title: Improvement in lactic acid production from starch using alpha-amylase-secreting Lactococcus lactis cells adapted to maltose or starch.
abstract: To achieve direct and efficient lactic acid production from starch, a genetically modified Lactococcus lactis IL 1403 secreting alpha-amylase, which was obtained from Streptococcus bovis 148, was constructed. Using this strain, the fermentation of soluble starch was achieved, although its rate was far from efficient (0.09 g l(-1) h(-1) lactate). High-performance liquid chromatography revealed that maltose accumulated during fermentation, and this was thought to lead to inefficient fermentation. To accelerate maltose consumption, starch fermentation was examined using L. lactis cells adapted to maltose instead of glucose. This led to a decrease in the amount of maltose accumulation in the culture, and, as a result, a more rapid fermentation was accomplished (1.31 g l(-1) h(-1) lactate). Maximum volumetric lactate productivity was further increased (1.57 g l(-1) h(-1) lactate) using cells adapted to starch, and a high yield of lactate (0.89 g of lactate per gram of consumed sugar) of high optical purity (99.2% of L: -lactate) was achieved. In this study, we propose a new approach to lactate production by alpha-amylase-secreting L. lactis that allows efficient fermentation from starch using cells adapted to maltose or starch before fermentation.
authors: Department of Molecular Science and Material Engineering, Graduate School of Science and Technology, Kobe University, 1-1 Rokkodaicho, Nada-ku, Kobe, 657-8501, Japan.
authors: Kenji
authors: K
authors: Okano
authors: Sakurako
authors: S
authors: Kimura
authors: Junya
authors: J
authors: Narita
authors: Hideki
authors: H
authors: Fukuda
authors: Akihiko
authors: A
authors: Kondo
mesh_terms: D019344:Lactic Acid / Q000096:biosynthesis*; D013294:Lactococcus lactis / Q000201:enzymology / Q000378:metabolism*; D008320:Maltose / Q000378:metabolism*; D013213:Starch / Q000378:metabolism*; D000516:alpha-Amylases / Q000378:metabolism*
chemical_list: D019344:Lactic Acid; D008320:Maltose; D013213:Starch; D000516:alpha-Amylases