Publications by authors named "Yukiya Ito"

6 Publications

  • Page 1 of 1

Isolation and characterization of bacteria from soil contaminated with diesel oil and the possible use of these in autochthonous bioaugmentation.

World J Microbiol Biotechnol 2007 Dec 15;23(12):1739-45. Epub 2007 May 15.

Laboratory of Environmental Molecular Biology, Graduate School of Environmental Earth Science, Hokkaido University, Kita-ku, Sapporo, 060-0810, Japan.

Two bacterial species (isolates N and O) were isolated from a paddy soil microcosm that had been artificially contaminated with diesel oil to which extrinsic Pseudomonas aeruginosa strain WatG, had been added exogenously. One bacterial species (isolate J) was isolated from a similar soil microcosm that had been biostimulated with Luria-Bertani (LB) medium. Isolates N and O, which were tentatively identified as Stenotrophomonas sp. and Ochromonas sp., respectively, by sequencing of their 16 S rRNA genes had no ability to degrade diesel oil on their own in any liquid medium. When each strain was cocultivated with P. aeruginosa strain WatG in liquid mineral salts medium (MSM) containing 1% diesel oil, isolate N enhanced the degradation of diesel oil by P. aeruginosa strain WatG, but isolate O inhibited it. In contrast, isolate J, which was tentatively identified as a Rhodococcus sp., degraded diesel oil contained not only in liquid LB and MSM, but also in paddy soil microcosms supplemented with LB medium. The bioaugmentation capacity of isolate J in soil microcosms contaminated with diesel oil was much higher than that of P. aeruginosa strain WatG. The possibility of using isolate J for autochthonous bioaugmentation is discussed.
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http://dx.doi.org/10.1007/s11274-007-9423-6DOI Listing
December 2007

Enhanced heterologous production of eicosapentaenoic acid in Escherichia coli cells that co-express eicosapentaenoic acid biosynthesis pfa genes and foreign DNA fragments including a high-performance catalase gene, vktA.

Biotechnol Lett 2007 May 13;29(5):803-9. Epub 2007 Feb 13.

Graduate School of Environmental Earth Science, Hokkaido University, Kita-ku, Sapporo, 060-0810, Japan.

Cellular eicosapentaenoic acid (EPA) makes up approximately 3% of total fatty acids in Escherichia coli DH5alpha, a strain that carries EPA biosynthesis genes (pEPADelta1). EPA was increased to 12% of total fatty acids when the host cell co-expressed the vector pGBM3::sa1(vktA), which carried the high-performance catalase gene, vktA. Where this vector was co-expressed, the transformant accumulated a large amount of VktA protein. However, the EPA production of cells carrying the vector, that included the insert lacking almost the entire vktA gene, was approximately 6%. This suggests that the retention of a large DNA insert in the vector and the accumulation of the resulting protein, but not the catalytic activity of VktA catalase, would potentially be able to increase the content of EPA.
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http://dx.doi.org/10.1007/s10529-007-9310-0DOI Listing
May 2007

Bacterial community changes in diesel-oil-contaminated soil microcosms biostimulated with Luria-Bertani medium or bioaugmented with a petroleum-degrading bacterium, Pseudomonas aeruginosa strain WatG.

J Basic Microbiol 2006 ;46(4):310-7

Laboratory of Environmental Molecular Biology, Graduate School of Environmental Earth Science, Hokkaido University, Kita 10 Nishi 6 Kita-ku, Sapporo 060-0810, Japan.

The microbial community structure of diesel-oil-contaminated soil microcosms biostimulated with Luria-Bertani medium (LB-BS) or bioaugmented with a petroleum-degrading bacterium, Pseudomonas aeruginosa strain WatG (WatG-BA), was investigated by denaturing gradient gel electrophoresis (DGGE) and by monitoring diesel oil degradation. The degradation in WatG-BA (64.0% +/- 4.2%) was higher than that in LB-BS (49.5% +/- 12.0%) during the first two weeks. The microbial community in WatG-BA, which was markedly dominated by strain WatG, was much simpler than that in LB-BS, where hydrocarbon degraders occurred after a lag of 3-7 days after the addition of diesel oil. The clustering profiles of the DGGE banding patterns of the two soil microcosms were only 12% similar. This difference is probably due to antibacterial substances, such as rhamnolipids, secreted by strain WatG.
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http://dx.doi.org/10.1002/jobm.200510116DOI Listing
September 2006

Escherichia coli engineered to produce eicosapentaenoic acid becomes resistant against oxidative damages.

FEBS Lett 2006 May 21;580(11):2731-5. Epub 2006 Apr 21.

Graduate School of Environmental Earth Science, Hokkaido University, Sapporo 060-0810, Japan.

The colony-forming ability of Escherichia coli genetically engineered to produce eicosapentaenoic acid (EPA) grown in 3mM hydrogen peroxide (H(2)O(2)) was similar to that of untreated cells. It was rapidly lost in the absence of EPA. H(2)O(2)-induced protein carbonylation was enhanced in cells lacking EPA. The fatty acid composition of the transformants was unaffected by H(2)O(2) treatment, but the amount of fatty acids decreased in cultures of cells lacking EPA and increased in cultures of cells producing EPA, suggesting that cellular EPA is stable in the presence of H(2)O(2) in vivo and may protect cells directly against oxidative damage. We discuss the possible role of EPA in partially blocking the penetration of H(2)O(2) into cells through membranes containing EPA.
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http://dx.doi.org/10.1016/j.febslet.2006.04.032DOI Listing
May 2006

Isolation and characterization of a novel thraustochytrid-like microorganism that efficiently produces docosahexaenoic acid.

Biotechnol Lett 2006 Feb;28(3):197-202

Laboratory of Environmental Molecular Biology, Graduate School of Environmental Earth Science, Hokkaido University, Sapporo, Kita-ku, 060-0810, Japan.

A thraustochytrid-like microorganism (strain 12B) was isolated from the mangrove area of Okinawa, Japan. On the basis of its ectoplasmic net structure and biflagellate zoospores we determined strain 12B to be a novel member of the phylum Labyrinthulomycota in the kingdom Protoctista. When grown on glucose/seawater at 28 degrees C, it had a lipid content of 58% with docosahexaenoic acid (DHA; 22:6 n-3) at 43% of the total fatty acids. It had a growth rate of 0.38 h(-1). The DHA production rate of 2.8 +/- 0.7 g l(-1) day(-1) is the highest value reported for any microorganism.
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http://dx.doi.org/10.1007/s10529-005-5335-4DOI Listing
February 2006