ISOLATION AND PARTIAL CHARACTERIZATION OF BACILLUS-MEGATERIUM MUTANTSDEFICIENT IN POLY(3-HYDROXYBUTYRATE) SYNTHESIS

Poly(3-hydroxybutyrate) (PHB)-negative mutants of Bacillus megaterium were isolated following mutagenesis with N-methyl-N'-nitro-N-nitrosogu anidine. Different strategies were used for isolation, including ultra centrifugation through sucrose gradients and selection for resistance to allyl alcohol. The mutants were detected on agar plates by staining the colonies with Sudan Black. Four mutants did not synthesize any PH B as revealed by gas chromatographic analysis. The enzymatic character ization showed no or extremely low synthase activity for all of the mu tants. In contrast, no significant alterations were observed in the be ta-ketothiolase and the NADPH-dependent acetoacetyl-CoA reductase acti vities. All mutants sporulated in complete and minimal media.