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Three bacterial species related to the genus Thalassospira (T. lucentensis, T. xianhensis and T. profundimaris), isolated from polluted sediment and seawater samples collected from Priolo Bay (eastern coast of Sicily, Ionian Sea), were analyzed for their biotechnological potential. For this purpose, the presence of specific catabolic genes associated to aliphatic and aromatic hydrocarbon metabolism, the production of biosurfactants and emulsification activity, the capability to degrade oil-derived linear, branched, cyclic alkanes, and polycyclic aromatic hydrocarbons (PAHs) were evaluated. Alkane hydroxylase gene (alkano-monoxygenase alkb and citocrome P450) were present in genome of all strains, confirming their hydrocarbons degrading capability. All strains of Thalassospira produced biosurfactants and showed emulsification activity. The two-dimensional gas chromatography analysis (GC×GC) showed that they were able to degrade oil fractions with the capacity ranging between 77% and 91%. The data obtained in this study demonstrated the biodegradation ability of Thalassospira and suggest that these strains play an important role in marine contaminated ecosystems

Bioremediation is among the most basic and reliable way to eliminate pollutants by transforming the toxic petroleum components into less toxic metabolites. In order to compare the change of bacteri...

In agriculture, the use of herbicides is necessary to prevent or restrict the growth of weeds that affect the yields of crops such as cereals and legumes. Intensive agriculture relies heavily on the use of herbicides to increase crop yields and provide abundant, inexpensive, and visually appealing food. However, the distribution and persistence of these chemicals in the field can negatively affect the growth and physiological parameters of the crop. The objective of this study was to evaluate the effect of different doses of two widely used pesticides (glyphosate and paraquat) in the Meknes region of Morocco on seed germination, amino acid content, and photosynthetic pigments of Vicia faba, Phaseolus vulgaris, and Sorghum bicolor. Results showed that pesticide application decreased seed germination and seedling efficiency. Both compounds acted as inhibitors and reduced the growth of V. faba, P. vulgaris, and S. bicolor when applied in higher concentrations, 5.4 g/L for glyphosate and 4 g/L for paraquat, which are the recommended doses in agriculture. Besides, similar herbicide effects on photosynthetic pigments and amino acid content were observed, with decreases in these parameters at higher doses. Our research concludes that the application of glyphosate and paraquat to V. faba, P. vulgaris, and S. bicolor seeds negatively affected germination, photosynthetic pigments and amino acids.

Microbial communities of coastal marine sediment play a key role in degradation of petroleum contaminants. Here the bacterial and archaeal communities of sub-surface sediments (5–10 cm) of the chronically polluted Priolo Bay (eastern coast of Sicily, Italy), contaminated mainly by n-alkanes and biodegraded/weathered oils, were characterized by cultural and molecular approaches. 16S-PCR-DGGE analysis at six stations, revealed that bacterial communities are highly divergent and display lower phylogenetic diversity than the surface sediment; sub-surface communities respond to oil supplementation in microcosms with a significant reduction in biodiversity and a shift in composition; they retain high biodegradation capacities and host hydrocarbon (HC) degraders that were isolated and identified. HC-degrading Alfa, Gamma and Epsilon proteobacteria together with Clostridia and Archaea are a common feature of sub-surface communities. These assemblages show similarities with that of subsurface petroleum reservoirs also characterized by the presence of biodegraded and weathered oils where anaerobic or microaerophilic syntrophic HC metabolism has been proposed.

This work presents the results of recovery efficacy of the system "BioFilm Membrane BioReactor" (BF-MBR), in the treatment of oily contaminated seawaters. To this aim, we proposed a multidisciplinary approach that integrates traditional chemical-physical measures together with the assessment on biological sentinel Mytilus galloprovincialis, maintained in a medium-scale artificial system named mesocosm. The setup included: (1) a mesocosm consisting of uncontaminated seawater; (2) a mesocosm composed of an untreated oily wastewater discharge; and (3) a mesocosm receiving the same oily wastewater previously treated by a BF-MBR pilot scale plant. The multidisciplinary approach that included traditional chemical measures on mesocosms together with the evaluation of morphological organization, mRNA expression of those genes involved in cellular stress response, immunohistochemistry and metabolomic analysis on mussel tissues, was able to provide a robust and holistic evidence of how the proposed treatment is able to reduce the overall impact of oily wastewater discharges on the marine ecosystem.

Marine sediments represent an important sink of harmful petroleum hydrocarbons after an accidental oil spill. Electrobioremediation techniques, which combine electrokinetic transport and biodegradation processes, represent an emerging technological platform for a sustainable remediation of contaminated sediments. Here, we describe the results of a long-term mesocosm-scale electrobioremediation experi- ment for the treatment of marine sediments contaminated by crude oil. A dimensionally stable anode and a stainless-steel mesh cathode were employed to drive seawater electrolysis at a fixed current density of 11 A/m2. This approach allowed establishing conditions conducive to contaminants biodeg- radation, as confirmed by the enrichment of Alcanivorax borkumensis cells harboring the alkB-gene and other aerobic hydrocarbonoclastic bacteria. Oil chemistry analyses indicated that aromatic hydrocarbons were primarily removed from the sediment via electroosmosis and low molecular weight alkanes (nC6 to nC10) via biodegradation., This work was financially supported by the European Commission within the Seventh Framework Programme under Grant Agreement No. 312139 (“Kill-Spill: Integrated biotechnological solutions for combating marine oil spills”).

Aims The Algerian coastline is exposed to several types of pollution, including hydrocarbons. The aim of this work was to isolate oil-degrading bacteria and to explore the intrinsic bioremediation potential of part of its contaminated harbour. Methods and results A collection of 119 strains, capable to grow on mineral medium supplemented with hydrocarbons, were obtained from polluted sediment and seawater collected from Sidi Fredj harbour (Algiers). Twenty-three strains were selected for further studies. Sequencing of the 16S rRNA gene showed that most isolates belong to genera of hydrocarbonoclastic bacteria (Alcanivorax), generalist hydrocarbons degraders (Marinobacter, Pseudomonas, Gordonia, Halomonas, Erythrobacter and Brevibacterium) and other bacteria not known as hydrocarbon degraders (Xanthomarina) but were able to degrade hydrocarbons. Strains related to Marinobacter and Alcanivorax were frequently isolated from our samples and resulted the most effective in degrading crude oil. Screening of catabolic genes alkB and xylA revealed the presence of alkB gene in several bacterial strains; one isolate harboured both catabolic genes while other isolates carried none of the studied genes. However, they grew in the presence of crude oil implying the existence of other biodegradation pathways. Conclusions The samples of seawater and sediment from the Algerian coast contain high level of hydrocarbon-degrading bacteria that could be interesting and useful for future bioremediation purposes. Significance and impact of the study This investigation demonstrates the diversity of hydrocarbon-degrading bacteria from a marine-contaminated area in Algeria, and their variable biodegradation abilities.

Bioremediation offers a viable alternative for the reduction of contaminants from the environment, particularly petroleum and its recalcitrant derivatives. In this study, the ability of a strain of Pseudomonas BUN14 to degrade crude oil, pristane and dioxin compounds, and to produce biosurfactants, was investigated. BUN14 is a halotolerant strain isolated from polluted sediment recovered from the refinery harbor on the Bizerte coast, north Tunisia and capable of producing surfactants. The strain BUN14 was assembled into 22 contigs of 4,898,053 bp with a mean GC content of 62.4%. Whole genome phylogeny and comparative genome analyses showed that strain BUN14 could be affiliated with two validly described Pseudomonas Type Strains, P. kunmingensis DSM 25974T and P. chloritidismutans AW-1T. The current study, however, revealed that the two Type Strains are probably conspecific and, given the priority of the latter, we proposed that P. kunmingensis DSM 25974 is a heteronym of P. chloritidismutans AW-1T. Using GC-FID analysis, we determined that BUN14 was able to use a range of hydrocarbons (crude oil, pristane, dibenzofuran, dibenzothiophene, naphthalene) as a sole carbon source. Genome analysis of BUN14 revealed the presence of a large repertoire of proteins (154) related to xenobiotic biodegradation and metabolism. Thus, 44 proteins were linked to the pathways for complete degradation of benzoate and naphthalene. The annotation of conserved functional domains led to the detection of putative genes encoding enzymes of the rhamnolipid biosynthesis pathway. Overall, the polyvalent hydrocarbon degradation capacity of BUN14 makes it a promising candidate for application in the bioremediation of polluted saline environments.

In Antarctic regions, the composition and metabolic activity of microbial assemblages associated with plastic debris (“plastisphere”) are almost unknown. A macroplastic item from land (MaL, 30 cm) and a mesoplastic from the sea (MeS, 4 mm) were collected in Maxwell Bay (King George Island, South Shetland) and analyzed by Fourier transform infrared spectroscopy in attenuated total reflectance geometry (FTIR-ATR), which confirmed a polystyrene foam and a composite high-density polyethylene composition for MaL and MeS, respectively. The structure and function of the two plastic-associated prokaryotic communities were studied by complementary 16S ribosomal RNA gene clone libraries, total bacterioplankton and culturable heterotrophic bacterial counts, enzymatic activities of the whole community and enzymatic profiles of bacterial isolates. Results showed that Gamma- and Betaproteobacteria (31% and 28%, respectively) dominated in MeS, while Beta- and Alphaproteobacteria (21% and 13%, respectively) in MaL. Sequences related to oil degrading bacteria (Alcanivorax,Marinobacter) confirmed the known anthropogenic pressure in King George Island. This investigation on plastic-associated prokaryotic structure and function represents the first attempt to characterize the ecological role of plastisphere in this Antarctic region and provides the necessary background for future research on the significance of polymer type, surface characteristics and environmental conditions in shaping the plastisphere.

Petrochemical industries and oil refineries are sources of hazardous chemicals into the aquatic environments, and often a leading cause of reduced oxygen availability, thus resulting in adverse effects in biota. This study is an expansion of our previous work on the assessment of the BioFilm-Membrane Bioreactor (BF-MBR) to mitigate the impact of oil-polluted wastewater on marine environments. Specifically, this study evaluated the reduction of selected chemical constituents (hydrocarbons and trace metals) and toxicity related to hypoxia and DNA damage to mussels Mytilus galloprovincialis, before and after treatment of oil-polluted wastewater with the BF-MBR. The application of a multidisciplinary approach provided evidence of the efficiency of BF-MBR to significantly reducing the pollutants load from oily contaminated seawaters. As result, the health status of mussels was preserved by a hypoxic condition due to oily pollutants, as evidenced by the modulation in the gene expression of HIF-1α and PHD and changes in the level of hypotaurine and taurine. Moreover, ameliorative effects in the energy metabolism were also found in mussel gills showing increased levels of glycogen, glucose and ATP, as well as a mitigated genotoxicity was revealed by the Micronucleus and Comet assays. Overall, findings from this study support the use of the BF-MBR as a promising treatment biotechnology to avoid or limiting the compromise of marine environments from oil pollution.

Plastic debris has been identified as a potential threat to Antarctic marine ecosystems, however, the impact of nanoplastics (

The peculiar biotechnological applications of Oleispira spp. in the natural cleansing of oil-polluted marine systems stimulated the study of the phenotypic characteristics of the Oleispira antarctica RB-8(T) strain and modifications of these characteristics in relation to different growth conditions. Bacterial abundance, cell size and morphology variations (by image analysis) and hydrocarbon degradation (by gas chromatography with flame ionization detection, GC-FID) were analysed in different cultures of O. antarctica RB-8(T). The effects of six different hydrocarbon mixtures (diesel, engine oil, naval oil waste, bilge water, jet fuel and oil) used as a single carbon source combined with two different growth temperatures (4° and 15 °C) were analysed (for 22 days). The data obtained showed that the mean cell volume decreased with increasing experimental temperature. Three morphological bacterial shapes were identified: spirals, rods and cocci. Morphological transition from spiral to rod and coccoid shapes in relation to the different substrates (oil mixtures) and/or growth temperatures was observed, except for one experimental condition (naval oil waste) in which spiral bacteria were mostly dominant. Phenotypic traits and physiological status of hydrocarbon-degrading bacteria showed important modifications in relation to culture conditions. These findings suggest interesting potential for strain RB-8(T) for ecological and applicative purposes.

The large volumes of oily wastewater discharged to marine environment cause heavy impacts on the coastal marine ecosystem. The selection of an appropriate technology to reduce these impacts should be based on the respect of the discharge limits and on the effective assessment and monitoring of its effects on biological organism preservation. To this aim, we set up a controlled microcosm-scale system to compare the effects of a treated and untreated oily wastewater discharge in which the restore process is performed through a Membrane Bio-Reactor. The system is completed by other three microcosms to control and isolate any possible concurrent effect on the Mytilus galloprovincialis, used as sentinel organism. Mytilus galloprovincialis have been kept in all these microcosms, and then mRNA expression and morphology were evaluated on gills and digestive gland. The genes considered in this work are Heat Shock Protein 70 and Metallothionein 10, involved in response to physicochemical sublethal stressors, Superoxide dismutase 1, Catalase, and Cytochrome P450 involved in oxidative stress response. Our results evidenced a significant overexpression, both in gills and digestive gland, of HSP70 in samples maintained in the microcosm receiving the untreated effluent, and of MT10 in those animals kept in microcosm where the effluent was treated. Even though the mRNA modifications are considered "primary" and transient responses which do not always correspond to protein content, the study of these modifications can help to gain insights into the mechanisms of action of xenobiotic exposure. Morphological analysis suggested that, although different, depending on the microcosm, the most serious damages were found in the gill epithelium accompanied with severe haemocyte infiltration, whilst in digestive gland the tissue architecture alterations and the haemocyte infiltration were less pronounced. These observations suggest that the immune system was activated as a general response to stressful stimuli such as the presence of toxic compounds. Moreover, the results indicate that the treatment process is useful. In fact, samples derived from the microcosm receiving the treated effluent, even though presenting some signs of stress, seemed to partially recover the normal structure, although their mRNA expression indicated some cellular suffering.

Bioremediation, that uses microorganisms to remove environmental pollutants, is the best way of restoring the environment due to its low cost and sustainability. Immobilization of microorganisms capable of degrading specific contaminants significantly promotes bioremediation processes. An innovative ready to use bioremediation system to clean up oil-contaminated water was developed immobilizing highly performant marine and soil HC degrading bacteria, on biodegradable oil-absorbing carriers. Two soil Actinobacteria (Gordonia sp. SoCg, Nocardia sp. SoB) and two marine Gammaproteobacteria (Alcanivorax sp. SK2, Oleibacter sp.5), were immobilized on biopolymeric membranes prepared by electrospinning (polylactic acid, PLA and polycaprolactone, PCL). These carriers are characterized by high uptake capacity, oil retention, buoyancy, durability, reusability and recoverability of the oil absorbed. The morphology of the carriers and microbial adhesion and proliferation were evaluated using scanning electron microscopy (SEM). A high capacity of adhesion and proliferation of bacterial cells was observed on membranes after 5 days. The bioremediation efficiency of the carrier-bacteria systems was tested on crude oil by GC-FID analysis and compared whit planktonic cells. The bacterial immobilization on PLA and PCL membranes was a promoting factor for biodegradation, increasing hydrocarbon removal up to 20%, in respect to planktonic cells. Biofilm-mediated bioremediation is a versatile tool to be developed for in situ and ex situ bioremediation of aquatic systems. Several applications can be designed to exploit both the high oil uptake capacity of the carriers, and the biodegradation potential of autochtonous microrganisms and/or of selected microorganisms that are immobilized on the carriers before exposure to the contaminated site.

A novel floatable and biodegradable sponge for the selective absorption of oil from water and potentially useful as cell carrier for bioremediation treatments was prepared in polycaprolactone (PCL). The eco-friendly process for fabricating the PCL sponge does not involve either synthetic routes or organic solvents, thus minimizing environmental hazard. In particular, the 3D porous materials have been prepared by mixing in the melt the polymer matrix with two water-soluble porogen agents (NaCl and PEG) and thereafter leaching the obtained PCL/NaCl/PEG composites in water. The PCL sponges here proposed are capable to remove different types of oily pollutants (up to 500 wt%), and were successfully tested as carrier materials of hydrocarbon(HC)-degrading bacteria for bioremediation. The bioremediation efficiency of the scaffold-bacteria system was analyzed on crude oil and n -alkanes using two highly performant HC-degrading bacterial strains: the marine hydrocarbonoclastic model strain Alcanivorax borkumensis SK2 and the soil long-chain n -alkane degrader Nocardia sp. SoB. Morphological analysis highlighted a high capacity of adhesion and proliferation of bacterial cells within the whole interconnected three-dimensional structure. HC degradation rates, evaluated by GC-FID analysis, demonstrated the higher degrading performance of immobilized-cells if compared with conventional submerged liquid culture.

The availability of dissolved inorganic mercury (DHg) in sediment pore water is a crucial step for the mechanisms of methylmercury (MeHg) generation in the aquatic system. The geochemical form of Hg in sediments and the redox-controlled microbial reactions taking place during early diagenesis regulate the pool of DHg and, consequently, the bioavailability of Hg for methylation. Here, we report new evidence on the biogeochemical mechanisms controlling the pool of DHg in sediment pore water from two box-cores collected from Augusta Bay (Sicily), a marine coastal zone heavily contaminated by chlor-alkali discharges. The content of the total Hg (THg) in the studied sediments (4.13 ÷ 22.2 mg Kg − 1 ) is largely present as an “immobile” phase, while the labile fractions account for minor percentages ( − 1 ) mainly in the deeper levels of the investigated sedimentary column. Specifically, most of the THg appears to be partially mobilized in the “Fe-Mn reduction” zone, as clearly suggested by significant correlations between DHg and dissolved Fe-Mn concentrations in the pore water. The irregular vertical distribution of SO 4 2 − , with evident enrichment in the Fe-Mn reduction zone, could also indicate mechanisms of sulphate generation by sulphide oxidation. Specific microbial populations identified in the sediments appear dominated by chemolithoautotrophic sulphur oxidizing bacteria (SOB, genera Sulfurovum and Thioalkalispira ) which could drive the microbial oxidation of sulphides and support, with effects of Mn-Fe oxide reduction, processes of Hg mobilization.

Immobilization of microorganisms capable of degrading specific contaminants significantly promotes bioremediation processes. In this study, innovative and ecofriendly biosorbent-biodegrading biofilms have been developed in order to remediate oil-contaminated water. This was achieved by immobilizing hydrocarbon-degrading gammaproteobacteria and actinobacteria on biodegradable oil-adsorbing carriers, based on polylactic acid and polycaprolactone electrospun membranes. High capacities for adhesion and proliferation of bacterial cells were observed by scanning electron microscopy. The bioremediation efficiency of the systems, tested on crude oil and quantified by gas chromatography, showed that immobilization increased hydrocarbon biodegradation by up to 23 % compared with free living bacteria. The resulting biosorbent biodegrading biofilms simultaneously adsorbed 100 % of spilled oil and biodegraded more than 66 % over 10 days, with limited environmental dispersion of cells. Biofilm-mediated bioremediation, using eco-friendly supports, is a low-cost, low-impact, versatile tool for bioremediation of aquatic systems.

The retrieval of a polystyrene macro-plastic piece stranded on the shores in King George Island (South Shetlands, Antarctica) gave the opportunity to explore the associated bacterial flora. A total of 27 bacterial isolates were identified by molecular 16s rRNA gene sequencing and 7 strains were selected and screened for their ability to produce biofilm and antibiotic susceptibility profiles. All the bacterial isolates were able to produce biofilm. The Kirby-Bauer disk diffusion susceptibility test to 34 antibiotics showed multiple antibiotic resistances against the molecules cefuroxime and cefazolin (belonging to cephalosporins), cinoxacin (belonging to quinolones) and ampicillin, amoxicillin + clavulanic acid, carbenicillin and mezlocillin (belonging to beta-lactams). The obtained results suggest that plastics can serve as vectors for the spread of multiple resistances to antibiotics across Antarctic marine environments and underline the relevance of future studies on this topic.

The work was addressed to study the sensitivity of the enzyme carbonic anhydrase (CA) to chemical pollution in the hepatopancreas of the bioindicator organism Mytilus galloprovincialis in the context of a multimarker approach in view of ecotoxicological biomonitoring and assessment application. The study was carried out by means of a transplanting experiment in the field, using caged organisms from an initial population exposed in the field in two areas of interest: Augusta-Melilli-Priolo, an heavy polluted industrial site (eastern Sicily, Italy), and Brucoli (eastern Sicily, Italy) an area not affected by any contamination and selected as a reference site. Mussels in Augusta presented a significant increase in the digestive gland CA activity and gene expression compared to the animals caged in the control site of Brucoli. The CA response in animals from the polluted site was paralleled by proliferation/increase in the size of lysosomes, as assessed by Lysosensor green charged cells, induction of metallothionein, up-regulation of hif-α (hypoxia-inducible factor), metabolic changes associated with protein metabolism, and changes in the condition factor. Biological responses data were integrated with information about sediment chemical analysis and metal residue concentration in animal soft tissues. In conclusion, obtained results highlighted the induction of CAs in the hepatopancreas of Mytilus galloprovincialis following to pollution exposure, and demonstrated its suitability to be integrated into a multimarker approach for the detection and characterization of the stress status induced by pollution exposure in this bioindicator organism.

The aims of this study were: (i) the characterization of the structure of the indigenous microbial community associated with the sediments under study; (ii) the isolation and characterization of microbial consortia able to degrade the aged hydrocarbons contaminating the sediments, and (iii) the assessment of related biodegradation capability of selected consortia. Samples of surface sediments were collected in Priolo Gargallo harbour (Sicily, Italy). The samples were analysed for physical, chemical (GC-FID analysis) and microbiological characteristics (qualitative (16S rDNA clone library) and quantitative (DAPI, CFU and MPN count) analysis). The sediment samples were used for the selection of two microbial consortia (indicated as PSO and PSM) with high biodegradation capacity for crude oil (~95%) and PAHs (~63%) respectively. Genetic analysis showed that Alcanivorax and Cycloclasticus were the dominant genera in both the PSO and PSM consortia. Oil-polluted environments naturally develop an elevated biorecovery potential. The presence of a highly specialized microbial flora (adapted to support the contamination) and their stimulation through favourable induced conditions provides a promising recovery strategy. The chance to identify and select indigenous bacteria and/or consortia with a high biodegradation capacity is fundamental for the development and optimization of bioaugmentation strategies especially for those concerning in situ applications.

This study aimed to develop a new assay based on the whole cell hybridization in order to monitor alkane hydroxylase genes (alkB system) of the marine bacterium Alcanivorax borkumensis SK2(T) commonly reported as the predominant microorganism responsible for the biodegradation of n-alkanes which are the major fraction of petroleum hydrocarbons. The assay based on the whole cell hybridization targeting alkB2 gene was successfully developed and calibrated on a pure culture of Alcanivorax borkumensis SK2(T) with a detection efficiency up to 80%. The approach was further successfully validated on hydrocarbon-contaminated seawater and provided cells abundance (6.74E+04alkB2-carryingcellsmL(-1)) higher of about one order of magnitude than those obtained by qPCR (4.96E+03alkB2genecopiesmL(-1)). This study highlights the validity of the assay for the detection at single cell level of key-functional genes involved in the biodegradation of n-alkanes.

A bacterial consortium composed by four metagenomic clones and Bacillus subtilis strain CBMAI 707, all derived from petroleum reservoirs, was entrapped in chitosan beads and evaluated regarding hydrocarbon degradation capability. Experiments were carried out in mesocosm scale (3000 L) with seawater artificially polluted with crude oil. At different time intervals, mesocosms were sampled and subjected to GC-FID and microbiological analyses, as total and heterotrophic culturable bacterial abundance (DAPI and CFU count), biological oxygen demand (BOD) and taxonomic diversity (massive sequencing of 16S rRNA genes). The results obtained showed that degradation of n-alkane hydrocarbons was similar between both treatments. However, aromatic compound degradation was more efficient in bioaugmentation treatment, with biodegradation percentages reaching up to 99% in 30 days. Community dynamics was different between treatments and the consortium used in the bioaugmentation treatment contributed to a significant increase in aromatic hydrocarbon degradation.

Many recent studies have focused their attention on the physiological stress experienced by marine organisms in measuring ecotoxicological responses. Here we suggest a new approach for investigating the effects of an anthropogenic pollutant on Life-History (LH) traits of marine organisms, to provide stakeholders and policy makers an effective tool to evaluate the best environmental recovery strategies and plans. A Dynamic Energy Budget (DEB), coupled with a biophysical model was used to predict the effects of a six-month oil spill on Mytilus galloprovincialis' LH traits and to test two potential recovery strategies in the central Mediterranean Sea. Oxygen consumption rates were used to check for increasing energetic maintenance costs [ṗM] respectively in oil-polluted system treatments (∼76.2%) and polluted systems with physical (nano-bubbles ∼32.6%) or chemical treatment (dispersant ∼18.4%). Our model outputs highlighted a higher growth reduction of intertidal compared to subtidal populations and contextually an effect on the reproductive output and on the maturation time of this latter. The models also enabled an estimation of the timing of the disturbance affecting both the intertidal and subtidal populations' growth and reproduction. Interestingly, results led to the identification of the chemical dispersant as being the best remediation technique in contexts of oil spill contamination.

Petroleum pollution has become a serious environmental problem, which can cause harmful damage to the environment and human health. Various physicochemical and biological treatments were developed for the cleanup of contaminated environments. However, bioremediation based on the metabolic capabilities of microorganisms is considered as the most basic and reliable way to eliminate contaminants, particularly petroleum and its recalcitrant compounds. It is more effective alternative comparing to classical remediation techniques.

Plastic pollution is an emerging threat with severe implications on animals' and environmental health. Nevertheless, interactions of plastic particles with both microbial structure and metabolism are a new research challenge that needs to be elucidated yet. To improve knowledge on the effects played by microplastics on free-living and fish gut-associated microbial community in aquatic environments, a 90 days-study was performed in three replicated mesocosms (control-CTRL, native polyvinyl chloride-MPV and weathered polyvinyl chloride-MPI), where sea bass specimens were hosted. In CTRL mesocosms, fish were fed with no-plastic-added food, while in MPV and MPI food was supplemented with native or exposed to polluted waters polyvinylchloride pellets, respectively. Particulate Organic Carbon (POC) and Nitrogen, total and culturable bacteria, extracellular enzymatic activities, and microbial community substrate utilization profiles were analyzed. POC values were lower in MPI than MPV and CRTL mesocosms. Microplastics did not affect severely bacterial metabolism, although enzymatic activities decreased and microbes utilized a lower number of carbon substrates in MPI than MPV and CTRL. No shifts in the bacterial community composition of fish gut microflora were observed by Denaturing Gradient Gel Electrophoresis fingerprinting analysis.

Oil spill microcosms experiments were carried out to evaluate the effect of bioemulsificant exopolysaccharide (EPS2003) on quick stimulation of hydrocarbonoclastic bacteria. Early hours of oil spill, were stimulated using an experimental seawater microcosm, supplemented with crude oil and EPS2003 (SW+OIL+EPS2003); this system was monitored for 2 days and compared to control microcosm (only oil-polluted seawater, SW+OIL). Determination of bacterial abundance, heterotrophic cultivable and hydrocarbon-degrading bacteria were carried out. Community composition of marine bacterioplankton was determined by 16S rRNA gene clone libraries. Data obtained indicated that bioemulsificant addition stimulated an increase of total bacterial abundance and, in particular, selection of bacteria related to Alcanivorax genus; confirming that EPS2003 could be used for the dispersion of oil slicks and could stimulate the selection of marine hydrocarbon degraders thus increasing bioremediation process.

Cycloclasticus sp. 78-ME isolated from petroleum deposits of the sunken tanker “Amoco Milford Haven” (Gulf of Genoa, Ligurian Sea, Italy) could effectively degrade polycyclic aromatic hydrocarbons of up to five condensed rings. The genome of 78-ME was sequenced and analysed to gain insights into its remarkable degrading capacities. It comprises two circular replicons, the 2,613,078 bp chromosome and the plasmid of 42,347 bp, with 41.84% and 53.28% of the G + C content respectively. A total of 2585 protein-coding genes were obtained, and three large operons with more than fifteen enzymes belonging to four different classes of ring-cleavage dioxygenases were found.

This work was designed to evaluate the biological effects of petrochemical contamination on marine mussels. Mytilus galloprovincialis, widely used as sentinel organisms in biomonitoring studies, were caged at the “Augusta-Melilli-Priolo” industrial site (eastern Sicily, Italy), chosen as one of the largest petrochemical areas in Europe, and Brucoli, chosen as reference site. Chemical analyses of sediments at the polluted site revealed high levels of PAHs and mercury, exceeding the national and international guideline limits. In mussels from the polluted site, severe morphological alterations were observed in gills, mainly involved in nutrient uptake and gas exchange. Changes in serotonergic and cholinergic systems, investigated through immunohistochemical, metabolomics and enzymatic approaches, were highlighted in gills, as well as onset of hypoxic adaptive responses with up-regulation of hypoxia-inducible factor transcript. Overall, the application of a multi-biomarker panel results effective in assessing the biological effects of petrochemical contamination on the health of aquatic organisms.

The Kongsfjorden Fjord, located in Svalbard Islands (Norway), is an important marine ecosystem widely investigated by the international scientific community. This area is considered the most representative than other open fjords in the Arctic and it is affected by the inflow of Atlantic waters as well as by glacier melt water runoff (Hop et al., 2002). Prokaryotic communities play a key role in relevant processes such as carbon fluxes, energy transfers and nutrient regeneration and can be viewed both as sentinels and amplifiers of global change. In this context, further research is needed to quantify the role of these microorganisms in the flux of organic matter in the Arctic marine food web. In this study the main principal chemical-physical parameters, bacterial abundance (DAPI, CFU and MPN count) and structure (16S rRNA clone libraries) and extracellular activity were analyzed at 3 sites in Ny-Ålesund harbour (Svalbard islands), 2 for seawater and 1 for sediment samplings. The metabolic function of the microbial community was studied through isolation of psychrophilic heterotrophic bacteria and measurements of potential enzymatic activity rates on organic polymers (leucine aminopeptidase_LAP, beta-glucosidase-GLU and alkaline phosphatase-AP) by fluorogenic substrates. Phylogenetic analysis of community structure reveals that Proteobacteria were the most abundant group. Many of analyzed sequences were affiliated to clones identified in cold areas, in ports, in biofilm covering, antifouling paint and in oil contaminated facility. These results highlight different signs of human settlement in sampling sites.

The real-time polymerase chain reaction (RT-PCR) was used to follow changes in the proportion of hydrocarbonoclastic bacteria in the marine microbial community in oil polluted mesocosms during bioremediation field trial. Assay for alk-B1 of Alcanivorax borkumensis and alk-BT of Thalassolituus oleivorans were validated and found to be both sensitive and reproducible. Quantification of alk-B1 from A. borkumensis SK2 in mesocosms show that in single bioaugmentation mesocosm (M1) this gene has high quantity in fifth day of sampling but in biostimulating mesocosm (M2) and consortium bioaugmentation mesocosm (M3) the high quantity of this gene was in tenth day of sampling. The comparison between expression of alk-BT and alk-B1 in M3 mesocosm show that alk-B1 copy number was more than alk-BT. The proportion of alk-B1 or alk-BT containing bacteria was positively correlated to the concentration of crude oil in the mesocosms. After the concentration of crude oil in the mesocosms decreased the gene copy number of alkane monooxygenase genes also decreased.

Bioaugmentation (amendment with selected bacterial strains) and/or biostimulation (nutrients addition and/or air supply) are relatively new fields in environmental microbiology for preventing pollution and cleanup contamination. In this study, the efficiency of application of bioaugmentation/biostimulation treatments, for recovery of crude oil-polluted seawater, was evaluated. Three different series of experiments were performed in a “Mesocosm Facility” (10.000 L). Natural seawater was artificially polluted with crude oil (1000 ppm) and was amended with inorganic nutrients (Mesocosm 1, M1), inorganic nutrient and an inoculum of Alcanivorax borkumensis SK2T (Mesocosm 2, M2) and inorganic nutrient and an inoculum of A. borkumensis SK2T and Thalassolituus oleivorans MIL-1T (Mesocosm 3, M3), respectively. During the experimental period (20 days) bacterial abundance (DAPI count), culturable heterotrophic bacteria (CFU count), MPN, microbial metabolic activity [Biochemical Oxygen Demand and enzymatic activity (leucine aminopeptidase LAP, β-glucosidase BG, alkaline phosphatase AP)] and quali-, quantitative analysis of the composition of total extracted and resolved hydrocarbons and their derivates (TERHCs) were carried out. The microbiological and physiological analysis of marine microbial community found during the three different biostimulation and bioaugmentation assays performed in mesocosms show that the load of crude oil increases total microbial abundance, inhibits the activity of some enzymes such as LAP while stimulates both AP and BG activities. The biodegradation results show that bioaugmentation with A. borkumensis SK2T alone is able to produce the highest percentage of degradation (95%) in comparison with the biostimulation treatment (80%) and bioaugmentation using an Alcanivorax-Thalassolituus bacterial consortium (70%). This result highlights the reduced biodegradation capability of the consortium used in this study, suggesting an unfavourable interaction between the two bacterial genera.

Environmental contamination with hydrocarbons though natural and anthropogenic activities is a serious threat to biodiversity and human health. Microbial bioremediation is considered as the effective means of treating such contamination. This study describes a biosurfactant producing bacterium capable of utilizing crude oil and various hydrocarbons as the sole carbon source. Strain BU33N was isolated from hydrocarbon polluted sediments from the Bizerte coast (northern Tunisia) and was identified as Alcaligenes aquatilis on the basis of 16S rRNA gene sequence analysis. When grown on crude oil and phenanthrene as sole carbon and energy sources, isolate BU33N was able to degrade ~86%, ~56% and 70% of TERHc, n-alkanes and phenanthrene, respectively. The draft genome sequence of the A. aquatilis strain BU33N was assembled into one scaffold of 3,838,299 bp (G+C content of 56.1%). Annotation of the BU33N genome resulted in 3,506 protein-coding genes and 56 rRNA genes. A large repertoire of genes related to the metabolism of aromatic compounds including genes encoding enzymes involved in the complete degradation of benzoate were identified. Also genes associated with resistance to heavy metals such as copper tolerance and cobalt-zinc-cadmium resistance were identified in BU33N. This work provides insight into the genomic basis of biodegradation capabilities and bioremediation/detoxification potential of A. aquatilis BU33N.

Biogenic catalysts have been studied over the last 10 years in freshwater and soil environments, but neither their formation nor their application has been explored in marine ecosystems. The objective of this study was to develop a biogenic nanopalladium-based remediation method for reducing chlorinated hydrocarbons from marine environments by employing indigenous marine bacteria. Thirty facultative aerobic marine strains were isolated from two contaminated sites, the Lagoon of Mar Chica, Morocco, and Priolo Gargallo Syracuse, Italy. Eight strains showed concurrent palladium precipitation and biohydrogen production. X-ray diffraction and thin section transmission electron microscopy analysis indicated the presence of metallic Pd nanoparticles of various sizes (5-20 nm) formed either in the cytoplasm, in the periplasmic space, or extracellularly. These biogenic catalysts were used to dechlorinate trichloroethylene in simulated marine environments. Complete dehalogenation of 20 mg L(-1) trichloroethylene was achieved within 1 h using 50 mg L(-1) biogenic nanopalladium. These biogenic nanoparticles are promising developments for future marine bioremediation applications.

Twenty-one oil-degrading bacteria were isolated from bilge water. Based on a high growth rate on crude oil and on hydrocarbon degradation ability, 7 strains were selected (from 21 isolated) for further studies. 16S rRNA gene sequencing showed that isolated strains were affiliated to Bacillus, Pseudomonas and Halomonas genera; in particular, isolate BW-B12 (Bacillus sp., 99%), BW-C12 (Halomonas boliviensis, 99%) and BW-E12 (Halomonas boliviensis, 98%) were the best crude-oil degraders; after 10 days of cultivation in ONR 7a mineral medium supplemented with crude oil as single carbon source BW-B12, BW-C12 and BW-E12 showed a degradation rate of 80, 60 and 59%, respectively. The strains showed also a high emulsification activity and biosurfactants production. Obtained results give an important contribution in order to utilize these bilge water autochthonous microorganisms in processes of bioremediation of marine environment chronically polluted from saline oily waste

A collection of forty-two (42) strains was obtained during microbiological screening of a Membrane Bioreactor (MBR) system developed for the treatment of saline oily waste originated from marine transportation. The diversity of the bacterial collection was analyzed by amplification and sequencing of the 16S rRNA gene. Taxonomic analysis showed high level of identity with recognized sequences of seven (7) distinct bacterial genera (Alcanivorax, Erythrobacter, Marinobacter, Microbacterium, Muricauda, Rhodococcus and Rheinheimera). The biotechnological potential of the isolates was screened considering an important factor such as the biosurfactant production. In particular fourteen (14) biosurfactant producing bacteria were selected and further tested, for growth on crude oil and hydrocarbon degradation. Data obtained from this study confirmed the high activity of bacteria related to genera Alcanivorax (isolates MBR-B11 and MBR-G10), Rheinheimera (isolates MBR-H02 and MBR-H05), Rhodococcus (isolates MBR-F04 and MBR-G05) and Muricauda (isolate MBR-G04) and underline the possible application of these bacteria in remediation of saline oily waste water. (C) 2016 Elsevier Ltd. All rights reserved.