Fig 1.
"From spore to bioactivity"—The workflow of the combined MTP cultivation system and an agar plug diffusion assay.
(A) Bottomless, stainless steel MTPs are closed on one side with silicone mats. The wells are filled with agar. (B) For inoculation, a cryo-replicator is first pressed onto the frozen surfaces of the spore suspensions. (C) Subsequently, the replicator pins are lowered onto the agar surface in the MTPs. (D) The plates are sealed with a gas-permeable membrane and stored in a water-saturated atmosphere. (E) After an appropriate incubation time, the MTPs are unsealed, and the growth of the bacteria is visually evaluated. (F) With the help of two plunger devices, agar plugs are pushed out into two square petri dishes. (G) An agar-plug assay reveals actinomycete strains secreting active natural products into their solid growth medium.
Fig 2.
(A) Screening plate containing the agar plug of Tü2700 (hazy halo on the top right; note the differences to the clear halos of three other strains indicating direct antibacterial activity). (B) Detailed view of the inhibition zone of Tü2700. (C) The same hazy halo (inhibitory activity of the strain on LacZ expression) was also observed when the strain was grown submersed. (D) Structure of Oxazolomycin A (1).