Bacteria-Triggered Mineralization of Silica Shells with Nanochannels for Biocatalysis in Harsh Conditions.

Biocatalytic processes using microorganisms are considered efficient and economically and environmentally friendly reactions. However, the viability and function of these microorganisms are prone to being hindered by various practical environments. Here, we reported a bacteria-induced nanochannel structure that endowed the microorganism with biocatalytic ability in harsh conditions. We revealed that the bacteria could trigger the fusion of silica nanoparticles on their surface by the secreted alkaline metabolite, resulting in silica shells with nanochannels on bacteria (bacteria@nSiO2). The nanochannel structure in silica shells endowed bacteria with biocatalytic ability in multiple harsh conditions. We revealed that these nanochannels could influence the mass transfer from the extracellular to the intracellular environment, which protected the bacteria from excessive toxic substance while preserving the mass exchange during biocatalysis. This feature ensured bacteria@nSiO2 with efficient bioactivity under harsh conditions for industrial catalysis and degradation of pollution, which cannot be achieved by corresponding native bacteria. Using the crude oil spill as a practical example, we presented that bacteria@nSiO2 could degrade highly concentrated crude oil, which any reported bacteria cannot achieve. This work emphasized the role of nanochannels in the regulation of cellular functions for enhanced biocatalysis. It also demonstrated a bacteria-triggered nanostructure formation, which is a promising methodology for nanotechnology and provides a strategy for more advanced organism-material hybrids.

Novel oil-associated bacteria in Arctic seawater exposed to different nutrient biostimulation regimes.

The Arctic Ocean is an oligotrophic ecosystem facing escalating threats of oil spills as ship traffic increases owing to climate change-induced sea ice retreat. Biostimulation is an oil spill mitigation strategy that involves introducing bioavailable nutrients to enhance crude oil biodegradation by endemic oil-degrading microbes. For bioremediation to offer a viable response for future oil spill mitigation in extreme Arctic conditions, a better understanding of the effects of nutrient addition on Arctic marine microorganisms is needed. Controlled experiments tracking microbial populations revealed a significant decline in community diversity along with changes in microbial community composition. Notably, differential abundance analysis highlighted the significant enrichment of the unexpected genera Lacinutrix, Halarcobacter and Candidatus Pseudothioglobus. These groups are not normally associated with hydrocarbon biodegradation, despite closer inspection of genomes from closely related isolates confirming the potential for hydrocarbon metabolism. Co-occurrence analysis further revealed significant associations between these genera and well-known hydrocarbon-degrading bacteria, suggesting potential synergistic interactions during oil biodegradation. While these findings broaden our understanding of how biostimulation promotes enrichment of endemic hydrocarbon-degrading genera, further research is needed to fully assess the suitability of nutrient addition as a stand-alone oil spill mitigation strategy in this sensitive and remote polar marine ecosystem.

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.

Bioremediation petroleum wastewater and oil-polluted soils by the non-toxigenic indigenous fungi.

Soil and wastewater samples contaminated by petroleum-related industries were collected from various locations in Saudi Arabia, a country known for its vast oil reserves. The samples were analyzed for their physicochemical properties, including the presence of metals, petroleum hydrocarbons, and aromatic compounds. A total of 264 fungal isolates were analyzed and categorized into eight groups of Aspergillus (194 isolates) and four groups of Penicillium (70 isolates). The potential of these fungal groups to grow in oil or its derivatives was investigated. Two isolates, Aspergillus tubingensis FA-KSU5 and A. niger FU-KSU69, were utilized in two remediation experiments-one targeting wastewater and the other focusing on polluted soil. The FA-KSU5 strain demonstrated complete removal of Fe3+, As3+, Cr6+, Zn2+, Mn2+, Cu2+ and Cd2+, with bioremediation efficiency for petroleum hydrocarbons in the wastewater from these sites ranging between 90.80 and 98.58%. Additionally, the FU-KSU69 strain achieved up to 100% reduction of Co2+, Ba2+, B3+, V+, Ni2+, Pb2+ and Hg2+, with removal efficiency ranging from 93.17 to 96.02% for aromatic hydrocarbons after 180 min of wastewater treatment. After 21 days of soil incubation with Aspergillus tubingensis FA-KSU5, there was a 93.15% to 98.48% reduction in total petroleum hydrocarbons (TPHs) and an 88.11% to 97.31% decrease in polycyclic aromatic hydrocarbons (PAHs). This strain exhibited the highest removal rates for Cd2+ and As3+ followed by Fe3+, Zn2+, Cr6+, Se4+ and Cu2+. Aspergillus niger FU-KSU69 achieved a 90.37% to 94.90% reduction in TPHs and a 95.13% to 98.15% decrease in PAHs, with significant removal of Ni2+, Pb2+ and Hg2+, followed by Co2+, V+, Ba2+ and B3+. The enzymatic activity in the treated soils increased by 1.54- to 3.57-fold compared to the polluted soil. Although the mixture of wastewater and polluted soil exhibited high cytotoxicity against normal human cell lines, following mycoremediation, all treated soils and effluents with the dead fungal biomass showed no toxicity against normal human cell lines at concentrations up to 500 µL/mL, with IC50 values ≥ 1000 µL/mL. SEM and IR analysis revealed morphological and biochemical alterations in the biomass of A. tubingensis FA-KSU5 and A. niger FA-KSU69 when exposed to petroleum effluents. This study successfully introduces non-toxigenic and environmentally friendly fungal strains play a crucial role in the bioremediation of contaminated environments. Both strains serve as low-cost and effective adsorbents for bio-remediating petroleum wastewater and oil-contaminated soil. Heavy metals and hydrocarbons, the primary pollutants, were either completely removed or reduced to permissible levels according to international guidelines using the dead biomass of FA-KSU5 and FA-KSU69 fungi. Consequently, the environments associated with this globally significant industry are rendered biologically safe, particularly for humans, as evidenced by the absence of cytotoxicity in samples treated with A. tubingensis FA-KSU5 and A. niger FA-KSU69 on various human cell types.

Improved chickpea growth, physiology, nutrient assimilation and rhizoremediation of hydrocarbons by bacterial consortia.

BACKGROUND: Soil pollution by petroleum hydrocarbons (PHCs) reduces yield by changing the physico-chemical properties of soil and plants due to PHCs' biotoxicity and persistence. Thus, removing PHCs from the soil is crucial for ecological sustainability. Microbes-assisted phytoremediation is an economical and eco-friendly solution. The current work aimed to develop and use bacterial consortia (BC) for PHCs degradation and plant growth enhancement in hydrocarbon-contaminated soil. Initially, the enriched microbial cultures (that were prepared from PHCs-contaminated soils from five distinct regions) were obtained via screening through microcosm experiments. Afterward, two best microbial cultures were tested for PHCs degradation under various temperature and pH ranges. After culture optimization, isolation and characterization of bacterial strains were done to construct two BC. These constructed BC were tested in a pot experiment for hydrocarbons degradation and chickpea growth in PHCs contaminated soil. RESULTS: Findings revealed that PHCs exerted significant phytotoxic effects on chickpea growth and physiology when cultivated in PHCs contaminated soil, reducing agronomic and physiological traits by 13-29% and 12-43%, respectively. However, in the presence of BC, the phytotoxic impacts of PHCs on chickpea plants were reduced, resulting in up to 24 - 35% improvement in agronomic and physiological characteristics as compared to un-inoculated contaminated controls. Furthermore, the bacterial consortia boosted chickpea's nutritional absorption and antioxidant mechanism. Most importantly, chickpea plants phytoremediated 52% of the initial PHCs concentration; however, adding BC1 and BC2 with chickpea plants further increased this removal and remediated 74% and 80% of the initial PHCs concentration, respectively. CONCLUSION: In general, BC2 outperformed BC1 (with few exceptions) in promoting plant growth and PHCs elimination. Therefore, using multi-trait BC for PHCs degradation and plant growth improvement under PHCs stress may be an efficient and environmentally friendly strategy to deal with PHCs pollution and toxicity.

Exploring the potential of biosurfactants produced by fungi found in soil contaminated with petrochemical wastes.

Biosurfactants are a diverse group of compounds derived from microorganisms, possessing various structures and applications. The current study was seeking to isolate and identify a new biosurfactant-producing fungus from soil contaminated with petrochemical waste. The bioprocess conditions were optimized to maximize biosurfactant production for Aspergillus carneus OQ152507 using a glucose peptone culture medium with a pH of 7.0 and a temperature of 35 °C. The carbon source was glucose (3%), and ammonium sulfate (0.25%) was utilized as the nitrogen source. For Aspergillus niger OQ195934, the optimized conditions involved a starch nitrate culture medium with a pH of 7.0 and a temperature of 30 °C. The carbon source used was sucrose (3.5%), and ammonium sulfate (0.25%) served as the nitrogen source. The phenol-H2SO4 and phosphate tests showed that the biosurfactants that were extracted did contain glycolipid and/or phospholipid molecules. They showed considerable antimicrobial activity against certain microbes. The obtained biosurfactants increased the solubility of tested polyaromatic hydrocarbons, including fluoranthene, pyrene, anthracene, and fluorine, and successfully removed the lubricating oil from contaminated soil and aqueous media surface tension reduction. Based on the obtained results, A. carneus and A. niger biosurfactants could be potential candidates for environmental oil remediation processes.

Bioremediation of petroleum-contaminated soil based on both toxicity risk control and hydrocarbon removal-progress and prospect.

Petroleum contamination remains a worldwide issue requiring cost-effective bioremediation techniques. However, establishing a universal bioremediation strategy for all types of oil-polluted sites is challenging. This difficulty arises from the heterogeneity of soil textures, the complexity of oil products, and the variations in local climate and environment across different oil-contaminated regions. Several factors can impede bioremediation efficacy: (i) differences in bioavailability and biodegradability between aliphatic and aromatic fractions of crude oil; (ii) inconsistencies between hydrocarbon removal efficiency and toxicity attenuation during remediation; (iii) varying adverse effect of aliphatic and aromatic fractions on soil microorganisms. This review examines the ecotoxicity risk of petroleum contamination to soil fauna and flora. It also discusses three primary bioremediation strategies: biostimulation with nutrients, bioaugmentation with petroleum degraders, and phytoremediation with plants. Based on current research and state-of-the-art challenges, we highlighted future research scopes should focus on (i) exploring the ecotoxicity differentiation of aliphatic and aromatic fractions of crude oil, (ii) establishing unified risk factors and indicators for evaluating oil pollution toxicity, (iii) determining the fate and transformation of aliphatic and aromatic fractions of crude oil using advanced analytical techniques, and (iv) developing combined bioremediation techniques that improve petroleum removal and ecotoxicity attenuation.

Bacterial specialists playing crucial roles in maintaining system stability and governing microbial diversity in bioremediation of oil-polluted sediments under typical deep-sea condition.

Ecologically, interactions and contributions of microbiota generalists and specialists remain largely unexplored in remediation of deep-sea oil pollution. Herein, ecological and evolutionary characteristics of the two taxa were comprehensively investigated in restoration of oil-polluted sediment at deep-sea microcosm. Niche-specialized taxa exhibited rapid speciation rate, more complex network structure and highly interspecific mutualism. In contrast, generalists possessed higher richness but with poor local performance, as evidenced by higher extinction rate, lower stability, and more interspecific antagonism. Generalists were the primary oil degraders, while specialists acted as auxiliaries promoting degradation via production of biofilm and biosurfactant. Evolutionarily, the continuous transition from specialists to generalists insured the exclusion of generalist at a relatively constant level for ecological trade-offs. Collectively, the findings emphasize the importance of specialists in facilitating oil degradation by elucidating their vital roles in maintaining system stability and regulating microbial diversity during process, and offer valuable guidance for designing remediation plans.

Petroleum hydrocarbons and colored dissolved organic matter shape marine oil-degrading microbiota in different patterns.

Both petroleum hydrocarbons (PHCs) from oil pollution and colored dissolved organic matter (CDOM) have great influences on the marine microbial community as carbon source factors. However, their combined effects and the specific influence patterns have been kept unclear. This study selected the northeastern South China Sea (NSCS), a typical oil contaminated area, and investigated the characteristics of oil-degrading microbiota in the seawaters by high-throughput sequencing and the relationships with PHCs and CDOM as well as other environmental factors. The results showed the oil pollution had induced the enrichment of oil-degrading bacteria and oil-degrading functional genes, resulting in the core function of oil-degrading microbiota for shaping the microbial community. The Mantel test indicated carbon source factors played the dominant role in shaping the oil-degrading microbiota, compared with geographical distance and other non­carbon source factors. The influence patterns and strength of PHCs and CDOM on oil-degrading microbiota were further comprehensively analyzed. PHCs played a driving role in the differentiation of oil-degrading microbiota, while CDOM played a stabilizing role for the community similarity. The constructed structural equation model confirmed their distinct influence patterns and also explored the mediating effects of bulk organic carbon. This work not only revealed the important impact of oil pollution on marine microbial communities, but also made people realize the self-regulation ability of the marine environment through the endogenous organic matter.

Deciphering the molecular interaction of extracellular polymeric substances of a marine bacterium Pseudomonas furukawaii PPS-19 with petroleum hydrocarbons and development of bioadsorbent.

Petroleum hydrocarbon contamination is a serious hazard to marine environments, affecting ecosystems and marine life. However, extracellular polymeric substances (EPS) of marine bacteria constituting various hydrophilic and hydrophobic functional groups sequester petroleum hydrocarbons (PHs). In this study, interaction of EPS of Pseudomonas furukawaii PPS-19 with PHs such as crude oil, n-dodecane, and pyrene and its impact on PHs adsorption was investigated. Protein component of EPS was increased after treatment with PHs. Red shift of UV-Vis spectra implied change in molecular structure of EPS. Functional groups of proteins (CO, NH2) and polysaccharides (C-C, C-OH, C-O-C) predominantly interacted with PHs. Interaction with PHs affected secondary structure of EPS. Change in binding energies of corresponding functionalities of C 1s, O 1s, and N 1s confirmed the interaction. Disruption of crystalline peaks led to increased pore size in EPS primarily due to the increase in surface electronegativity. Static quenching mechanism unveils formation of complex between fulvic acid of EPS and PHs. Relative expression of alg8 gene was significantly increased in the presence of n-dodecane (6.31 fold) (P < 0.05; One way ANOVA). n-dodecane and pyrene adsorption capacity of Immobilized EPS was significantly higher (356.5 and 338.2 mg g-1, respectively) (P < 0.001; One way ANOVA) than control. Adsorption rate fits into the pseudo-second-order kinetic model. This study establishes that interaction of PHs causes structural and physical changes in EPS and EPS could be used as an adsorbent material for the sequestration of PHs pollution.

Compositional change of bacterial communities in oil-polluted seawater amid varying degrees of nanoplankton bacterivory.

Petroleum hydrocarbons are being released into the marine environment continuously. They will undergo weathering and may eventually be biodegraded by bacteria and other microbes. While nanoplankton (2-20 µm) are the major consumers of marine bacteria, their effect on the process of biodegradation of oil hydrocarbons is still debated. A 14-day microcosm experiment was conducted to investigate the effects of crude oil hydrocarbons on nanoplankton bacterivory and bacterial community in coastal waters. The coefficients of population growth (0.56-1.80 d-1 for all treatments considered) and grazing mortality (0.38-1.65 d-1 for all treatment considered) of bacteria estimated with the dilution method did not differ among the treatments of control (Ctrl), low dose chemically dispersed oil (LDOil, 2 µL L-1 of crude oil), and high dose chemically dispersed oil (HDOil, 8 µL L-1 of crude oil). Bacterial abundance ranged between 0.21-0.86 × 106 cells mL-1 on average for all treatments. The lack of drastic increases in the cell density of bacterial cells in the oil-loaded treatments was observed throughout the experiment period. Sequencing analysis of the 16S rRNA gene revealed the progressive changes in the community compositions of bacteria in all treatments. The relatively high abundance of oil-degrading bacteria, including Cycloclasticus and Alcanivorax on Days 3-14 of the experiment reflected the presence of biodegradation of oil in the LDOil and HDOil treatments. Throughout the 14 days, the community composition of bacteria in the LDOil and HDOil treatments became more similar and they both differed from that in the Ctrl treatment. This study concluded that, in oil-polluted seawater, the changes in the bacterial community composition were mainly resulting from the addition of chemically dispersed crude oil.

A seawater field study of crude and fuel oil depletion in Northern Norway at two different seasons - Chemistry and bacterial communities.

After marine oil spills, natural processes like photooxidation and biodegradation can remove the oil from the environment. However, these processes are strongly influenced by environmental conditions. To achieve a greater understanding of how seasonal variations in temperature, light exposure and the bacterial community affect oil depletion in the marine environment, we performed two field experiments during the spring and autumn. Field systems equipped with a thin oil film of Statfjord, Grane or ULSFO were deployed in northern Norway. Depletion of the total extractable matter was faster during the spring than during the autumn. Statfjord showed faster depletion of n-alkanes during spring, while depletion of polycyclic aromatic hydrocarbons varied between the seasons based on the degree of alkyl-substitutions. ULSFO displayed the overall slowest depletion. Biodegradation of the oils was associated with high abundances of unassigned bacteria during the spring but was governed by Alcanivorax, Cycloclasticus, Oleibacter and Oleispira during the autumn.

Nitrogen utilization efficiency assessment during bioremediation of petroleum-contaminated loess soils: insights from metagenomic analysis.

Nitrogen addition is commonly used to remediate total petroleum hydrocarbons (TPH) in petroleum-contaminated soils. However, acceptable exogenous nitrogen dosages and their utilization efficiency for the degradation of hydrocarbons in oil-polluted soils are not well understood. This study compared the hydrocarbon bioremediation capacity by applying different doses of NH4Cl as a stimulant in soils contaminated with TPH at 8553 and 17090 mg/kg. The results showed acceptable exogenous nitrogen levels ranging from 60 to 360 mg N/kg soil, and the optimal nitrogen dosage for TPH remediation was 136 mg N/kg in soils with different TPH concentrations. The nitrogen availability efficiency (NAE) and nitrogen polarization factor availability (NPFA) in the 136 mg N/kg addition treatments were 6.69 and 20.47 mg/mg in 8533 mg/kg TPH-polluted soil, and 6.03 and 31.11 mg/mg in 17090 mg/kg TPH-polluted soil, respectively. Metagenomic analysis revealed that the application of 136 mg/kg nitrogen facilitated ammonia oxidation and nitrite reduction to nitric oxide, and induced soil microorganisms to undergo regulatory or adaptive changes in energy supply and metabolic state, which could aid in restoring the ecological functions of petroleum-contaminated soils. These findings underscore that 136 mg/kg of nitrogen dosage application is optimal for remediation of petroleum-contaminated soils irrespective of the TPH concentrations. This exogenous nitrogen application dosage for TPH remediation aligns with the nitrogen requirements for crop growth in agriculture.

Enhancing bioremediation of petroleum-contaminated soil by sophorolipids-modified biochar: Combined metagenomic and metabolomic analyses.

In this study, sophorolipids (SLs)-modified biochar (BC-SLs) was used to enhance the bioremediation of petroleum hydrocarbons (PHs) contaminated soil. The biodegradation rate of petroleum hydrocarbons (PHs) by BC-SLs and BC treatments were 62.86 % and 52.64 % after 60 days of remediation experiments, respectively, higher than non-biochar treatment group (24.09 %). The metagenomic analysis showed that the abundance of petroleum-degrading bacteria Actinobacteria and Proteobacteria were increased by 3.8 % and 5.3 %, respectively in BC-SLs treatment, and the abundance of functional genes for PHs degradation, such as alkB, nidA and pcaG, were significantly increased by 12.85 %, 30.08 % and 21.01 %, respectively. The metabolomic analysis showed that BC-SLs facilitated the metabolic process of PHs, the microbial metabolism of petroleum hydrocarbons (PHs) became more active. Fatty acid degradation and polycyclic aromatic hydrocarbons (PAHs) degradation were up-regulated, indicating the promoting effect of the BC-SLs for PHs metabolism. The combined metagenomic and metabolomic analysis demonstrated the strong positive correlations between PHs metabolites and PHs-degrading bacteria, such as lauric acid vs. Actinobacteria, benzoic vs. Proteobacteria. The strong positive correlations between PHs metabolites and PHs-degrading genes were also observed, such as o-ehyltoluene vs. nahD, 4-isopropylbenzoic acid vs. etbAa. The modification of biochar with SLs increased the oxygen-containing functional groups on the surface of biochar. Meanwhile, the emulsification and solubilization of SLs promoted the bioavailability of PHs. The effects of BC-SLs on the nitrogen cycle during PHs remediation showed that it facilitated the accumulation of nitrogen-fixing genes, promoted nitrification but inhibited denitrification process. This study confirms that the application of BC-SLs is an effective remediation of PHs contamination and a sustainable method for controlling agricultural waste resources.

Identification of carbon fixation microorganisms and pathways in an aquifer contaminated with long-chain petroleum hydrocarbons.

Petroleum hydrocarbons (PHCs) can be biodegraded into CO2, and PHC-contaminated aquifers are always deemed as carbon sources. Fortunately, some carbon fixation microorganisms have been found in PHC-contaminated sites. However, most of the studies are related to volatile short-chain PHC, and few studies focus on long-chain PHC-contaminated sites. To reveal the carbon fixation microorganisms in these sites, in the study, a long-chain PHC polluted site in North China was selected. Through hydrochemical and metagenomics analysis, the structure and capacity of carbon fixing microorganisms in the site were revealed. Results showed that there were many kinds of carbon fixed microorganisms that were identified such as Flavobacterium, Pseudomonas. HP/4HB, rTCA, and DC/4HB cycles were dominated carbon fixation pathways. The long-chain PHC were weakly correlated with carbon fixation microorganisms, but it may stimulate the growth of some carbon fixation microorganisms, such as microorganisms involved in rTCA cycle. PRACTITIONER POINTS: The microorganisms with carbon fixation gene exist in the aquifer contaminated by long-chain petroleum hydrocarbon. Microorganisms that have the ability to degrade petroleum also have the ability to carbon fixation. Long-chain petroleum hydrocarbon may promote the growth of carbon fixation microorganisms.

Exposure of Polycyclic Aromatic Hydrocarbons (PAHs) and Crude Oil to Atlantic Haddock (Melanogrammus aeglefinus): A Unique Snapshot of the Mercapturic Acid Pathway.

Fish exposed to xenobiotics like petroleum-derived polycyclic aromatic hydrocarbons (PAHs) will immediately initiate detoxification systems through effective biotransformation reactions. Yet, there is a discrepancy between recognized metabolic pathways and the actual metabolites detected in fish following PAH exposure like oil pollution. To deepen our understanding of PAH detoxification, we conducted experiments exposing Atlantic haddock (Melanogrammus aeglefinus) to individual PAHs or complex oil mixtures. Bile extracts, analyzed by using an ion mobility quadrupole time-of-flight mass spectrometer, revealed novel metabolites associated with the mercapturic acid pathway. A dominant spectral feature recognized as PAH thiols set the basis for a screening strategy targeting (i) glutathione-, (ii) cysteinylglycine-, (iii) cysteine-, and (iv) mercapturic acid S-conjugates. Based on controlled single-exposure experiments, we constructed an interactive library of 33 metabolites originating from 8 PAHs (anthracene, phenanthrene, 1-methylphenanthrene, 1,4-dimethylphenanthrene, chrysene, benz[a]anthracene, benzo[a]pyrene, and dibenz[a,h]anthracene). By incorporation of the library in the analysis of samples from crude oil exposed fish, PAHs conjugated with glutathione and cysteinylglycine were uncovered. This qualitative study offers an exclusive glimpse into the rarely acknowledged mercapturic acid detoxification pathway in fish. Furthermore, this furnishes evidence that this metabolic pathway also succeeds for PAHs in complex pollution sources, a notable discovery not previously reported.

Composition and metabolic flexibility of hydrocarbon-degrading consortia in oil reservoirs.

Hydrocarbon-degrading consortia (HDC) play an important role in petroleum exploitation. However, the real composition and metabolic mechanism of HDC in the microbial enhanced oil recovery (MEOR) process remain unclear. By combining 13C-DNA stable isotope probing microcosms with metagenomics, some newly reported phyla, including Chloroflexi, Synergistetes, Thermotogae, and Planctomycetes, dominated the HDC in the oil reservoirs. In the field trials, the HDC in the aerobic-facultative-anaerobic stage of oilfields jointly promoted the MEOR process, with monthly oil increments of up to 189 tons. Pseudomonas can improve oil recovery by producing rhamnolipid in the facultative condition. Roseovarius was the novel taxa potentially oxidizing alkane and producing acetate to improve oil porosity and permeability in the aerobic condition. Ca. Bacteroidia were the new members potentially degrading hydrocarbons by fumarate addition in the anaerobic environment. Comprehensive identification of the active HDC in oil reservoirs provides a novel theoretical basis for oilfield regulatory scheme.

Chronic Exposure to Petroleum-Derived Hydrocarbons Alters Human Skin Microbiome and Metabolome Profiles: A Pilot Study.

Petroleum-derived substances, like industrial oils and grease, are ubiquitous in our daily lives. Comprised of petroleum hydrocarbons (PH), these substances can come into contact with our skin, potentially causing molecular disruptions and contributing to the development of chronic disease. In this pilot study, we employed mass spectrometry-based untargeted metabolomics and 16S rRNA gene sequencing analyses to explore these effects. Superficial skin samples were collected from subjects with and without chronic dermal exposure to PH at two anatomical sites: the fingers (referred to as the hand) and arms (serving as an intersubject variability control). Exposed hands exhibited higher bacterial diversity (Shannon and Simpson indices) and an enrichment of oil-degrading bacteria (ODB), including Dietzia, Paracoccus, and Kocuria. Functional prediction suggested enriched pathways associated with PH degradation in exposed hands vs non-exposed hands, while no differences were observed when comparing the arms. Furthermore, carboxylic acids, glycerophospholipids, organooxygen compounds, phenol ethers, among others, were found to be more abundant in exposed hands. We observed positive correlations among multiple ODB and xenobiotics, suggesting a chemical remodeling of the skin favorable for ODB thriving. Overall, our study offers insights into the complex dysregulation of bacterial communities and the chemical milieu induced by chronic dermal exposure to PH.

Resting for viability: Gordonia polyisoprenivorans ZM27, a robust generalist for petroleum bioremediation under hypersaline stress.

The intrinsic issue associated with the application of microbes for practical pollution remediation involves maintaining the expected activity of engaged strains or consortiums as effectively as that noted under laboratory conditions. Faced with various stress factors, degraders with dormancy ability are more likely to survive and exhibit degradation activity. In this study, a hydrocarbonoclastic and halotolerant strain, Gordonia polyisoprenivorans ZM27, was isolated via stimulation with resuscitation-promoting factor (Rpf). Long-term exposure to dual stresses of 10% NaCl and starvation induced ZM27 to enter a viable but nonculturable (VBNC)-like state, and ZM27 cells could be resuscitated upon Rpf stimulation. Notable changes in both morphological and physiological characteristics between VBNC-like ZM27 cells and resuscitated cells confirmed the response to Rpf and their robust resistance against harsh environments. Whole-genome sequencing and analysis indicated ZM27 could be a generalist degrader with dormancy ability. Subsequently, VBNC-like ZM27 was applied in a soil microcosm experiment to investigate the practical application potential under harsh conditions. VBNC-like ZM27 combined with Rpf stimulation exhibited the most effective biodegradation performance, and the initial n-hexadecane content (1000 mg kg-1) decreased by 63.29% after 14-day incubation. Based on 16S rRNA amplicon sequencing and analysis, Gordonia exhibited a positive response to Rpf stimulation. The relative abundance of genus Gordonia was negatively correlated with that of Alcanivorax, a genus of obligate hydrocarbon degrader with the greatest abundance during soil incubation. Based on the degradation profile and community analysis, generalist Gordonia may be more efficient in hydrocarbon degradation than specialist Alcanivorax under harsh conditions. The characteristics of ZM27, including its sustainable culturability under long-term stress, response to Rpf and robust performance in soil microcosms, are valuable for the remediation of petroleum pollution under stressful conditions. Our work validated the importance of dormancy and highlighted the underestimated role of low-activity degraders in petroleum remediation.

Genetically modified indigenous Pseudomonas aeruginosa drove bacterial community to change positively toward microbial enhanced oil recovery applications.

AIMS: Microbial enhanced oil recovery (MEOR) is cost-effective and eco-friendly for oil exploitation. Genetically modified biosurfactants-producing high-yield strains are promising for ex-situ MEOR. However, can they survive and produce biosurfactants in petroleum reservoirs for in-situ MEOR? What is their effect on the native bacterial community? METHODS AND RESULTS: A genetically modified indigenous biosurfactants-producing strain Pseudomonas aeruginosa PrhlAB was bioaugmented in simulated reservoir environments. Pseudomonas aeruginosa PrhlAB could stably colonize in simulated reservoirs. Biosurfactants (200 mg l-1) were produced in simulated reservoirs after bio-augmenting strain PrhlAB. The surface tension of fluid was reduced to 32.1 mN m-1. Crude oil was emulsified with an emulsification index of 60.1%. Bio-augmenting strain PrhlAB stimulated the MEOR-related microbial activities. Hydrocarbon-degrading bacteria and biosurfactants-producing bacteria were activated, while the hydrogen sulfide-producing bacteria were inhibited. Bio-augmenting P. aeruginosa PrhlAB reduced the diversity of bacterial community, and gradually simplified the species composition. Bacteria with oil displacement potential became dominant genera, such as Shewanella, Pseudomonas, and Arcobacter. CONCLUSIONS: Culture-based and sequence-based analyses reveal that genetically modified biosurfactants-producing strain P. aeruginosa PrhlAB are promising for in-situ MEOR as well.