Table 1 - Hyper-production of a thermotolerant b-xylosidase by a deoxy-D-glucose and cycloheximide resistant mutant derivative of Kluyveromyces marxianus PPY 125

Table 1. Comparative kinetic parameters of Kluyveromyces marxianus ppY125 and its mutant derivative (M 125) for β-xylosidase formation following growth on different substrates (2%, w/v) in yeast fermentation medium (pH 5.5) at 35ºC up to 48 hrs in time course studies.

C-source	Y_P/S(IU/g)	Specific activity (IU/mg)	Q_p^(IU/l h)**	Y_P/X(IU/.g cells)
Galactose P M	41.7h 84.0g	1.8g 3.7f	11g 23f	88j 166i
Glucose P M	1.1j 4.1i	0.2i 0.6h	1i 4h	2.0 l 11k
Xylose P M	192.0d 391.2a	15.8c 24.4a	98b 154a	333e 653a
Cellobiose P M	191.0d 389.1a	15.0d 23.2b	96b 153a	315f 425b
Lactose P M	122.2f 246.1c	7.5e 14.8d	41e 83d	244h 365c
Sucrose P M	135.1e 273.1b	7.7e 15.0d	43e 87c	267g 361c

Each value is a mean of three replicates. Values followed by different letters differ significantly from each other at p ≤ 0.05 using MstatC software **Q_p= volumetric productivity (IU/l.h), Y_p/X = Specific product yield (IU/g cells), Y_p/s= Product yield (IU/g substrate consumed).