title: Regulatory effects of alanine-group amino acids on serine alkaline protease production by recombinant Bacillus licheniformis.
abstract: Influences of the concentration and addition time of alanine-group amino acids, i.e. alanine, leucine and valine, on serine alkaline protease (SAP) synthesis were investigated by Bacillus licheniformis (DSM 1969) carrying pHV1431:: sub C in a defined medium to identify the amino acids creating intracellular reaction-rate limitation in SAP production. While the precursors of alanine-group amino acids, pyruvate and alanine, did not affect SAP production considerably within the range 0-15 mM, the addition of leucine decreased both SAP production and cell formation, because of the inhibition of valine synthesis. Although valine inhibits reactions starting with pyruvate towards 2-oxo-isovalerate, due to conversion of valine into 2-oxo-isovalerate and from 2-oxo-isovalerate to leucine, valine did not inhibit leucine synthesis. Val (7.5 mM) supply at t =0 h increased SAP activity to an activity of 1070 units.cm(-3) which was 1.3-fold higher than that of the reference production medium. The highest cell growth yield on substrate (Y (X/S)) was obtained as 0.24 g.g(-1) with the supply of alanine; and the highest product formation yield on substrate was obtained as 0.134 units.g(-1) with the supply of valine. By using the results obtained, strategies for increasing SAP production and complex medium design were also discussed.
authors.affiliation: Industrial Biotechnology Laboratory, Department of Chemical Engineering, Middle East Technical University, 06531 Ankara, Turkey. pcalik@metu.edu.tr
authors.forename: Pinar
authors.initials: P
authors.lastname: Calik
authors.forename: Arzu
authors.initials: A
authors.lastname: Bayram
authors.forename: Tunçer H
authors.initials: TH
authors.lastname: Ozdamar
mesh_terms: D000409:Alanine / Q000378:metabolism*; D001407:Bacillus / Q000145:classification / Q000201:enzymology* / Q000235:genetics* / Q000378:metabolism; D006706:Homeostasis / Q000502:physiology; D007930:Leucine / Q000378:metabolism*; D011994:Recombinant Proteins / Q000096:biosynthesis; D012697:Serine Endopeptidases / Q000096:biosynthesis* / Q000235:genetics*; D014633:Valine / Q000378:metabolism*
chemical_list: D011994:Recombinant Proteins; D012697:Serine Endopeptidases; D007930:Leucine; D014633:Valine; D000409:Alanine