Poly- β -hydroxybutyrate (PHB) depolymerase from Fusarium solani Thom

Fusarium solani thom produced maximum phb depolymerase by 48 h when grown in bhm containing 0.2%,w/v phb,ph 8.0 at 25 ° c. statistical optimization studies using plackett burman design of phb depolymerase production yielded maximum phb depolymerase activity after 2 days as against 4 days in the unoptimized conditions with a 2-fold increase in activity. partial purification of the extracellular poly-β-hydroxybutyrate (phb) depolymerase phaz fus from f. solani thom by two steps using ammonium sulphate (80% saturation) and affinity chromatography using concanavalin-a yielded 162.3-fold purity and 63 recovery of protein. the enzyme composed of a single polypeptide chain of 85 kda,as determined by sds-page. the enzyme stained positive for glycoprotein by pas staining. optimum enzyme activity was detected at ph 7.0 and 55 ° c. the enzyme was stable at ph 7.0 and 55°c for 24 h with a residual activity of almost 85%. paper chromatography revealed β-hydroxybutyrate monomer as the major end product of phb hydrolysis. complete inhibition of the enzyme by 1 mm hgcl 2(100%) indicated the importance of essential disulfide bonds (cystine residues) for enzyme activity or probably for maintaining the native enzyme structure. © 2013 srividya shivakumar.