GROWTH-KINETICS OF THE THERMOPHILIC FUNGUS THERMOMYCES-LANUGINOSUS

The growth kinetics and morphology of a thermophile fungus, Thermomyce s lanuginosus, were studied at 50-degrees-C in semi-solid and liquid ( stationary, shake flask, and fermenter culture) media; complex (yeast plus soluble starch: YPS) and defined media (yeast-free, with NH4-N) w ere used. On YPS agar, the colony radial growth rate was 367 +/- 5 mum h-1 (mean +/- S.E.) as compared with 217 +/- 4 mum h-1 on the defined medium. In liquid culture growth was biphasic. In YPS medium in shake flask cultures at 220 rpm the initial specific growth rate (mu1) unti l 8 h was 0.89 h-1 decreasing thereafter (mu2) to 0.46 h-1, and in sta tionary cultivation mu1 and mu2 were 0.55 and 0.28 h-1 respectively. G rowth in a 2 l (1.5 l working volume) fermenter was also biphasic (mu1 , 0.84 h-1; mu2, 0.35 h-1). The hyphal growth unit length (G) on solid medium (YPS) was 156 +/- 7 mum. In liquid culture the G-value seemed to be inversely related to the shear stress, showing a decrease from 1 88 +/- 5 mum (stationary culture) to 116 +/- 12 mum (400 rpm, shake fl ask). In fermenter at 900 rpm G was 85 +/- 2 mum. The mean hyphal diam eter after 14 h of growth was: stationary culture, 1.77 +/- 0.05 mum; shake flask culture, 1.11 +/- 0.06 mum; in fermenter, 1.20 +/- 0.06 mu m after 13.5 h.