Energy production from L-malic acid degradation and protection against acidic external pH in Lactobacillus plantarum CECT 220

SUMMARY: Malate degradation by Lactobacillus plantarum CECT 220 provides energy which enables this organism to remain viable for longer at low environmental pH values. Energy production was not coupled to H+-ATPase activity. This protective mechanism against acidic external pH is complemented by another system of ΔpH maintenance. The H+-ATPase did not seem to be involved in this system of pH maintenance as the system was not sensitive to N, N'-dicyclohexylcarbodiimide (DCCD) and was functional at very low pH values where ATPase activity was severely inhibited.