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Amylase, β‐Glucanase and Protease Activities from a Mutant of Bacillus subtilis
Author(s) -
Yin X. S.,
Li Y. X.,
Stark J. R.
Publication year - 1991
Publication title -
starch ‐ stärke
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.62
H-Index - 82
eISSN - 1521-379X
pISSN - 0038-9056
DOI - 10.1002/star.19910431008
Subject(s) - glucanase , protease , proteases , bacillus subtilis , amylase , biochemistry , enzyme , extracellular , chemistry , enzyme assay , size exclusion chromatography , bacillales , biology , chromatography , bacteria , genetics
Enzymes in the shake culture of a mutant of Bacillus subtilis developed mainly during the stationary phase of growth. Extracellular α‐amylase and protease activities increased and then declined to relatively low levels after 48 h of incubation while the β‐glucanase activity remained high. The production of extracellular proteolytic activity commenced only when the low molecular weight nitrogen source in the medium was completely consumed. Enzymes were fractionated by ionexchange chromatography and the molecular weights of β‐glucanase, α‐amylase, protease I and protease II were estimated by gel filtration to be 1.3 × 10 4 , 3.2 × 10 4 , 6.3 × 10 3 and 2.0 × 10 4 , respectively. The β‐glucanase and α‐amylase showed maximum activities at around pH 7, but the two proteases had different pH optima (pH 6–7 and 8.5, respectively). The presence of proteolytic activity in the enzyme preparation had a significant effect on the stability of the β‐glucanase and the α‐amylase at 65°C.