M-Theory Superalgebra From Multiple Membranes

We investigate space-time supersymmetry of the model of multiple M2-branes proposed by Bagger-Lambert and Gustavsson. When there is a central element in Lie 3-algebra, the model possesses an extra symmetry shifting the fermions in the central element. Together with the original worldvolume supersymmetry transformation, we construct major part of the eleven dimensional space-time super-Poincar\'{e} algebra with central extensions. Implications to transverse five-branes in the matrix model for M-theory are also discussed.