефтезагрязненных участках. Количественный химический анализ на суммарное содержание нефтепродуктов в почве выполняли флуориметрическим методом. Результаты. В ходе исследования из нефтезагрязненных почв в Томской области выделены и охарактеризованы 3 новых штамма углеводородокисляющих бактерий, принадлежащие к родам Acinetobacter и Oleomonas. Аборигенные микроорганизмы характеризуются сниженными оптимумами температуры и рН по сравнению с типовыми штаммами. На основе выделенных микроорганизмов разработан коммерческий биопрепарат «Абориген», предназначенный для биоремедиации нефтезагрязненных почв и ветландов. Экспериментальное восстановление нефтезагрязненных почв с помощью препарата аборигенных микроорганизмов-биодеструкторов позволило значительно сократить сроки по сравнению с самостоятельным восстановлением почвенного покрова в ходе естественных процессов. Полевые испытания показали высокую эффективность деструкции нефти под действием биопрепарата – в среднем по восьми опытным участкам суммарное содержание нефтепродуктов в почве было снижено в 12,4 раз за три месяца.

Enhanced bioremediation of hydraulic fracturing flowback and produced water using an indigenous biosurfactant-producing bacteria Acinetobacter sp. Y2

In this study, a biosurfactant-producing strain Y2 was isolated from hydraulic fracturing flowback and produced water (HF-FPW) and identified as Acinetobacter sp. The biosurfactant produced by Y2 could reduce surface tension of water from 72.2 mN/m to 30.2 mN/m with a CMC value of 187.5 mg/L and showed strong tolerance against wide ranges of pH (2–12), temperatures (4–100 °C), and salinity (0–100 g/L). Through thin layer chromatography, Fourier transform infrared spectroscopy, and gas chromatography–mass spectrometry analysis, the biosurfactant was characterized as lipopeptide. Inoculation of Acinetobacter sp. Y2 into HF-FPW greatly increased the activity and growth of the microcosm. Meanwhile, it significantly (P < 0.05) promoted the removal of chemical oxygen demand (reduction from 6646.7 mg/L to 1546.7 mg/L), and the degradation of n-alkanes (reduction from 2635.4 mg/L to 159.7 mg/L) and polycyclic aromatic hydrocarbons (reduction from 918.6 μg/L to 209.6 μg/L) in 7 days. High-throughput sequencing analysis revealed that the inoculation of indigenous biosurfactant producer modified the bacterial community structure and enriched the hydrocarbon-degrading microorganisms including Pseudomonas sp. and Rhizobium sp. The real-time quantitative PCR results showed that the expression of several key functional genes was greatly enhanced by Y2 addition and was significantly correlated with Acinetobacter sp. This study proved the introduction of native biosurfactant-producing microorganisms as a promising in situ strategy for HF-FPW bioremediation and the underlying mechanisms were proposed.

Microbial Community Composition in Crude Oils and Asphalts from the Kurdistan Region of Iraq

To identify hydrocarbon-degrading microorganisms contributing to the formation of heavy oil we investigated the microbial community composition in different types of crude oils from oil-production facilities and in crude oil and asphalt from different natural seeps from the Kurdistan Region of Iraq (KRI). Crude oils from five out of six production facilities did not contain microorganisms detectable by 16S rRNA gene PCR amplicon sequencing likely reflecting a low microbial abundance in these samples. Crude oil and asphalt from the natural seeps hosted diverse microbial communities. The same phylotypes of uncultivated Deferribacteres and Thermodesulfobacteraceae were predominant community members across crude oils and asphalts from separate geographical locations. Soils surrounding seeps did not contain these phylotypes suggesting that they originate from the subsurface and although they seem commonly detected in hydrocarbon-rich environments their role in hydrocarbon-degradation is unknown. GC-MS analyses showed that mainly aromatic hydrocarbons were present in the crude oil and asphalt and that they were undergoing biodegradation - likely with sulfate and nitrate as terminal oxidants. In agreement, only bssA gene, but not assA gene-carrying microorganisms were detectable in the analyzed sampled. Overall our study identified several abundant uncultivated taxa with likely roles in transformation of nitrate, sulfate and hydrocarbons.

Coagulation-flocculation and moving bed biofilm reactor as pre-treatment for water recycling in the petrochemical industry.

Water recycling and reuse is of important value in water-using sectors like petrochemical industry. The aim of this research was to optimise the pre-treatment of petrochemical wastewater to undergo a further membrane treatment, with the final objective of water recycling within the same industry. Laboratory coagulation-flocculation tests prior to biological treatment were performed using Actiflo® Veolia commercial technology and an optimal coagulant dose of 30 mg/L ferric chloride was obtained. A bench-scale Moving Bed Biofilm Reactor (MBBR) system with two sequential reactors with working volumes of 5 L was filled with Z-carriers at 35% of their working volume. Organic loading rate (OLR) was varied from 0.2 to 3.25 kg/(m3 d) and the hydraulic retention time (HRT) ranged from 23.4 h to 4.5 h. High soluble chemical oxygen demand (sCOD) removals were obtained in stationary states (80-90%) and the calculated maximum sCOD that the system could degrade was 4.96 ± 0.01 kg/(m3 d) at 23 ± 2 °C. Changes in feed composition did not decrease sCOD removals showing that MBBR is a robust technology and the coagulation-flocculation step could be by-passed. Further removal of total suspended solids (TSS) and turbidity from the MBBR effluent would be required before a reverse osmosis (RO) step could be performed. A biofilm-forming genus, Haliscomenobacter spp., and an oil degrading genus Flavobacterium spp. were found in all the attached biomass samples. Acinetobacter spp. was the major bacterial genera found in suspended biomass. Proteobacteria and Bacteroidetes were the major phyla detected in the carrier samples while Proteobacteria the main one detected in the suspended biomass. The lack of fungal annotated sequences in databases led to a major proportion of fungal sequences being categorized as unclassified Fungi. The results obtained indicate that MBBR is an appropriate technology for hydrocarbon-degrading microorganism growth and, thus, for petrochemical wastewater pre-treatment for water regeneration.

Evolution of humic acids during ex situ bioremediation on a pilot level: The added value of the microbial activity

Environmental pollution is a global problem, while bioremediation technology removes pollutants from the environment using microorganisms. This study was aimed at investigating how a bioremediation process affected soil humification. In soil polluted with petroleum and its derivatives that was submitted to bioremediation, besides the total petroleum hydrocarbons and the number of microorganisms, quantitative and qualitative changes of isolated humic acids were determined during the process. The bioremediation of 150 m3 of polluted soil lasted 150 days. The level of total petroleum hydrocarbons decreased by 86.6 %, while the level of humic acids increased by 26.5 %. The elemental analysis showed the reduction of C and the H/C ratio and the increase of O and the O/C ratio of isolated humic acids during the process. The ratio of absorbencies at 465 and 665 nm also increased. Based on this and the Fourier-transform infrared spectra, it was shown that the humic acids isolated at the end of bioremediation were enriched with oxygen functional groups and aromatic structures. This study provides one of the first insights into the relationship between bioremediation and humification, as well as evidence of how hydrocarbon-degrading microorganisms have a significant influence on changes to humic acid structure during bioremediation.

Bioelectrochemical remediation of phenanthrene in a microbial fuel cell using an anaerobic consortium enriched from a hydrocarbon-contaminated site

Polycyclic aromatic hydrocarbons (PAH) are organic pollutants that require remediation due to their detrimental impact on human and environmental health. In this study, we used a novel approach of sequestering a model PAH, phenanthrene, onto a solid carbon matrix bioanode in a microbial fuel cell (MFC) to assess its biodegradation coupled with power generation. Here, the bioanode serves as a site for enrichment of electroactive and hydrocarbon-degrading microorganisms, which can simultaneously act to biodegrade a pollutant and generate power. Carbon cloth electrodes loaded with two rates of phenanthrene (2 and 20 mg cm−2) were compared using dual chamber MFCs that were operated for 50 days. The lower loading rate of 2 mg cm−2 was most efficient in the degradation of phenanthrene and had higher power production capacities (37 mW m−2) as compared to the higher loading rate of 20 mg cm−2 (power production of 19.2 mW m−2). FTIR (Fourier-Transform Infrared Spectroscopy) analyses showed a depletion in absorbance peak signals associated with phenanthrene. Microbes known to have electroactive properties or phenanthrene biodegradation abilities like Pseudomonas, Rhodococcus, Thauera and Ralstonia were enriched over time in the MFCs, substantiating the electrochemical and FTIR analyses. The MFC approach taken here thus offers great promise towards PAH bioelectroremediation.