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PubMed2004

Mesophilic aerobic degradation of a metal lubricant by a biological consortium.

The metal-forming industries require the use of greases to lubricate metal surfaces during manufacturing operations, and the residues of these lubricants must be removed prior to finishing processes to protect and improve the appearance of the final product. An aqueous, biological metal-cleaning process operating under mild conditions (pH 9, 42 degrees C) eliminates the use of environmentally unfriendly cleaning materials such as chlorinated solvents by employing microorganisms to degrade greases and oils naturally. This process was characterized in terms of initial degradation rates of a representative metal lubricant and by phylogenetic identification of the active bacteria. The metal lubricant in a surfactant solution was degraded by a bacterial consortium, and its concentration was determined by a novel gas chromatography assay. The maximum degradation rate Vmax and the apparent Km were obtained as 45 mg/(day mg protein) and 24 g/l on cellular basis, and 4.6 g/(day l) and 33 g/l on a volumetric basis, respectively. Mineralization of the metal lubricant was shown by analyzing the evolved CO2 and Cl-, and the bacterial consortium utilized the metal lubricant as a sole carbon and energy source (micro=0.05+/-0.01 h(-1) at 0.5 vol% lubricant concentration). The active bacteria in the biological metal-cleaning process were identified as Bacillus licheniformis for the higher lubricant concentrations (3, 5, and 7.5 vol%), Bacillus cereus at 1 vol%, and Pseudomonas aeruginosa, Rhizobiaceae strain M100, and Achromobacter sp. LMG 5431 at 0.3 vol%.

Achromobacter↗
PubMed2004

Degradation of estradiol and ethinyl estradiol by activated sludge and by a defined mixed culture.

The aerobic degradation of the natural hormone 17-beta-estradiol (E2) and the synthetic hormone 17-alpha-ethinyl estradiol (EE2) was investigated in batch experiments with activated sludge from a conventional and a membrane sewage treatment plant. E2 was converted to estrone (E1), the well known metabolite, and further completely transformed within 3 days. The turnover rates of E2 did not differ greatly between conventional and membrane activated sludge. EE2 was persistent in both sludges. By several transfers into fresh E2-medium an enrichment culture could be selected that used E2 as growth substrate. Further enrichment and isolation led to a defined mixed culture consisting of two strains, which were identified by a polyphasic approach as Achromobacter xylosoxidans and Ralstonia sp., respectively. The culture used E2 and E1 as growth substrates and transformed estriol (E3) and 16-alpha-hydroxyestrone but not the xenoestrogens bisphenol A, alpha-zearalenol, mestranol or EE2. The turnover rates of E2 were 0.025-0.1 microg h(-1) cfu(-1) and did not depend on the steroid concentration.

Achromobacter denitrificans↗
PubMed2004

Phosphonium ionic liquids for degradation of phenol in a two-phase partitioning bioreactor.

Six ionic liquids (ILs), which are organic salts that are liquid at room temperature, were tested for their biocompatibility with three xenobiotic-degrading bacteria, Pseudomonas putida, Achromobacter xylosoxidans, and Sphingomonas aromaticivorans. Of the 18 pairings, seven were found to demonstrate biocompatibility, with one IL (trihexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl) amide) being biocompatible with all three organisms. This IL was then used in a two-phase partitioning bioreactor (TPPB), consisting of 1 l aqueous phase loaded with 1,580 mg phenol and 0.25 l IL, inoculated with the phenol degrader P. putida. This initially toxic aqueous level of phenol was substantially reduced by phenol partitioning into the IL phase, allowing the cells to utilize the reduced phenol concentration. The partitioning of phenol from the IL to the aqueous phase was driven by cellular demand and thermodynamic equilibrium. All of the phenol was consumed at a rate comparable to that of previously used organic-aqueous TPPB systems, demonstrating the first successful use of an IL with a cell-based system. A quantitative (31)P NMR spectroscopic assay for estimating the log P values of ILs is under development.

Achromobacter denitrificans↗
PubMed2006

Benzene vapor treatment using a two-phase partitioning bioscrubber: an improved steady-state protocol to enhance long-term operation.

The performance and stability of a two-phase partitioning bioscrubber (TPPB) containing 33% (vol.) n-hexadecane as an immiscible phase was investigated during 30 days of continuous gaseous benzene treatment. Elimination capacities of 141 +/- 12 g/m(3) h were achieved by Achromobacter xylosoxidans Y234 while maintaining >99% removal throughout. A new steady-state operating strategy that limits excessive biomass production by directing substrate consumption to maintenance energy has eliminated the requirement for frequent exchange of liquid contents. Simplifying the operating protocols in this manner has dramatically reduced material costs and rendered the TPPB operational requirements as more comparable (in terms of frequency of required operator inputs) with other vapor-phase bioreactors. The practicality of the proposed simplification to the operating protocol was confirmed by demonstrating that intermediate metabolites were not accumulating in the TPPB, inorganic nutrient requirements were readily predictable, and that high culture viability could be sustained for prolonged cell retention times (30 days).

Achromobacter denitrificans↗
PubMed2005

[Use of 16S rRNA gene sequencing for identification of "Pseudomonas-like" isolates from sputum of patients with cystic fibrosis].

Since nonfermenting, Gram negative bacilli recovered from patients with cystic fibrosis could be misidentified with phenotypic procedures, we used partial 16S ribosomal RNA gene (16S gene) sequencing to identify these "Pseudomonas-like" isolates. 473 isolates were recovered from 66 patients in 2003. Sequencing was used to identify 29 (from 24 patients) of the 473 isolates, showing unclear results with routine tests. PCR with specific primers was carried out to amplify a 995 bp fragment, which was then sequenced. The sequences were analyzed with GenBank database for species assignment. Phenotypic and genotypic results were concordant for 20/29 isolates (10 Pseudomonas aeruginosa, 5 Burkholderia cepacia, 3 Stenotrophomonas maltophilia, 2 Achromobacter xylosoxidans). However, 3 of the 5 B. cepacia isolates were then identified as Burkholderia multivorans with a PCR-RFLP procedure. Phenotypic misidentification was observed for 9/29 isolates: 4 A. xylosoxidans, 1 P. aeruginosa, 1 Bordetella petrii, 1 Bordetella bronchiseptica, 1 Ralstonia respiraculi and 1 Ralstonia mannitolilytica. Partial 16S gene sequencing improved the identification of "Pseudomonas-like" isolates from cystic fibrosis patients, but the accuracy to distinguish between genomovars of the B. cepacia complex was inadequate.

Achromobacter denitrificans↗
PubMed2004

Plant growth-promoting bacteria confer resistance in tomato plants to salt stress.

The object of the work is to evaluate whether rhizobacteria populating dry salty environments can increase resistance in tomato to salt stress. Seven strains of plant growth-promoting bacteria that have 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity were isolated from soil samples taken from the Arava region of southern Israel. Following growth of these seedlings in the presence of 43 mM NaCl for 7 weeks, the bacterium that promoted growth to the greatest extent was selected for further study. DNA analysis of the 16S RNA indicated that the selected bacterium was Achromobacter piechaudii. This bacterium significantly increased the fresh and dry weights of tomato seedlings grown in the presence of up to 172 mM NaCl salt. The bacterium reduced the production of ethylene by tomato seedlings, which was otherwise stimulated when seedlings were challenged with increasing salt concentrations, but did not reduce the content of sodium. However, it slightly increased the uptake of phosphorous and potassium, which may contribute in part to activation of processes involved in the alleviation of the effect of salt. In the presence of salt the bacterium increased the water use efficiency (WUE). This may suggest that the bacterium act to alleviate the salt suppression of photosynthesis. However, the detailed mechanism was not elucidated. The work described in this report is a first step in the development of productive agricultural systems in saline environments.

Achromobacter↗
PubMed2003

[Phenotypic and genotypic characteristics of non fermenting atypical strains recovered from cystic fibrosis patients].

We used partial 16S rRNA gene (16S DNA) sequencing for the prospective identification of nonfermenting Gram-negative bacilli recovered from patients attending our cystic fibrosis center (hôpital Necker-Enfants malades), which gave problematic results with conventional phenotypic tests. During 1999, we recovered 1093 isolates of nonfermenting Gram-negative bacilli from 702 sputum sampled from 148 patients. Forty-six of these isolates (27 patients) were not identified satisfactorily in routine laboratory tests. These isolates were identified by 16S DNA sequencing as Pseudomonas aeruginosa (19 isolates, 12 patients), Achromobacter xylosoxidans (10 isolates, 8 patients), Stenotrophomonas maltophilia (9 isolates, 9 patients), Burkholderia cepacia genomovar I/III (3 isolates, 3 patients), Burkholderia vietnamiensis (1 isolate), Burkholderia gladioli (1 isolate) and Ralstonia mannitolilytica (3 isolates, 2 patients). Fifteen isolates (33%) were resistant to all antibiotics in routine testing. Sixteen isolates (39%) resistant to colistin were recovered on B. cepacia-selective medium: 2 P. aeruginosa, 3 A. xylosoxidans, 3 S. maltophilia and the 8 Burkholderia--Ralstonia isolates. The API 20NE system gave no identification for 35 isolates and misidentified 11 isolates (2 P. aeruginosa, 2 A. xylosoxidans and 1 S. maltophilia classified as B. cepacia ). Control measures and/or treatment were clearly improved as a result of 16S DNA sequencing in three of these cases. This study confirms the weakness of phenotypic methods for identification of atypical nonfermenting Gram-negative bacilli recovered from cystic fibrosis patients. The genotypic methods, such as 16S DNA sequencing which allows identification of strains in routine practice, appears to have a small, but significant impact on the clinical management of CF patients.

Achromobacter↗
PubMed2005

Transient performance of a two-phase partitioning bioscrubber treating a benzene-contaminated gas stream.

The dynamic performance of a prototype, two-phase partitioning bioscrubber in response to fluctuating benzene waste gas feeds has been characterized through a series of spike, step, and shutdown-restart experiments. From stable operation at a nominal loading capacity of 62 +/- 6 g/(m3 h) and removal efficiencies of over 99%, the bioscrubber was subjected to influent benzene concentration step changes and spikes as high as 10- and 20-fold, respectively. The bioscrubber responded rapidly and effectively to all feed concentration spikes and steps, as well as to step changes in the feed flow rate, maintaining nearly undisturbed performance. Although benzene absorption by the two liquid phases was found to dominate the early stages of each transient, Achromobacter xylosoxidans Y234 responded quickly to prolonged disturbances, readily consuming most of the excess absorbed substrate. The results demonstrate that the two-phase partitioning bioscrubber can rapidly acclimate to and recover from fluctuations, ensuring that stable performance can be maintained both during and aftertransients. The presence of n-hexadecane promotes benzene capture in the two-phase system by increasing the absorption driving force, an important characteristic during high intermittent loadings. Rapid recovery from two different shutdown scenarios further demonstrates the practical potential of the two-phase partitioning bioscrubber as a high-performance biotechnology alternative for the treatment of toxic waste gases.

Achromobacter↗
PubMed2004

Reductively activated nitrous oxide reductase reacts directly with substrate.

In the terminal step of bacterial denitrification, N2O is converted to N2 at the mu4-sulfide bridged tetranuclear CuZ center of nitrous oxide reductase. The enzyme can be activated by reduced methyl viologen, with up to a 15-fold increase in specific activity. The reductively activated nitrous oxide reductase from Achromobacter cycloclastes was isolated and characterized by visible absorption and EPR spectroscopy, and both methods showed that the CuZ center can attain a [4Cu(I)] oxidation state. When N2O was added to the activated, reductant-free enzyme, distinct spectral changes were observed, indicating that this state of the enzyme interacts with substrate. This was further supported by the detection of 15N-labeled product in the absence of steady-state turnover conditions. A new absorption band around 970 nm appeared following reaction of activated nitrous oxide reductase with N2O, which may represent a catalytic intermediate state of the enzyme.

Achromobacter cycloclastes↗
PubMed2005

Dynamic kinetic resolution of amino acid amide catalyzed by D-aminopeptidase and alpha-amino-epsilon-caprolactam racemase.

Amino acid amide racemizing activity was discovered in alpha-amino-epsilon-caprolactam (ACL) racemase (EC 5. 1. 1. 15) from Achromobacter obae. The enzymatic synthesis of d-alanine from l-alanine amide has been demonstrated by use of d-aminopeptidase (DAP; EC 3. 4. 11. 19) from Ochrobactrum anthropi C1-38 and ACL racemase. The conversion of 45 mM l-alanine amide was carried out at 30 degrees C for 7 h; l-alanine amide was completely converted to d-alanine, and no l-alanine was detected. The result of successive enzymatic reaction shows that the combination of ACL racemase and DAP can be applied for dynamic kinetic resolution of dl-amino acid amides to yield d-amino acids.

Achromobacter↗
PubMed2004

Structural investigations and identification of the extracellular bacteriolytic endopeptidase L1 from Lysobacter sp. XL1.

The N-terminal amino acid sequence (23 amino acid residues) and the amino acid composition of the extracellular bacteriolytic enzyme L1 of 21 kD from the bacterium Lysobacter sp. XL1 have been determined. The enzyme was hydrolyzed by trypsin, the resulting peptides were isolated, and their primary structures were determined. A high extent of homology (92%) of the N-terminal amino acid sequence and the primary structure of isolated peptides of the enzyme L1 (62 amino acid residues or 31% of protein sequence) to the corresponding sites of alpha-lytic proteinases (EC 3.4.21.12) of Lysobacter enzymogenes and Achromobacter lyticus was found. These data allowed identification of the endopeptidase L1 of Lysobacter sp. XL1 as alpha-lytic proteinase EC 3.4.21.12.

Achromobacter↗
PubMed2005

Atomic resolution structures of resting-state, substrate- and product-complexed Cu-nitrite reductase provide insight into catalytic mechanism.

Copper-containing nitrite reductases catalyze the reduction of nitrite to nitric oxide (NO), a key step in denitrification that results in the loss of terrestrial nitrogen to the atmosphere. They are found in a wide variety of denitrifying bacteria and fungi of different physiology from a range of soil and aquatic ecosystems. Structural analysis of potential intermediates in the catalytic cycle is an important goal in understanding enzyme mechanism. Using "crystal harvesting" and substrate-soaking techniques, we have determined atomic resolution structures of four forms of the green Cu-nitrite reductase, from the soil bacterium Achromobacter cycloclastes. These structures are the resting state of the enzyme at 0.9 A, two species exhibiting different conformations of nitrite bound at the catalytic type 2 Cu, one of which is stable and also has NO present, at 1.10 A and 1.15 A, and a stable form with the product NO bound side-on to the catalytic type 2 Cu, at 1.12 A resolution. These structures provide incisive insights into the initial binding of substrate, its repositioning before catalysis, bond breakage (O-NO), and the formation of a stable NO adduct.

Achromobacter cycloclastes↗
PubMed2004

Structure-based engineering of Alcaligenes xylosoxidans copper-containing nitrite reductase enhances intermolecular electron transfer reaction with pseudoazurin.

The intermolecular electron transfer from Achromobacter cycloclastes pseudoazurin (AcPAZ) to wild-type and mutant Alcaligenes xylosoxidans nitrite reductases (AxNIRs) was investigated using steady-state kinetics and electrochemical methods. The affinity and the electron transfer reaction constant (k(ET)) are considerably lower between AcPAZ and AxNIR (K(m) = 1.34 mM and k(ET) = 0.87 x 10(5) M(-1) s(-1)) than between AcPAZ and its cognate nitrite reductase (AcNIR) (K(m) = 20 microM and k(ET) = 7.3 x 10(5) M(-1) s(-1)). A negatively charged hydrophobic patch, comprising seven acidic residues around the type 1 copper site in AcNIR, is the site of protein-protein interaction with a positively charged hydrophobic patch on AcPAZ. In AxNIR, four of the negatively charged residues (Glu-112, Glu-133, Glu-195, and Asp-199) are conserved at the corresponding positions of AcNIR, whereas the other three residues are not acidic amino acids but neutral amino acids (Ala-83, Ala-191, and Gly-198). Seven mutant AxNIRs with additional negatively charged residues surrounding the hydrophobic patch of AxNIR (A83D, A191E, G198E, A83D/A191E, A93D/G198E, A191E/G198E, and A83D/A191E/G198E) were prepared to enhance the specificity of the electron transport reaction between AcPAZ and AxNIR. The k(ET) values of these mutants become progressively larger as the number of mutated residues increases. The K(m) and k(ET) values of A83D/A191E/G198E (K(m) = 88 microM and k(ET) = 4.1 x 10(5) M(-1) s(-1)) are 15-fold smaller and 4.7-fold larger than those of wild-type AxNIR, respectively. These results suggest that the introduction of negatively charged residues into the docking surface of AxNIR facilitates both the formation of electron transport complex and the electron transfer reaction.

Achromobacter denitrificans↗
PubMed2004

Pitfalls of polymyxin antimicrobial susceptibility testing of Pseudomonas aeruginosa isolated from cystic fibrosis patients.

OBJECTIVES AND METHODS: With their potent activity against Gram-negative bacteria, the polymyxins are important alternative antibiotics for cystic fibrosis (CF) patients. A retrospective evaluation of polymyxin activity against 6001 Pseudomonas aeruginosa, 150 Achromobacter xylosoxidans and 506 Stenotrophomonas maltophilia CF isolates was initiated. In addition, we looked at how polymyxin susceptibility testing was affected by the testing method (agar dilution versus microdilution), the agent (polymyxin E versus polymyxin B), incubation time (24 h versus 48 h) and by different interpretative criteria (German DIN, French FSM, British BSAC). RESULTS: Polymyxin B exhibited reasonable activity against P. aeruginosa (MIC(90)< or =2 mg/L), whereas it was less active against A. xylosoxidans (MIC(90)< or =16 mg/L) and S. maltophilia (MIC(90)< or =16 mg/L). During 2000-2002, polymyxin B resistance in P. aeruginosa, S. maltophilia and A. xylosoxidans was found to be 6.7%, 17.0% and 29.9% (corresponding to 12.4%, 20.7% and 35.4% of infected patients), respectively. When the agar dilution method was used, polymyxin E exhibited higher MICs than polymyxin B. The microdilution method produced lower polymyxin MICs than the agar dilution method. Therefore, the microdilution MICs after prolonged incubation (48 h) and the agar dilution MICs of polymyxin B correlated best (AUC of 0.93, r(2) of 0.44 and s of 0.83). CONCLUSIONS: Polymyxin resistance among common CF pathogens is not rare, thus underlining the necessity of accurate susceptibility testing. When compared with the agar dilution method, it was found that the microdilution method is a valid, rapid and cost effective alternative for the determination of polymyxin activity. The performance of the microdilution method was most reliable after prolonged incubation (48 h) at a susceptibility breakpoint of < or =4 mg/L according to the BSAC guidelines (specificity 91%, sensitivity 89%, 1.5% very major errors).

Achromobacter denitrificans↗
PubMed2004

Degradation of 2,4,6-tribromophenol by bacterial cells attached to chalk collected from a contaminated aquifer.

AIM: To investigate the factors governing the adhesion and activity of the 2,4,6-tribromophenol (TBP) degrading bacterium Achromobacter piechaudii TBPZ-N61 on chalk from a contaminated aquifer. METHODS AND RESULTS: Adhesion kinetics of TBPZ-N61 to grey and white chalk from a polluted fractured chalk aquifer was tested in a batch system. Both grey and white chalk contain ca 80% CaCO3, while grey chalk contains more organic matter (2.4%) than the white chalk (0.3%) and also contains Dolmite and Clinoptilolite. Adhesion of the bacterial cells to the chalk particles (<0.2 mm) occurred rapidly (96% of the cells within 15 min). Langmuir-fitted adhesion isotherms suggest that cells in the stationary phase, which are more hydrophobic, adhere to both grey and white chalk more efficiently than cells in the logarithmic growth phase. Increasing the pH (from 6.7 to 8.1) caused a significant reduction in cell adhesion to the chalk. Activity of attached cells was evaluated in both batch and column experiments. Logarithmic cells adhering to white and grey chalk were more active in TBP degradation than cells in suspension. In column experiments, significant TBP degradation was retained up to 30 days after a single injection of TBPZ cells. Thereafter, activity was fully recovered by amendment of yeast extract. Chalk surfaces that were incubated in situ in contaminated groundwater for 20 days still allowed the adhesion and activity of TBPZ cells. CONCLUSIONS: Taken together, our results show that bacteria adhere efficiently to specific sites on the chalk surfaces, and that sustained bacterial activity of the attached cells can be achieved by adding a carbon source such as yeast extract which also overcome toxic constituents that may occur in some chalk types. SIGNIFICANCE AND IMPACT OF THE STUDY: Bioremediation of TBP-contaminated chalk aquifers is made possible by the injection of bacterial cultures.

Achromobacter↗
PubMed2005

Plant-microbe interactions: identification of epiphytic bacteria and their ability to alter leaf surface permeability.

Bacteria were either isolated from leaf surfaces of Hedera helix or obtained from a culture collection in order to analyse their effect on barrier properties of isolated Hedera and Prunus laurocerasus cuticles. On the basis of the 16S rDNA sequences the genera of the six bacterial isolates from Hedera were identified as Pseudomonas sp., Stenotrophomonas sp. and Achromobacter. Water permeability of cuticles isolated from H. helix was measured before and after inoculation with the six bacterial strains. In addition water permeability of cuticles isolated from P. laurocerasus was measured before and after inoculation with the three bacterial strains Pseudomonas aeruginosa, Xanthomonas campestris and Corynebacterium fascians. Rates of water diffusing across isolated cuticles of both species significantly increased by up to 50% after inoculation with all bacterial strains. Obtained results show that epiphytic bacteria have the ability of increasing water permeability of Hedera and Prunus cuticles, which in turn should increase the availability of water and dissolved compounds in the phyllopshere. Consequently, living conditions in the habitat phyllosphere are improved. It can be concluded that the ability to change leaf surface properties will improve epiphytic fitness of leaf surface bacteria.

Achromobacter↗
PubMed2006

Assessing the impact of denitrifier-produced nitric oxide on other bacteria.

A series of experiments was undertaken to learn more about the impact on other bacteria of nitric oxide (NO) produced during denitrification. The denitrifier Rhodobacter sphaeroides 2.4.3 was chosen as a denitrifier for these experiments. To learn more about NO production by this bacterium, NO levels during denitrification were measured by using differential mass spectrometry. This revealed that NO levels produced during nitrate respiration by this bacterium were in the low muM range. This concentration of NO is higher than that previously measured in denitrifiers, including Achromobacter cycloclastes and Paracoccus denitrificans. Therefore, both 2.4.3 and A. cycloclastes were used in this work to compare the effects of various NO levels on nondenitrifying bacteria. By use of bacterial overlays, it was found that the NO generated by A. cycloclastes and 2.4.3 cells during denitrification inhibited the growth of both Bacillus subtilis and R. sphaeroides 2.4.1 but that R. sphaeroides 2.4.3 caused larger zones of inhibition in the overlays than A. cycloclastes. Both R. sphaeroides 2.4.3 and A. cycloclastes induced the expression of the NO stress response gene hmp in B. subtilis. Taken together, these results indicate that there is variability in the NO concentrations produced by denitrifiers, but, irrespective of the NO levels produced, microbes in the surrounding environment were responsive to the NO produced during denitrification.

Achromobacter cycloclastes↗
PubMed2004

The completely sequenced plasmid pEST4011 contains a novel IncP1 backbone and a catabolic transposon harboring tfd genes for 2,4-dichlorophenoxyacetic acid degradation.

The herbicide 2,4-dichlorophenoxyacetic acid (2,4-D)-degrading bacterium Achromobacter xylosoxidans subsp. denitrificans strain EST4002 contains plasmid pEST4011. This plasmid ensures its host a stable 2,4-D(+) phenotype. We determined the complete 76,958-bp nucleotide sequence of pEST4011. This plasmid is a deletion and duplication derivative of pD2M4, the 95-kb highly unstable laboratory ancestor of pEST4011, and was self-generated during different laboratory manipulations performed to increase the stability of the 2,4-D(+) phenotype of the original strain, strain D2M4(pD2M4). The 47,935-bp catabolic region of pEST4011 forms a transposon-like structure with identical copies of the hybrid insertion element IS1071::IS1471 at the two ends. The catabolic regions of pEST4011 and pJP4, the best-studied 2,4-D-degradative plasmid, both contain homologous, tfd-like genes for complete 2,4-D degradation, but they have little sequence similarity other than that. The backbone genes of pEST4011 are most similar to the corresponding genes of broad-host-range self-transmissible IncP1 plasmids. The backbones of the other three IncP1 catabolic plasmids that have been sequenced (the 2,4-D-degradative plasmid pJP4, the haloacetate-catabolic plasmid pUO1, and the atrazine-catabolic plasmid pADP-1) are nearly identical to the backbone of R751, the archetype plasmid of the IncP1 beta subgroup. We show that despite the overall similarity in plasmid organization, the pEST4011 backbone is sufficiently different (51 to 86% amino acid sequence identity between individual backbone genes) from the backbones of members of the three IncP1 subgroups (the alpha, beta, and gamma subgroups) that it belongs to a new IncP1subgroup, the delta subgroup. This conclusion was also supported by a phylogenetic analysis of the trfA2, korA, and traG gene products of different IncP1 plasmids.

2,4-Dichlorophenoxyacetic Acid↗