Isolation and Characterization of Unusual Bacterial Amylases

Abstract

The thermoacidophilic amylases produced by Bacillus acidocaldurius strains have very acid pH optima as expected but the temperature optima are not much higher than that of Bacillus amyloliquefaciens which is a mesophile and they are not as high as that of Bacillus lichenformis which is a facultative thermophile. Alkaline amylases produced by Bacillus alcalophilus subsp. haloduruns strains which are insensitive to sequestering agents and stable at high temperatures, expand the range of potential amylase uses to conditions of high alkalinity. Comparison of the pH and temperature profiles of different Bacillus species amylases demonstrates that amylases have evolved in a single genus in such a way that they can function optimally at almost any pH value and temperature. The properties of these amylases reflect extensivemicrobial adaptation and demonstrate the wide variety of enzymes potentially available for biochemical processing. lsolierung und Charakterisierung ungewohnlichet bakterieller Amylasen. Die von Bacillus acidocaldarius gebildeten thermoacidophilen Amylasen besitzen wie erwartet pH-Optima im sehr sauren Bereich, jedoch liegen die Temperatur-Optima nicht vie1 hoher als das Optimum der Amylase aus Bacillus amyloliquefaciens, der mesophil ist, und sie sind nicht so hoch wie das Optimum der Amylase aus Bacillus lichmijbrmis, welcher fakultativ thermophil ist. Alkalische Amylasen aus Bacillus ulcalophilus subsp. hulodurans-Stammen, welche unempfindlich gegen komplexbildende Agentien und stabil gegen hohe Temperaturen sind, dehnen den Anwendungsbereich von Amylasen auf Bereiche hoher pH-Werte aus. Ein Vergleich der pHund Temperaturprofile der verschiedenen Bacillus-Amylasen zeigt, daljdieEvolutionineinemeinzigenGendergestaltstattgefunden hat, daB die Amylasen optimal bei fast allen pH-und Temperaturwerten wirksam sind. Die Eigenschaften dieser Amylasen spiegeln die extreme Anpassungsfahigkeit von Mikroorganismen wider und zeigen die grolje Bandbreite von Enzymen, die potentiell fur biochemische Prozesse verfugbar sind. Starch/Starke 31 (1979) Nr. 5 , S. 166-171

Cloning and sequencing of a gene encoding acidophilic amylase from Bacillus acidocaldarius

“…Previously, no amylase activity had been observed in culture supernatant when B. acidocaldarius was grown in liquid culture, but amylase activity could be released from cells grown on plates by washing with 0.5 M-Na acetate buffer (pH 5.0) (Boyer et al, 1979). This suggests that the protein is associated with the cytoplasmic membrane or cell wall at least under the growth conditions tested.…”

“…The optimal pH reported by Boyer et al (1979) was 4.5. The amylase activity was fourfold higher at 60 "C than at 37 "C. According to Boyer et al (1979) the optimal temperature for the amylase was 60-63 "C.…”

“…The results obtained by chromato focusing and isoelectric focusing are consistent with the possibility that the two amylases may either be closely related or the smaller amylase could be a breakdown product of the larger. The molecular mass of the B. acidocaldarius ATCC 27009 amylase had not been determined previously but the protein was retained by a 30kDa cut-off membrane (Boyer et al, 1979). The…”

“…It is a thermoacidophilic endoamylase with a pH optimum of 4-5 and temperature optimum of 60-63 "C (Boyer et al, 1979). The enzyme is not released to growth medium, but has been extracted from plate cultures (Boyer et al, 1979).…”

Bacillus

“…a-Amylase is secreted by B. alcalophilus, B. acidocaldarius, B. amyloliquefaciens, "B. caldolyticus," B. circulans, B. coagulans, B. licheniformis, B. macerans, B. megaterium, B. stearothermophilus, B. subtilis, and B. thuringiensis (reviewed by Priest, 1977;Ingle and Erickson, 1978;Boyer et at., 1979;Kindle, 1983;Fogarty, 1983). These enzymes vary widely in their pH and temperature optima for activity and the size of limit dextrins produced from amylose.…”