Exploiting the fungal highway: development of a novel tool for thein situisolation of bacteria migrating along fungal mycelium

Abstract

Fungi and bacteria form various associations that are central to numerous environmental processes. In the so-called fungal highway, bacteria disperse along fungal mycelium. We developed a novel tool for the in situ isolation of bacteria moving along fungal hyphae as well as for the recovery of fungi potentially involved in dispersal, both of which are attracted towards a target culture medium. We present the validation and the results of the first in situ test. Couples of fungi and bacteria were isolated from soil. Amongst the enriched organisms, we identified several species of fast-growing fungi (Fusarium sp. and Chaetomium sp.), as well as various potentially associated bacterial groups, including Variovorax soli, Olivibacter soli, Acinetobacter calcoaceticus, and several species of the genera Stenotrophomonas, Achromobacter and Ochrobactrum. Migration of bacteria along fungal hyphae across a discontinuous medium was confirmed in most of the cases. Although the majority of the bacteria for which migration was confirmed were also positive for flagellar motility, not all motile bacteria dispersed using their potential fungal partner. In addition, the importance of hydrophobicity of the fungal mycelial surface was confirmed. Future applications of the columns include targeting different types of microorganisms and their interactions, either by enrichment or by state of the art molecular biological methods.

Enhanced Tolerance to Cadmium in Bacterial-Fungal Co-Cultures as a Strategy for Metal Biorecovery from e-Waste

“…The FH columns described in Simon et al [48] allowed for the isolation of several bacterial and fungal strains directly from a Cd-contaminated soil. During the field sampling the Cd-containing target-media of the FH columns permitted to isolate Cd-tolerant bacterial and fungal strains showing the good performance of the isolation device.…”

“…One striking aspect of the BF couple isolation is that the FH column device was designed to isolate bacterial-fungal couples that present the FH interaction [48]. Despite this, passing from soil to isolation in Petri dishes averted the FH mechanism.…”

“…Total Cd concentration rises in the deepest part of the soil but Cd bioavailability can be higher at the surface as a result of organic acid leaching by plants and microbes [46]. Therefore, BF couples were isolated from the surface of these soils using FH columns as designed by Simon et al [48]. Both the attracting and the target media consisted of a malt extract (12 g/L; SIOS Home Brewing) and agar (15 g/L; Biolife italiana; MA) medium enriched with 0.05 mM and 0.1 mM Cd (as cadmium sulfate octahydrate-CdSO 4 ·8H 2 O; Sigma-Aldrich, St. Louis, MO, USA) in order to represent the highest and lowest Cd concentrations measured in Quezada-Hinojosa et al [36].…”

“…In order to isolate pure fungal and bacterial strains, the target media of each FH column was cut in 4 pieces as described in Simon et al [48]. From these, 2 pieces were inoculated on a MA medium and the other 2 pieces were immersed in 1 mL physiologic water (9 g/L NaCl; Sigma-Aldrich) and agitated using a vortex.…”

Distinctive Feature of Microbial Communities and Bacterial Functional Profiles in Tricholoma matsutake Dominant Soil

“…Enrichment of fungiphiles in the hyphal dominant environment is thought to be connected with specific traits. For example, fungiphiles can use surface of hyphae to move on like a highway [82, 83], and have T3SS mediating interactions with fungi [60]. Moreover, fungiphiles can use the material excreted from the hyphae ( e .…”