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Biopolymers and Bioplastics 2016
September 12-14, 2016
Volume 7, Issue 5(Suppl)
J Bioremed Biodeg 2016
ISSN: 2155-6199 JBRBD, an open access journal
conferenceseries
.com
September 12-14, 2016 San Antonio, USA
3
rd
International Conference and Exhibition on
Biopolymers & Bioplastics
Kenji Tanaka et al., J Bioremed Biodeg 2016, 7:5(Suppl)
http://dx.doi.org/10.4172/2155-6199.C1.003Biosynthesis of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) with high C
6
-monomer composition
from CO
2
by recombinant of
Ralstonia eutropha
Kenji Tanaka
1
, Shunya Mori
1
, Kouki Maruo
1
, Orita Izumi
2
and
Toshiaki Fukui
2
1
Kindai University, Japan
2
Tokyo Institute of Technology, Japan
P
oly((R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoate) [P(3HB-co-3HHx)], a flexible and practical biodegradable
plastic, is generally produced from plant oils and fatty acids by several wild and recombinant bacteria. Fukui and his
coworkers constructed many recombinants of
Ralstonia eutropha
for studying biosynthesis of [P(3HB-co-3HHx)] with high
3HHx composition from the structurally unrelated carbon source. The engineered strain with
ΔphaB1
genotype expressing
ccr, phaJ4a, and emd (R. eutropha
strain MF01ΔB1/pBPP-ccr
Me
J4a-emd) produced P (3HB-co-3HHx) composed of 22 mol%
3HHx at high cellular content from fructose (Metabolic Engineering, 27:38–45, 2015). Such high C
6
–monomer composition
was achieved by improving artificial pathway for biosynthesis of monomer unit as follows: (i) Depression of (R)-specific
reduction of acetoacetyl-CoA by the deletion of
phaB1
for formation of the C
6
–monomer unit from fructose driven by
crotonyl-CoA carboxylase/reductase (Ccr), (ii) co-overexpression of
phaJ4a
, which encodes medium-chain-length (R)-enoyl-
CoA hydratase, with ccr promoted the incorporation of both 3HB and 3HHx units (iii) introduction of emd
Mm
,a synthetic gene
encoding ethylmalonyl-CoA decarboxylase derived from mouse which is probably converting ethylmalonyl-CoA generated
by the reductive carboxylase activity of Ccr back into butyryl-CoA.
R. eutropha
is a facultative hydrogen-oxidizing bacterium
that chemolithoautotrophically grows due to carbon dioxide fixation using H
2
and O
2
as the energy source. Hence, we also
investigated the production of P(3HB-co-3HHx) from CO
2
by the engineered strains of
R. eutropha
in chemolithoautotrophic
condition using the substrate gas mixture (H
2
/O
2
/CO
2
::8:1:1) and mineral salts medium. As a result, the strain MF01ΔB1/
pBPP-ccr
Me
J4a-emd produced P(3HB-co-3HHx) with a remarkably high composition of 3HHx (51.7 mol%) at a high cellular
content (65.1 wt%) from CO
2
.
Biography
Kenji Tanaka has completed his PhD from Kyushu University. He is a Professor of Depatment of Biological and Environmental Chemistry, School of Humanity-
Oriented Science & Engineering, Kindai University. His research field is Bioprocess Engineering. He has published many papers on microbial production of
biodegradable plastic from CO
2
and biomass.
tanaka@fuk.kindai.ac.jp