Biotransformation of adenine and cytokinins by the rhizobacterium Serratia proteamaculans
PHYTOCHEMISTRY
Authors: Taylor, Janet L.; Zaharia, L. Irina; Chen, Hao; Anderson, Erica; Abrams, Suzanne R.
Abstract
Approximately 60,000 microorganisms from Saskatchewan soil were screened for growth on the cytokinin N-6-benzyladenine (BA) as C source. A single isolate, identified as Serratia proteamaculans, grew well on BA. The culture filtrates from S. proteamaculans were screened using reversed phase high performance liquid chromatography (RP-HPLC) for the presence of secondary metabolites. The analysis revealed a major metabolite and its chemical structure was deduced as 8-hydroxy-N-6-benzyladenine (8-OHBA). Subsequently, the S. proteamaculans isolate was also found to metabolize N-6-(2-isopentenyl)adenine and adenine through oxidation of C-8 of the purine ring. A clone of the S. proteamaculans xanthine dehydrogenase (Xdh, EC 1.1.1.204) encoding genes was isolated in Escherichia coli. This E. coli isolate metabolized BA to 8-OHBA. Similar to other bacterial Xdh, the S. proteamaculans enzyme was composed of two subunits. The derived amino acid sequences of these Xdh subunits were most similar (XdhA, 60%; XdhB, 72%) to those of Pseudomonas aeruginosa. Crown Copyright (c) 2006 Published by Elsevier Ltd. All rights reserved.
Microbial and Enzymatic Process for Xylitol Production from D-glucose
CURRENT ORGANIC CHEMISTRY
Authors: Qi, Xianghui; Wang, Xu; Lin, Jing; Zhu, Jingfei; Luo, Yan; Deng, Wenying; Wang, Fei; Sun, Wenjing; Meng, Jianzong
Abstract
A microbial and enzymatic process for xylitol production that initiates from D-glucose occurs by virtue of a three-step process in which D-arabitol is the first intermediate product and D-xylulose is the second. To date, the steps of the formation of D-arabitol and the conversion of xylitol from D-xylulose are key points of departure for promoting the overall process for xylitol production from D-glucose. This review provides comprehensive insights regarding potential methods of xylitol production from D-glucose, which might be an alternative to the classical process that utilizes D-xylose as substrate.