Summary: Thermophilic mutants were isolated from mesophilic Bacillus suhtilis and Bacillus pumilus by platinglarge numbers of cells and incubating them for several days at a temperature about 10 °C above the upper growth temperature limit for the parent mesophiles. Under these conditions we found thermophilic mutant strains that were able to grow at temperatures between 50 °C and 70 °C at a frequency of less than 10−10. The persistence of auxotrophic and antibiotic resistance markers in the thermophilic mutants confirmed their mesophilic origin. Transformation of genetic markers between thermophilic mutants and mesophilic parents was demonstrated at frequencies of 10−3 to 10−2 for single markers and about 10−7 for two unlinked markers. With the same procedure we were able to transfer the thermophilic trait from the mutant strains of Bacillus to the mesophilic parental strains at a frequency of about 10−7, suggesting that the thermophilic trait is a phenotypic consequence of mutations in two unlinked genes.
FriedmanS. M.,
MojicaT.1978; Transformants of Bacillus subtilis capable of growth at elevated temperatures. In Biochemistry of Thermophily pp 117–126 Edited by
FriedmanS. M.
New York: Academic Press;
GibsonT.,
GordonR. E.1974; Endospore forming rods and cocci. In Bergey’s Manual of Determinative Bacteriology, 8th. edn pp 529–550 Edited by
BuchananR. E.,
GibbonsN. E.
Baltimore: Williams & Wilkins;
GrayR. J. H.,
JacksonH.1973; Growth and macromolecular composition of a psychrophile, Micrococcus cryophilus, at elevated temperatures. Antonie van Leeuwenhoek 39:497–504
HeinenU. J.,
HeinenW.1972; Characteristics and properties of a caldo-active bacterium producing extracellular enzymes and two related strains. Archiv für Mikrobiologie 82:1–23
JohnsonE. J.1979; Thermophile genetics and the genetic determinants of thermophily. In Strategies of Microbial Life in Extreme Enrironments pp 471–487 Edited by
ShiloM.
Weinheim: Verlag Chemie;
NormoreW. M.1976; Guanine-plus-cytosine (GC)composition of the DNA of bacteria, fungi, algae and protozoa. In Handbook of Biochemistry and Molecular Biology, 3rd. edn vol 11: p 85 Edited by
FasmanG. D.
Cleveland, Ohio: CRC Press;