title: Amylolytic Enzymes Acquired from L-Lactic Acid Producing Enterococcus faecium K-1 and Improvement of Direct Lactic Acid Production from Cassava Starch.
abstract: An amylolytic lactic acid bacterium isolate K-1 was isolated from the wastewater of a cassava starch manufacturing factory and identified as Entercoccus faecium based on 16S rRNA gene sequence analysis. An extracellular α-amylase was purified to homogeneity and the molecular weight of the purified enzyme was approximately 112 kDa with optimal pH value and temperature measured of 7.0 and 40 °C, respectively. It was stable at a pH range of 6.0-7.0, but was markedly sensitive to high temperatures and low pH conditions, even at a pH value of 5. Ba2+, Al3+, and Co2+activated enzyme activity. This bacterium was capable of producing 99.2% high optically pure L-lactic acid of 4.3 and 8.2 g/L under uncontrolled and controlled pH at 6.5 conditions, respectively, in the MRS broth containing 10 g/L cassava starch as the sole carbon source when cultivated at 37 °C for 48 h. A control pH condition of 6.5 improved and stabilized the yield of L-lactic acid production directly from starch even at a high concentration of starch at up to 150 g/L. This paper is the first report describing the properties of purified α-amylase from E. faecium. Additionally, pullulanase and cyclodextrinase activities were also firstly recorded from E. faecium K-1.
authors.affiliation: Division of Biotechnology, School of Agro-Industry, Faculty of Agro-Industry, Chiang Mai University, Chiang Mai, 50100, Thailand.
authors.forename: Kridsada
authors.initials: K
authors.lastname: Unban
authors.affiliation: Division of Biotechnology, School of Agro-Industry, Faculty of Agro-Industry, Chiang Mai University, Chiang Mai, 50100, Thailand.
authors.forename: Apinun
authors.initials: A
authors.lastname: Kanpiengjai
authors.affiliation: Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, Miki-cho, Kagawa, 761-0795, Japan.
authors.forename: Goro
authors.initials: G
authors.lastname: Takata
authors.affiliation: Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, Miki-cho, Kagawa, 761-0795, Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Uechi
authors.affiliation: Department of Chemical Engineering, Systems Biology and Tissue Engineering Research Center, National Chung Cheng University, Minhsiung, Chiayi, 621, Taiwan.
authors.forename: Wen-Chien
authors.initials: WC
authors.lastname: Lee
authors.affiliation: Division of Biotechnology, School of Agro-Industry, Faculty of Agro-Industry, Chiang Mai University, Chiang Mai, 50100, Thailand. chartchai.k@cmu.ac.th.
authors.forename: Chartchai
authors.initials: C
authors.lastname: Khanongnuch
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D016984:Enterococcus faecium / Q000201:enzymology* / Q000254:growth & development; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000096:biosynthesis*; D002365:Manihot / Q000737:chemistry*; D013213:Starch / Q000737:chemistry*; D000516:alpha-Amylases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D019344:Lactic Acid; D013213:Starch; D000516:alpha-Amylases
keywords: ALAB; Amylolytic lactic acid bacterium; Enterococcus faecium; L-lactic acid; Starch; α-amylase