Calcium Rescues D39 Δ Manganese-Sensitive Growth Phenotype.

Calcium (Ca) functions as a universal signal messenger in eukaryotes but in bacteria, the physiological roles for Ca are limited. Here, we examine the role of Ca in during manganese (Mn) intoxication. mutants, lacking the Mn efflux transporter, exhibit impaired growth due to accumulation of Mn when exposed to elevated exogenous Mn. This Mn-sensitive growth defect is restored to wild-type growth level by exogenous Ca, in a Ca-dependent manner. Despite growth restoration of the mutant to wild-type levels, cellular Mn remains elevated in this strain. Bacterial capsule production is also increased for the mutant, resulting in reduced adherence capacity to surfaces and poor biofilm formation, which is consistent with it experiencing Mn intoxication. Ca presence did not significantly impact bacterial capsule production or biofilm formation. Further analysis of the cell morphology demonstrates that Ca contributes to cell division and reduces cell chain lengths. Together, these data describe the first role of Ca in that has potential implications in bacterial virulence since Ca affects cell division and likely Mn-associated cellular processes.