Isolation of Serratia marcescens involved in chitin degradation in the bulb mite Rhizoglyphus robini

There is an increasing awareness of the importance of the microbiome of arthropods to understand their host’s biology. In the bulb mite, Rhizoglyphus robini, associated bacteria have been found to be involved in its chitinolytic abilities. The bulb mite, a plant pest feeding on below- ground parts of mostly Liliaceae crops, prefers fungus- infested plants. Moreover its fitness is higher when feeding on a fungal food source than when feeding on non-infected plants. In this study we isolated a chitinolytic bacterium from mite homogenate and identified it molecularly as Serratia marcescens (Bizio 1823), which is a model organism for chitin degradation. Precise identification of the bacterium can be important for the development of biological control programs of the mite as well as for further studies investigating Serratia marcescens and its chitinolytic machinery.

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Symbiontes et arthropodes – quelles implications pour la lutte biologique?

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Une version vulgarisée (en français AFS_01_13_F_Aebi et en allemand AFS_02_13_D_Aebi) d’un article paru dans le Journal of Applied Ecology, publiée dans Recherche Agronomique Suisse.

Zindel R, Gottlieb Y, Aebi A. (2011) Arthropod symbiosis, a neglected parameter in pest and disease control programs. Journal of Applied Ecology 48: 864–872

Gut microbiome rules what a mite can eat. New paper in The FASEB Journal

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The biology of many arthropods can only be understood when their associated microbiome is considered. The nutritional requirements of the bulb mite Rhizoglyphus robini Claparede (Acari: Astigmata: Acaridae) in the laboratory have been shown to be very easily satisfied, and in the field the mites prefer fungus-infected over uninfected plants. To test whether symbiotic bacteria facilitate the survival of R. robini on a nutritionally-unbalanced diet, we investigated the composition of its microbiome. Using 454 pyrosequencing of 16S rRNA gene fragments, three genera were found to dominate the bacterial community: Myroides  (41.4%), Serratia  (11.4%) and Alcaligenes  (4.5%); the latter two are known to include chitinase producing species. Laboratory experiments demonstrated that mite fecundity is significantly higher (2 times) on fungus than on controls (sterilized potato dextrose agar and filter paper). Also, when mite homogenate was applied to a chitin layer, the halo produced through degradation was clearly visible while the saline control did not produce a halo. We thus concluded that R. robini utilizes fungal chitin, at least to a certain extent, as a food source with the help of its associated bacteria. This information supports the general concept of multigenome organisms and the involvement of bacteria in the mite’s nutritional ecology.

Renate Zindel, Maya Ofek, Dror Minz, Eric Palevsky, Einat Zchori-Fein, and Alexandre Aebi (2013) The role of the bacterial community in the nutritional ecology of the bulb mite Rhizoglyphus robini (Acari: Astigmata: Acaridae) FASEB J fj.12-216242; published ahead of print January 10, 2013, doi:10.1096/fj.12-216242 available here