Table 1.
Fungi and bacteria used in this study.
Fig 1.
Bleached and pigmented wood after fungal infection in nature.
(A) Pigmented wood near to fruiting bodies of S. commune and bleaching around P. ostreatus, (B) corresponding demarcation lines in walnut wood with pigmented area in the right, which is expected to be colonized by S. commune, (C) pigment production by S. commune in walnut wood.
Fig 2.
Behavior of S. commune on wood blocks.
(A) aerial mycelium formation and (B) fruiting body formation beginning at the bark on ash wood, (C) wood decay on bright walnut wood all with S. commune 1-32x12-43 after 1 month of incubation, (D) co-culture of S. commune 4–39 with P. ostreatus on apple tree wood after 1 month, microscopic investigation of S. commune hyphae penetrating vessels (red arrow) of apple tree wood with (E) depth resolution from 0 μm (red) to 20 μm (blue), which is a small section of (F, G) showing a reduction of cell walls in axial direction of wood (white arrows) close to hyphae, and a tangential longitudinal section of wood with cellulose and chitin staining.
Fig 3.
Phenotypic changes due to bacterial interactions.
Interactions were investigated (A-H) and recognition of nutrient sources by S. commune (I-K) is shown. (A) Zone of inhibition with blocked S. commune 4–39 growth besides inoculation with B. subtilis on PDA, (B) compacted mycelium around fungal inocula of 12-43x4-39 with dark yellow bacterial colonies of B. subtilis growing on the fungal hyphae (white arrows) on CYM and an empty line between hyphae and colony formed around the bacterial inoculation strike (black arrow), (C) dark spots on bacterial colonies of S. acidiscabies with MG101028_06 on PDA, (D) MG101028_06 with pigment secretion by E. amylovora Ea273 into PDA medium, (E) red bacteria stain of S. marcescens shown on S. commune 4–39 mycelium on PDA, (F) increased aerial mycelium formation of 12-43x4-39 alongside the inoculum E. amylovora Ea273 on PDA, (G) hyphal aggregates (white arrow) formed on a bacterial colony of P. agglomerans C9-1 with 12-43x4-39 on CYM, and (H) primordia induction (black arrow) on non-fertile S. commune monokaryon 12–43 with B. subtilis on CYM. Mycelium of S. commune 12–43 formed to reach colonies of E. amylovora (left line) in co-inoculation on MM after 21 d (I) in a distance of 6 cm; (J) at a distance of 8 cm, the mycelium starts to overgrow bacteria; (K) in 10 cm distance, directed growth toward the colony of the bacteria by submerged hyphae was shown; (L) and bacteria of S. marcescens hiking on the fungal hyphae could be observed on agar medium in glass bottom dishes. A-H were inoculated in 9 cm Petri dishes, I-K in 12 cm Petri dishes.
Fig 4.
Fungal interactions showing (A) deadlock, (B) replacement, and (C) induction of fruiting bodies in the interaction zone.
The light grey area represents the colony of S. commune, the dark grey area represents the colony of the interacting fungus and the white box the agar plug. (A) F. velutipes and S. commune 12–43 at 10°C, (B) S. lacrymans and S. commune 12–43 at 28°C, and (C) G. lucidum and S. commune 12-43x4-39 at 28°C after 1 month of co-cultivation.
Fig 5.
Induced pigment production of S. commune in interaction.
(A) Here S. commune MG_101028_06 with K. mutabilis inoculated at the right side of the agar plate, (B) slightly magnified rear view with S. commune in the upper and K. mutabilis in the lower part of the photo, and (C) excreted blue pigments from hyphae of S. commune on the left visualized by light microscopy. (D) Aerial mycelium of S. commune 12-43x4-39 with excreted blue pigments in guttation droplets, (E) dark homogenous gel-like structures within hyphae, and (F) dark crystals in the medium.
Table 2.
Metabolites from co-cultures of S. commune/ K. mutabilis, measured by UHPLC-ESI-MS (1st two blocks) and UHPLC-APCI-MS (3rd block).
Fig 6.
Relative expression of laccases and laccase-like multi-copper oxidases.
Data show (A) monokaryon S. commune 4–39 compared to the dikaryon 4-39x12-43, (B) monokaryon S. commune 4–39 of fungus-fungus interaction, (C) dikaryon 4-39x12-43 of fungus-fungus interaction, all after 4 dpi, and (D) 4–39 during lignin degradation after 5 dpi. *Significance level, p < 0.05.
Fig 7.
Laccase activity assay for fungus-fungus interaction of the monokaryon S. commune 4–39 and the dikaryon S. commune 4-39x12-43 with (A) intracellular and (B) extracellular laccase activity measurement for the dikaryon after 4 dpi.
No extracellular laccase activity was measurable for the monokaryon S. commune 4–39. *Significance level with regard to single cultivation, p < 0.05.