Abstract (eng)
Carnivorous plants trap and utilise tiny animals to supplement their mineral nutrition. The process of prey capture consists of four steps: (1) Attraction of animals, (2) their retention by specialised trap leaves, (3) degradation of the prey either by enzymes produced by the plant or by symbiotic organisms and (4) absorption of nutrients by the plant.
This thesis deals with the occurrence of bacteria and fungi in the traps of two unrelated species of pitcher plants, Sarracenia purpurea (Sarraceniaceae) and Nepenthes ×ventrata (Nepenthaceae). For the characterisation of traps and inquilines, different microscopical techniques like CLSM, REM and conventional light microscopy were used. New molecular methods, like the full cycle 16S rRNA approach, which cover the whole bacterial diversity, in comparison with common cultivation methods were applied.
Quantification of bacteria by DAPI staining in situ (total number of bacteria) in comparison with cultivation on different media (cultivable units per ml) showed that only about 2% of the pitcher fluid’s bacteria are cultivable. The numbers of bacteria do not significantly differ between the two species.
Traps of S. purpurea host a higher biodiversity of bacteria, especially more symbionts / mutualists, which are beneficial for the plant. N. x ventrata secrets a wide range of digestive enzymes and features an acid pitcher fluid, which may be the reason for the low species diversity. It’s likely that a large part of the pitcher inquilines, mostly bacteria, are responsible for the degradation of the prey in S. purpurea, whereas N. ventrata relies on digestive enzymes produced by the plant itself.