Release of spirosin associated with potassium phosphate-induced autolysis in Lactobacillus reuteri DSM 20016.

We have studied the effect of medium components on spirosin production in Lactobacillus reuteri DSM 20016 to get some insight into the function of spirosome in Lactobacillus. Among those investigated, only potassium phosphate was found to influence the production of spirosin. Though it was not effective at concentrations lower than 0.6%, it promoted the spirosin production and its accumulation into culture medium in particular, at higher concentrations. The accumulation has been demonstrated to originate inthe release of spirosin due to the bacterial autolysis induced by the higher concentrations of potassium phosphate, The autolytic effect of potassium phosphate was assumed to be a concerted action by phosphate and potassium ions at the concentrations higher than 0.1 and 0.4 M, respectively. A possible role of spirosin as a sensor protein of bacterial two-component regulatory system was discussed.