Methods for Studying Biofilms in Azospirillum and Other PGPRs

Abstract

To produce beneficial effects, plant growth promoting bacteria have to interact with the plant surface to form complex multicellular assemblies and aggregates named biofilms. The study of biofilm development and its physiology is an emerging topic in the knowledge of plant microbe interaction. Therefore, techniques to study its formation and functions are evolving from easy approaches to more complex, time consuming, and with expensive equipment requirement ones. The multiwell microtiter plate assay is the most widely used method due to its versatility to reveal the biofilm and that it allows the analysis of different stages of biofilm. Other more sophisticated protocols based on the use of fluorochromes are described. Care should be taken in analyzing results and their interpretation as differences among roots colonizing and biofilm formed on inert supports are normally to occur. Here, we make a presentation of the methods used to study biofilm and then describe in detail the most commonly used in investigations of rhizobacteria biofilms and its components with application to root colonization.