1. Bacterial Heavy Metal Resistance System in Microbial Ecology

 Mercury is highly toxic and has no beneficial role for living organisms. However, some bacteria possess systems that are resistant
to this toxic metal. The best-characterized bacterial biotransformation of mercury is reduction by the mer resistance determinants found
on plasmids and transposons in both Gram-positive and -negative bacteria.
 TnMERI1, a class II mercury resistance transposon, was first identified in a Gram-positive Bacillus megaterium MB1 strain isolated
from sediment in Minamata Bay Japan, the site of an infamous mercury poisoning disaster. However, our study revealed that TnMERI1-like
class II transposons are distributed worldwide, including among environmental Bacilli strains isolated from non-contaminated sites.
This observation provoked a variety of questions related to bacterial dissemination, horizontal gene transfer, bacterial settlement in microbial
communities, and potential significance for bioremediation. Our laboratory aimed to address these questions using both molecular and ecological approaches.

<Related publications>

  1. Matsui, K., S. Yoshinami, M. Narita, M. F. Chien, L. Phung, S. Silver, and G. Endo. 2016. Mercury resistance transposons in Bacilli strains from different geographical regions. FEMS Microbiology Letters 363: fnw013. Abstract
  2. Chien, M. F., M. Narita, K. H. Lin, Matsui, K., C. C. Huang, and G. Endo. 2010. Organomercurials removal by heterogeneous merB genes harboring bacterial strains. Journal of Bioscience and Bioengineering110: 94-98. Abstract
  3. Matsui, K., M. Narita, G. Endo. 2007. Transoceanic and transcontinental dispersal of bacteria and genes : Global dissemination of mercury resistance bacteria and mercury resistance genes.(in Japanese) Japanese Journal of Ecology 57: 390-397. Abstract
  4. Matsui, K., K. Yusa, H. Sugawara, M. Narita, G. Endo. 2007. Development of Bacterial Biosensor for Detecting Organomercurials Using Organomercurial Lyase Gene and Bioluminescence Reporter System. (in Japanese) Journal of Japan Society on Water Environment 30: 77-81.Abstract
  5. Endo, G., K. Matsui, M. Narita. 2006. Horizontal gene transfer in environmental purification microorganisms: consideration of the use of living modified organisms in the uncontained environments from the evidence of mercury resistance genes as microbial common properties. (in Japanese)  Journal of Environmental Biotechnology, 6: 27-32. Abstract
  6. Matsui, K., M. Narita, H. Ishii, G. Endo. 2005. Participation of the recA determinant in the transposition of class II transposon mini-TnMERI1FEMS Microbiology Letters 253: 309-314. Abstract
  7. Narita, M., K. Matsui, C. C. Huang, Z. Kawabata, G. Endo. 2004. Dissemination of TnMERI1-like mercury resistance transposons among Bacillus isolated from worldwide environmental samples. FEMS Microbiology Ecology 48: 47-55. Abstract
  8. Gupta, A., K. Matsui, J.F. Lo and S. Silver. 1999. Molecular basis for resistance to silver in SalmonellaNature Medicine 5: 183-188. Abstract
  9. Silver, S., A. Gupta, K. Matsui and J. F. Lo. 1999. Resistance to Ag(I) cations in bacteria: environments, genes and proteins. Metal-Based Drugs 6: 315-320. Abstract

2. Biodiversity and multifunctionality in microbial ecology

<Related publications>

  1. Miki, T., T. Yokokawa, K. Matsui. 2014. Biodiversity and multifunctionality in a microbial community: a novel theoretical approach to quantify functional redundancy. Proceedings of the Royal Society B 281: 20132498. Open access

3. Dissolved DNA & Horizontal Gene Transfer in aquatic environment

<Related publications>

  1. Ishii, N., K. Matsui,. S. Fuma, H. Takeda, Z. Kawabata. 2004. Release of transforming plasmid DNA from actively growing genetically engineered Escherichia coliFEMS Microbiology Letters 240: 151-154. 抄録
  2. Matsui, K., N. Ishii, M. Honjo, Z. Kawabata. 2004. Use of the SYBR Green I fluorescent dye and a centrifugal filter device for rapid determination of dissolved DNA concentration in fresh water. Aquatic Microbial Ecology 36: 99-105. 抄録
  3. Matsui, K., N. Ishii and Z. Kawabata. 2003. Microbial interactions affecting the natural transformation of Bacillus subtilis in a model aquatic ecosystem. FEMS Microbiology Ecology 45: 211-218. 抄録
  4. Matsui, K., N. Ishii and Z. Kawabata. 2003. Release of extracellular transformable plasmid DNA from Escherichia coli cocultivated with algae. Applied and Environmental Microbiology 69: 2399-2404. 抄録
  5. Matsui, K., M. Honjo and Z. Kawabata. 2001. Estimation of the fate of dissolved DNA in thermally stratified lake water from the stability of exogenous plasmid DNA. Aquatic Microbial Ecology 26: 95-102. 抄録

4. Microbial community composition and water quarity in urban river