초록
<P><B>Graphical abstract</B></P><P><ce:figure id='f0025'></ce:figure></P><P><B>Highlights</B></P><P>► A new robust thermo- and alkalitolerant extracellular α-<SMALL>L</SMALL>-rhamnosidase from <I>Aspergillus terreus</I> was found. ► Rutin was converted into quercetin-3-β-<SMALL>D</SMALL>-glucopyranoside (isoquercitrin) by the biotransformation with α-<SMALL>L</SMALL>-rhamnosidase. ► Biotransformation procedure was scaled up to 30 L and up to volumetric productivity of over 150g/L. ► A new concept of the “immobilized substrate”, e.g. bioconversion in the solid state substrate was developed. ► The procedure is waste-free; the liberated rhamnose was recycled for the enzyme production in the fermentation.</P> <P><B>Abstract</B></P><P>Extensive screening for a robust producer of α-<SMALL>L</SMALL>-rhamnosidase activity from well-defined strains of filamentous fungi, including multifactorial optimization (inducers, cultivation conditions) was accomplished. Enzyme production of the optimal producer <I>Aspergillus terreus</I> (non-toxigenic) was scaled up to 50L. α-<SMALL>L</SMALL>-Rhamnosidase, which was fully characterized, proved to be thermo- and alkali-tolerant, thus enabling effective operation at 70°C and pH 8.0. These conditions allow for a very high substrate (rutin) load up to 100–300g/L, thus enabling very high volumetric productivity of the reaction product quercetin-3-β-<SMALL>D</SMALL>-glucopyranoside (isoquercitrin). Here, a novel concept of “immobilised substrate” is used. Isoquercitrin is a highly effective and biocompatible antioxidant with strong anti-inflammatory activities. Rutin biotransformation was optimized and scaled up to ca 10kg production and thus the robustness of the large-scale production was demonstrated. Isoquercitrin can be produced to a very high purity (98%) in multikilogram amounts, without any quercetin and directly applicable in nutraceuticals.</P>