ABSTRACT
Microbial biofilms are formed by the aggregation or communities of single or multiple microbial species (bacteria, fungi, and algae), surrounded by polymeric matrix (lipopolysaccharides, proteins, etc.) and associated with biotic or abiotic surfaces (natural and artificial). Generally, biofilm formed by microbial cells is a strategy of microorganism to protect themselves from exogenous environmental stresses (physical, chemical, and biological). Moreover, it is a responsive mechanism of microbes to overcome the problem of nutrient depletion in the surrounding environment as well as to maintain pH and other physiochemical parameters. Biofilm can be developed in vitro, and hence can play an important role in various disciplines, including agriculture, environment, biotechnology, industries, health, and wastewater management. Plants have very close interaction with soil for their survival, growth, and development. Additionally, soil is a rich source of various nutrients and thus acts as a nutrient reservoir for plants. But sometimes depletion of essential nutrients (nitrogen, sulfur, magnesium, manganese, potassium, etc.) in plants may occur in the soil, resulting in retardation of plant growth and development. Microorganisms have been reported for their nutrient fixation capabilities and thus act as an alternate source of nutrient supply. These microbes interact with plants through a specific mechanism for the exchange of nutrients. But these mutual interactions are not only important for nutrient exchange, plant growth promotion, environmental stress mitigation, and biocontrol, but also influences soil physiochemical and biological properties, as a result of which facilitation of nutrient balance occurs through a mechanism called biogeochemical cycles. The interactions of plants and microbes which are beneficial include diazotrophs, mycorrhizae, phosphorus solubilizers, Plant growth promoting rhizobacteria (PGPRs), endophytes bacteria for nitrogen fixation, and biocontrol agents. Biofilms play an important role in the biological treatment of wastewater to degrade organic contaminants. The major requirements for biological treatment of municipal wastewater are (1) the presence of active microorganism in a bioreactor and (2) their collection from the treated effluent and recycling mechanism. They may be the active agents in drinking water treatment, i.e., biofiltration to purify water. This chapter focuses on the microbial biofilms, their role in plant growth and development, soil nutrients availability, agricultural environment maintenance, and management.
