title: Phosphate enrichment and fed-batch operation for prolonged beta-lactamase production by Bacillus licheniformis.
abstract: OBJECTIVE
  Investigation of the phosphate effect and feeding strategy, i.e. linear and exponential feeding, to improve beta-lactamase production by Bacillus licheniformis considering the viability of the cells.
  
  
  RESULTS
  Effect of phosphate enrichment on beta-lactamase production was investigated and resulted in 1.2-fold increase in beta-lactamase activity. Thereafter, exponential and linear feed profiles were established, after an initial batch phase for t = 0-7.5 h. The highest beta-lactamase activity was obtained at fed-batch operation with exponential feeding (FBO1) condition as A = 106 U cm(-3), which is c. 1.7-fold higher than that of the phosphate-enriched batch operation (PE-BO).
  
  
  CONCLUSIONS
  Biphasic variations in beta-lactamase production was enhanced to monophasic variation with the exponential feeding strategy where the activity was obtained as A = 106 U cm(-3) at t = 16 h.
  
  
  CONCLUSIONS
  Phosphate enrichment decreases the intracellular ammonium concentration and organic acid excretion, but increrases beta-lactamase production. When batch operation (BO) and PE-BO are compared, it is seen that succinic acid formation decreased with the phosphate enrichment as a result of smooth operation of the tricarboxylic acid cycle. At FBO1 despite the increased lactic and acetic acid formation, beta-lactamase production increased 1.7-fold, and 92% of the cells were alive at the end of the fermentation.
authors: Department of Chemical Engineering, Industrial Biotechnology and Metabolic Engineering Laboratory, Middle East Technical University, Ankara, Turkey.
authors: N
authors: N
authors: Ileri
authors: P
authors: P
authors: Calik
authors: A
authors: A
authors: Sengül
mesh_terms: D001407:Bacillus / Q000737:chemistry / Q000254:growth & development / Q000378:metabolism*; D019149:Bioreactors / Q000382:microbiology; D003470:Culture Media; D010710:Phosphates / Q000378:metabolism*; D001618:beta-Lactamases / Q000096:biosynthesis* / Q000378:metabolism
chemical_list: D003470:Culture Media; D010710:Phosphates; D001618:beta-Lactamases