Applied Microbiology and Biotechnology

, Volume 23, Issue 6, pp 456–461

Stability of the recombinant plasmid carrying theBacillus amyloliquefaciens α-amylase gene inB. subtilis

  • Jari Olavi Vehmaanperä
  • Matti Pellervo Korhola
Applied Microbiology

DOI: 10.1007/BF02346060

Cite this article as:
Vehmaanperä, J.O. & Korhola, M.P. Appl Microbiol Biotechnol (1986) 23: 456. doi:10.1007/BF02346060


Theα-amylase gene ofBacillus amyloliquefaciens has previously been cloned into pUB110 to give the recombinant plasmid, pKTH10 (Palva 1982. Gene 19:81–87). Strains transformed by this plasmid are promising candidates for industrialα-amylase production. The stability of pKTH10 was determined in variousB. subtilis strains possessing specific alleles which affect the level ofα-amylase secretion.B. subtilis strains carrying pKTH10 were cultivated in starch-containing medium for up to 50 generations without antibiotic selection and then screened for the presence of pKTH10. The plasmid proved stable enough (< 1.0% cured after 50 generations) for industrial batchwise enzyme production in two strains, but in asacU9 strain (thesacU9 mutation increases concominantly the production ofα-amylase levansucrase and proteases) 99.9% of cells had lost pKTH10 after 50 generations, although the parental plasmid (pUB110) was stable in this strain (0.09% cured after 50 generations). The instability of pKTH10 in thesacU9 strain seems somehow to be related to high expression of the clonedα-amylase gene: when grown in a medium restrictingα-amylase production, only 0.53% ofsacU9 cells had lost pKTH10 after 50 generations.

Copyright information

© Springer-Verlag 1986

Authors and Affiliations

  • Jari Olavi Vehmaanperä
    • 1
  • Matti Pellervo Korhola
    • 1
  1. 1.Research Laboratories of the Finnish State Alcohol Company, Alko LtdHelsinkiFinland

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