Beyond the Keller-Segel model - Microscopic modelling of bacterial colonies P. Romanczuk, U. Erdmann, H. Engel and L. Schimansky-Geier Eur. Phys. J. Special Topics, 157 (2008) 61-77 Published online: 23 April 2008 DOI: 10.1140/epjst/e2008-00631-1