Analysis of batrachochytrium dendrobatidis gene expression in planktonic versus biofilm life cycle stages

Batrachochytriun dendrobatidis(Bd) is a chytrid fungus that has been recognized as the most likely cause for the massive amphibian declines worldwide. Previous studies in our lab have shown the ability of Bd to form a biofilm. Genes, GGDEF, EAL, Zap1, ADH3, CS1, CS2, and Cps1p, that play roles in biosynthesis and hydrolysis of cyclic-di-GMP, inhibition of extracellular matrix production, regulation of chitinous cell wall production, respectively, are known to be involved in the biofilm formation of both fungi and bacteria. Expression profiles of these genes were compared between biofilm and planktonic cells, through reverse transcriptase and quantitative real-time polymerase chain reactions (RT-PCR & qPCR). Analyses were carried out using the 5.8S rRNA gene as an internal standard. A phenotypic microarray (FUNGILOG) was also used to compare carbon utilization differences between biofilm and planktonic cells. Our results indicate that Cps1p, ADH3, Zap1, CS1 and CS2 genes are highly expressed in the biofilm stage being up-regulated 12-fold, 10-fold, 5-fold and 3-fold respectively. Differential expression of Cps1p and ADH were statistically significant (p value = 0.0104 and 0.0016 respectively). The carbon utilization studies indicate that there were no significant differences in carbon utilization between the two life stages of the fungus. These studies will provide good insight about the survival of Bd in the environment without its animal host.