Heterologous Expression of Various PHA Synthase Genes in Rhodospirillum rubrum

Klask, Christian-Marco; Raberg, Matthias; Heinrich, Daniel; Steinbüchel, Alexander

doi:10.15255/cabeq.2014.2249

Cited by 11 publications

(7 citation statements)

References 45 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Different Class I and Class IV PHA synthases were investigated in PHA-negative R. rubrum as the host organism; all of the new strains revealed PHA biosynthesis. As a major outcome, the authors proved that insufficient PHA synthase activity in R. rubrum wild type displays the bottle neck of this process, which can be solved by means of genetic engineering [120]. As a follow up, a genetically engineered R. rubrum strain harboring P. putida KT2440 PHA synthesis genes was successfully used by these authors for mcl-PHA biosynthesis in simple flasks aerated with artificial syngas [121].…”

Section: Use Of Gaseous Substrates Ch 4 Co 2 and Syngasmentioning

confidence: 99%

A Review on Established and Emerging Fermentation Schemes for Microbial Production of Polyhydroxyalkanoate (PHA) Biopolyesters

Koller

2018

Fermentation

145

View full text Add to dashboard Cite

Polyhydroxyalkanoates (PHA) are microbial biopolyesters utilized as "green plastics". Their production under controlled conditions resorts to bioreactors operated in different modes. Because PHA biosynthesis constitutes a multiphase process, both feeding strategy and bioreactor operation mode need smart adaptation. Traditional PHA production setups based on batch, repeated batch, fed-batch or cyclic fed-batch processes are often limited in productivity, or display insufficient controllability of polyester composition. For highly diluted substrate streams like is the case of (agro) industrial waste streams, fed-batch enhanced by cell recycling has recently been reported as a viable tool to increase volumetric productivity. As an emerging trend, continuous fermentation processes in single-, two-and multi-stage setups are reported, which bring the kinetics of both microbial growth and PHA accumulation into agreement with process engineering and allow tailoring PHA's molecular structure. Moreover, we currently witness an increasing number of CO 2-based PHA production processes using cyanobacteria; these light-driven processes resort to photobioreactors similar to those used for microalgae cultivation and can be operated both discontinuously and continuously. This development is parallel to the emerging use of methane and syngas as abundantly available gaseous substrates, which also calls for bioreactor systems with optimized gas transfer. The review sheds light on the challenges of diverse PHA production processes in different bioreactor types and operational regimes using miscellaneous microbial production strains such as extremophilic Archaea, chemoheterotrophic eubacteria and phototrophic cyanobacteria. Particular emphasis is dedicated to the limitations and promises of different bioreactor-strain combinations and to efforts devoted to upscaling these processes to industrially relevant scales.

show abstract

Section: Use Of Gaseous Substrates Ch 4 Co 2 and Syngasmentioning

confidence: 99%

A Review on Established and Emerging Fermentation Schemes for Microbial Production of Polyhydroxyalkanoate (PHA) Biopolyesters

Koller

2018

Fermentation

145

View full text Add to dashboard Cite

show abstract

“…Together with the low production costs, as compared to sugar fermentation by recombinant E. coli strains, H 2 was also produced, which is of great industrial interest. More recently, a number of PHA synthase genes were expressed in phaC deletion mutants of R. rubrum , obtaining up to a 25% PHA content increase compared with the parental strain …”

Section: Bacterial Strains Using Waste Streams Can Be Engineered For mentioning

confidence: 99%

“…More recently, a number of PHA synthase genes were expressed in phaC deletion mutants of R. rubrum, obtaining up to a 25% PHA content increase compared with the parental strain. 166 Although promising, the use of E. coli and other gramnegative bacteria for the production of PHAs could be considered as unsuitable for medical applications because of lipopolysaccharide (LPS) endotoxins, requiring further purification processes to be removed. 167 With the aim of generating functional PHA granules for biomedical applications, the gram-positive Lactococcus lactis, generally regarded as safe, food-grade bacterium, was therefore assayed.…”

Section: Phas From Waste Glycerolmentioning

confidence: 99%

Improving polyhydroxyalkanoate production from inexpensive carbon sources by genetic approaches: a review

Favaro

Basaglia

Casella

2018

Biofuels Bioprod Bioref

131

View full text Add to dashboard Cite

Polyhydroxyalkanoates (PHAs) are a family of biodegradable intracellular polyesters that a number of Eubacteria and Archaea can accumulate for energy and carbon storage. Most of the genetic modifications to the producing bacterial species have been accomplished to clarify basic biochemical, genetic, and metabolic aspects of PHA metabolism. However, due to its plastic‐like properties and complete biodegradability, this bio‐based polymer has attracted the attention of a variety of manufacturers. A number of genetic approaches have therefore been reported, aimed at improving the performance of the microorganisms with a potential for use in a production process. Indeed, genetic tools may find useful applications in all the phases of the PHA production chain, from the isolation and characterization of new microbial strains through all the production steps until they reach the downstream processes. The substrates generally used for PHA production are expensive, so the search for low‐cost feedstock is necessary. These materials, possibly deriving from agri‐food processes, are unfortunately not easily degraded or converted directly into PHAs. Thus, the development of engineered microbes is in progress to process waste streams and covert them to valuable polymers. This review will summarize the most relevant results obtained through genetic engineering tools for the production of PHAs from cheap carbon sources in view of possible industrial applications. © 2018 Society of Chemical Industry and John Wiley & Sons, Ltd.

show abstract

“…For this, the phaC1 and phaC2 genes coding for the two PHA synthases in this bacterium, which are essential for the polymerization of 3-hydroxybutyryl-CoA and 3-hydroxyvaleryl-CoA, were deleted. This resulted in a R. rubrum ⌬phaC1 ⌬phaC2 strain incapable of synthesizing PHA SCL (30,31). Applying the findings of previous studies, three genes of the known PHA MCL producer P. putida KT2440 were cloned into the broad-host-range expression vector pBBR1MCS-2 and overexpressed in R. rubrum ⌬phaC1 ⌬phaC2:…”

Section: Resultsmentioning

confidence: 99%

Synthesis Gas (Syngas)-Derived Medium-Chain-Length Polyhydroxyalkanoate Synthesis in Engineered Rhodospirillum rubrum

Heinrich

Raberg

Fricke

et al. 2016

Appl Environ Microbiol

View full text Add to dashboard Cite

The purple nonsulfur alphaproteobacterium Rhodospirillum rubrum S1 was genetically engineered to synthesize a heteropolymer of mainly 3-hydroxydecanoic acid and 3-hydroxyoctanoic acid [P(3HD-co-3HO)] from CO-and CO 2 -containing artificial synthesis gas (syngas). For this, genes from Pseudomonas putida KT2440 coding for a 3-hydroxyacyl acyl carrier protein (ACP) thioesterase (phaG), a medium-chain-length (MCL) fatty acid coenzyme A (CoA) ligase (PP_0763), and an MCL polyhydroxyalkanoate (PHA) synthase (phaC1) were cloned and expressed under the control of the CO-inducible promoter P cooF from R. rubrum S1 in a PHA-negative mutant of R. rubrum. P(3HD-co-3HO) was accumulated to up to 7.1% (wt/wt) of the cell dry weight by a recombinant mutant strain utilizing exclusively the provided gaseous feedstock syngas. In addition to an increased synthesis of these medium-chain-length PHAs (PHA MCL ), enhanced gene expression through the P cooF promoter also led to an increased molar fraction of 3HO in the synthesized copolymer compared with the P lac promoter, which regulated expression on the original vector. The recombinant strains were able to partially degrade the polymer, and the deletion of phaZ2, which codes for a PHA depolymerase most likely involved in intracellular PHA degradation, did not reduce mobilization of the accumulated polymer significantly. However, an amino acid exchange in the active site of PhaZ2 led to a slight increase in PHA MCL accumulation. The accumulated polymer was isolated; it exhibited a molecular mass of 124.3 kDa and a melting point of 49.6°C. With the metabolically engineered strains presented in this proof-of-principle study, we demonstrated the synthesis of elastomeric second-generation biopolymers from renewable feedstocks not competing with human nutrition. IMPORTANCEPolyhydroxyalkanoates (PHAs) are natural biodegradable polymers (biopolymers) showing properties similar to those of commonly produced petroleum-based nondegradable polymers. The utilization of cheap substrates for the microbial production of PHAs is crucial to lower production costs. Feedstock not competing with human nutrition is highly favorable. Syngas, a mixture of carbon monoxide, carbon dioxide, and hydrogen, can be obtained by pyrolysis of organic waste and can be utilized for PHA synthesis by several kinds of bacteria. Up to now, the biosynthesis of PHAs from syngas has been limited to short-chain-length PHAs, which results in a stiff and brittle material. In this study, the syngas-utilizing bacterium Rhodospirillum rubrum was genetically modified to synthesize a polymer which consisted of medium-chain-length constituents, resulting in a rubber-like material. This study reports the establishment of a microbial synthesis of these so-called medium-chain-length PHAs from syngas and therefore potentially extends the applications of syngas-derived PHAs. Biodegradable and biocompatible polyhydroxyalkanoates (PHAs) are naturally occurring polyesters, which are synthesized by various bacteria. Depending on their...

show abstract

Heterologous Expression of Various PHA Synthase Genes in Rhodospirillum rubrum

Cited by 11 publications

References 45 publications

A Review on Established and Emerging Fermentation Schemes for Microbial Production of Polyhydroxyalkanoate (PHA) Biopolyesters

A Review on Established and Emerging Fermentation Schemes for Microbial Production of Polyhydroxyalkanoate (PHA) Biopolyesters

Improving polyhydroxyalkanoate production from inexpensive carbon sources by genetic approaches: a review

Synthesis Gas (Syngas)-Derived Medium-Chain-Length Polyhydroxyalkanoate Synthesis in Engineered Rhodospirillum rubrum

Contact Info

Product

Resources

About