Kluyveromyces marxianus CDBB-L-278: A wild inulinase hyperproducing strain

Abstract

Kluyveromyces marxianus CDBB-L-278 is an inulinase hyperproducing strain. It was able to grow in a medium containing inulin as the unique carbon source in the presence of 2-deoxyglucose. It produced up to 3.3 times the activity of the control strain K. marxianus NCYC-1429 in an inulin medium, and 3.6 times in a medium with glycerol as the sole carbon source. Although the strain CDBB-L-278 was able to produce inulinase in the presence of 2-deoxyglucose, it was demonstrated that it is not a de-repressed strain since enzyme production was reduced when the concentration of glucose or fructose was increased in the medium. Since inulinase was produced in a glycerol medium without an inducer, it can be considered that the enzyme production was partially constitutive in K. marxianus CDBB-L-278 as well as strain NCYC-1429. The inulinase from K. marxianus CDBB-L-278 was characterized. It had a higher affinity for inulin than for sucrose. Temperature and pH profiles were different for both of these two substrates. The enzyme was stable to high temperatures, with a half-life of 180 min at 50°C.