Height Matters in Microbe Slime Jungles Say Scientists

Posted on April 23, 2014

Mutant cells position themselves at the top of a slime jungle, or biofilm

An international team of scientists led by Oxford University researchers has demonstrated a link between the success of cells within a slime jungle and their ability to position themselves. In a series of experiments with a soil bacterium (Pseudomonas fluorescens), the team found that mutant bacteria that used secretions to grow upwards into 'towers' were more successful than 'normal' bacteria that lay low. The height enables cells to gain the best access to oxygen. The researchers compare it to trees in a jungle growing tall to get the best access to sunlight. The 3D rendering above shows multiple patches of loosely packed mutant cells (yellow) pushing through and over the densely packed parent cells (red).

Studying biofilms is important because bacterial communities account for 80% off all chronic infections. Some have evolved resistance to antibiotics.

Professor Kevin Foster of Oxford University's Department of Zoology, an author of the paper published in PNAS, says in a statement, "These biofilm colonies are the jungles of the microbial world, where bacteria live in close proximity and jostle for space and nutrients. This makes for a very competitive world where getting to the best position can be everything, like trees growing tall in a jungle to get the best access to light."

Dr Wook Kim of Oxford University's Department of Zoology, first author of the paper, says, "Our experiments show that in these dense communities bacteria that evolve to push themselves to the surface of a colony gain a considerable advantage over their rivals - an advantage that disappears if these cells are moved around or prevented from building upwards."

The research paper, "Importance of positioning for microbial evolution," can be found here on PNAS.

Image: Oxford