Abstract:
Members of the Archaeal family have been determined to accumulate Poly (3-hydroxybutyrate) (PHB) during
their growth. A total of 13 extremely Halophilic Archaeal isolates designated as NPW-1 to NPW-13 were
capable of accumulating large amounts of PHB. Out of which best four isolates were selected from enzyme
assay. Since measurements of enzyme activities related to Archaeal PHB biosynthesis have never been
achieved, we investigated the first enzyme of PHB biosynthesis in Haloarcula sp.1 i.e., β-ketothiolase. Crude
extracts of strain cultivated under accumulating conditions showed maximum β-ketothiolase activity. β ketothiolase was partially purified by ammonium sulfate fractionation and highest activity was obtained in 60%
saturation fraction. This is the first description of an archaebacterial β-ketothiolase . Silver staining of the
purified enzyme (fraction 8) with SDS – PAGE showed that enzyme subunited molecular weight putatively
identified was 45 kDa.
