Abstract

Tannase enzymes hydrolyze tannins, a class of plant polyphenolics that defend against herbivory. Prior to the 1980’s, most studies were focused on the tannase gene in fungi owing to the interest surrounding their industrial value. Since then a large number of bacterial tannase genes have also been discovered. I performed phylogenetic analysis on 110 fungal and bacterial tannase reference sequences in an effort to observe the relationships between fungal and bacterial tannase. The generated maximum likelihood tree shows eight strongly supported tannase clades, with a rift among fungal tannases, which either align with proteobacterial tannase or actinobacterial tannase. Metagenomes were used to assess the biogeographical distribution of the tannase clades, revealing that they may have environmental specificity.

An unpublished observation made by the Despland lab of Concordia University suggested that forest tent caterpillars (Malacosoma disstria) from western Canada are unable to survive on tannin-rich sugar maple foliage (Acer saccharum), whereas populations in eastern Canada develop on sugar maple. In Chapter 2 I examine this observation, and explore the possibility of tannase-expressing secondary symbionts in eastern M. disstria. For the first time, the microbiome of M. disstria has been described using 16S rRNA gene sequencing and is shown to contain several genera known for expressing the tannase gene.