A strain of Penicillium currently under study in this laboratory has revealed some unexpected features in response to salts and UV-radiation. These responses include: (a) stimulation of growth by one molar NaCl and KCl at 23 degrees but not at 5 degrees C, (b) total inhibition by LiCl and RbCl at 5 degrees but not at 23 degrees C, (c) stimulation by 254 nm radiation (2 x 10(6) erg cm-2 min-1, 30-90 minutes) at 23 degrees and 5 degrees C, and (d) very elevated growth rates at 23 degrees after incubation at 5 degrees C.