► Crude-oil degrading bacteria were isolated from Persian Gulf and Caspian Sea. ► There is high diversity of crude-oil degrading bacteria in these two marine environments. ► Theses degradative ...bacteria are very useful for management of oil pollution in the sea.
Twenty-five crude-oil-degrading bacteria were isolated from oil-contaminated sites in the Persian Gulf and the Caspian Sea. Based on a high growth rate on crude oil and on hydrocarbon degradation ability, 11 strains were selected from the 25 isolated strains for further study. Determination of the nucleotide sequence of the 16S rRNA gene showed that these isolated strains belonged to genera Acinetobacter, Pseudomonas, Gordonia, Rhodococcus, Cobetia, Halomonas, Alcanivorax, Marinobacter and Microbacterium. Among the 11 isolates, strains BS (Acinetobacter calcoaceticus, 98%) and PG-12 (Alcanivorax dieselolei, 98%) were the most effective in degrading crude oil. Rate of crude-oil degradation of 82% (isolate BS) and 71% (isolate PG-12) were observed after 1week of cultivation in mineral medium. These strains had high emulsification activity and biosurfactant production. GC–MS analysis showed that A. dieselolei PG-12 can degrade different alkanes in crude oil. Screening of the distribution of the alkane hydroxylase gene in 25 isolates in relation to the source of isolation indicated that the group (II) alkane hydroxylase is prevalent in the Caspian Sea, but in the Persian Gulf, the frequency of the group (III) alkane hydroxylase gene is greater than that of the group (II) alkane hydroxylase gene.
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.
Pesticide usage is becoming increasingly necessary to escalate agricultural productivity and meet food production needs. However, it harms in different degrees all living organisms, plants, and ...animals, whether terrestrial or aquatic. Soil microorganisms, are microbes belonging to microorganisms, are the first to be specifically affected by pesticides. This study aims to evaluate the impact of two herbicides, paraquat and glyphosate, on symbiotic nitrogen-fixing bacteria. Our study was carried out in the greenhouse.
Bituminaria bituminosa
plants were inoculated with four different nitrogen-fixing bacteria,
Pantoea agglomerans, Rhizobium nepotum, Rhizobium radiobacter,
and
Rhizobium tibeticum
, and then treated with varying herbicide concentrations were selected according to the doses recommended by the National Office of Food Safety (ONSSA) and according to a survey conducted among farmers in the Meknes region-Morocco, (0.05, 0.1, 5.4, 10.8 g/L glyphosate and 0.05, 0.1, 2, 4 g/L paraquat). After 6 months after sowing, the following parameters were evaluated: nodule number, nodule mass, nodule weight, nodule dry, and fresh weight, nitrogen content, and symbiotic efficiency. At higher doses (5.4, 10.8 g/L for glyphosate and 2, 4 g/L for paraquat), both herbicides decreased the number and the size of nodules, the weight of nodules, nitrogen content of
Bituminaria bituminosa
and symbiotic efficiency of the four different nitrogen-fixing bacteria studied. The effect of herbicides increased as the used concentration increased. The current research demonstrates that the decreased growth of herbicide-treated plants was caused by herbicides' direct effects on rhizobia rather than herbicides' indirect effects on
Bituminaria bituminosa
.
Graphical Abstract
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 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 25974
and P. chloritidismutans AW-1
. 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-1
. 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 order to better understand the effects of biostimulation and bioaugmentation processes on a marine microbial community, three different mesocosm experiments were planned. Natural seawater（10.000 ...L） was artificially polluted with crude oil（1 L） and（1） inorganic nutrients（Biostimulating Mesocosm, BM）,（2） inorganic nutrients and an inoculum of Alcanivorax borkumensis SK2（Single Bioaugmentation Mesocosm, SBM）,（3） inorganic nutrients and inoculums of A. borkumensis SK2 and Thalassolituus oleivorans MIL-1（Consortium Bioaugmentation Mesocosm, CBM）. During the experimental period（20 days）, samples were taken from each mesocosm and the community structure was analyzed by PCR–DGGE. The 16 S r RNA gene DGGE banding patterns and sequence analysis demonstrated that biostimulation had the lowest effect on microbial biodiversity in the mesocosms; however, the biodiversity of the marine microbial community dramatically decreased in the CBM（Shannon index was 0.6 in T3）. The community structures among the three mesocosms were also markedly different,and major bacteria derived from DGGE bands were related to uncultured Gamma Proteobacteria. The biodegradation results show that the Single Bioaugmentation Mesocosm（SBM） system had the highest percentage of degradation（95%） in comparison to the BM mesocosm（80%） and CBM（70%）.
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.
This study combines a traditional chemical characterization with a simultaneous biological evaluation through histological, immunohistochemical, and enzymatic observations to assess the efficiency ...and sustainability of soil washing on Hg-contaminated sediment in terms of the bioavailability of the contaminant before and after the treatment, as well as the potential drawbacks of the treatment that are not revealed by a simple chemical characterization of treated sediments on its own. Different extracting agents, that is, ethylenedinitrilotetraacetic acid (EDTA), ethylenediaminedisuccinic acid (EDDS), sodium thiosulfate, potassium iodide (KI), and iodine (I2), have been compared in this work to evaluate their efficiency in the removal of Hg from contaminated sediments. Speciation analysis was applied to assess the mobility of Hg from different fractions of aged sediments. Biological evaluation was carried out through the use of large mesocosms and Mytilus galloprovincialis as biological sentinels. Results from bench scale tests have shown Hg removal of up to 93% by means of the multi-step KI/I2 washing process of the sediment. Results from histological, immunohistochemical, and enzymatic analysis have shown significant differences in the degree of alteration of biological tissues and their functional integrity between organisms in contact with contaminated and restored sediments. The reduction in 5-HT3R immunopositivity in the mesocosm with treated sediments suggests a tendency for mussels to recover a healthy condition. This result was also confirmed by the measurement of the enzymatic activity of AChE in mussel gills, which was significantly reduced in organisms from the mesocosm with polluted sediments compared with those from the one with restored sediments. The proposed approach could help stakeholders all over the world select, at an early stage, the most efficient cleaning action from a more holistic perspective, including not only pollutant concentration and economic reduction but also a direct assessment of the ultimate impact of the selected process on the biological system.
The need to ensure adequate antifouling protection of the hull in the naval sector led to the development of real painting cycles, which involve the spreading of three layers of polymeric material on ...the hull surface exposed to the marine environment, specifically defined as primer, tie coat and final topcoat. It is already well known that coatings based on suitable silanes provide an efficient and non-toxic approach for the hydrophobic and antifouling/fouling release treatment of surfaces. In the present work, functional hydrophobic hybrid silica-based coatings (topcoats) were developed by using sol-gel technology and deposited on surfaces with the “doctor blade” method. In particular, those organic silanes, featuring opportune functional groups such as long (either fluorinated) alkyl chains, have a notable influence on surface wettability as showed in this study. Furthermore, the hydrophobic behavior of this functionalized coating was improved by introducing an intermediate commercial tie-coat layer between the primer and the topcoat, in order to decrease the wettability (i.e., decreasing the surface energy with a matching increase in the contact angle, CA) and to therefore make such coatings ideal for the design and development of fouling release paints. The hereby synthesized coatings were characterized by optical microscopy, contact angle analysis and a mechanical pull-off test to measure the adhesive power of the coating against a metal substrate typically used in the nautical sector. Analysis to evaluate the bacterial adhesion and the formation of microbial biofilm were related in laboratory and simulation (microcosm) scales, and assessed by SEM analysis.
Within the Svalbard archipelago, Kongsfjorden is an important marine ecosystem that is recognised as one of the main representative Arctic glacial fjords. Prokaryotic organisms are key drivers of ...important ecological processes such as carbon fluxes, nutrient mineralisation, and energy transfer, as well as sentinels of environmental pollution, especially in sediments, that are a repository of contaminants. In some areas of the Arctic, the structure and metabolic activity of the microbial community in the organic matter turnover and globally in the functioning of the benthic domain are mostly still unknown. A snapshot of the main microbial parameters such as bacterial abundance (by microscopic and plate counts), structure (by 16S rRNA sequencing), and metabolic activity was provided in Ny-Ålesund harbour, contextually in seawater and sediment samples. Fluorogenic substrates were used to assess the microbial ability to utilise organic substrates such as proteins, polysaccharides, and organic phosphates through specific enzymatic assays (leucine aminopeptidase—LAP, beta-glucosidase—ß-GLU, and alkaline phosphatase—AP, respectively). The metabolic profiles of psychrophilic heterotrophic bacterial isolates were also screened using a qualitative assay. The phylogenetic analysis of the microbial community revealed that Proteobacteria prevailed among the observed taxonomic groups. Several of the observed sequences were assigned to clones found in harbours, microbial biofilms, antifouling paints, or oil-polluted facilities of cold environments, highlighting a signature of human pressure on the polar habitat of Ny-Ålesund harbour.
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