African Journal of

  • Abbreviation: Afr. J. Biotechnol.
  • Language: English
  • ISSN: 1684-5315
  • DOI: 10.5897/AJB
  • Start Year: 2002
  • Published Articles: 12487

Full Length Research Paper

Growth responses of Escherichia coli and Myxococcus xanthus on agar gel substrates with different levels of stiffness

Eun-Jung PARK1#, Myoung-Ock CHO1#, Donghee LEE1 and Jung Kyung KIM2,3*
  1Department of Mechanical Engineering, Graduate School, Republic of Korea. 2Department of Integrative Biomedical Science and Engineering, Graduate School, Republic of Korea. 3School of Mechanical Systems Engineering, Kookmin University, Jeongneung-ro 77, Seongbuk-Gu, Seoul 136-702, Republic of Korea.
Email: [email protected]

  •  Accepted: 24 September 2012
  •  Published: 01 November 2012



Bacteria colonize surfaces responding to the physicochemical properties of substrates. A systematic study was carried out with growing single bacterial colonies on the surface of agar media to decipher the interaction between bacterial growth and substrate stiffness. We investigated the growth kinetics of wild-type Escherichia coli, non-motile E. coli, and Myxococcus xanthus, cultured on semi-solid agar substrates containing different amounts of nutrient and agar. We found that substrate stiffness, which was controlled by agar concentration, modulates the growth of motile bacteria, such as wild-type E. coli and M. xanthus, independently of the nutrient level, but does not affect the growth response of non-motile E. coli. Interestingly, growth of M. xanthus moving with type IV pili correlates negatively with the substrate stiffness in contrast to wild-type E. coli propelled by flagella. The present study demonstrates that the type of surface motility is a key determinant of the growth response of bacteria to substrate stiffness, and has potential application to the design of surfaces that prevent or promote biofilm formation.

Key words: Bacterial colonization, substrate stiffness, surface motility, swarming, Escherichia coli, Myxococcus xanthus