Polycyclic Aromatic Hydrocarbon-degrading Bacteria Research Articles

Responses of a polycyclic aromatic hydrocarbon-degrading bacterium, Paraburkholderia fungorum JT-M8, to Cd (II) under P-limited oligotrophic conditions

For the bioremediation of mixed-contamination sites, studies on polycyclic aromatic hydrocarbon (PAH) degradation or Cd (II) tolerance in bacteria are commonly implemented in nutrient-rich media. In contrast, in the field, inocula usually encounter harsh oligotrophic habitats. In this study, the environmental strain Paraburkholderia fungorum JT-M8 was used to explore the overlooked Cd (II) defense mechanism during PAH dissipation under P-limited oligotrophic condition. The results showed that the growth and PAH degradation ability of JT-M8 under Cd (II) stress were correlated with phosphate contents and exhibited self-regulating properties. Phosphates mainly affected the Cd (II) content in solution, while the cellular distribution of Cd (II) depended on Cd (II) levels; Cd (II) was mainly located in the cytoplasm when exposed to less Cd (II), and vice versa. The unique Cd (II) detoxification pathways could be classified into three aspects: (i) Cd (II) ionic equilibrium and dose–response effects regulated by environmental matrices (phosphate contents); (ii) bacterial physiological self-regulation, e.g., cell surface-binding, protein secretion and active transport systems; and (iii) specific adaptive responses (flagellum aggregation). This study emphasizes the importance of considering culture conditions when assessing the metal tolerance and provides new insight into the bacterial detoxification process of complex PAH-Cd (II) pollutants.

Nitrogen transfer and cross-feeding between Azotobacter chroococcum and Paracoccus aminovorans promotes pyrene degradation

Nitrogen is a limiting nutrient for degraders function in hydrocarbon-contaminated environments. Biological nitrogen fixation by diazotrophs is a natural solution for supplying bioavailable nitrogen. Here, we determined whether the diazotroph Azotobacter chroococcum HN can provide nitrogen to the polycyclic aromatic hydrocarbon-degrading bacterium Paracoccus aminovorans HPD-2 and further explored the synergistic interactions that facilitate pyrene degradation in nitrogen-deprived environments. We found that A. chroococcum HN and P. aminovorans HPD-2 grew and degraded pyrene more quickly in co-culture than in monoculture. Surface-enhanced Raman spectroscopy combined with 15N stable isotope probing (SERS − 15N SIP) demonstrated that A. chroococcum HN provided nitrogen to P. aminovorans HPD-2. Metabolite analysis and feeding experiments confirmed that cross-feeding occurred between A. chroococcum HN and P. aminovorans HPD-2 during pyrene degradation. Transcriptomic and metabolomic analyses further revealed that co-culture significantly upregulated key pathways such as nitrogen fixation, aromatic compound degradation, protein export, and the TCA cycle in A. chroococcum HN and quorum sensing, aromatic compound degradation and ABC transporters in P. aminovorans HPD-2. Phenotypic and fluorescence in situ hybridization (FISH) assays demonstrated that A. chroococcum HN produced large amounts of biofilm and was located at the bottom of the biofilm in co-culture, whereas P. aminovorans HPD-2 attached to the surface layer and formed a bridge-like structure with A. chroococcum HN. This study demonstrates that distinct syntrophic interactions occur between A. chroococcum HN and P. aminovorans HPD-2 and provides support for their combined use in organic pollutant degradation in nitrogen-deprived environments.

Polycyclic Aromatic Hydrocarbon-Degrading Bacteria in Three Different Functional Zones of the Cities of Moscow and Murmansk.

We performed a comparative study of the total bacterial communities and communities of cultivable polycyclic aromatic hydrocarbons (PAH)-degrading bacteria in different functional zones of Moscow and Murmansk that were formed under the influence of the PAH composition in road and leaf dust. The PAHs were determined by high-performance liquid chromatography (HPLC); the bacterial communities’ diversity was assessed by metabarcoding. The degraders were isolated by their direct plating on a medium with the PAHs. The PAH total quantity declined in the leaf dust from the traffic to the recreational zone. For the road dust, a negative gradient with pollution was observed for Rhodococcus and Acinetobacter degraders and for their relative abundance in the microbiome for the functional zones of Moscow. The opposite effect was observed in the Murmansk leaf dust for the Rothia and Pseudomonas degraders and in the Moscow road dust for Microbacterium. The PCA and linear regression analyses showed that the Micrococcus degraders in the dust were sensitive to anthropogenic pollution, so they can be used as a tool for monitoring anthropogenic changes in the biosphere. The data on the degraders’ and microbial communities’ diversity suggest that minor degrading strains can play a key role in PAH degradation.

A highly effective polycyclic aromatic hydrocarbon-degrading bacterium, Paracoccus sp. HPD-2, shows opposite remediation potential in two soil types

Bioaugmentation is an efficient and eco-friendly strategy for the bioremediation of polycyclic aromatic hydrocarbons (PAHs). Since the degrading abilities of soils can greatly alter the abilities of PAH-degrading bacteria, illustrating the potential and mechanism of highly efficient degrading bacteria in different soil environments is of great importance for bioremediation. A PAH-degrading bacterium, Paracoccus aminovorans HPD-2, and two soil types, red and paddy soils, with distinct PAH-degrading abilities, were selected for this study. A soil microcosm experiment was performed by adding pyrene (PYR) and benzo[a]pyrene (B[a]P). Illumina sequencing was used to examine bacterial community structure. The results showed that inoculation with HPD-2 significantly elevated PYR and B[a]P degradation rates by 44.7% and 30.7%, respectively, in the red soil, while it only improved the degradation rates by 1.9% and 11%, respectively, in the paddy soil. To investigate the underlying mechanism, the fate of strain HPD-2 and the response of the indigenous bacterial communities were determined. Strain HPD-2 occupied certain niches in both soils, and the addition of the bacterium changed the native community structure more noticeably in the red soil than in the paddy soil. The addition of PAHs and strain HPD-2 significantly changed the abundances of 7 phyla among the 15 detected phyla in the red soil. In the paddy soil, 5 of the 12 dominant phyla were significantly affected by PAHs and the inoculation of HPD-2, while 6 new phyla were detected in the low-abundance phyla (< 0.1%). The abundances of Massilia, Burkholderia , and Rhodococcus genera with PAH degradation efficiency were significantly increased by the inoculation of HPD-2 in the red soil during 42 d of incubation. Meanwhile, in the paddy soil, the most dominant effective genus, Massilia , was reduced by HPD-2 inoculation. This research revealed the remediation ability and inherent mechanism of the highly effective PAH-degrading strain HPD-2 in two different soil types, which would provide a theoretical basis for the application of degrading bacteria in different soils.

Functionalization of the model asphaltene 1-dodecylnaphthalene by Pseudomonas aeruginosa KK6 through subterminal metabolism

Asphaltenic compounds in heavy oils may be biologically functionalized in the contexts of oil upgrading and in mitigating contamination however there are knowledge gaps in regard to the mechanisms of asphaltene functionalization by microorganisms. Due to the challenges of studying asphaltene functionalization, model asphaltene compounds comprised of polyaromatic centers and long alkyl chains may be utilized. In this work, a soil bacterium identified as Pseudomonas aeruginosa KK6 was characterized and it was found to extensively biotransform the water insoluble polycyclic n-alkylaromatic model asphaltene, 1-dodecylnaphthalene (1-DDN). Gas chromatography was utilized to quantify 1-DDN transformation and liquid chromatography with UV detection coupled to electrospray ionization tandem mass spectrometry (LC-UV/ESI-MS/MS) was used to analyze transformation products. An unusual transformation product profile occurred that showed that varying alkyl chain length compounds that differed by one methylene unit each were detected attached to their polycyclic aromatic chromophores. CID product ion scan analyses revealed that 1-DDN was transformed into oxidized, alkyl chain-shortened, reduced molecular weight 1-naphthyl-alkanoic acids and 1-naphthyl-alkanals and results interpretation supported that these compounds were produced through subterminal oxidation mechanisms by strain KK6. Based upon the results, biotransformation pathways that described the biological functionalization of a model asphaltene compound were constructed. On its own or in conjunction with polycyclic aromatic hydrocarbon-degrading bacteria, this strain may be applied to upgrading heavy oil.

Co-treatment of an oily sludge and aged contaminated soil: permanganate oxidation followed by bioremediation

The bioremediation of an oily sludge (321 ± 30 mg of polycyclic aromatic hydrocarbons/kgDRY SLUDGE and 13420 ± 1300 mg of aliphatic hydrocarbons/kgDRY SLUDGE) by mixture with contaminated soil (23 ± 2 mg of polycyclic aromatic hydrocarbons/kgDRY SOIL and 98 ± 10 mg of aliphatic hydrocarbons/kgDRY SOIL) was studied. Furthermore, the effect of oxidative pretreatments (persulfate and permanganate) on the performance of the global process was examined.The treatments reached contamination levels lower than the original residues, indicating the presence of synergic processes between a highly contaminated sludge and soil with a selected hydrocarbon-degrading community.Pretreatment with permanganate significantly improved biodegradation, possibly due to the increase in bioavailability and biodegradability of petroleum hydrocarbons. Two months of incubation was enough to reach the complete elimination of polycyclic aromatic hydrocarbons and 92% elimination of aliphatic hydrocarbons. Monitoring using five parameters (concentration of total petroleum hydrocarbons, total cultivable heterotrophic bacteria count, lipase and dehydrogenase activities, and polycyclic aromatic hydrocarbon-degrading bacteria count) as an approach for a preliminary scanning of the effectiveness of a treatment is proposed based on principal components analysis.

The Degradation of Phenanthrene, Pyrene, and Fluoranthene and Its Conversion into Medium-Chain-Length Polyhydroxyalkanoate by Novel Polycyclic Aromatic Hydrocarbon-Degrading Bacteria.

Screening of high-efficient polycyclic aromatic hydrocarbon (PAH)-degrading bacteria is important due to environmental contamination by PAHs. In this study, sediment contaminated with phenanthrene (Phe), pyrene (Pyr), and fluoranthene (Fluo) was used as a source of bacteria. The ability of these isolated bacteria to convert PAHs into valuable products was determined. Based on a primary screening, 20 bacterial isolates were obtained; however, only three strains showed a good PAH-degrading ability, and were identified as Pseudomonas aeruginosa, Pseudomonas sp., and Ralstonia sp. PAH-degrading genes were detected in all isolates. Notably, all selected strains could degrade PAHs using the ortho or meta cleavage pathways due to the presence of catechol dioxygenase genes. The ability of isolated strains to convert PAHs into polyhydroxyalkanoate (PHA) was also evaluated in both single and mixed cultures. Single cultures of P. aeruginosa PAH-P02 showed 100% degradation of PAHs, with the highest biomass (1.27 ± 0.02gl-1) and PHA content (38.20 ± 1.92% dry cell weight). However, degradative ability and PHA production were decreased when mixtures of PAHs were used. This study showed that P. aeruginosa, Pseudomonas sp., and Ralstonia sp. were able to degrade PAHs and convert them into medium-chain-length (mcl)-PHA. A high content of 3-hydroxydecanoate (3HD, C10) was observed in this study. The formation of mcl-PHA with high 3HD content from Pyr and Fluo, and the assessment of mixed cultures converting PAHs to mcl-PHA, were novel contributions.

Isolasi Bakteri Pendegradasi Minyak Mentah dan Polisiklik Aromatik Hidrokarbon dari Sedimen Mangrove Bintan

&lt;strong&gt;Isolation of Crude Oil and Polycyclic Aromatic Hydrocarbon-Degrading Bacteria from Mangrove Sediments in Bintan.&lt;/strong&gt; Bintan is known for its extensive mangrove areas, but it is prone to pollution from oil spills due to it is close to the international shipping lane. Indigenous bacteria plays important roles in bioremediation of oil spills in the natural environment. This research aims to explore indigenous bacteria from Bintan’s mangrove sediments which may have ability to degrade crude oil and polycyclic aromatic hydrocarbon (PAH). The mangrove sediment samples were taken in March 2018 from the sediments near four different mangrove plant species, i.e. &lt;em&gt;Rhizophora apiculata, Xylocarpus granatum, Ceriops tagal &lt;/em&gt;and &lt;em&gt;Lumnitzera littorea&lt;/em&gt;. Isolation of oil degrading bacteria was carried out using enrichment media supplemented with crude oil ALCO. A total of 45 strains of oil degrading bacteria were successfully isolated from the sediment samples. By using sublimation method, 13 bacterial isolates showed the ability to degrade various PAHs, including phenanthrene, acenaphthene, dibenzothiophene and fluorene. Sequencing analysis of 16s rRNA genes confirmed that the 13 isolated bacteria belong to the genera &lt;em&gt;Rhodococcus, Bacillus&lt;/em&gt;, &lt;em&gt;Sphingopyxis&lt;/em&gt;, &lt;em&gt;Rhizobium&lt;/em&gt;, &lt;em&gt;Mycobacterium&lt;/em&gt;, and &lt;em&gt;Gordonia&lt;/em&gt;

Taxonomy and Characterization of Biofilm Forming Polycyclic Aromatic Hydrocarbon Degrading Bacteria from Marine Environments

Marine environment is a dynamic habitat for survival of many microbes with unique metabolic potential. Biofilm formation benefits the marine bacteria to thrive and persist even in hostile environments. Besides, biofilm formation ability of bacteria enhances the efficiency of bioremediation of organic pollutants. In the present study, biofilm forming and polycyclic aromatic hydrocarbon (phenanthrene and pyrene) degrading bacteria were isolated and taxonomic identification was carried out by 16S rRNA gene sequencing. The isolates were able to grow on multiple aromatic hydrocarbons such as toluene, biphenyl, anthracene and naphthalene. The potential isolates were characterized by 16S rRNA gene sequencing. The isolates were identified and belong to the genera Pseudomonas, Stenotrophomonas, Paenibacillus, Alcaligenes, Sporosarcina and Lysinibacillus. Proteobacteria were found to be leading bacterial group at the pollutant sites. 75% of the isolates screened were able to establish biofilm and grow on either of aromatic hydrocarbon. This study shows the dominance of biofilm forming bacteria with ability to grow on multiple organic compounds in the marine environment.

Colonization of polycyclic aromatic hydrocarbon-degrading bacteria on roots reduces the risk of PAH contamination in vegetables

This is a primary investigation on the mitigation of polycyclic aromatic hydrocarbon (phenanthrene as a model PAH) contamination in vegetables including water spinach (Ipomoea aquatica Forsk), pakchoi (Brassica campestris) and Chinese cabbage (Brassica chinensis) using a gfp-labeled PAH-degrading bacterium (RS1-gfp). Effective root colonization led to dense RS1-gfp populations inhabiting the rhizosphere and endosphere of the vegetables, which subsequently led to a reduction in phenanthrene accumulation and risk in vegetables. When compared with the controls without RS1-gfp, the amount of phenanthrene accumulation due to strain RS1-gfp colonization reduced by up to ~93.7% in roots and ~75.2% in shoots of vegetables, respectively. The estimated incremental lifetime cancer risk (ILCR) for adults due to phenanthrene in vegetables was reduced by 24.6%–48% through RS1-gfp inoculation. The proposed method was developed to circumvent the risk of phenanthrene contamination in vegetables by inoculating PAH-degrading bacteria. The findings provide an in-depth understanding of PAH detoxification in agricultural plants grown on contaminated sites by exploiting bacteria like RS1-gfp, which portray both rhizo- and endophytic lifestyles.

Comments on “Influence of thermally modified palygorskite on the viability of polycyclic aromatic hydrocarbon-degrading bacteria” by B. Biswas, B. Sarkar, and R. Naidy Applied Clay Science 134 (2016) 153–160, DOI 10.1016/j.clay.2016.07.003

Comments on “Influence of thermally modified palygorskite on the viability of polycyclic aromatic hydrocarbon-degrading bacteria” by B. Biswas, B. Sarkar, and R. Naidy Applied Clay Science 134 (2016) 153–160, DOI 10.1016/j.clay.2016.07.003

Isolation and characterization of polycyclic aromatic hydrocarbon-degrading bacteria with tolerance to hypoxic environments

ABSTRACTHypoxic conditions are considerably different from aerobic and anaerobic conditions, and they are widely distributed in natural environments. Many pollutants, including polycyclic aromatic hydrocarbons (PAHs), tend to accumulate in hypoxic environments. However, PAH biodegradation under hypoxic conditions is poorly understood compared with that under obligate aerobic and obligate anaerobic conditions. In the present study, PAH-degrading bacteria were enriched, and their biodegradation rates were tested using a hypoxic station with an 8% oxygen concentration. PAH-degrading bacteria collected from sediments in low-oxygen environments were enriched using phenanthrene (Phe) or pyrene (Pyr) as the sole carbon and energy source. Individual bacterial colonies showing the ability to degrade Phe or Pyr were isolated and identified by 16S rDNA gene sequencing. Morphological and physiological characterizations of the isolated bacterial colonies were performed. The isolated bacteria were observed by scanning electron microscopy (SEM) and were identified as Pseudomonas sp., Klebsiella sp., Bacillus sp., and Comamonas sp. Phylogenetic tree of the isolated PAH-degrading bacteria was also constructed. The biodegradation ability of these bacteria was tested at an initial Phe or Pyr concentration of 50 mg L−1. The biodegradation kinetics were best fit by a first-order rate model and presented regression coefficients (r2) that varied from 0.7728 to 0.9725 (P < 0.05). The half-lives of the PAHs varied from 2.99 to 3.65 d for Phe and increased to 60.3–82.5 d for Pyr. These half-lives were much shorter than those observed under anaerobic conditions but were similar to those observed under aerobic conditions.

Microbial Transformation of Multiwalled Carbon Nanotubes by Mycobacterium vanbaalenii PYR-1.

Carbonaceous nanomaterials are widely used in industry and consumer products, but concerns have been raised regarding their release into the environment and subsequent impacts on ecosystems and human health. Although many efforts have been devoted to understanding the environmental fate of carbonaceous nanomaterials, information about their microbial transformation is still rare. In this study, we found that within 1 month a polycyclic aromatic hydrocarbon-degrading bacterium, Mycobacterium vanbaalenii PYR-1, was able to degrade both pristine and carboxyl-functionalized multiwalled carbon nanotubes (p-MWCNT and c-MWCNT), as demonstrated by consistent results from high resolution transmission electron microscopy, Raman spectroscopy, and confocal Raman microspectroscopy. Statistical analysis of Raman spectra identified a significant increase in the density of disordered or amorphous carbon in p-MWCNT and c-MWCNT after biodegradation. Microbial respiration further suggested potential mineralization of MWCNTs within about 1 month. All of our analyses consistently showed higher degradation or mineralization of c-MWCNT compared to p-MWCNT. These results highlight the potential of using bacteria in engineered systems to remove residual carbonaceous nanomaterials and reduce risk of human exposure and environmental impact. Meanwhile, our finding suggests possible transformation of carbonaceous nanomaterials by polycyclic aromatic hydrocarbon-degrading bacteria in the natural environment, which should be accounted for in predicting the environmental fate of these emerging contaminants and in nanotechnology risk regulation.

Detection and Quantification of Sulfate-Reducing and Polycyclic Aromatic Hydrocarbon-Degrading Bacteria in Oilfield Using Functional Markers and Quantitative PCR

Oilfield water samples from injection water treatment facility and soil/sludge samples from Gas Oil Separation Plant (GOSP) at Saudi Aramco were analyzed for the presence of SRB and PAH-degrading bacteria. SRB were detected by targeting a fragment of the apsA gene encoding adenosine-5-phosphosulfate reductase, which is characteristic of all SRB. The PAH-degrading bacteria were detected using a primer pair that amplifies a fragment of the gene encoding the large subunit of the naphthalene dioxygenase gene nahA. The nahA gene was detected in almost half of the soil/sludge samples with the highest copy number of 60540 copies/g soil/sludge. Most of the analyzed water samples contained high copy numbers of nahA gene with the highest copy number 3846 copies/ml. Most of the analyzed water samples revealed the presence of high copy numbers of the apsA gene with the highest copy number of 44 x 106/ml in sample number 2. Only 7 of the soil/sludge samples revealed the presence of the apsA gene with the highest copy number of 107920/g soil/sludge in sample number 11. In contrast to the nahA gene, the highest copy numbers of the apsA gene were detected in the water samples. SRB and PAH-degrading bacteria exist in some Saudi oilfields and appear to play a role in the H2S production and PAH degradation.

Draft genome of Nocardia farcinica TRH1, a linear and polycyclic aromatic hydrocarbon-degrading bacterium isolated from the coast of Trindade Island, Brazil

Here, we report the draft genome sequence and annotation of Nocardia farcinica TRH1, a petroleum hydrocarbons degrading Actinobacteria isolated from the coastal water of Trindade Island, Brazil.

Influence of thermally modified palygorskite on the viability of polycyclic aromatic hydrocarbon-degrading bacteria

Thermal activation of palygorskite is considered as a simple and cost-effective method for modifying its structural and surface properties, which can be congenial for the adsorptive removal of environmental contaminants. However, for a more efficient removal of organic contaminants like polycyclic aromatic hydrocarbons (PAH), clay-microbial synergy combining both adsorption and biodegradation is an emerging strategy. In this study, we investigated the compatibility of heat treated palygorskite products (100–900°C) with a PAH-degrading soil bacterium Burkholderia sartisoli. The mineralogical and physico-chemical properties were characterised in detail, and the bacterial adhesion to the substrate and their growth were observed in relation to these properties. The major variation in the cation exchange capacity (CEC), surface area, water content and the elemental dissolution in the aqueous medium occurred in the palygorskite products heated at extreme temperature (700–900°C). These changes significantly influenced the bacterial growth and attachment. The maximum viability was imparted by the palygorskite product obtained at 400°C. Dissolution of Al from products heated above 500°C also posed inhibitory effect on bacterial growth in the aqueous media. This study provided valuable information about the mechanisms of bacterial viability as affected by modified clay minerals, which is important for developing a novel clay-modulated-bioremediation technology.

Isolation and characterization of heavy polycyclic aromatic hydrocarbon-degrading bacteria adapted to electrokinetic conditions.

Polycyclic aromatic hydrocarbon (PAH)-degrading bacteria capable of growing under electrokinetic conditions were isolated using an adjusted acclimation and enrichment procedure based on soil contaminated with heavy PAHs in the presence of an electric field. Their ability to degrade heavy PAHs under an electric field was individually investigated in artificially contaminated soils. The results showed that strains PB4 (Pseudomonas fluorescens) and FB6 (Kocuria sp.) were the most efficient heavy PAH degraders under electrokinetic conditions. They were re-inoculated into a polluted soil from an industrial site with a PAH concentration of 184.95 mg kg(-1). Compared to the experiments without an electric field, the degradation capability of Pseudomonas fluorescens and Kocuria sp. was enhanced in the industrially polluted soil under electrokinetic conditions. The degradation extents of total PAHs were increased by 15.4 and 14.0% in the electrokinetic PB4 and FB6 experiments (PB4 + EK and FB6 + EK) relative to the PB4 and FB6 experiments without electrokinetic conditions (PB4 and FB6), respectively. These results indicated that P. fluorescens and Kocuria sp. could efficiently degrade heavy PAHs under electrokinetic conditions and have the potential to be used for the electro-bioremediation of PAH-contaminated soil, especially if the soil is contaminated with heavy PAHs.

ISOLATION AND DISTRIBUTION OF CRUDE OIL AND POLYCYCLIC AROMATIC HYDROCARBON-DEGRADING BACTERIA FROM POLLUTED HARBOURS IN NORTH JAKARTA

Several harbours in North Jakarta have been polluted by spills of oil and their derivates. We suggest that diverse species of crude oil and polycyclic aromatic hydrocarbon-degrading bacteria  inhabit these harbours. An experiment was undertaken in 2007 to isolate crude oil and polycyclic aromatic hydrocarbon (PAH)-degrading bacteria from oil-polluted harbours, such as Muara Baru, Sunda Kelapa and Tanjung Priok. Sea water and sediment samples were collected twice, in March and April. Crude oil and PAH-degrading bacteria were isolated from enrichment culture of samples in an enrichment medium (SWP), using ONR7a medium with the addition of 5 types of PAH gases or Arabian Light Crude Oil 210 (ALCO 210) onto medium. This study reported that fluoranthene and crude oil-degrading bacteria were the major bacteria isolated from the three polluted harbours. In total, 109 isolates have been collected which can degrade crude oil (29% of total isolates), fluoranthene (33%), fluorene (20%), pyrene (7%), dibenzothiopene (6%), and phenantrene (5 %). Among these isolates, 5 isolates have the capability to degrade 5 types of PAH and ALCO 210. They were Alcanivorax sp. B-1084, Pseudomonas sp. D5-38b, Alcanivorax sp. TE-9, Bacillus sp. L41, Alcanivorax dieselolei strain B-5 clone 1. Culturable bacteria have been isolated mostly from the Sunda Kelapa samples, with fewer in those from Muara Baru and Tanjung Priok, respectively

Sphingobium barthaii sp. nov., a high molecular weight polycyclic aromatic hydrocarbon-degrading bacterium isolated from cattle pasture soil.

A Gram-stain-negative, yellow, rod-shaped bacterium, designated strain KK22(T), was isolated from a microbial consortium that grew on diesel fuel originally recovered from cattle pasture soil. Strain KK22(T) has been studied for its ability to biotransform high molecular weight polycyclic aromatic hydrocarbons. On the basis of 16S rRNA gene sequence phylogeny, strain KK22(T) was affiliated with the genus Sphingobium in the phylum Proteobacteria and was most closely related to Sphingobium fuliginis TKP(T) (99.8%) and less closely related to Sphingobium quisquiliarum P25(T) (97.5%). Results of DNA-DNA hybridization (DDH) revealed relatedness values between strain KK22(T) and strain TKP(T) and between strain KK22(T) and strain P25(T) of 21 ± 4% (reciprocal hybridization, 27 ± 2%) and 15 ± 2% (reciprocal hybridization, 17 ± 1%), respectively. Chemotaxonomic analyses of strain KK22(T) showed that the major respiratory quinone was ubiquinone Q-10, that the polar lipid profile consisted of phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, phosphatidyl-N-methylethylethanolamine and sphingoglycolipid, and that C18 : 1ω7c and C14 : 0 2-OH were the main fatty acid and hydroxylated fatty acids, respectively. This strain was unable to reduce nitrate and the genomic DNA G+C content was 64.7 mol%. Based upon the results of the DDH analyses, the fact that strain KK22(T) was motile, and its biochemical and physiological characteristics, strain KK22(T) could be separated from recognized species of the genus Sphingobium. We conclude that strain KK22(T) represents a novel species of this genus for which the name Sphingobium barthaii sp. nov. is proposed; the type strain is KK22(T) ( = DSM 29313(T) = JCM 30309(T)).

Complete Genome Sequence of a Novel Bacterium within the Family Rhodocyclaceae That Degrades Polycyclic Aromatic Hydrocarbons.

A polycyclic aromatic hydrocarbon-degrading bacterium designated strain Ca6, a member of the family Rhodocyclaceae and a representative of the uncharacterized pyrene group 1 (PG1), was isolated and its genome sequenced. The presence of several genes suspected to be associated with PG1 was confirmed, and additional genes for aromatic compound metabolism were detected.