The LIBI project (International Laboratory of BioInformatics) aims to develop an advanced bioinformatics and computational biology laboratory, focusing on basic and applied research in modern biology and biotechnologies. The paper presents the core part of the system, a Grid Problem Solving Environment, built on top of EGEE, DEISA and SPACI infrastructures, allowing the submission and monitoring of jobs mapped to complex experiments in bioinformatics. Several case studies on different bioinformatics applications and related results which have been obtained using the LIBI platform are also reported.