title: High yield recombinant thermostable alpha-amylase production using an improved Bacillus licheniformis system.
abstract: BACKGROUND
  Some strains of Bacillus licheniformis have been improved by target-directed screening as well as by classical genetic manipulation and used in commercial thermostable alpha-amylase and alkaline protease production for over 40 years. Further improvements in production of these enzymes are desirable.
  
  
  RESULTS
  A new strain of B. licheniformis CBBD302 carrying a recombinant plasmid pHY-amyL for Bacillus licheniformis alpha-amylase (BLA) production was constructed. The combination of target-directed screening and genetic recombination led to an approximately 26-fold improvement of BLA production and export in B. licheniformis. Furthermore, a low-cost fermentation medium containing soybean meal and cottonseed meal for BLA production in shake-flasks and in a 15 liter bioreactor was developed and a BLA concentration of up to 17.6 mg per ml growth medium was attained.
  
  
  CONCLUSIONS
  This production level of BLA by B. licheniformis CBBD302(pHY-amyL) is amongst the highest levels in Gram-positive bacteria reported so far.
authors.affiliation: Center for Bioresource and Bioenergy, School of Biotechnology & Culture and Information Center of Industrial Microorganisms of China Universities, Jiangnan University, Wuxi 214122, PR China.
authors.forename: Dandan
authors.initials: D
authors.lastname: Niu
authors.forename: Zhirui
authors.initials: Z
authors.lastname: Zuo
authors.forename: Gui-Yang
authors.initials: GY
authors.lastname: Shi
authors.forename: Zheng-Xiang
authors.initials: ZX
authors.lastname: Wang
mesh_terms: D001407:Bacillus / Q000201:enzymology / Q000254:growth & development*; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics; D010450:Endopeptidases / Q000096:biosynthesis / Q000235:genetics; D010957:Plasmids / Q000235:genetics; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics; D011995:Recombination, Genetic; D000516:alpha-Amylases / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D011994:Recombinant Proteins; D000516:alpha-Amylases; D010450:Endopeptidases; C087822:alkaline protease