Agriculturally important microbial biofilms: Biodiversity, ecological significances, and biotechnological applications

A biofilm is an assemblage, aggregation, or community of microbial cells bounded by a polymeric matrix comprising polysaccharides that are associated with an inert or biotic surface. Biofilm formation is a universal trait, exhibited by microbes, when growing attached to natural and artificial surfaces. Microbial biofilms are an attractive subject, due to their important roles in the different sectors including agriculture, environment, industry, and health. Biofilms in agriculture have acquired interest due to their immense possibilities in crop production, protection, and improvement through their role in colonization of surface soils, roots/shoots of plants, and enabling proliferation in the desired niche, as well as enhancing soil fertility. Biofilm-forming microbes have been reported worldwide and they belong to Gram-positive, Gram-negative species, cyanobacteria, archaea, fungi, and microalgae. The microbial biofilm formation has been reported by all three domain systems of archaea, bacteria, and eukarya of different phylum including Actinobacteria, Ascomycota, Bacteroidetes, Basidiomycota, Chloroflexi, Crenarchaeota, Cyanobacteria, Euryarchaeota, Firmicutes, Oomycetes, and Proteobacteria. The most dominant genera involve in biofilms formation belong to Agrobacterium, Anabaena, Azospirillum, Azotobacter, Bacillus, Bradyrhizobium, Burkholderia, Gluconacetobacter, Paenibacillus, Pseudomonas, Rhizobium, Trichoderma, Xanthomonas, and Xylella. The agriculturally-important microbial communities and their interactions can have several implications on climate change, plant nutrition, plant protection, biofertilization, and bioremediation for sustainable agriculture and environments. This chapter deals with the fundamental aspects of biofilms, mechanisms of formation, the genes that are involved, biodiversity, and biotechnological applications in agriculture, industry, environmental studies, and allied sectors.