Novel methods and tools for lactonases acylases and proteases Biotechnologie Biokatalyse Enzym Proteine Quorum sensing Quorum quenching N Acyl L Homoserinlakton Protease Proteinreinigung Screening This thesis is about the establishment and the application of novel methods and tools that are re lated to the most widely This thesis is about the establishment and the application of novel methods and tools that are re lated to the most widely used enzyme class: hydrolases. It covers all fields from the identification to the application of these valuable enzymes with particular focus on lactonases acylases and proteases. The activity assay introduced in Article I substantially extends the method toolbox for studies on lactonases and acylases that interfere with the bacterial cell cell communication system. Article II describes a fully automatized robotic platform that represents the next level tool for the high throughput enzyme screening in the microtiter plate format. It was used for instance for the screening for improved porcine aminoacylase I variants. Diverse aspects of the protease mediated hydrolysis of non resistant proteins for the purification of resistant target proteins are highlighted in Article III.