Rhodesianum

The 3-ketothiolase has been purified and investigated from several poly(3HB)-synthesizing bacteria including Azotobacter beijerinckii [10], Ral-stonia eutropha [11], Zoogloea ramigera [12], Rhodococcus ruber [13], and Methylobacterium rhodesianum [14]. In R. eutropha the 3-ketothiolase occurs in two different forms, called A and B, which have different substrate specificities [11,15]. In the thiolytic reaction, enzyme A is only active with C4 and C5 3-ketoacyl-CoA whereas the substrate spectrum of enzyme B is much broader, since it is active with C4 to C10 substrates [11]. Enzyme A seems to be the main biosynthetic enzyme acting in the poly(3HB) synthesis pathway, while enzyme B should rather have a catabolic function in fatty-acid metabolism. However, in vitro studies with reconstituted purified enzyme systems have demonstrated that enzyme B can also contribute to poly(3HB) synthesis [15]. 

In M. rhodesianum no isoenzymes of the 3-ketothiolase have been found [ 14]. The enzyme s capability to react with long-chain acyl-CoAs has not been tested. The enzyme was found to be very similar to the 3-ketothiolases from R. eutropha, A. beijerinckii, Z. ramigera, and R. ruber with respect to molecular weight, optimum pH, and kinetic properties [14]. 

Such a situation occurs in continuous processes, and can be realized in special cases with cells growing unlimited in discontinuous processes, e. g., as reported in several studies of Alcaligenes latus [60], Azotobacter vinelandii [98], or Methylobacterium rhodesianum [74]. 

Bormann, E.J. and Roth, M. 1999. The Production of Polyhydroxybutyrate by Methylobacterium Rhodesianum and Ralstonia Eutropha in Media Containing Glycerol and Casein Hydrolysates. Biotechnol. Lett., 21, 1059-1063. 

Crude glycerol phase Biodiesel production Glycerol Haloferax mediterranei. Bacillus sphaericus, Methylobacterium rhodesianum Halorcula sp., Methylobacterium extorquens, Novosphingobium capsulatum, Cupriavidus necator. Pseudomonas oleovorans. Pseudomonas corrugata [35, 42 6)... 

Bormann, E. J. and Roth, M. (1999). The production of polyhydroxybutyrate by Methylobac-terium rhodesianum and Ralstonia eutropha in media containing glycerol and casein hydrolysates. Biotechnology Letter 2, 1059-1063. 

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