Transition of a solitary to a biofilm community life style in bacteria: a survival strategy with division of labour.

Multicellularity is associated with higher eukaryotes having an organized division of labour and a coordinated action of different organs composed of multiple cell types. This division of different cell types and organizations to form a multicellular structure by developmental programming is a key to the multitasking of complex traits that enable higher eukaryotes to cope with fluctuating environmental conditions. Microbes such as bacteria, on the other hand, are unicellular and have flourished in diverse environmental conditions for a much longer time than eukaryotes in evolutionary history. In this review, we will focus on different strategies and functions exhibited by microbes that enable them to adapt to changes in lifestyle associated with transitioning from a unicellular solitary state to a complex community architecture known as a biofilm. We will also discuss various environmental stimuli and signaling processes which bacteria utilize to coordinate their social traits and enable themselves to form complex multicellular-like biofilm structures, and the division of labour operative within such communities driving their diverse social traits. We will also discuss here recent studies from our laboratory using a plant-associated bacterial pathogen as a model organism to elucidate the mechanism of bacterial cell-cell communication and the transition of a bacterial community to a multicellular-like structure driven by the complex regulation of traits influenced by cell density, as well as environmental sensing such as chemotaxis and nutrient availability. These studies are shedding important insights into bacterial developmental transitions and will help us to understand community cooperation and conflict using bacterial cell-cell communication as a model system.