Some microorganisms stick together to form impenetrable, drug-resistant biofilms that can contaminate surfaces such as those of medical devices. The yeast Candida albicans is one such microbe, but certain strains form another type of biofilm — one that is susceptible to drugs and is regulated by a different molecular pathway.

David Soll and his colleagues at the University of Iowa in Iowa City found that about 10% of C. albicans strains form this second type of biofilm, which is also permeable to immune cells. These strains have a genetic difference at one locus that allows the yeast to reproduce sexually. The authors suggest that this minority type of biofilm aids in the mating process by mediating the movement of hormone signals.

Comparing the different pathways that regulate the two types of biofilm could yield clues about what makes a biofilm drug-susceptible, which could aid in the development of treatments to disrupt harmful biofilms.

PLoS Biol. 9, e1001117 (2011)