TECHNOLOGY FOCUS - BIOTECHNOLOGY - Preferred Peroxidase: The improved manganese peroxidase comprises an amino acid at one or more positions corresponding to a position selected from: (a) position 17 of SEQ ID NO: 1, when the amino acid corresponding to position 17 is an amino acid other than Gln; (b) position 57 of SEQ ID NO: 1, when the amino acid corresponding to position 57 is an amino acid other than Asp; (c) position 80 of SEQ ID NO: 1, when the amino acid corresponding to position 80 is an amino acid other than Ser; (d) position 107 of SEQ ID NO: 1, when the amino acid corresponding to position 107 is an amino acid other than Asn; (e) position 109 of SEQ ID NO: I, when the amino acid corresponding to position 109 is an amino acid other than His; (f) position 111 of SEQ ID NO: 1, when the amino acid corresponding to position 111 is an amino acid other than Asn; (g) position 152 of SEQ ID NO: 1, when the amino acid corresponding to position 152 is an amino acid other than Gln; (h) position 278 of SEQ ID NO: 1, when the amino acid corresponding to position 278 is an amino acid other than Trp; and/or (i) position 204 of SEQ ID NO: 1, when the amino acid corresponding to position 204 is an amino acid other than Thr. The improved manganese peroxidase comprises an amino acid at one or more positions corresponding to a position selected from: (a) position 17 of SEQ ID NO: 1, when the amino acid corresponding to position l7 is Ser; (b) position 57 of SEQ ID NO: 1, when the amino acid corresponding to position 57 is Lys; (c) position 80 of SEQ ID NO: 1, when the amino acid corresponding to position 80 is Asn; (d) position 107 of SEQ ID NO: 1, when the amino acid corresponding to position 107 is Ser; (e) position 109 of SEQ ID NO: 1, when the amino acid corresponding to position 109 is Leu; (f) position 111 of SEQ ID NO: 1, when the amino acid corresponding to position 111 is Leu; (g) position 152 of SEQ ID NO: 1, when the amino acid corresponding to position 152 is Ala; (h) position 278 of SEQ ID NO: 1, when the amino acid corresponding to position 278 is Ala; and/or (i) position 204 of SEQ ID NO: 1, when the amino acid corresponding to position 204 is Ser. Preferred Polynucleotide: The polynucleotide comprises an expression cassette, the expression cassette comprising a heterologous promoter operably linked to the nucleic acid. Preferred Cell: The cell is a yeast cell, where the cell is a Saccharomyces cerevisiae. The improved manganese peroxidase is secreted from the cell. Preferred Method: In converting the cellulose-containing biomass feedstock to the sugar or the non-sugar biomass-derived intermediate, the cellulose-containing biomass feedstock is converted into sugar. The method further comprises fermenting the sugar to ethanol. The cellulose-containing biomass feedstock is converted into a non-sugar biomass-derived intermediate. The cellulose-containing biomass feedstock is a woody material, where the woody material is cellulosic or lignocellulosic plant material selected from orchard prunings, chaparral, mill waste, urban wood waste, municipal waste, logging waste, forest thinnings, short-rotation woody crops, and industrial waste. The cellulose-containing biomass feedstock is a non-woody material. The non-woody material is selected from gramineous agricultural residue, wheat straw, oat straw, rice straw, barley straw, rye straw, flax straw, sugar cane, corn stover, corn stalks, corn cobs, corn husks, prairie grass, switchgrass, gamagrass, foxtail, sugar beet pulp, citrus fruit pulp, seed hulls, cellulosic animal wastes, lawn clippings, seaweed, bagasse, energy cane, and giant reed. The cellulose-containing biomass feedstock is corn grain, barley grain, milo grain, wheat grain or rice grain. EXAMPLE - No suitable example given.