ISSN:
1432-0614
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Process Engineering, Biotechnology, Nutrition Technology
Notes:
Summary A cDNA for mature human salivary α-amylase was directly joined to a sequence encoding the signal peptide of the middle wall protein (MWP) gene of Bacillus brevis 47. This hybrid gene was placed downstream from the multiple promoter region of the MWP gene on a low copy-number plasmid vector, pHW1. B. brevis 47 carrying the plasmid produced 0.9 mg/l of active human α-amylase in the medium. A B. brevis 47 mutant obtained on mutagenesis with N-methyl-N′-nitro-N-nitrosoguanidine produced an increased amount of the α-amylase (6 mg/l). When the fused gene was inserted into a high copy-number expression vector, pNU200, and then introduced into the mutant, a large amount (60 mg/l) of the α-amylase was produced in the medium. The α-amylase showed approximately the same specific activity and molecular weight as those of the natural enzyme. The mutant showed higher sensitivity to various antibiotics than the original strain, and altered cell wall and cytoplasmic membrane protein compositions. The results of reversion analysis suggested that a single mutation is responsible for the above phenotypes and hyper-productivity of human α-amylase.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00170046
