Bioremediation Of Hydrocarbons Research Articles

Assessing hydrocarbon degradation capacity of Isoptericola peretonis sp. nov. and related species: a comparative study

Since the beginning of their production and use, fossil fuels have affected ecosystems, causing significant damage to their biodiversity. Bacterial bioremediation can provide solutions to this environmental problem. In this study, the new species Isoptericola peretonis sp. nov. 4D.3T has been characterized and compared to other closely related species in terms of hydrocarbon degradation and biosurfactant production by in vitro and in silico analyses. Biosurfactants play an important role in microbial hydrocarbon degradation by emulsifying hydrocarbons and making them accessible to the microbial degradation machinery. The tests performed showed positive results to a greater or lesser degree for all strains. In the synthesis of biosurfactants, all the strains tested showed biosurfactant activity in three complementary assays (CTAB, hemolysis and E24%) and rhamnolipid synthesis genes have been predicted in silico in the majority of Isoptericola strains. Regarding hydrocarbon degradation, all the Isoptericola strains analyzed presented putative genes responsible for the aerobic and anaerobic degradation of aromatic and alkane hydrocarbons. Overall, our results highlight the metabolic diversity and the biochemical robustness of the Isoptericola genus which is proposed to be of interest in the field of hydrocarbon bioremediation.

Biosurfactant Production by Yarrowia lipolytica in Corn Steep Liquor-Based Media for Hydrocarbon Bioremediation

Bioremediation using microorganisms offers a sustainable approach to addressing hydrocarbon contamination. This study explores biosurfactant production by Yarrowia lipolytica IMUFRJ 50682 during crude oil and asphaltene-free fraction biodegradation in corn steep liquor (CSL)-based media. By evaluating CSL concentrations (5–30 g/L) and combinations with glucose, molasses, and crude oil, this study demonstrates that CSL is an effective nutrient source for supporting microbial growth and biosurfactant production. The highest emulsification index (EI = 73.3%) was achieved with 20 g/L of CSL after 48 h, while media containing mixed carbon sources (glucose and crude oil) enhanced metabolic efficiency, yielding a maximum cell growth of 8 g/L after 150 h. Despite inhibiting cell growth, the asphaltene-free fraction promoted biosurfactant activity, with the EI reaching 35.8% after 264 h. The results emphasize the importance of pH control, with the optimal emulsification being observed at pH ~6. This work highlights the potential of CSL as a cost-effective and sustainable additive, advancing applications in bioremediation and biosurfactant production and contributing to the development of environmentally compatible hydrocarbon degradation strategies.

Bioremediation of petroleum hydrocarbon contaminated soil by xylanase enzyme

Background: The global spread of petrochemical and petroleum contamination, such as petroleum hydrocarbons (PHCs), is currently a significant environmental risk. The global biosphere is badly harmed by these pollutants, and biodiversity is significantly reduced. This study was to screen for xylanase synthesis in Pseudomonas spp. and evaluate its efficiency as a bioremediator in removal of hydrocarbons from hydrocarbon-contaminated soil.Methods: Soil samples from Al-Dora oil plant Baghdad, Iraq, were cultured in nutritional agar medium containing 0.5% of corn cob xylan for determination of xylanase producers and measuring of xylanase activity, after that xylanaseproducers were identified. The xylanase was purified with DEAE-cellulose chromatography and the percentage of hydrocarbon degradation was calculated after treatment of hydrocarbon-contaminated soil with purified xylanase and detection of hydrocarbon degradation percentage.Results: Pseudomonas putida had the highest productivity for xylanase in comparison with other Pseudomonas species such as Pseudomonas syringae and Pseudomonas aeruginosa, which revealed lower levels in xylanase production. Ammonium salt saturation and ion exchange chromatography were used to purify the xylanase enzyme on a DEAE-cellulose column with ultimate recovery of 43% and 4.3 fold of purification. With pure xylanase, hydrocarbons degraded over time, peaking after two weeks and then progressively diminishing.Conclusions: Pseudomonas putida is the best producer foe xylanase than other species. The purified xylanase led to removal of hydrocarbons from hydrocarbon-contaminated soil with time increasing manner until maximum removal after 15 days. Authors recommend using xylanase for cleaning up of oil-contaminated areas. Therefore, employing microorganisms as biological tools may be a more feasible way to handle one of the most serious issues in modern society which might be a more workable and affordable way to minimize waste and preserve natural resources.Keywords: Petroleum hydrocarbons; Pseudomonas putida; Xylanase; Bioremediation; Soil contamination

Genome Sequencing Reveals the Potential of Enterobacter sp. Strain UNJFSC003 for Hydrocarbon Bioremediation.

Bioremediation induced by bacteria offers a promising alternative for the contamination of aromatic hydrocarbons due to their metabolic processes suitable for the removal of these pollutants, as many of them are carcinogenic molecules and dangerous to human health. Our research focused on isolating a bacterium from the rhizosphere of the tara tree with the ability to degrade polycyclic aromatic hydrocarbons, using draft genomic sequencing and computational analysis. Enterobacter sp. strain UNJFSC 003 possesses 4460 protein-coding genes, two rRNA genes, 77 tRNA genes, and a GC content of 54.38%. A taxonomic analysis of our strain revealed that it has an average nucleotide identity (ANI) of 87.8%, indicating that it is a new native Enterobacteria. Additionally, a pangenomic analysis with 15 strains demonstrated that our strain has a phylogenetic relationship with strain FDAARGOS 1428 (Enterobacter cancerogenus), with a total of 381 core genes and 4778 accessory genes. Orthologous methods predicted that strain UNJFSC 003 possesses genes with potential for use in hydrocarbon bioremediation. Genes were predicted in the sub-pathways for the degradation of homoprotocatechuate and phenylacetate, primarily located in the cytoplasm. Studies conducted through molecular modeling and docking revealed the affinity of the predicted proteins in the degradation of benzo[a]pyrene in the homoprotocatechuate sub-pathway, specifically hpcB, which has enzymatic activity as a dioxygenase, and hpcC, which functions as an aldehyde dehydrogenase. This study provides information on native strains from Lomas de Lachay with capabilities for the bioremediation of aromatic hydrocarbons and other compounds.

Novel Approaches to Decomposing Hydrocarbon Pollutants from the Environment

In the modern era, petrochemical industries' production of hydrocarbon pollution is a significant environmental problem that causes biodiversity loss. Alkanes constitute a substantial proportion of crude oil, and refined fuels are found in small amounts in various uncontaminated environments. They are prevalent in underground fossil fuel reserves and shallow subsurface habitats polluted with hydrocarbons, such as aquifers. Using microorganisms to break down alkane hydrocarbon pollutants in environmental areas has great potential. Considerable advancements have been achieved in identifying microorganisms and metabolic processes responsible for the breakdown of alkanes in both oxygen-free and oxygen-rich conditions in the last two decades. A wide range of prokaryotic and eukaryotic organisms have been identified and observed to possess the ability to utilize various carbon and energy sources as substrates. Bioremediation is essential for environmental safety and management; various methods have been established for petroleum hydrocarbon bioremediation. Numerous microbial species have been employed to investigate the bioremediation of petroleum hydrocarbons, highlighting the crucial functions of varied microbial communities. Phytoremediation is an environmentally sustainable method that may effectively rehabilitate heavy metal- contaminated soil cost-efficiently. This manuscript provides an overview of prevalent alkane hydrocarbon pollutants, microorganisms capable of degrading hydrocarbons, key pathways and enzymes involved in hydrocarbon degradation, factors influencing hydrocarbon degradation, and various strategies employed to harness the degrading capabilities of microbes for remedial purposes.

Characterizing the Contaminant-Adhesion of a Dibenzofuran Degrader Rhodococcus sp.

The adhesion between dibenzofuran (DF) and degrading bacteria is the first step of DF biodegradation and affects the efficient degradation of DF. However, their efficient adhesion mechanism at the molecular level remains unclear. Therefore, this study first examined the adhesive behaviors and molecular mechanisms of Rhodococcus sp. strain p52 upon exposure to DF. The results showed that the adhesion between strain p52 and DF is mediated by extracellular polymeric substances (EPSs). Compared with sodium acetate as a carbon source, the percentages of glucose and proteins related to electron transfer, toxin-antitoxin, and stress responses were elevated, which were analyzed by polysaccharide composition and proteomics, and the contents of extracellular polysaccharides and proteins were increased. Moreover, biofilm analysis suggested an increase in EPS content, and the change in components increased biofilm yield and promoted loose and porous aggregation between the bacteria; this aggregation caused an increase in the specific surface area in contact with DF. The surface characteristics analysis indicated that the production of EPS reduced the absolute value of the zeta potential and increased the hydrophobicity of strain p52, which was beneficial for the adhesion of strain p52 and DF. These findings help us to enhance the understanding of the adhesion mechanisms and bioremediation of polycyclic aromatic hydrocarbons by degrading bacteria.

Role of microbes in the bioremediation of hydrocarbons, pesticides and municipal wastes

With the rapid explosion of industrialization and human population, the levels of pollutants in the environment have become alarmingly high. Many of these persist in the biosphere for a long period of time and cannot be degraded by physico-chemical methods. Microbes with their nutritional diversity can metabolize a vast range of substrates; thus, microbial degradation has been explored for the purpose of reducing the levels of these persistent pollutants. In general, microbial degradation is preferred because it uses the inherent ability of the microbes to metabolize toxic compounds and hence is cost-effective as well as eco-friendly. The microbes involved are mostly bacteria and fungi from marine and soil environment. It is important to understand the physiology and biochemistry of the microbes as well as microbial consortia involved in order to optimize the process of bioremediation. In this review, we discuss the three major categories of pollutants, viz., hydrocarbons from petrochemical industries, pesticides and municipal wastes including solid wastes and wastewater. For each of these areas of microbial degradation, we discuss the different kinds of wastes generated, limitation of physico-chemical methods, the microbial species or consortium involved in the degradation, insight into the mode of action or mechanisms of enzymatic breakdown and the factors affecting the efficiency of the microbes.

Microbial–physicochemical interplay in Iko River estuary, unraveling the hidden mystery in bioremediation of petroleum hydrocarbons

ABSTRACT The aquatic microbial communities are relatively complex with a high level of prokaryotic diversities. Standard and novel microbiological, analytical, and statistical techniques were employed in the collection, analysis, and comprehensive study of the samples. From the study, the mean values of total heterotrophic bacteria were determined to be 1.35 ± 0.18 (×107), 1.59 ± 0.64 (×107), and 1.56 ± 0.52 (×107) for upstream, midstream, and downstream, respectively, while the mean values for crude oil-utilizing bacteria were 1.08 ± 0.12 (×106), 1.28 ± 0.58 (×106), and 1.24 ± 0.44 (×106) for upstream, midstream, and downstream, respectively. The mean concentrations of physicochemical parameters and heavy metals obtained in the benthic sediment were significantly higher than the mean concentrations in the water samples (tidal and intertidal) (p < 0.02). The result of the component analysis of total petroleum hydrocarbons (including polycyclic aromatic hydrocarbon and benzene, toluene, ethylbenzene, and xylene) revealed significantly higher levels in the sediment than tidal and intertidal water. Structural metagenomics revealed seven top phyla, namely, Proteobacteria, Actinobacteria, Firmicutes, Bacteroidetes, Planctomycetes, Fusobacteria, and Chloroflexi. The significantly (p < 0.05) high levels of hydrocarbon-utilizing microorganisms in Iko River estuary can be taken as a sensitive index of environmental exposure to hydrocarbon pollutants in the estuary. This research revealed the response patterns of microorganisms to natural and anthropogenic gradients toward sustainability in Iko River estuary.

Biosurfactants Used in the Bioremediation of Soils Contaminated With Hydrocarbons - Overview of the State of the Art and Future Perspectives.

The increasing industrialization and hydrocarbon use have led to concerning soil contamination. Oil spills and improper disposal of oily waste pose threats to ecosystems and human health. The recovery of these environments is essential, but separating oily components from soil remains challenging. Current bioremediation strategies using synthetic surfactants can cause secondary contamination. Microbial biosurfactants, which are biodegradable and low in toxicity, emerge as promising solutions, and this study reviews methods for utilizing these biosurfactants in the environmental bioremediation of hydrocarbons. This study explores the efficient and eco-friendly use of biosurfactants for hydrocarbon- contaminated soil management, providing a market-oriented analysis of recent patents and trends, and highlighting the transition from academic research to industrial applications. The methodology involves an extensive literature review, careful selection of recent studies and patents on biosurfactants in hydrocarbon bioremediation, critical analysis of in-situ and ex-situ application methods, assessment of commercial viability, and synthesis of findings to contribute to sustainable solutions in contaminated environments. The present study demonstrates the extensive applicability of biosurfactants across various industrial sectors. The increasing interest in incorporating biosurfactants into industrial processes is driven by the pressing need for sustainable solutions to address tangible market challenges. Notably, the cosmetics industry exhibited the highest number of patents related to the use of biosurfactants, underscoring its significant role in advancing the adoption of these environmentally friendly agents. This trend highlights the critical demand for sustainable alternatives in product formulations and underscores the pivotal role of biosurfactants in fostering eco-innovation within the industry.

Exploring Novel Fungal-Bacterial Consortia for Enhanced Petroleum Hydrocarbon Degradation.

Bioremediation, involving the strategic use of microorganisms, has proven to be a cost-effective alternative for restoring areas impacted by persistent contaminants such as polycyclic aromatic hydrocarbons (PAHs). In this context, the aim of this study was to explore hydrocarbon-degrading microbial consortia by prospecting native species from soils contaminated with blends of diesel and biodiesel (20% biodiesel/80% diesel). After enrichment in a minimal medium containing diesel oil as the sole carbon source and based on 16S rRNA, Calmodulin and β-tubulin gene sequencing, seven fungi and 12 bacteria were identified. The drop collapse test indicated that all fungal and four bacterial strains were capable of producing biosurfactants with a surface tension reduction of ≥20%. Quantitative analysis of extracellular laccase production revealed superior enzyme activity among the bacterial strains, particularly for Stenotrophomonas maltophilia P05R11. Following antagonistic testing, four compatible consortia were formulated. The degradation analysis of PAHs and TPH (C5-C40) present in diesel oil revealed a significantly higher degradation capacity for the consortia compared to isolated strains. The best results were observed for a mixed bacterial-fungal consortium, composed of Trichoderma koningiopsis P05R2, Serratia marcescens P10R19 and Burkholderia cepacia P05R9, with a degradation spectrum of ≥91% for all eleven PAHs analyzed, removing 93.61% of total PAHs, and 93.52% of TPH (C5-C40). Furthermore, this study presents the first report of T. koningiopsis as a candidate for bioremediation of petroleum hydrocarbons.

Bioremediation of polyaromatic hydrocarbon polluted sewage sludge soil employing a bacterial consortium and phytotoxicity evaluation.

A consortium of five distinct bacterial strains was evaluated for their ability to biodegrade multiple polyaromatic hydrocarbons (PAHs) in sewage sludge under microcosm studies. The presence of PAHs was determined from the sludge samples collected during pre- and post-monsoon seasons from three different wastewater treatment plants (WWTPs). Among the sixteen PAHs found, the lowest concentration detected was 1.75 ng g-1 of benz(k)fluoranthene, and the highest concentration of 5.41 mg g-1 indeno(1,2,3-cd) pyrene was found in both dry and wet samples, perhaps owing to its multiple origin of contamination. A bacterial consortium comprising of well characterized bacteria Stenotrophomonas maltophilia IITR87, Ochrobactrum anthropi IITR07, Microbacterium esteraromaticum IITR47, Pseudomonas aeruginosa IITR48 and Pseudomonas mendocina IITR46 employed for PAHs bioremediation in a microcosm study. In 20 days, 65-70% of PAHs were remediated, and low molecular weight PAHs such as naphthalene, phenanthrene, and pyrene showed enhanced degradation. Bioremediated samples showed a significant reduction in phytotoxicity using plant germination of wheat (Triticum aestivum), black chickpea (Cicer arietinum), and mustard (Brassica juncea), whereas the contaminated soil showed severe inhibition of plant growth. The results comprehensively suggest a possible remediation option for PAHs occurring in complex sewage sludge, preventing further contamination into other environmental compartments.

Microbe-plant-nanoparticle interactions: role in bioremediation of petroleum hydrocarbons.

Petroleum hydrocarbons (PHCs) are organic substances that occur naturally on earth. PHCs have emerged as one of the most prevalent and detrimental contaminants in regions comprising soil and water resources. The limitations of conventional physicochemical and biological remediation solutions could be solved by combining remediation techniques. An effective, affordable, and environmentally benign method of reducing petroleum toxins is provided by the advanced idea of bioremediation, which has evolved into nanobioremediation. Environments contaminated with PHCs have been restored through microbe-plant-nanoparticle (NP)-mediated remediation, this review emphasizes how various metallic NPs interact with microbes and plants changing both their activity and that of enzymes, therefore accelerating the remediation process. This work further examines the challenges and possible uses of nanobioremediation, as well as the application of novel technologies in the interactions between bacteria, plants, and NPs for the bioremediation of PHCs. Furthermore, it has been shown that the use of plant-based, microbe-based, microbe-plant-based, and microbe-plant-NP-based techniques to remediate contaminated soils or water bodies is economical and environmentally beneficial. Microbial consortia have been reported as the treasure houses for the cleaning and recovery of hydrocarbon-contaminated environments, and the development of technologies for bioremediation requires an understanding of hydrocarbon degradation mechanisms.

Evaluating effect of aeration and sand addition on soil physicochemical properties and soil total petroleum hydrocarbon bioremediation efficiency by indigenous isolated bacteria

In line with different investigations for bioremediation of oil-polluted soil at the global scale, the present study designed new insight about qualified physicochemical properties along with bioremediation of oil-polluted soil. The principle of presented bioremediation technique of oil-polluted soil in the present study was a combination of physical and biological procedure for the remediation of oil-polluted soils. The study investigates the impact of aeration and sand addition on bioremediation efficiency of two types oil-polluted soil with different ages of oil pollution. The experiment involves isolating and identifying indigenous bacteria, preparing the inoculum, and inoculating it into oil-contaminated soils. The physical and chemical properties of the soil samples were analyzed, and total petroleum hydrocarbon (TPH) levels were assessed before and after the bioremediation period followed by sand addition and air-forced soil aeration. The achieved results from laboratory-scale investigation show about 80% in soil TPH decreasing followed by sand addition and aeration for two types of fresh and aged polluted soils, while TPH decreasing in soil without sand addition and aeration was about 48% from studied soils. The findings of the present study can be utilized as parametric investigation in designing bioreactors of oil-polluted soil bioremediation purposes.

Bioremediation of hydrocarbon pollutants by Pseudomonas putida under optimal conditions

Background: The extreme toxicity of petroleum products to human and environmental health, particularly when linked to large-scale unintentional spills, has made them one of the most serious and current environmental pollution issue. Petroleum products are a complex mixture of hydrocarbons.Methods: Oil-contaminated soil samples were gathered and utilized to isolate hydrocarbon-degrading bacterial isolates. The bacterial isolates possessing bioremediation capabilities were identified using phenotypic determination and biochemical properties. The Optimal conditions including incubation period, temperature, different pH values and different carbon sources were studied for bioremediation of crude oil by bacterial isolates.Result: In Wasit province of Iraq, Pseudomonas putida, P. fluorescens, and P. aeruginosa isolated from soil samples tainted with petroleum hydrocarbons. Pseudomonas putida have more ability for bioremediation of crude oil (68%) compared to P. aeruginosa and P. fluorescens (47%, 58%) respectively. The results of optical density (600nm), biomass and (E24%) index for Pseudomonas putida were (1.080, 1.98 and 60%) respectively. The Optimal conditions (incubation period, temperature, different pH values and different carbon sources) were studied for bioremediation of crude oil by Pseudomonas putida by using liquid BHM supplemented with 1% crude oil. The result of this study showed that the incubation period of 9 days was the optimum for bioremediation of hydrocarbons which was 88.33%. The optimum temperature and pH were 35 °C and 7 respectively. The carbon source (glucose and fructose) was optimal for hydrocarbon bioremediation.Conclusion: This bacterial isolate Pseudomonas putida can be use in petroleum hydrocarbon bioremediation process.Keywords: Pseudomonas putida; Bioremediation; Optical density

Metabolism of Benzo[a]pyrene by Paenibacillus sp. PRNK-6 through novel metabolite phenalene-1,9-dicarboxylic acid

Benzo[a]pyrene (BaP) is a persistent carcinogenic environmental pollutant with high bioaccumulation potential and is resistant to bacterial biodegradation. Therefore, its removal from the biosphere is a priority. In the current study, the bacterial culture Paenibacillus sp. PRNK-6 was evaluated for the degradation of BaP. Paenibacillus sp. PRNK-6 efficiently utilizes BaP as a sole carbon source and degrades 89.43% of BaP within 120 h at an initial concentration of 100 mg L−1. Maximum growth was observed at 96 h with 28.96 × 107 colony-forming units (CFU). The BaP metabolic intermediates were characterized by High-performance liquid chromatography (HPLC) and, Gas chromatography-mass spectrometry (GC-MS). Based on the metabolite characterization, utilization of probable metabolic intermediates, and investigation of the enzyme involved, a putative pathway of the BaP degradation in PRNK-6 was proposed. The metabolites formed includes a novel ring cleavage metabolite phenalene-1,9-dicarboxylic acid. The two terminal monoaromatic metabolites catechol and protocatechuate (PCA) undergo ring fission by catechol 1,2-dioxygenase and protocatechuate 3,4-dioxygenase, individually and get into the tricarboxylic acid (TCA) cycle. In both pathways there is no accumulation of any dead-end products. The results suggest that the strain PRNK-6 could be a promising biodegradation tool for high molecular weight polycyclic aromatic hydrocarbons (HMW PAHs) like BaP and may be equally used for bioremediation of other polycyclic aromatic hydrocarbons (PAHs).

Biosurfactant production by Bacillus cereus GX7 utilizing organic waste and its application in the remediation of hydrocarbon-contaminated environments.

The use of biosurfactants represents a promising technology for remediating hydrocarbon pollution in the environment. This study evaluated a highly effective biosurfactant strain-Bacillus cereus GX7's ability to produce biosurfactants from industrial and agriculture organic wastes. Bacillus cereus GX7 showed poor utilization capacity for oil soluble organic waste but effectively utilized of water- soluble organic wastes such as starch hydrolysate and wheat bran juice as carbon sources to enhance biosurfactant production. This led to significant improvements in surface tension and emulsification index. Corn steep liquor was also effective as a nitrogen source for Bacillus cereus GX7 in biosurfactant production. The biosurfactants produced by strain Bacillus cereus GX7 demonstrated a remediation effect on oily beach sand, but are slightly inferior to chemical surfactants. Inoculation with Bacillus cereus GX7 (70.36%) or its fermentation solution (94.38%) effectively enhanced the degradation efficiency of diesel oil in polluted seawater, surpassing that of indigenous degrading bacteria treatments (57.62%). Moreover, inoculation with Bacillus cereus GX7's fermentation solution notably improved the community structure by increasing the abundance of functional bacteria such as Pseudomonas and Stenotrophomonas in seawater. These findings suggest that the Bacillus cereus GX7 as a promising candidate for bioremediation of petroleum hydrocarbons.

The influence of Cu2+ and Pb2+ on the characteristics of extracellular polymeric substances (EPSs) from Mucor mucedo and its relationship with pyrene biodegradation

The bioremediation of polycyclic aromatic hydrocarbons (PAHs) may be facilitated by the presence of heavy metals (HMs) via extracellular polymeric substances (EPSs). However, the variability of EPS characteristics influenced by HMs in relation to PAHs degradation remains uncertain, particularly in the case of fungi. It is therefore crucial to elucidate the impact of HMs on the characteristics of EPSs and their interaction in the process of PAHs biodegradation. The present study observed the cell membrane of Mucor mucedo under conditions of Cu2+ and Pb2+ stress, as well as determining the characteristics of EPSs. The findings demonstated that the presence of HM ions led to a disruption of the fungal cell membrane. The production of EPSs, the content of their main components and EPS property exhibited changes in accordance with the increasing concentration of HMs. It is noteworthy that the degradation of pyrene was enhanced as the concentration of HMs within the range of 0–80 mg L−1, particularly in the presence of EPSs. A positive correlation was observed between pyrene degradation and the total organic carbon, total nitrogen, polysaccharides, proteins, and surface tension of EPSs. It was thus demonstrated that pyrene biodegradation was enhanced under the stress of HMs (less than 80 mg L−1) by varying the characteristics of EPSs. The conceptual framework outlines the pyrene biodegradation process by EPSs under HM stress. This study provides new insights into the potential mechanism by which HMs influence the biodegradation of PAHs through the involvement of EPSs.

Metagenomic analyses of a consortium for the bioremediation of hydrocarbons polluted soils.

A bacterial consortium was isolated from a soil in Noblejas (Toledo, Spain) with a long history of mixed hydrocarbons pollution, by enrichment cultivation. Serial cultures of hydrocarbons polluted soil samples were grown in a minimal medium using diesel (1mL/L) as the sole carbon and energy source. The bacterial composition of the Noblejas Consortium (NC) was determined by sequencing 16S rRNA gene amplicon libraries. The consortium contained around 50 amplicon sequence variants (ASVs) and the major populations belonged to the genera Pseudomonas, Enterobacter, Delftia, Stenotrophomonas, Achromobacter, Acinetobacter, Novosphingobium, Allorhizobium-Neorhizobium-Rhizobium, Ochrobactrum and Luteibacter. All other genera were below 1%. Metagenomic analysis of NC has shown a high abundance of genes encoding enzymes implicated in aliphatic and (poly) aromatic hydrocarbons degradation, and almost all pathways for hydrocarbon degradation are represented. Metagenomic analysis has also allowed the construction of metagenome assembled genomes (MAGs) for the major players of NC. Metatranscriptomic analysis has shown that several of the ASVs are implicated in hydrocarbon degradation, being Pseudomonas, Acinetobacter and Delftia the most active populations.

Efficacy of Indigenous Bacteria in the Biodegradation of Hydrocarbons Isolated from Agricultural Soils in Huamachuco, Peru.

Pollution from crude oil and its derivatives poses a serious threat to human health and ecosystems, with accidental spills causing substantial damage. Biodegradation, using microorganisms to break down these contaminants, presents a promising and cost-effective solution. Exploring and utilizing new bacterial strains from underexplored habitats could improve remediation efforts at contaminated sites. This study aimed to evaluate the hydrocarbon biodegradation capacity of bacteria isolated from agricultural soils in Huamachuco, Peru. Soil samples from Oca crops were collected and bacteria were isolated. Biodegradation assays were conducted using diesel as the sole carbon source in the Bushnell Haas Mineral medium. Molecular characterization of the 16S rRNA gene identified four strains. Diesel biodegradation assays at 1% concentration were performed under agitation conditions at 150 rpm and 30 °C, and monitored on day 10 by measuring cellular biomass (OD600), with hydrocarbons analyzed by gas chromatography. The results showed Pseudomonas protegens (PROM2) achieved the highest efficiency in removing total hydrocarbons (91.5 ± 0.7%). Additionally, Pseudomonas citri PROM3 and Acinetobacter guillouiae ClyRoM5 also demonstrated high capacity in removing several individual hydrocarbons. Indigenous bacteria from uncontaminated agricultural soils present a high potential for hydrocarbon bioremediation, offering an ecological and effective solution for soil decontamination.

Enzymatic bioremediation of polycyclic aromatic hydrocarbons (PAHs) in contaminated soil: a study on the recombinant laccase TVL

ABSTRACT Polycyclic aromatic hydrocarbons (PAHs) are pervasive and persistent pollutants in contaminated soil, posing a severe health and environmental threat. Enzymatic bioremediation presents a viable solution for the remediation of PAH-contaminated soil. In this study, a recombinant laccase with the encoding gene originating from Trametes villosa and recombinantly expressed in Aspergillus oryzae, designated as TVL, was discovered to possess strong PAH reduction capabilities. The specific enzyme activity of TVL was 73485 and 5102 LAMU/g enzyme protein at pH 5.0/7.0 and 37°C. Furthermore, it exhibited significant benzo[a]pyrene degradation, with 100% and 90.48% degradation at pH 5.0/7.0 after 24 h in the liquid phase. The degradation process of benzo[a]pyrene in soil was thoroughly investigated. Optimal conditions were identified as 15 mg/g NK-BSoil-3 and 1.35 mg/g HBT, resulting in a removal rate of 37.54% within 7 days when 0.01 U/g of TVL was applied. The potential mechanisms were investigated using molecular docking simulation. The binding energy between benzo[a]pyrene and TVL protein is notably robust, suggesting a higher propensity for enzyme binding. The TVL protein pocket contains nine amino acids that can interact most strongly with benzo[a]pyrene. Consequently, the recombinant laccase TVL holds considerable practical significance in bioremediation.