title: Isolation of a Xanthomonas campestris strain with elevated beta-galactosidase activity for direct use of lactose in xanthan gum production.
abstract: OBJECTIVE
  To isolate a Xanthomonas campestris strain that can use lactose directly for xanthan gum production.
  
  
  RESULTS
  The presence of indigenous beta-galactosidase gene in the wild-type Xc17 was detected by PCR and Southern hybridization. Treatment of Xc17 with nitrous acid resulted in the isolation of Xc17L with a 3.5-fold elevation of beta-galactosidase activity capable of growing in lactose-based medium. Xc17L is stable for at least 100 generations in terms of beta-galactosidase expression. The amounts of xanthan produced by Xc17L in lactose-based medium are comparable to those in glucose-based medium.
  
  
  CONCLUSIONS
  Xc17L is potentially useful for xanthan production from whey, a waste containing lactose.
  
  
  CONCLUSIONS
  A lactose-utilizing strain of X. campestris strain can be constructed without incorporation of any exotic DNA or antibiotic resistance gene and therefore concern of a gene-modified organism and fear of a spread of an antibiotic-resistant gene are avoided.
authors.affiliation: Institute of Molecular Biology and Department of Botany, National Chung Hsing University, Taichung, Taiwan. yhtseng@dragon.nchu.edu.tw
authors.forename: T-C
authors.initials: TC
authors.lastname: Yang
authors.forename: G-H
authors.initials: GH
authors.lastname: Wu
authors.forename: Y-H
authors.initials: YH
authors.lastname: Tseng
mesh_terms: D001431:Bacteriological Techniques; D002244:Carbon / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D007218:Industrial Microbiology; D007785:Lactose / Q000378:metabolism*; D009154:Mutation; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis*; D016959:Xanthomonas campestris / Q000201:enzymology / Q000302:isolation & purification* / Q000378:metabolism; D001616:beta-Galactosidase / Q000032:analysis / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D011135:Polysaccharides, Bacterial; D002244:Carbon; D001616:beta-Galactosidase; D005947:Glucose; D007785:Lactose; C002563:xanthan gum