No abstract

Pleurotus fossulatus (Cooke) Sace is member of oyster mushroom can produced extracellular laccase (benzenediol: oxygen oxidoreductase; EC 1.10.3.2) in submerged fermentation. To analyze the optimum production for laccase P. fossulatus was cultured both in stationary and shaking condition in different media. Partial purification of laccase was done after 0-80% ammonium sulphate precipitation, followed by DEAE (Diethylaminoethyl) Sephadex (A-50) anion exchange chromatography. Potato-sucrose peptone (PSP) medium and Potato-dextrose (PD) medium showed highest laccase production in shaking and stationary conditions, respectively. Though the time required for optimum laccase production in stationary condition was much more than the shaking condition but the amount of laccase was about 2.75t greater in former condition. The laccase produced in stationary condition was more stable than the enzyme produced in shaking condition. The partially purified enzyme showed highest affinity towards o-dianisidine than guaiacol and ABTS (2,2'-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) as evidenced by their K(m). The physico-chemical properties of the laccase suggested the significance of this enzyme in industrial applications.

The growth of a red-pigmented yeast, isolated from yogurt and identified as Rhodotorulu rubra, was studied on various industrial and agricultural by-products. Peat hydrolysate when supplemented with peptone and yeast extract supported a satisfactory growth of the yeast. Ammonium hydroxide and ammonium sulfate were the best inorganic nitrogen sources. A yield of 11.8 g/1 was obtained on molasses and wort used in aconcentration of 10 and 40% (v/v), respectively. Molasses were pre-treated to be effective. The best yield of 14 g/l, however, was obtained on a richer medium composed of molasses, peptone and yeast extract. The pH profiles were also studied and growth was found within a broad pH zone of 3 -10.