Laccases are copper-containing oxidase enzymes, widely distributed in microorganisms such as basidomycetes, filamentous fungi, actinomycetes and bacteria. Basidomycetes and filamentous fungi have been more studied on capacity of laccase synthesis than the others. The study was conducted in order to know capacity oflaccase production nom Ascomycetes isolated nom different enviroments such as rotten rice straw. From four samples of rotten rice straw collected in Ninh Binh, FNBLal strain was isolated on PDA medium with initial activity of 200 U/l. Based on traditional method and sequence of 18S the partial rRNA coding gene, FNBLal strain belonged to Myrothecium genus and was named Myrothecium sp. FNBLal. FNBLal was capable of producing laccase with high activity at pH 6,5
0,1 mM CuSO4 as an inducer, 12 g/l glucose as a carbon source and a mixture of 1 g/l casein and 3 g/l NaNO3 as nitrogen sources. On suitable medium, FNBLal strain produced laccase with the highest activity of 30.016 U/l and 10.410 U/l in 250 ml-flasks after 96 h and 15 liter bioreactor after 57 h, respectively.