Symbiosis with bacteria enhances the use of chitin by the springtail,Folsomia candida(Collembola)

摘要

The relationship betweenFolsomia candidaand chitin-degrading microorganisms was studied. On chitin agar, 1010bacteria were isolated per g faeces, and 3.8×1011bacteria per g gut contents, 1/3 of them showing a clear (chitin-free) zone around the colony. The most abundant chitin-degrading bacteria wereXanthomonas maltophiliaandCurtobacteriumsp. To determine the bacterial contribution in the use of chitin byF. candida, a feeding experiment was carried out.F. candidawere fed with chitin, either amended with or without tetracycline as an inhibitor of bacteria. When tetracycline was omitted the biomass ofF. candidawas increased compared to those fed chitin with tetracycline. However, this result was observed only when the food replacement intervals were long enough to allow bacterial colonization before ingestion of the food. In a food-selection experiment, a preference for chitin colonized with microorganisms as opposed to sterile chitin was found. The results indicate that a mutualistic symbiosis ofF. candidawith chitinolytic microorganisms is likely to enhance chitin degradation. This relationship is not only intra-intestinal but also involves an extra-intestinal phase