Bacterial morphogenesis vis-à-vis cell size in the various stages of biofilm development

Abstract

Bacterial cell division is regulated by the bacterial cytoskeletal protein FtsZ/ RodZ and the level of Z ring assembly. MreB actin protein is found to regulate the cell wall component peptidoglycan synthesis and insertion. The cytokinesis process also is regulated during the biofilm stage at nutrient limiting conditions. However, if the nutrients are available during normal growth of life, the cell division rates and cytokinesis will be faster to reach to the optimum density to exhibit the density dependent gene network. Besides, bacterial pleomorphism was found to occur in biofilm under overcrowding condition to facilitate the cells to escape and settle at a new substratum. Rod shaped cells align their orientations with nearby cells and colonize at the base and edges, whereas coccoid cells dominate the upper surfaces in a biofilm. Phenotypic heterogeneity helps to optimize the interactions with cells and the attached surfaces. Cell morphology, aggregation and arrangement within biofilm were studied in Paenibacillus lautus and found that the biofilm was composed of numerous pleomorphic cells attached to the surface. Coccoid cells preferred to live in biofilm mode, whereas the transformed rods acquired the flagellar motility. It is hypothesized that the biofilm stage of bacterial cells are regulated by the genes which regulate cytokinesis, morphology and cell wall synthesis for morphogenesis.