Factors Affecting Biofilm Formation inin vitroand in the Rhizosphere

The biofilm formation by the microbes is considered as a strategy of survival under natural conditions. Microbes form biofilm on the abiotic surfaces also under in vitro conditions with the availability of optimum nutrients and moisture content. Considerable amount of work on biofilms associated with environment, medical, and food industry has been done. However, in the recent past, interest has been generated on the role of microbial biofilms associated with plants and in the rhizosphere for their impact on the plant health. Various factors are known to influence the process of biofilm formation. This chapter discusses the influence of biotic and abiotic factors on the formation of biofilm, especially under rhizosphere and on plant surfaces. These factors are affected by the characteristics of microbial cells, its structures and products, nature of surfaces, and plant root exudates, along with the soil environmental conditions (both biotic and abiotic factors). Common abiotic factors of soil include pH and salt concentration, temperature, moisture, nutrient availability, antibiotic effects, heavy metals, and other interfering chemicals in soil. Biotic factors in the rhizosphere can also be contributed as competition by other organisms for surface attachment, plant genotype, and soil macro and microflora, including soil bacterial viruses and protozoans regulating bacterial population. It is concluded that biofilm formation is a multistep process and influenced by various factors. Therefore, a better understanding on the factors influencing biofilms in the rhizosphere is a prerequisite to explore biofilm role in the management of soil and plant health.