Purification and characterization of Mn-peroxidase from Musa paradisiaca (banana) stem juice.

Mn-peroxidase (MnP), a biotechnologically important enzyme was purified for the first time from a plant source Musa paradisiaca (banana) stem, which is an agro-waste easily available after harvest of banana fruits. MnP was earlier purified only from the fungal sources. The enzyme was purified from stem juice by ultrafiltration and anion-exchange column chromatography on diethylamino ethylcellulose with 8-fold purification and purification yield of 65%. The enzyme gave a single protein band in SDS-PAGE corresponding to molecular mass 43 kDa. The Native-PAGE of the enzyme also gave a single protein band, confirming the purity of the enzyme. The UV/VIS spectrum of the purified enzyme differed from the other heme peroxidases, as the Soret band was shifted towards lower wavelength and the enzyme had an intense absorption band around 250 nm. The Km values using MnSO4 and H2O2 as the substrates of the purified enzyme were 21.0 and 9.5 μM, respectively. The calculated kcat value of the purified enzyme using Mn(II) as the substrate in 50 mM lactate buffer (pH 4.5) at 25°C was 6.7s-1, giving a kcat/Km value of 0.32 μM-1s-1. The kcat value for the MnP-catalyzed reaction was found to be dependent of the Mn(III) chelator molecules malonate, lactate and oxalate, indicating that the enzyme oxidized chelated Mn(II) to Mn(III). The pH and temperature optima of the enzyme were 4.5 and 25°C, respectively. The enzyme in combination with H2O2 liberated bromine and iodine in presence of KBr and KI respectively. All these enzymatic characteristics were similar to those of fungal MnP. The enzyme has the potential as a green brominating and iodinating agent in combination with KBr/KI and H2O2.

Decolorization of pulp paper mill effluent by Pleurotus sajorcaju.

Pleurotus sajorcaju MTCC-141 procured from Microbial Type Culture Collection Centre and Gene Bank, Institute of Microbial Technology, Chandigarh has been used for color removal from paper mill effluent. The paper mill effluent amended with basal medium supports the growth of Pleurrotus sajorcaju and removes the colour. The optimum concentrations of carbon source (glucose) and nitrogen source (NH4NO3) for the maximum decolourization of paper mill effluent were found to be 1% and 0.2% respectively. During the fungal growth process, the pH of the paper mill effluent decreased from 7.94 to 4.0.

Enzymatic characteristics of ligninperoxidases from Penicillium citrinum, Fusarium oxysporum and Aspergillus terreus using n-propanol as substrate.

The activities of ligninperoxidases from Penicillium citrinum MTCC 3565, Fusarium oxysporum MTCC 3379 and Aspergillus terreus MTCC 3374 have been assayed and the enzymatic characteristics like Km, pH and temperature optima using n-propanol as the substrate have been reported. The results suggest that n-propanol can substitute veratryl alcohol as substrate for assaying ligninperoxidase activities from different fungal strains, without affecting the enzymatic characteristics. The above strains were selected, as they were known to secrete ligninperoxidase in the liquid culture medium.