Journal of Microbiology

Research Support, Non-U.S. Gov'ts

Strain Improvement of Candida tropicalis for the Production of Xylitol:Biochemical and Physiological Characterization of Wild-type and Mutant Strain CT-OMV5: Ravella Sreenivas Rao , Cherukuri Pavana Jyothi , Reddy Shetty Prakasham , Chaganti Subba Rao , Ponnupalli Nageshwara Sarma , Linga Venkateswar Rao; J. Microbiol. 2006;44(1):113-120.; DOI: https://doi.org/2328 [pii]

Abstract: Candida tropicalis was treated with ultraviolet (UV) rays, and the mutants obtained were screened for xylitol production. One of the mutants, the UV1 produced 0.81g of xylitol per gram of xylose. This was further mutated with N-methyl-N’-nitro-N-nitrosoguanidine (MNNG), and the mutants obtained were screened for xylitol production. One of the mutants (CT-OMV5) produced 0.85g/g of xylitol from xylose. Xylitol production improved to 0.87 g/g of xylose with this strain when the production medium was supplemented with urea. The CT-OMV5 mutant strain differs by 12 tests when compared to the wild-type Candida tropicalis strain. The XR activity was higher in mutant CT-OMV5. The distinct difference between the mutant and wild-type strain is the presence of numerous chlamydospores in the mutant. In this investigation, we have demonstrated that mutagenesis was successful in generating a superior xylitol-producing strain, CT-OMV5, and uncovered distinctive biochemical and physiological characteristics of the wild-type and mutant strain, CT-OMV5.

Electrochemical Reduction of Xylose to Xylitol by Whole Cells or Crude Enzyme of Candida peltata: Sun Mi Park , Byung In Sang , Dae Won Park , Doo Hyun Park; J. Microbiol. 2005;43(5):451-455.; DOI: https://doi.org/2276 [pii]

Abstract: In this study, whole cells and a crude enzyme of Candida peltata were applied to an electrochemical bioreactor, in order to induce an increment of the reduction of xylose to xylitol. Neutral red was utilized as an electron mediator in the whole cell reactor, and a graphite-Mn(IV) electrode was used as a catalyst in the enzyme reactor in order to induce the electrochemical reduction of NAD+ to NADH. The efficiency with which xylose was converted to xylitol in the electrochemical bioreactor was five times higher than that in the conventional bioreactor, when whole cells were employed as a biocatalyst. Meanwhile, the xylose to xylitol reduction efficiency in the enzyme reactor using the graphite-Mn (IV) electrode and NAD+ was twice as high as that observed in the conventional bioreactor which utilized NADH as a reducing power. In order to use the graphite-Mn(IV) electrode as a catalyst for the reduction of NAD+ to NADH, a bioelectrocatalyst was engineered, namely, oxidoreductase (e.g. xylose reductase). NAD+ can function in this biotransformation procedure without any electron mediator or a second oxidoreductase for NAD+/NADH recycling

Search