Bacteria diversify

Infectious bacteria often grow in their hosts as biofilms. Blaise Boles, Matthew Thoendel, and Pradeep Singh (University of Iowa, Iowa City, IA) now report that growth in biofilms causes Pseudomonas aeruginosa bacteria to diversify. The resultant diverse populations are probably more able to cope with changing environmental conditions, providing a bacterial correlate of the resistance of diverse forest ecosystems.

Earlier workers recognized that these bacteria, when isolated from their human hosts, show a remarkable degree of diversification. Singh's group noted a similar diversity of colony morphology after a brief in vitro passage through biofilm conditions. After ruling out contamination, the team observed that diversity extended to bacterial nutrient requirements, swimming abilities, and production levels of a protective pigment. Biofilms grown from small flat colonies were better at dispersing their progeny and biofilms grown from tall,...