Separation of Two Functional Roles of l -Alanine in the Initiation of Bacillus subtilis Spore Germination

Abstract

Spores of the standard transformable Marburg strain of Bacillus subtilis can be initiated to germinate by l -alanine alone. We isolated mutants which required for this process, in addition to l -alanine, the combination of d -glucose + d -fructose + K + or NH 4 + ions. In place of fructose, autoclaved or caramelized glucose could be used. Even the standard type strain required the addition of these three agents when d -alanine was present or when the temperature was raised. These findings show that l -alanine normally performs two functions during initiation, one of which is absent in the mutants or is blocked by d -alanine or elevated temperature. One of our mutants was not absolutely dependent on the addition of external l -alanine, because it could be initiated at a reduced rate by the sole addition of glucose + K + or NH 4 + . When K + or NH 4 + was replaced by Na + , the initiation rate was greatly reduced. The divalent metal ions Mg ++ , Mn ++ , and Ca ++ could not satisfy the cation requirement.