SRA

Carnivorous plants of the genus Nepenthes have been studied for over a century, but surprisingly little is known about associations with microorganisms. The two species Nepenthes rafflesiana and Nepenthes hemsleyana differ in their primary nutrient source, sequestering nitrogen from arthropod prey and bat faeces, respectively. We expected bacterial communities living in the pitchers to resemble this diet difference. Samples were taken from different parts of the pitchers (leaf, peristome, inside, outside, digestive fluid) of both species. Bacterial communities were determined using culture-independent high-throughput amplicon sequencing. Bacterial diversity and community structure was comparable across plant species and most tissues, except digestive fluids. These showed opposing trends with N. hemsleyana harbouring a more diverse bacterial community. In N. rafflesiana fluid, high levels of Acidocella spp. implied a close association with the plant. In N. hemsleyana fluid, vertebrate gut symbionts as well as saprophytic taxa could be detected, the latter of which might act as competitors for nutrients. Generally, digestive fluid communities were highly variable in structure, which might be applicable to a difference in digestion status. Nitrogen-fixing bacteria were present in both study species, which might provide essential nutrients to the plant at times of low prey capture and rare encounters with bats, respectively.