ABSTRACT
Very few studies have been dedicated to R-hydroxyacids (R-HA) production using extracellular polyhydroxyalkanoate depolymerases (ePhaZs). Penicillium expansum produced maximum extracellular polyhydroxybutyrate depolymerase (~6 U/mL) by 72 h when grown in mineral salt medium containing 0.2 % w/v PHB, pH 5.0, at 30 °C and 200 rpm shaking conditions. Partial purification of the extracellular poly(-ß-hydroxybutyrate) depolymerase PHAZ Pen from P. expansum by two steps using ammonium sulphate (80 % saturation) and affinity chromatography using concanavalin A yielded 22.76-fold purity and 43.15 % recovery of protein. The enzyme composed of a single polypeptide chain of apparent molecular mass of 20 kDa, as determined by SDS-PAGE, stained positive for glycoprotein by periodic-schiff base (PAS) staining. Optimum enzyme activity was detected between pH 4.0 and 6.0 at 45-50 °C with pH 5.0 and 50 °C supporting maximum activity. The enzyme was stable between pH 4.0 and 6.0 at 55 °C for 1 h with a residual activity of almost 70-80 %. The enzyme was completely inhibited by 1 mM DTT/1 mM HgCl2 and N-ethylmaleimide (10 mM) indicating the importance of essential disulphide bonds (cystine residues) and tyrosine for enzyme activity or probably for maintaining the native enzyme structure. Among the various divalent and trivalent metal ions, mercuric chloride, ferric citrate and ferrous sulphate inhibited enzyme activity. The enzyme showed substrate specificity towards only PHB and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and no other lipid or other p-nitrophenyl fatty acids or with polycaprolactone, showing that it was a true depolymerase and not any lipase or cutinase. Preliminary investigation revealed ß-hydroxybutyrate as the end product of PHB hydrolysis by P. expansum, suggesting that the enzyme acted principally as an exo-type hydrolase. The above properties when compared with other fungal PHB depolymerases reported till date suggest the distinct nature of the PHB depolymerase of P. expansum.
ABSTRACT
SETTING: A South Indian district providing anti-tuberculosis services through the Revised National TB Control Programme (RNTCP) and private health care facilities. OBJECTIVE: To ascertain the profile of tuberculosis (TB) patients diagnosed and/or treated in private health care facilities. METHODS: Data on TB cases diagnosed and/or treated in all clinical departments of the medical college, 83 nursing homes and RNTCP health care facilities were collected prospectively. RESULTS: About 83% of new TB cases recorded in the private medical college, 47% in nursing homes and 24.5% in RNTCP TB registers were extra-pulmonary. The proportion of retreatment cases was respectively 5.5%, 9.6% and 19.8%. The proportion of males and those in the economically productive age group were similar in the three data sources. About 94% of cases diagnosed in the medical college and 55% in nursing homes were registered for treatment under the RNTCP. About 11% of the smear-positive patients diagnosed in RNTCP were initial defaulters. CONCLUSION: The proportion of extra-pulmonary cases was higher in the medical college and nursing homes and that of retreatment cases was lower than in the RNTCP.
