Bacteria Could Help Build Better Bone Replacements

Serratia bacteria, which manufacture nanoscale hydroxyapatite (HA), could be used to make stronger, more durable bone implants, claims a new study.

Researchers from the University of Birmingham (UK) have shown that when challenged with a solution containing calcium chloride and phosphatase substrate, Serratia bacteria manufactures a biofilm containing biopolymers that adhered tightly to different surfaces, such as titanium alloy, polypropylene, porous glass, and polyurethane foam. The biofilm-bound material was identified as containing HA, a coating of which then builds up over the surface. This HA biocoating method is able to reach hidden recesses and surfaces that the bacteria can reach, but that regular industrial processes cannot. The bacterial HA also has better properties than HA that is manufactured chemically, since the nanocrystals of HA produced are much smaller, giving them a high mechanical strength.

For practical use, the materials need to be dried and heated to destroy the Serratia bacteria. Testing bond strength showed that dried biofilm bond to the surfaces was 20-times stronger than fresh biofilm. When coating with HA was completed, the adhesion was several times higher again; and slightly roughening the surfaces made the bioglue much more effective. The study was presented at the Society for General Microbiology's annual meeting, held during September 2009 in Edinburgh (UK).

"The bacteria are destroyed by heating, leaving just the HA stuck to the surface with their own glue--rather akin to a burnt milk-saucepan," said study presenter Prof. Lynne Macaskie, Ph.D., of the school of biosciences. "We need to do more work actually to turn the materials into materials we can use in biomedicine and the environment. Then they need to be tested in real life situations with clinical and environmental trials."

Serratia is a genus of Gram-negative, facultatively anaerobic, rod-shaped bacteria of the Enterobacteriaceae family. Members of this genus produce characteristic red pigment called prodigiosin.

University of Birmingham


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