Peranan Kosubstrat terhadap Aktivitas Enzim dalam Metabolisme Xilosa untuk Produksi Xilitol oleh Candida shehatae WAY 08

Wisnu Adi Yulianto, Kapti Rahayu Kuswanto, Tranggono Tranggono, Retno Indrati


The experiment investigated the influence of arabinose, glucose, galactose, and mannose, as a substrat and cosubstrate in xylose metabolism and xylitol production by Candida shehatae WAY 08. Activity of key enzymes involved in the xylose metabolism was measured under substrates containing 6% of each sugars and different ratio addition of 6% xylose with 1, 2, or 3% other sugars as cosubstrate. The enzyme activity on 6% xylose without cosubstrate was used as a control. The activity of xylose reductase (XR) and glucose-6-phosphate dehydrogenase (G6PDH) were induced by 1% of arabinose addition, while glucose, galactose, and mannose repressed the activities of both enzymes. The activity of xylitol dehidrogenase (XDH), acetaldehide dehydrogenase, and alcohol dehydrogenase were slightly repressed by cosubstrates. Specific growth rate of C. shehatae with hexose (glucose, galactose, and mannose) was higher than that of pentose (arabinose and xylose). Addition of 1% arabinosa to 6% xylose didn’t decrease specific growth rate, in fact it induced XR and G6PDH, however it slightly repressed XDH and produced optimum xylitol production. The ratio of XR:XDH:G6PDH in that condition was found to be 47:10:148.

Key words: Candida shehatae WAY 08, cosubstrates, xylose, xylitol