Fungus-associated bacteriome in charge of their host behavior

Abstract

25Bacterial-fungal interactions are widespread in nature and there is a growing number of 26 studies reporting distinct fungus-associated bacteria. However, little is known so far about how 27 shifts in the fungus-associated bacteriome will affect the fungal host's lifestyle. In the present 28 study, we describe for the first time the bacterial community associated with the saprotrophic 29 fungus Mucor hiemalis, commonly found in soil and rhizosphere. Two broad-spectrum 30 antibiotics that strongly altered the bacterial community associated with the fungus were 31 applied. Our results revealed that the antibiotic treatment did not significantly reduce the 32 amount of bacteria associated to the fungus but rather changed the community composition 33 by shifting from initially dominating Alpha-Proteobacteria to dominance of Gamma-34 Proteobacteria. A novel approach was applied for the isolation of fungal-associated bacteria 35which also revealed differences between bacterial isolates obtained from the original and the 36 antibiotic-treated M. hiemalis. The shift in the composition of the fungal-associated bacterial 37 community led to significantly reduced fungal growth, changes in fungal morphology, behavior 38 and secondary-metabolites production. Furthermore, our results showed that the antibiotic-39 treated isolate was more attractive and susceptible to mycophagous bacteria as compared to 40 the original isolate. Overall, our study highlights the importance of the fungus-associated 41 bacteriome for the host's lifestyle and interactions and indicate that isolation with antibacterials 42 is not sufficient to eradicate the associated bacteria. 43 44 3

Calling from distance: attraction of soil bacteria by plant root volatiles

“…Moreover, it is unknown if plants can actively recruit beneficial soil microorganisms by emitting VOCs into the rhizosphere. Recent studies on microbial VOCs demonstrated that bacterial motility can be stimulated by VOCs [23][24][25], although the applied test systems were rather artificial.…”

The ecological role of volatile mediated interactions belowground

“…shown to affect the production of VOCs in fungi (Schulz-Bohm et al 2016;Splivallo et al 2015) and in addition, they can affect the fungal plant-pathogenicity and repress the expression of fungal virulence genes (Minerdi et al 2009). Therefore, a holistic approach considering the effect of mVOCs on belowground soil community is needed.…”

“…A fungal plug (1 cm diameter) with F. culmorum pre-grown on 0.5 PDA was transferred to the top of a Petri-dish which was filled with 20 ml WA + ARE (Schulz-Bohm et al 2016).…”

“…After 24 h incubation at 25°C, 50 µl of a bacterial suspension consistent of 10 8 CFU ml -1 was spread out in the middle of the Petri-dish (Schulz-Bohm et al 2016). The bacterial suspension was prepared as described above.…”

“…Moreover, it is unknown if plants can actively recruit beneficial soil microorganisms by emitting VOCs into the rhizosphere. Recent studies on microbial VOCs demonstrated that bacterial motility can be stimulated by VOCs (Garbeva et al 2014a;Schmidt et al 2016;Schulz-Bohm et al 2016), although the applied test systems were rather artificial.…”