TAILIEUCHUNG - Lertwattanasakul et al. AMB Express 2011, 1:20

Lertwattanasakul et al. AMB Express 2011, 1:20 ORIGINAL Open Access Utilization capability of sucrose, raffinose and inulin and its less-sensitiveness to glucose repression in thermotolerant yeast Kluyveromyces marxianus DMKU 3-1042 Noppon Lertwattanasakul1, Nadchanok Rodrussamee1, Suprayogi1, Savitree Limtong2, Pornthap Thanonkeo3, Tomoyuki Kosaka4 and Mamoru Yamada1,4* Abstract Kluyveromyces marxianus possesses a useful potential to assimilate a wide variety of substrates at a high temperature, but the negative effect by coexisting glucose is critical for utilization of biomass containing various sugars. Such a negative effect on the activity of inulinase, which is the sole enzyme to hydrolyze sucrose, raffinose and inulin, has been demonstrated in K. marxianus. | Lertwattanasakul et al. AMB Express 2011 1 20 http content 1 1 20 o AMB Express a SpringerOpen Journal ORIGINAL Open Access Utilization capability of sucrose raffinose and inulin and its less-sensitiveness to glucose repression in thermotolerant yeast Kluyveromyces marxianus DMKU 3-1042 Noppon Lertwattanasakul1 Nadchanok Rodrussamee1 Suprayogi1 Savitree Limtong2 Pornthap Thanonkeo3 Tomoyuki Kosaka4 and Mamoru Yamada1 4 Abstract Kluyveromyces marxianus possesses a useful potential to assimilate a wide variety of substrates at a high temperature but the negative effect by coexisting glucose is critical for utilization of biomass containing various sugars. Such a negative effect on the activity of inulinase which is the sole enzyme to hydrolyze sucrose raffinose and inulin has been demonstrated in K. marxianus without analysis at the gene level. To clarify the utilization capability of sucrose raffinose and inulin and the glucose effect on inulinase in K. marxianus DMKU 3-1042 its growth and metabolite profiles on these sugars were examined with or without glucose under a static condition in which glucose repression evidently occurs. Consumption of sucrose was not influenced by glucose or 2-deoxyglucose. On the other hand raffinose and inulin consumption was hampered by glucose at 30 C but hardly hampered at 45 C. Unlike Saccharomyces cerevisiae increase in glucose concentration had no effect on sucrose utilization. These sugar-specific glucose effects were consistent with the level of inulinase activity but not with that of the KmINU1 transcript which was repressed in the presence of glucose via KmMig1p. This inconsistency may be due to sufficient activity of inulinase even when glucose is present. Our results encourage us to apply K. marxianus DMKU 3-1042 to high-temperature ethanol fermentation with biomass containing these sugars with glucose. Keywords Kluyveromyces marxianus inulinase glucose repression INU1 MIG1 Introduction Glucose-mediated

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