Affiliation:
1. TNO Quality of Life, Business Unit Bioconversion and Food Processes, P.O. Box 342, 7300 AH Apeldoorn, The Netherlands
Abstract
ABSTRACT
Efficient bioconversion of glucose to phenol via the central metabolite tyrosine was achieved in the solvent-tolerant strain
Pseudomonas putida
S12. The
tpl
gene from
Pantoea agglomerans
, encoding tyrosine phenol lyase, was introduced into
P. putida
S12 to enable phenol production. Tyrosine availability was a bottleneck for efficient production. The production host was optimized by overexpressing the
aroF-1
gene, which codes for the first enzyme in the tyrosine biosynthetic pathway, and by random mutagenesis procedures involving selection with the toxic antimetabolites
m
-fluoro-
dl
-phenylalanine and
m
-fluoro-
l
-tyrosine. High-throughput screening of analogue-resistant mutants obtained in this way yielded a
P. putida
S12 derivative capable of producing 1.5 mM phenol in a shake flask culture with a yield of 6.7% (mol/mol). In a fed-batch process, the productivity was limited by accumulation of 5 mM phenol in the medium. This toxicity was overcome by use of octanol as an extractant for phenol in a biphasic medium-octanol system. This approach resulted in accumulation of 58 mM phenol in the octanol phase, and there was a twofold increase in the overall production compared to a single-phase fed batch.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
180 articles.
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