Alcaligenes eutropha

Intracellular PHB Depolymerase of Cupriavidus necator. Note that C. necator was previously known as Ralstonia eutropha, Wautersia eutropha, Alcaligenes eutropha and Hydrogenomonas eutropha. iPHB depolymerases of PHAscl-accumulating bacteria were not described before the year 2000 but since then not less than seven putative iPHB depolymerases and two 3-hydroxybutyrate oligomer hydrolases have been postulated for C. 

Benzoate dioxygenase (BZDO) Ralstonia eutropha (former Alcaligenes eutrophus) 1971 [236] [224]... 

In Table 2, different carbon sources were evaluated and it was foimd that each strain produced different amounts of PHAs. For example, Alcaligenes eutrophus or Rastonta eutropha prefers to use fructose (Khanna Srivastava, 2005). A. latus is in favour of sucrose (Grothe... 

Ralstonia eutropha (Alcaligenes eutrophus) strain NH9 is able to degrade 3-chlorobenzene by the modified ortho pathway. The cbnA gene that encodes 3-chlorocatechol-l, 2-dioxygenase was introduced into rice plants (Oryza sativa -p.japonicd) under the control of a virus 35S promoter. 3-Chlorocatechol induced dioxygenase activity in the callus of the plants, and leaf tissues oxidized 3-chlorocatechol with the production of 2-chloromuconate... 

R. eutropha, formerly known as Alcaligenes eutrophus, has been used for the commercial production of P(3HB-co-3HV) [72]. This bacterium grows well in a relatively inexpensive minimal medium and accumulates a large amount of P(3HB) under the unbalanced growth condition. In R. eutropha, acetyl-CoA is converted to P(3HB) by three enzymes (genes) /J-ketothiolase (phaA), aceto-acetyl-CoA reductase (phaB), and PHA synthase (phaC) [6]. 

PI IB/V, an scl- copolymer (Fig. 7.2B) produced by Alcaligenes eutrophus (since reclassified as Ralstonia eutropha) from propionic acid and glucose. This new polymer was tougher than PFIB and had a lower processing temperature making it more appealing to industry. Ultimately, this polymer was marketed under the trade name Biopol. In 1988, Doi and coworkers found that a new scZ-PHA copolymer of PHB-co-4-hydroxybutyrate (PHB/4HB Fig. 7.2C) could be synthesized from 4-hydroxybutyric acid or y-butyrolactone (Doi et al., 1988 Kunioka et al., 1989). 

A second variant, the enzyme from Ralstonia eutropha H16 (previously Alcaligenes eutrophus HI6), is monomeric (encoded by norB) and lacks the small subunit that binds the electron donating centers of the other enzymes. Residues proposed to ligate hemes b and Fes are conserved in norB of R. eutropha and the enzyme contains heme b and nonheme Fe in a 2 1 ratio. The enzyme has an extended N-terminus of 280 amino acids that is essential for activity, with a proposed role in allowing quinols rather than cytochrome c to function as electron donor. These NORs, which are also membrane bound, have biochemical and spectral properties indicating that the catalytic center is the same as in prototype NOR. 

PHA is produced by different bacterial strains. One of the most studied strain is C. necator (formerly known as Wautersia eutropha, Ralstonia eutropha or Alcaligene eutrophus). It was used in industrial production by Imperial Chemical Industries (ICI PLC) to produce P(3HB-co-3HV) under the trade name of BiopoF. The Biopol patents have now been acquired by Metabolix Inc. (USA) (Verlinden et al. 2007). Until now, C. necator is still being used widely for bacterial fermentation as it is an efficient strain. Other important strains that have been studied for PHA production are Bacillus spp., Alcaligenes spp.. Pseudomonas spp., Aeromonas hydrophila, Rhodopseudomonas palustris, recombinant Escherichia coli, Burkholderia sacchari, and Halomonas boliviensis (Verlinden et al. 2007). 

Madden L.A. and Andrason, A.J., 1998, Synthesis and characterization of poly(3-hydroxy-butyrate and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) polymer mixtures produced in high-density fed-batch cultures of Ralstonia eutropha Alcaligenes eutrophus). Macromolecules 31 5660... 

For the bacterial production of PHAs by wild-type strains, the Ralstonia eutropha (formerly called Alcaligenes eutrophus, Wautersia eutropha, or Cupri-avidus necator) has been the most commonly used wild-type strain for the industrial production of PHB, P3HB4HB, and PHBV. 

Azhar EA, Hemmat M, Abdelhady AM, Abdel H, KhodairTA. Batch production of polyhydroxybutyrate (PHB) by Ralstonia eutropha and Alcaligenes latus using bioreactor different culture strategics. /App/ Sci Res 2009 5 556-64. 

---