AME 40:77-83 (2005)  -  doi:10.3354/ame040077

Do nematode mucus secretions affect bacterial growth?

Tom Moens1,*, Giovanni Amadeu Paiva dos Santos1,2, Fabiano Thompson3,4,Jean Swings3,4, Verônica Fonsêca-Genevois2, Magda Vincx1, Ilse De Mesel1,3

1Ghent University, Biology Department, Marine Biology Section, Krijgslaan 281/S8, 9000 Gent, Belgium
2Federal University of Pernambuco, Centre for Biological Sciences, Zoology Department, Avenida dos Reitores 1235-CidadeUniversitaria, 50670-420 Recife-Pernambuco, Brazil
3Ghent University, Laboratory of Microbiology, K.L. Ledeganckstraat 35, 9000 Gent, Belgium
4BCCMTM/LMG Culture Collection, Laboratory of Microbiology, K.L. Ledeganckstraat 35, 9000 Gent, Belgium

ABSTRACT: Many aquatic nematodes secrete mucus while moving, and prominent microbial growth on nematode mucus tracks has been observed. This has been interpreted as a mutualistic interaction in which nematodes may feed on the micro-organisms that colonise their tracks (i.e. the mucus-trap hypothesis). Because of recent evidence that nematodes can affect bacterial community composition, we tested whether bacterial communities growing on nematode mucus differ from extant communities. We characterised the bacterial epigrowth of tracks produced on agar by 2 estuarine nematode species (the facultative predator Adoncholaimus fuscus and the bacterivore Geomonhystera disjuncta) and compared it to that of artificial tracks and to the bacterial inocula. The experiment lasted 8 d, with bacterial community analyses (using fatty acid methyl ester [FAME] analysis) after 2, 4, 6 and 8 d. Although our experimental design promoted a low-diversity bacterial community, multidimensional scaling generally separated communities on nematode tracks from inocula, artificial track communities typically being intermediate and highly variable. In a total of 6 bacterial inocula spotted with A. fuscus, only 1 bacterial strain was recorded on nematode tracks, compared to 6 on artificial tracks and 7 in the inocula. In addition, colony morphology of this particular bacteria, Pseudoalteromonas tetraodonis, was less diverse on nematode tracks than on artificial tracks or inocula. Treatments with G. disjuncta yielded similar yet less consistent and less pronounced results. Our results suggest that nematode mucus may affect colonisation and succession patterns of bacteria. This may have important implications for food-web interactions and ecosystem functions involving both bacteria and nematodes.

KEY WORDS: Nematodes · Bacteria · Nematode mucus · Microbial community composition ·Facilitation · Microbial food webs

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