30
accumulation either in an autotrophic way (r1 and r2) which uses directly CO 2 or in
a heterotrophic way (r3), where the carbon source is glucose, for instance.
(r1) 21.36 H 2 + 6.21 O 2 + 4.09 CO 2 + 0.76 NH 3 → C 4.09 H 7.13 O 1.89 N 0.76 + 18.7 H 2 O
(r2) 33 H 2 + 12 O 2 + 4 CO 2 → C 4 H 6 O 2 + 30 H 2 O
(r3) C 6 H 12 O 6 + 1.97 O 2 + 0.72 NH4
+
→ 3.79 CH 1.74 O 0.46 N 0.19 + 2.21 CO 2 + 0.72 H
+
+ 3.78 H 2 O
A productivity of PHB of 28 g/L from CO 2 on waste-glycerol grown cell mass
was found. Tanaka et al. (2011) isolated a novel hydrogen–oxygen-oxidizing bacteria, i.e., Ideonella sp. strain O-1, which can produce P(3HB) in a concentration of
77.9% (w/w). This strain is particularly suitable for syngas fermentation because it
can tolerate up to 50% of CO, with respect to the 5–25% of Cupriavidus necator
(Tanaka et al. 2011). Another well-known microorganism for producing poly-3-hydroxybutyrate P(3HB) and P(3HB)-co-3HP from CO and CO 2 is the Gram-negative
Rhodospirillum rubrum. Heinrich et al. (2015) engineered R. rubrum strain by
inserting a gene encoding the membrane-bound transhydrogenase PntAB from
Escherichia coli MG1655 and a second coding for an NADPH-dependent acetoacetyl-CoA reductase (phaB1) from Ralstonia eutropha H16 (Heinrich et al. 2015).
This genetic manipulation allows R. rubrum to increase the content of 3 HV up to
55% mol from CO and CO 2 . Also cyanobacteria such as Spirulina platensis UMACC
161 and Synechocystis sp. PCC 6803 can produce PHAs (Chee et al. 2010).
Miyasaka et al. (2013) developed a shuttle vector between the cyanobacterium
Synechococcus sp. PCC 7002 and E. coli able to directly convert CO 2 into PHAs
(Miyasaka et al. 2013). However, this study does not mention how much and which
type of PHA is produced.
Medium-Chain Length Polyhydroxyalkanoates
Medium-chain length polyhydroxyalkanoates (PHAmcl), which have 6 to 14
C-atoms, are more elastic than PHAscl, with only 25% of crystallinity. For this
reason they are highly requested in pharmaceutical production (Heinrich et al. 2016).
The major producers of PHAmcl are fluorescent Pseudomonas strains
(Pseudomonas oleovorans and Pseudomonas putida). However, those strains use
organic feedstock as carbon sources. Although the use of syngas for PHAmcl synthesis is rather rare, Rhodospirillum rubrum is among the few microorganisms
which owns the potential of synthesizing them from gas mixture including CO
and CO 2 .
Heinrich et al. 2016 succeeded in the production of 3-hydroxydecanoic acid and
3-hydroxyoctanoic acid units by applying a genetic modified Rhodospirillum
rubrum S1 for the conversion of CO and CO 2 (Heinrich et al. 2016). The engineered
R. rubrum could synthetize up to 7.1% of PHAmcl (wt/wt of CDW) from an
A. A. Azim et al.
accumulation either in an autotrophic way (r1 and r2) which uses directly CO 2 or in
a heterotrophic way (r3), where the carbon source is glucose, for instance.
(r1) 21.36 H 2 + 6.21 O 2 + 4.09 CO 2 + 0.76 NH 3 → C 4.09 H 7.13 O 1.89 N 0.76 + 18.7 H 2 O
(r2) 33 H 2 + 12 O 2 + 4 CO 2 → C 4 H 6 O 2 + 30 H 2 O
(r3) C 6 H 12 O 6 + 1.97 O 2 + 0.72 NH4
+
→ 3.79 CH 1.74 O 0.46 N 0.19 + 2.21 CO 2 + 0.72 H
+
+ 3.78 H 2 O
A productivity of PHB of 28 g/L from CO 2 on waste-glycerol grown cell mass
was found. Tanaka et al. (2011) isolated a novel hydrogen–oxygen-oxidizing bacteria, i.e., Ideonella sp. strain O-1, which can produce P(3HB) in a concentration of
77.9% (w/w). This strain is particularly suitable for syngas fermentation because it
can tolerate up to 50% of CO, with respect to the 5–25% of Cupriavidus necator
(Tanaka et al. 2011). Another well-known microorganism for producing poly-3-hydroxybutyrate P(3HB) and P(3HB)-co-3HP from CO and CO 2 is the Gram-negative
Rhodospirillum rubrum. Heinrich et al. (2015) engineered R. rubrum strain by
inserting a gene encoding the membrane-bound transhydrogenase PntAB from
Escherichia coli MG1655 and a second coding for an NADPH-dependent acetoacetyl-CoA reductase (phaB1) from Ralstonia eutropha H16 (Heinrich et al. 2015).
This genetic manipulation allows R. rubrum to increase the content of 3 HV up to
55% mol from CO and CO 2 . Also cyanobacteria such as Spirulina platensis UMACC
161 and Synechocystis sp. PCC 6803 can produce PHAs (Chee et al. 2010).
Miyasaka et al. (2013) developed a shuttle vector between the cyanobacterium
Synechococcus sp. PCC 7002 and E. coli able to directly convert CO 2 into PHAs
(Miyasaka et al. 2013). However, this study does not mention how much and which
type of PHA is produced.
Medium-Chain Length Polyhydroxyalkanoates
Medium-chain length polyhydroxyalkanoates (PHAmcl), which have 6 to 14
C-atoms, are more elastic than PHAscl, with only 25% of crystallinity. For this
reason they are highly requested in pharmaceutical production (Heinrich et al. 2016).
The major producers of PHAmcl are fluorescent Pseudomonas strains
(Pseudomonas oleovorans and Pseudomonas putida). However, those strains use
organic feedstock as carbon sources. Although the use of syngas for PHAmcl synthesis is rather rare, Rhodospirillum rubrum is among the few microorganisms
which owns the potential of synthesizing them from gas mixture including CO
and CO 2 .
Heinrich et al. 2016 succeeded in the production of 3-hydroxydecanoic acid and
3-hydroxyoctanoic acid units by applying a genetic modified Rhodospirillum
rubrum S1 for the conversion of CO and CO 2 (Heinrich et al. 2016). The engineered
R. rubrum could synthetize up to 7.1% of PHAmcl (wt/wt of CDW) from an
A. A. Azim et al.