title: Effects of MAL61 and MAL62 overexpression on maltose fermentation of baker's yeast in lean dough.
abstract: The predominant fermentable sugar in lean dough is maltose. To improve the leavening ability of baker's yeast in lean dough, maltose metabolism should be improved. Maltase (alpha-glucosidase, encoded by MAL62) and maltose permease (encoded by MAL61) are the major factors involved in maltose metabolism. The major rate-limiting factor in maltose metabolism and leavening ability of baker's yeast remains unclear. In this work, MAL61 and/or MAL62 overexpression strains were constructed to investigate the decisive factor for maltose metabolism of industrial baker's yeast in lean dough. Our results show that elevated maltose permease activity by MAL61 overexpression yielded less improvement in maltose fermentation compared to elevated maltase activity by MAL62 overexpression. Significant increase in maltase activity by MAL62 overexpression could result in a 44% increase in leavening ability of industrial baker's yeast in lean dough and a 39% increase in maltose metabolism in a medium containing glucose and maltose. Thus, maltase was the rate-limiting factor in maltose fermentation of industrial baker's yeast in lean dough. This study lays a foundation for breeding of industrial baker's yeast for quick dough leavening.
authors.affiliation: Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin Industrial Microbiology Key Laboratory, College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300457, People's Republic of China, cyzhangcy@tust.edu.cn.
authors.forename: Cui-Ying
authors.initials: CY
authors.lastname: Zhang
authors.forename: Xue
authors.initials: X
authors.lastname: Lin
authors.forename: Hai-Yan
authors.initials: HY
authors.lastname: Song
authors.forename: Dong-Guang
authors.initials: DG
authors.lastname: Xiao
mesh_terms: D005285:Fermentation; D005433:Flour / Q000032:analysis / Q000382:microbiology*; D008320:Maltose / Q000378:metabolism*; D009004:Monosaccharide Transport Proteins / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D027981:Symporters / Q000235:genetics / Q000378:metabolism*; D000520:alpha-Glucosidases / Q000235:genetics / Q000378:metabolism*
chemical_list: D009004:Monosaccharide Transport Proteins; D029701:Saccharomyces cerevisiae Proteins; D027981:Symporters; C067575:maltose transport system, S cerevisiae; D008320:Maltose; C582346:MAL62 protein, S cerevisiae; D000520:alpha-Glucosidases