Open AccessGrowth and symbiotic effectiveness of an arbuscular mycorrhizal fungus in organic matter in competition with soil bacteria
Author(s) -
Leigh Joanne,
Fitter Alastair H.,
Hodge Angela
Publication year - 2011
Publication title -
fems microbiology ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.377
H-Index - 155
eISSN - 1574-6941
pISSN - 0168-6496
DOI - 10.1111/j.1574-6941.2011.01066.x
Subject(s) - biology , hypha , lolium perenne , organic matter , fungus , microcosm , glomeromycota , botany , lysis , mycorrhiza , microorganism , colonization , arbuscular mycorrhiza , competition (biology) , shoot , bacteria , symbiosis , microbiology and biotechnology , ecology , poaceae , biochemistry , genetics
Arbuscular mycorrhizal (AM) fungi can enhance the rate of decomposition of organic material, and can acquire nitrogen (N) from organic sources, although they are not saprotrophs. These fungi may instead indirectly influence decomposition through interactions with other soil microorganisms. We investigated the impact of both AM hyphae and a bacterial filtrate on N capture by a host plant from sterilized organic material ( Lolium perenne shoots dual labelled with 15 N and 13 C), using compartmented microcosms. The addition of a bacterial filtrate considerably suppressed AM hyphal growth in the patch and reduced the root phosphorus content, demonstrating that bacterial populations can reduce symbiotic effectiveness. In contrast, AM hyphae had only a limited impact on bacterial community structure. Uptake of 15 N greatly exceeded that of 13 C, demonstrating that fungi acquired N in an inorganic form. We also examined the ability of AM fungi in gnotobiotic hairy root culture to acquire N directly from organic materials of varying complexities (glutamic acid, urea, bacterial lysate and L. perenne shoots). AM colonization did not enhance root N capture from these materials, although the bacterial lysate reduced both total AM colonization and arbuscule frequency. Collectively, these data demonstrate antagonistic interactions between AM fungi and bacteria that reflect resource competition for decomposition products.