Aerial mycelium

Nevertheless, many mutants lacking hydrophobins produce aerial mycelium. Other hydrophobic proteins have been implicated as possible candidates for the hydrophobin-independent formation of aerial mycelium such as repellents of Ustillago maydi or Scl5 protein of SchizophylU... 

There are indications that an additional regulatory pathway, sky, is involved in the full differentiation of aerial mycelium following its release from the substrate. 

Antibiotic production and morphological differentiation (formation of aerial mycelium and sporulation) in Streptomyces species and in some other actinomycetes is regulated by small signaling molecules called y-butyrolactones or butanolids. These quorum-sensing signals bind to... 

Ma H, Kendall K, Cloning and analysis of a gene cluster from S. coelicolor that causes accelerated aerial mycelium formation in S. lividansj Bacteriol 176 3800-3811, 1994. 

Willey JM, Schwedock J, Losick R, Multiple extracellular signals govern the production of a morphogenetic protein involved in aerial mycelium formation hy Streptomyces coelicolor, Genes Dev7 A95-90 i, 1993. 

Figure 1 Life cycle of Streptomyces. The life cycle of S. griseus, a representative of Streptomyces, is shown. A-factor is essentially required for the progression of the step from substrate mycelium to aerial mycelium. Sm, streptomycin GX, grixazone. Reproduced from Y. Ohnishi S. Horinouchi, Biofilms 2004, 1, 319-328.

Our next question was whether ArpA targets only adpA. Because ArpA acts as a repressor of aerial mycelium formation and secondary metabolism, an arpA disruptant forms aerial hyphae and spores earlier than the wild-type strain and overproduces streptomycin and other secondary metabolites. On the other hand, mutant KM2, expressing a mutant ArpA (Trpl 19Ala), neither produces secondary metabolites nor forms aerial hyphae, since this A-factor-insensitive mutant ArpA always binds to and represses the adpA promoter. Trp-119 of ArpA is essential for A-factor binding, and replacement of this Trp residue with Ala abolishes its A-factor-binding... 

If the colony surface is scratched by a needle the vegetative mycelium, which lies under the aerial mycelium, presents a ink or fleshy color. The above-said characteristics represent a particul8ir feature of these strains, that have never been observed in other strains of Claviceps isolated. 

Corn steep medium.—Vegetative growth abundant, compact, smooth, deep red-brown (15-lOE) margin radiative aerial mycelium fasciculate, light brown (11-2E) colorless exudate brown soluble pigment. 

Potato-glucose medium.— Vegetative growth moderate, red-brown (14-11E3) aerial mycelium floccose, white neither exudate nor soluble pigment produced. 

Sasamino acid-sucrose medium.—Vegetative growth fair, restricted, deep brown (16-lOA), margin radiative aerial mycelium floccose, dark brown (12-6E) brown soluble pigment. 

Alphacel-coconut milk medium.— Vegetative growth fair, smooth, brown (14-8F) aerial mycelium white, velutinose brown soluble pigment. 

In 1986, Keller-Schierlein, ZShner and their respective coworkers isolated ( )-differolide (135, Figure 5.14) from cultures of an actinomycete, Streptomyces aurantiogriseus Tii 3149. This compound ( )-135, whose structure was determined by X-ray diffraction studies, was reported to enhance the formation of aerial mycelium and spores of Streptomyces glaucescens. Especially noteworthy was the fact that the natural product was racemic. There are some examples of the occurrence of racemic and bioactive natural products such as magnosalicin (10) and olean (116), but they are rare. Although there was a straightforward Diels-Alder synthesis of ( )-135 by dimerization of 2-vinyl-2-buten-4-olide, this method would not afford the enantiomers of 135. 

Carbazomycinal and 6-methylcarbazomycinal, inhibitors of aerial mycelium formation, are produced by Streptoverticillium sp. [217]. 

Conidia subglobose to short-ellipsoidal, sometimes short-falcate, often cyanophilic dictyochlamydospores spherical or irregularly shaped, often present in the aerial mycelium or in the agar mostly parasites of nematode cysts or saprotrophic, soilborne crystals absent... 

Kondo, S., Yasu, K., Natsume, M., Katayama, M., and Marumo, S. (1988). Isolation, physicochemical properties and biological activity of pamamycin-607, an aerial mycelium-inducing substance from Streptomyces alboniger. J. Antibiot. 41, 1196-1204. 

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