Enhanced Xylitol Production by Mutant Kluyveromyces marxianus 36907-FMEL1 Due to Improved Xylose Reductase Activity

Abstract

A directed evolution and random mutagenesis were carried out with thermotolerant yeast Kluyveromyces marxianus ATCC 36907 for efficient xylitol production. The final selected strain, K. marxianus 36907-FMEL1, exhibited 120 and 39 % improvements of xylitol concentration and xylitol yield, respectively, as compared to the parental strain, K. marxianus ATCC 36907. According to enzymatic assays for xylose reductase (XR) activities, XR activity from K. marxianus 36907-FMEL1 was around twofold higher than that from the parental strain. Interestingly, the ratios of NADH-linked and NADPH-linked XR activities were highly changed from 1.92 to 1.30 when K. marxianus ATCC 36907 and K. marxianus 36907-FMEL1 were compared. As results of KmXYL1 genes sequencing, it was found that cysteine was substituted to tyrosine at position 36 after strain development which might cause enhanced XR activity from K. marxianus 36907-FMEL1.

Synthesis of polyketides from low cost substrates by the thermotolerant yeast Kluyveromyces marxianus

“…This yeast has also been observed to readily secrete enzymes, an attribute that has been utilized for simultaneous saccharification and fermentation of cellulose for ethanol production (Ballesteros, Oliva, Negro, Manzanares, & Ballesteros, ; Tomás‐Pejó, Oliva, González, Ballesteros, & Ballesteros, ). These traits make K. marxianus particularly suited to industrial production of enzymes such as pectinase (Espinoza, Bárzana, García‐Garibay, & Ǵmez‐Ruiz, ), inulinase (Galindo‐Leva et al, ; Kushi, Monti, & Contiero, ), and β‐galactosidase (Rech, Cassini, Secchi, & Ayub, ; H. X. Zhou, Xu, Chi, Liu, & Chi, ), PCV2 virus‐like particles (Duan et al, ), as well as other chemicals such as ethyl acetate (Löbs, Engel, Schwartz, Flores, & Wheeldon, ; Löser, Urit, Gruner, & Bley, ), xylitol (Kim, Park, Jang, & Ha, ; Zhang et al, ), and 2‐phenylethanol (Gao & Daugulis, ; Martínez, Sánchez, Font, & Barrena, ).…”

Assessing the Potential of Newly Isolated Pichia Fermentans for Xylitol Production Using Non-Detoxified Xylose Rich Pre-Hydrolysate Derived from Sugarcane Bagasse

“…The random mutagenesis is unpredictable compared to rational design and can signi cantly alter the genome of the microbes creating a strain having superior phenotypic characteristics. The application of inverse metabolic engineering by creating a random mutation in the genome result in microbial systems with desired traits [15]. In the present study, when P. fermentans was subjected to EMS mutagenesis by exposing the growing cells to 20 mM EMS solution for different time intervals, in total seven mutants were obtained.…”

Model-based biotechnological potential analysis of Kluyveromyces marxianus central metabolism

“…Xylose is a pentose and the main sugar of plant hemicellulose; its content in hard wood wastes can be up to 30 % [50]. K. marxianus has been engineered for xylitol production from xylose [42]. Cheese whey is a lactose rich by-product of the dairy industry produced in an approximate 10 to 1 (v/w) ratio to cheese.…”

“…Medium scale modelling also proved to be a successful strategy for describing the uncharacterised central metabolism of the non-conventional yeast Pichia pastoris on the basis of limited wet experimentation [87]. Recent extensive attempts at K. marxianus metabolic engineering [33,42,43,105,109] underline the immediate need for modelling of limits of its metabolic potential.…”