Ultrastructure of the microbial consortia

of the orange slime of Cornus controversa

Junhyung Park1, Eunjin Kim2, Minkyung Park2,

Sujin Jang2, Ohkyung Kwon2, Ki Woo Kim1,3

1Department of Ecology and Environmental System, Kyungpook National University

2National Instrumentation Center for Environmental Management,

Seoul National University

3Tree Diagnostic Center, Kyungpook National University

E-mail: kiwoo@knu.ac.kr

The microbial consortia of the orange slime of Cornus controversa were observed using a transmission electron microscope. The tree sap was exuded from a wounded stem in early spring and turned to the orange slime thereafter. The orange slime comprised microbial consortia composed of bacteria and fungi including filamentous fungi and budding yeasts. The bacteria were mostly rod-shaped and present among fungal hyphae. No degradation of fungal cell walls was found around bacteria. The fungi formed mycelial mats having septate hyphae with Woronin bodies and three-celled conidia. Budding yeasts were often found with asymmetric division yielding a daughter cell outside the mother cell. Some hyphae were not partitioned by septa, forming pseudohyphae. These observations suggest that the microbial consortia may establish non-parasitic associations, sharing ecological niches on the tree bark. The yeasts are assumed to undergo the dimorphic switch to the pseudohyphae form for nutrient acquisition.

Keyword: giant dogwood, orange slime, transmission electron microscope