Hydrocarbon-degrading Bacteria Research Articles

Characterization of Efficient Biosufactants Producing Bacteria and its Efficacy on Bioremediation of Crude Oil

The present work was aimed to isolate efficient hydrocarbon degrading and biosurfactant producing bacteria strain from oil contaminated site. Biosurfactant are low molecular surface active compounds involved in the degradation of hydrocarbons. Biosurfactant activity of isolated strain were detected by using different screening method. The study showed that efficient biosurfactant producing bacteria were identified as Arthrobacter globiformis. More over, crude oil degradation as consortium degraded more effectively than individual strain.

Diversity of hydrocarbon-degrading bacteria in Pulau Pari and their potential roles for bioremediation

Oil spill accidents occur several times in the Indonesian sea, including Jakarta Bay. Studies on the application of oil spill bio-degradation techniques need to be developed but require baseline data on microbe species diversity and functions. We isolated several bacteria from Pulau Pari that can degrade hydrocarbons (hexadecane, phenantrene, and dibenzothiophene) by using two step enrichment culture technique. The isolated microbes belong to several taxa, including α-subclass Proteobacteria, β-subclass Proteobacteria, γ-subclass Proteobacteria, the gram-positive high GC content (Actinobacteria), and Bacillus group. These marine bacteria degrade not only alkanes but also polyaromatic hydrocarbons (phenanthrene and dibenzothiophene). Alpha and gamma Proteobacteria were predominant alkane and polyaromatic hydrocarbons-degrading bacteria. The ability of those bacteria to degrade both alkanes and polyaromatic hydrocarbon is a key-important trait for enhancing bioremediation of oil spills.

Isolation and Characterization of Hydrocarbon-degrading Bacteria in Soils of Mechanical Workshops in Maiduguri, Borno State

The study was conducted to determine the distribution of hydrocarbon utilizing bacteria in spent engine oil (SEO) contaminated soil. Five mechanical workshops within Maiduguri Metropolis. Five bulk soil sample comprising of one each of the five sites; the sites are Leventis Area on Kashim Ibrahim Way, Damboa Raod, Boiler (commonly called Bola) near Maiduguri Monday Market, Ngomari, on Kano Road, and 1000 Housing Estate, also on Kano Road. Nutrient agar was used, or isolation and enumeration total heterotrophic bacteria and Mineral salt agar was used for the isolation and enumeration of hydrocarbon utilizing bacteria. The result shows THB (92.0x104) at Damboa road (DR) to as higher and (78.8x104) at Bola area (BL) while HUB (2.0x104) at Damboa road (DR) and as high as (9.3x104) at Bola area (BL). The bacterial species isolated were species of Bacillus licheniformis, Bacillus subtilis, Bacillus coagulans, Bacillus alvei, Bacillus cereus, Bacillus lentus other are Pseudomonas aeruginosa, Klebsiella pneumonia. Bacillus licheniformis, and Bacillus subtilis are the most occurring bacterial isolates identified. The ability of those bacterial isolate to degrade hydrocarbon buoyantly will help in remediation of oil polluted environments.

Non-syntrophic methanogenic hydrocarbon degradation by an archaeal species.

The methanogenic degradation of oil hydrocarbons can proceed through syntrophic partnerships of hydrocarbon-degrading bacteria and methanogenic archaea1-3. However, recent culture-independent studies have suggested that the archaeon 'Candidatus Methanoliparum' alone can combine the degradation of long-chain alkanes with methanogenesis4,5. Here we cultured Ca. Methanoliparum from a subsurface oil reservoir. Molecular analyses revealed that Ca. Methanoliparum contains and overexpresses genes encoding alkyl-coenzyme M reductases and methyl-coenzyme M reductases, the marker genes for archaeal multicarbon alkane and methane metabolism. Incubation experiments with different substrates and mass spectrometric detection of coenzyme-M-bound intermediates confirm that Ca. Methanoliparum thrives not only on a variety of long-chain alkanes, but also on n-alkylcyclohexanes and n-alkylbenzenes with long n-alkyl (C≥13) moieties. By contrast, short-chain alkanes (such as ethane to octane) or aromatics with short alkyl chains (C≤12) were not consumed. The wide distribution of Ca. Methanoliparum4-6 in oil-rich environments indicates that this alkylotrophic methanogen may have a crucial role in the transformation of hydrocarbons into methane.

New insights into the functioning and structure of the PE and PP plastispheres from the Mediterranean Sea

Plastic debris are accumulating in the marine environment and aggregate microorganisms that form a new ecosystem called the plastisphere. Better understanding the plastisphere is crucial as it has self-sufficient organization and carries pathogens or organisms that may be involved in the pollutant adsorption and/or plastic degradation. To date, the plastisphere is mainly described at the taxonomic level and the functioning of its microbial communities still remains poorly documented. In this work, metagenomic and metaproteomic analyzes were performed on the plastisphere of polypropylene and polyethylene plastic debris sampled on a pebble beach from the Mediterranean Sea. Our results confirmed that the plastisphere was organized as self-sufficient ecosystems containing highly active primary producers, heterotrophs and predators such as nematode. Interestingly, the chemical composition of the polymer did not impact the structure of the microbial communities but rather influenced the functions expressed. Despite the fact that the presence of hydrocarbon-degrading bacteria was observed in the metagenomes, polymer degradation metabolisms were not detected at the protein level. Finally, hydrocarbon degrader (i.e., Alcanivorax) and pathogenic bacteria (i.e., Vibrionaceae) were observed in the plastispheres but were not very active as no proteins involved in polymer degradation or pathogeny were detected. This work brings new insights into the functioning of the microbial plastisphere developed on plastic marine debris.

Bacterial community profile of the crude oil-contaminated saline soil in the Yellow River Delta Natural Reserve, China

Crude oil contamination greatly influence soil bacterial community. Proliferative microbes in the crude oil-contaminated soil are closely related to the living conditions. Oil wells in the Yellow River Delta Natural Reserve (YRDNR) region is an ideal site for investigating the bacterial community of crude oil-contaminated saline soil. In the present study, 18 soil samples were collected from the depths of 0–20 cm and 20–40 cm around the oil wells in the YRDNR. The bacterial community profile was analyzed through high-throughput sequencing to trace the oil-degrading aerobic and anaerobic bacteria. The results indicated that C15–C28 and C29–C38 were the main fractions of total petroleum hydrocarbon (TPH) in the sampled soil. These TPH fractions had a significant negative effect on bacterial biodiversity (Shannon, Simpson, and Chao1 indices), which led to the proliferation of hydrocarbon-degrading bacteria. A comprehensive analysis between the environmental factors and soil microbial community structure showed that Streptococcus, Bacillus, Sphingomonas, and Arthrobacter were the aerobic hydrocarbon-degrading bacteria; unidentified Rhodobacteraceae and Porticoccus were considered to be the possible facultative anaerobic bacteria with hydrocarbon biodegradation ability; Acidithiobacillus, SAR324 clade, and Nitrosarchaeum were predicted to be the anaerobic hydrocarbon-degrading bacteria in the sub-surface soil. Furthermore, large amount of carbon sources derived from TPH was found to cause depletion of bioavailable nitrogen in the soil. The bacteria associated with nitrogen transformation, such as Solirubrobacter, Candidatus Udaeobacter, Lysinibacillus, Bradyrhizobium, Sphingomonas, Mycobacterium, and Acidithiobacillus, were highly abundant; these bacteria may possess the ability to increase nitrogen availability in the crude oil-contaminated soil. The bacterial community functions were significantly different between the surface and the sub-surface soil, and the dissolved oxygen concentration in soil was considered to be potential influencing factor. Our results could provide useful information for the bioremediation of crude oil-contaminated saline soil.

Insight into Bacterial Community Responses to Polycyclic Aromatic Hydrocarbons and the Degradation Potentials of Three Bacterial Isolates in Seagrass Halophila ovalis Sediments.

Seagrass meadows constitute a prestigious ecosystem in the marine environment, providing valuable ecological and commercial services. Among the various causes, pollutions are considered one of the significant reasons for seagrass decline globally. This study investigates the impacts of polycyclic aromatic hydrocarbons mixture (pyrene, phenanthrene, and fluorene) on bacterial communities in Halophila ovalis sediments. The seagrass sediment bacterial microbiome was evaluated in a batch culture experiment by Illumina MiSeq sequencing. Culture-able bacterial strains were isolated and characterized by 16S rRNA gene sequencing. The results demonstrated an excellent alpha diversity in the original sediments with a Shannon index of (8.078) compared to the subsequent control group (5.908) and PAH-treated group (PAH-T) (4.916). Three phyla, Proteobacteria, Firmicutes, and Bacteroidetes, were detected in high abundance in the control and PAH-T groups. However, a significant difference (P < 0.05) was observed at the genus level between control and PAH-T group bacterial consortia. Pseudomonas, Mycobacterium, Idiomarina, Hydrogenophaga, Alteromonas, Sphingobacterium, and several others were highly abundant in PAH-T groups. Most of the culture-able isolates recovered in this study showed the closest resemblance to previously identified hydrocarbon-degrading bacteria. Among the three strains, Mix-16 (Citricoccus yambaruensis) and Mix-20 (Gordonia rubripertincta) showed a higher degradation of PAHs than Mix-19 (Isoptericola halotolerans) in the monoculture experiment. The most increased degradation of PAHs was recorded in the co-culture experiment. The present work revealed that PAHs could act as environmental stress and can influence bacterial community succession. Moreover, the co-culture strategy significantly enhanced the biodegradation of PAHs.

Exploring the toxicity of the aged styrene-butadiene rubber microplastics to petroleum hydrocarbon-degrading bacteria under compound pollution system

As a new pollutant, microplastics have increasingly drawn public attention to its toxic behavior in the environment. The aim was to investigate the effect of styrene-butadiene-rubber microplastics (mSBR) with different degrees of aging on petroleum hydrocarbon (PHC) degrading bacteria in an environment with simultaneously existing pollutants. A series of experiments were carried out to investigate the changes in the physical and chemical properties of mSBR with aging and to examine the influence of these changes on the inhibition of PHC-degrading bacteria by mSBR in the vicinity of coexisting pollutants. The results showed that in the early stage of ultraviolet aging (10d), the particle surface shows wrinkles, but the structure is intact. After reaching the late stage of aging (20d), nano-scale fragments were generated on the surface of mSBR, the average particle size decreased from 3.074 µm to 2.297 µm, and the zeta potential increased from − 25.1 mV to − 33.1 mV. The inhibitory effect of bacteria is greater. At the same time, these changes in the physicochemical properties increase the adsorption effect of Cd by 20%, and also improve the stability of mSBR in solution, whereby bacterial growth is inhibited by inhibiting the LPO activity and protein concentration of PHC degrading bacteria.

Bioaugmentation with zeolite-immobilized bacterial consortium OPK results in a bacterial community shift and enhances the bioremediation of crude oil-polluted marine sandy soil microcosms

A pyrene-degrading consortium OPK containing Mycolicibacterium strains PO1 and PO2, Novosphingobium pentaromativorans PY1 and Bacillus subtilis FW1 effectively biodegraded medium- and long-chain alkanes as well as mixed hydrocarbons in crude oil. The detection of alkB and CYP153 genes in the genome of OPK members supports its phenotypic ability to effectively degrade a broad range of saturated hydrocarbons in crude oil. Zeolite-immobilized OPK was developed as a ready-to-use bioproduct and it exhibited 74% removal of 1000 mg L−1 crude oil within 96 h in sterilized seawater without nutrient supplementation and maintained high crude oil-removal activity under a broad range of pH values (5.0–9.0), temperatures (30–40 °C) and salinities (20–60‰). In addition, the immobilized OPK retained a high crude oil removal efficacy in semicontinuous experiments and showed reusability for at least 5 cycles. Remarkably, bioaugmentation with zeolite-immobilized OPK in sandy soil microcosms significantly increased crude oil (10,000 mg kg−1 soil) removal from 45% to 80.67% within 21 days compared to biostimulation and natural attenuation. Moreover, bioaugmentation with exogenous immobilized OPK stimulated an increase in the relative abundances of Alcanivorax genus, indigenous hydrocarbon-degrading bacteria, which in turn enhanced removal efficiency of crude oil contamination from sandy soil microcosms. The results indicate positive interactions between the bioaugmented immobilized consortium, harboring Mycolicibacterium as a key player, and indigenous Alcanivorax, which exhibited crucial functions for improving crude oil removal efficacy. The knowledge obtained forms an important basis for further synthesis and handling of a promising bio-based product for enhancing the in situ bioremediation of crude oil-polluted marine environments.

Soil microbiota and microarthropod communities in oil contaminated sites in the European Subarctic

The present comprehensive study aimed to estimate the aftermath of oil contamination and the efficacy of removing the upper level of polluted soil under the conditions of the extreme northern taiga of northeastern European Russia. Soil samples from three sites were studied. Two sites were contaminated with the contents of a nearby sludge collector five years prior to sampling. The highly contaminated upper soil level was removed from one of them. The other was left for self-restoration. A chemical analysis of the soils was conducted, and changes in the composition of the soil zoocoenosis and bacterial and fungal microbiota were investigated. At both contaminated sites, a decrease in the abundance and taxonomic diversity of indicator groups of soil fauna, oribatid mites and collembolans compared to the background site were found. The pioneer eurytopic species Oppiella nova, Proisotoma minima and Xenyllodes armatus formed the basis of the microarthropod populations in the contaminated soil. A complete change in the composition of dominant taxonomic units was observed in the microbiota, both the bacterial and fungal communities. There was an increase in the proportion of representatives of Proteobacteria and Actinobacteria in polluted soils compared to the background community. Hydrocarbon-degrading bacteria—Alcanivorax, Rhodanobacter ginsengisoli, Acidobacterium capsulatum, and Acidocella—and fungi—Amorphotheca resinae abundances greatly increased in oil-contaminated soil. Moreover, among both bacteria and fungi, a sharp increase in the abundance of uncultivated organisms that deserve additional attention as potential oil degraders or organisms with a high resistance to oil contamination were observed. The removal of the upper soil level was partly effective in terms of decreasing the oil product concentration (from approximately 21 to 2.6 g/kg of soil) and preventing a decrease in taxonomic richness but did not prevent alterations in the composition of the microbiota or zoocoenosis.

English

The accidental release of diesel and other hydrocarbon to the environment lead to the pollution of the environment. The search for an environmentally friendly technique for the remediation of such polluted environment is not to be overemphasis. Microorganisms are used in the bioremediation of polluted environments. Hydrocarbon-degrading bacterium isolated from the hydrocarbon exploration site soil of Kukawa North-eastern Nigeria, and was studied for its biodegradation potential of diesel. Culture base techniques using nutrient agar and mineral salt medium supplemented with 1% diesel was used. The bacterium isolate was identified as Enterobacter sp. strain IAA-01.&nbsp; Identification was carried out using 16S rRNA sequencing and molecular phylogeny analysis using the Phylip software. Gravimetric analysis was conducted to measure the percentage biodegradation of the bacterium for 21 days, and confirmed using Gas chromatography (GC) analysis where the bacterium degraded diesel hydrocarbon 78% after 21 days and total degradation was revealed in GC analysis after 21 days. The results prevailed the ability of Enterobacter sp. strain IAA-01 effectively biodegrade diesel oil. &nbsp; Key words: Enterobacter sp., biodegradation, gas chromatography, pollution.

Bioemulsification and Microbial Community Reconstruction in Thermally Processed Crude Oil.

Utilization of low-cost, environmental-friendly microbial enhanced oil recovery (MEOR) techniques in thermal recovery-processed oil reservoirs is potentially feasible. However, how exogenous microbes facilitate crude oil recovery in this deep biosphere, especially under mesophilic conditions, is scarcely investigated. In this study, a thermal treatment and a thermal recurrence were processed on crude oil collected from Daqing Oilfield, and then a 30-day incubation of the pretreated crude oil at 37 °C was operated with the addition of two locally isolated hydrocarbon-degrading bacteria, Amycolicicoccus subflavus DQS3-9A1T and Dietzia sp. DQ12-45-1b, respectively. The pH, surface tension, hydrocarbon profiles, culture-dependent cell densities and taxonomies, and whole and active microbial community compositions were determined. It was found that both A. subflavus DQS3-9A1T and Dietzia sp. DQ12-45-1b successfully induced culture acidification, crude oil bioemulsification, and residual oil sub-fraction alteration, no matter whether the crude oil was thermally pretreated or not. Endogenous bacteria which could proliferate on double heated crude oil were very few. Compared with A. subflavus, Dietzia sp. was substantially more effective at inducing the proliferation of varied species in one-time heated crude oil. Meanwhile, the effects of Dietzia sp. on crude oil bioemulsification and hydrocarbon profile alteration were not significantly influenced by the ploidy increasing of NaCl contents (from 5 g/L to 50 g/L), but the reconstructed bacterial communities became very simple, in which the Dietzia genus was predominant. Our study provides useful information to understand MEOR trials on thermally processed oil reservoirs, and proves that this strategy could be operated by using the locally available hydrocarbon-degrading microbes in mesophilic conditions with different salinity degrees.

Response and oil degradation activities of a northeast Atlantic bacterial community to biogenic and synthetic surfactants

BackgroundBiosurfactants are naturally derived products that play a similar role to synthetic dispersants in oil spill response but are easily biodegradable and less toxic. Using a combination of analytical chemistry, 16S rRNA amplicon sequencing and simulation-based approaches, this study investigated the microbial community dynamics, ecological drivers, functional diversity and robustness, and oil biodegradation potential of a northeast Atlantic marine microbial community to crude oil when exposed to rhamnolipid or synthetic dispersant Finasol OSR52.ResultsPsychrophilic Colwellia and Oleispira dominated the community in both the rhamnolipid and Finasol OSR52 treatments initially but later community structure across treatments diverged significantly: Rhodobacteraceae and Vibrio dominated the Finasol-amended treatment, whereas Colwellia, Oleispira, and later Cycloclasticus and Alcanivorax, dominated the rhamnolipid-amended treatment. Key aromatic hydrocarbon-degrading bacteria, like Cycloclasticus, was not observed in the Finasol treatment but it was abundant in the oil-only and rhamnolipid-amended treatments. Overall, Finasol had a significant negative impact on the community diversity, weakened the taxa-functional robustness of the community, and caused a stronger environmental filtering, more so than oil-only and rhamnolipid-amended oil treatments. Rhamnolipid-amended and oil-only treatments had the highest functional diversity, however, the overall oil biodegradation was greater in the Finasol treatment, but aromatic biodegradation was highest in the rhamnolipid treatment.ConclusionOverall, the natural marine microbial community in the northeast Atlantic responded differently to crude oil dispersed with either synthetic or biogenic surfactants over time, but oil degradation was more enhanced by the synthetic dispersant. Collectively, our results advance the understanding of how rhamnolipid biosurfactants and synthetic dispersant Finasol affect the natural marine microbial community in the FSC, supporting their potential application in oil spills.43fSDwbdHYX3Ei4X1BHK1YVideo abstract

Biodiversity and oil degradation capacity of oil-degrading bacteria isolated from deep-sea hydrothermal sediments of the South Mid-Atlantic Ridge

Studies have reported that various hydrocarbons and hydrocarbon-degrading bacteria are found in global deep-sea hydrothermal regions. However, little is known about degradation characteristics of culturable hydrocarbon-degrading bacteria from these regions. We speculate that these bacteria can be used as resources for the bioremediation of oil pollution. In this study, six oil-degrading consortia were obtained from the hydrothermal region of the Southern Mid-Atlantic Ridge through room-temperature enrichment experiments. The dominant oil-degrading bacteria belonged to Nitratireductor, Pseudonocardia, Brevundimonas and Acinetobacter. More varieties of hydrocarbon-degrading bacteria were obtained from sediments (preserved at 4 °C) near hydrothermal vents. Most strains had the ability to degrade high molecular weight petroleum components. In addition, Pseudonocardia was shown to exhibit a high degradation ability for phytane and pristine for the first time. This study may provide new insights into the community structure and biodiversity of culturable oil-degrading bacteria in deep-sea hydrothermal regions.

Oil contamination drives the transformation of soil microbial communities: Co-occurrence pattern, metabolic enzymes and culturable hydrocarbon-degrading bacteria

The land-based oil extraction activity has led to serious pollution of the soil. While microbes may play an important role in the remediation of contaminated soils, ecological effects of oil pollution on soil microbial relationships remain poorly understood. Here, typical contaminated soils and undisturbed soils from seven oilfields of China were investigated in terms of their physicochemical characteristics, indigenous microbial assemblages, bacterial co-occurrence patterns, and metabolic enzymes. Network visualization based on k-core decomposition illustrated that oil pollution reduced correlations between co-existing bacteria. The core genera were altered to those related with oil metabolism (Pseudarthrobacter, Alcanivorax, Sphingomonas, Chromohalobacter and Nocardioides). Under oil pollution pressure, the indigenous bacteria Gammaproteobacteria was domesticated as biomarker and the enzyme expression associated with the metabolism of toxic benzene, toluene, ethylbenzene, xylene and polycyclic aromatic hydrocarbons was enhanced. Functional pathways of xenobiotics biodegradation were also stimulated under oil contamination. Finally, twelve culturable hydrocarbon-degrading microbes were isolated from these polluted soils and classified into Stenotrophomonas, Delftia, Pseudomonas and Bacillus. These results show that the soil microbial communities are transformed under oil pollution stress, and also provide useful information for future bioremediation processes.

Hydrocarbon-Degrading Bacteria’s Selection from Soil Contaminated Engine Oil Waste of South Lampung

Waste containing hydrocarbon compounds is classified as hazardous and toxic waste. Waste management must be done properly to prevent environmental pollution that ultimately has an impact on environmental damage. Engine oil is one of the hydrocarbon compound products that are widely used by motor vehicles. Waste engine oil from automotive repair shops has not been properly managed because Waste engine oil is often thrown away on the ground around the workshop. This condition has been going on for a long time due to soil contamination by waste engine oil. Thus, most microbes cannot live in polluted soils. Isolation of microorganisms in polluted soils is carried out to obtain bacteria that can grow in hydrocarbon-contaminated soils and have the potential to degrade hydrocarbon compounds. After isolation bacteria from two selected locations (Way Hui and Way Kandis), this research got four bacteria. These four isolates were selected by growing on selective media which added with engine oil with a concentration of 2% for 7 days. selection is done by counting the population of each isolate that lives in the media. Bacteria population was calculated on t1 (day 1), t4 (day 4) and on t7 (day 7). In addition, the selection is also done by calculating TPH (Total Petroleum Hydrocarbon) at t1 and t7. From these stages, it got one isolate (B7) which showed the highest results in population and three isolates showed the highest TPH decreasing (B1, B6 and B7).

Native bilge water bacteria as biosurfactant producers and implications in hydrocarbon-enriched wastewater treatment

Seawater and bilge water samples were used to isolate hydrocarbon-degrading bacteria to be screened for biosurfactant production in the presence of different carbon sources, namely tetradecane, d-glucose and sunflower oil. The panel of tested isolates, affiliated to Alcanivorax, Acinetobacter, Pseudomonas, Halomonas and Marinobacter genera, showed promising results both in terms of emulsifying activity and surface tension reduction. The selected strains Marinobacter sp. BIC3M3, Alcanivorax sp. BIC1A5 and Halomonas sp. BIC1H44 achieved total raw biosurfactant amount of 3.148, 2.922 and 2.596 g/L, respectively. The sunflower oil, here proposed as low-cost carbon source, was successfully used by all strains as substrate for biosurfactant production, with the only exception of Halomonas sp. BIC1H44, while different efficiency levels were detected during incubation in the presence of glucose and tetradecane. Among all strains, Marinobacter spp. strains from bilge waters were proven to be very competitive, although this genus has been poorly reported for biosurfactant production. The high efficiency exhibited by some strains (especially Alcanivorax sp. BIC1A5, Acinetobacter sp. BIC1AC, and Marinobacter sp. BIC3M3) during growth with tetradecane and sunflower oil suggested a promising potential for application in bioremediation purposes and hydrocarbon-enriched wastewater treatment.

Design of a Microbial Remediation Inoculation Program for Petroleum Hydrocarbon Contaminated Sites Based on Degradation Pathways.

This paper analyzed the degradation pathways of petroleum hydrocarbon degradation bacteria, screened the main degradation pathways, and found the petroleum hydrocarbon degradation enzymes corresponding to each step of the degradation pathway. Through the Copeland method, the best inoculation program of petroleum hydrocarbon degradation bacteria in a polluted site was selected as follows: single oxygenation path was dominated by Streptomyces avermitilis, hydroxylation path was dominated by Methylosinus trichosporium OB3b, secondary oxygenation path was dominated by Pseudomonas aeruginosa, secondary hydroxylation path was dominated by Methylococcus capsulatus, double oxygenation path was dominated by Acinetobacter baylyi ADP1, hydrolysis path was dominated by Rhodococcus erythropolis, and CoA path was dominated by Geobacter metallireducens GS-15 to repair petroleum hydrocarbon contaminated sites. The Copeland method score for this solution is 22, which is the highest among the 375 solutions designed in this paper, indicating that it has the best degradation effect. Meanwhile, we verified its effect by the Cdocker method, and the Cdocker energy of this solution is −285.811 kcal/mol, which has the highest absolute value. Among the inoculation programs of the top 13 petroleum hydrocarbon degradation bacteria, the effect of the best inoculation program of petroleum hydrocarbon degradation bacteria was 18% higher than that of the 13th group, verifying that this solution has the best overall degradation effect. The inoculation program of petroleum hydrocarbon degradation bacteria designed in this paper considered the main pathways of petroleum hydrocarbon pollutant degradation, especially highlighting the degradability of petroleum hydrocarbon intermediate degradation products, and enriching the theoretical program of microbial remediation of petroleum hydrocarbon contaminated sites.

Dereplication of antimicrobial biosurfactants from marine bacteria using molecular networking

Biosurfactants are amphiphilic surface-active molecules of microbial origin principally produced by hydrocarbon-degrading bacteria; in addition to the bioremediation properties, they can also present antimicrobial activity. The present study highlights the chemical characterization and the antimicrobial activities of biosurfactants produced by deep-sea marine bacteria from the genera Halomonas, Bacillus, Streptomyces, and Pseudomonas. The biosurfactants were extracted and chemically characterized through Chromatography TLC, FT-IR, LC/ESI–MS/MS, and a metabolic analysis was done through molecular networking. Six biosurfactants were identified by dereplication tools from GNPS and some surfactin isoforms were identified by molecular networking. The half-maximal inhibitory concentration (IC50) of biosurfactant from Halomonas sp. INV PRT125 (7.27 mg L−1) and Halomonas sp. INV PRT124 (8.92 mg L−1) were most effective against the pathogenic yeast Candida albicans ATCC 10231. For Methicillin-resistant Staphylococcus aureus ATCC 43300, the biosurfactant from Bacillus sp. INV FIR48 was the most effective with IC50 values of 25.65 mg L−1 and 21.54 mg L−1 for C. albicans, without hemolytic effect (< 1%), and non-ecotoxic effect in brine shrimp larvae (Artemia franciscana), with values under 150 mg L−1, being a biosurfactant promising for further study. The extreme environments as deep-sea can be an important source for the isolation of new biosurfactants-producing microorganisms with environmental and pharmaceutical use.

Impacts of benzo(a)pyrene exposure on scallop (Chlamys farreri) gut health and gut microbiota composition

The gut tissue interacts with nutrients and pollutants which can impact gut health. Gut microbiota is essential to the host health, but is also easily affected by external environment. However, little is known about the toxicological assessment of environmental contaminants on gut health and microbiota, especially in marine invertebrates. In this study, we first explored the effect of benzo(a)pyrene (BaP) on the gut health and gut microbiota of scallops (Chlamys farreri). The scallops were exposed to different concentrations (0, 0.4, 2 and 10 μg/L) of BaP for 21 days. The histological morphology, immune- and oxidative enzyme-related gene expression, and lipid peroxidation of the scallops were analyzed at 7, 14 and 21 days. The results revealed that BaP could impair intestinal barrier function, increasing the intestinal permeability of scallops. Moreover, immune and antioxidant responses were induced in the gut tissue. After a 21-day exposure to different concentrations of BaP, the intestinal microbial community was analyzed based on 16S rRNA sequencing. Our results suggested that BaP exposure altered the gut microbial diversity and composition in scallops. Many beneficial genera declined after BaP treatment, while the potential pathogens were increased, such as Mycoplasma and Tenacibaculum. A series of hydrocarbon-degrading bacteria were recognized in BaP-treated groups, such as Pseudomonas, Polaribacter, Amphritea and Kordiimonas. Interestingly, the degrading bacteria present varied after exposure to different concentrations of BaP. Overall, this study provides new insights into gut health and gut microbiota in marine invertebrates following exposure to persistent organic pollutants.