Abstract
To clarify the mechanism to maintain high pH in the digestive juice (DJ) in the silkworm, Bombyx mori, which is considered to be a control factor on the bacterial growth in DJ, buffering capacity of DJ was measured in vitro and the changes of pH value of DJ were investigated with the growth in DJ of anti-alkaline bacteria such as Streptococcus faecalis, and S. faecium.
Buffering capacity of DJ in the range of between 11 and 9 in pH value was about from 0.04 to 0.07 when measured with the each 0.25 interval of pH. The culture solution which contained 0.2% glucose and was obtained after the growth of S. faecalis showed the capacities between 0.025 and 0.010. pH changes of DJ were more sensitive against addition of the culture solution than that of 0.1N HCl, though the buffering capacity of the solution itself was smaller than that of DJ. The buffering capacity of the culture solution which contained the reducing sugar at the concentration to be matched for that in mulberry leaves was almost identical to the capacity of DJ. Therefore, it seemed that the abnormal growth of S. faecalis in digestive tract should induce the pH shift of DJ. By dialysis of DJ, K+, Na+ and Ca++ were separated, of which quantities were enough to explain the high pH of DJ.
