Microbial Biocontrol Agents for Agricultural Soil Remediation: Prospects and Application

Soil pollution is rampant in recent years, attributed mainly to various anthropogenic activities. The pollutants, organic or inorganic in nature, reside in the soils and accumulate to levels exceeding permissible safe levels, posing hazards to living organisms. As a result, soils can harbour various pollutants such as polycyclic aromatic hydrocarbons (PAHs), persistent organic pollutants (chlorinated and brominated aromatic substances, organochlorine-based pesticides, and dioxins), heavy metals, and metalloids. And often, soils that are heavily contaminated are agricultural soils due to the extensive use of fertilizer and pesticides resulting in residual accumulation of heavy metals, PAHs, and dichlorodiphenyltrichloroethane. Conventional approaches to soil remediation include physicochemical means that is costly, laborious, and non-sustainable. In response, biological means is sought as an alternative due to its environmental-friendly, better sustainability, and cost-effective traits. The biological remediation utilizes plants (phytoremediation) or the typical soil microflora (microbial remediation). In this chapter, the alternative of exploring microbial biocontrol agents for soil remediation is proposed. Microbial biocontrol agents are often introduced into the soil to suppress disease development or to enhance growth of plants. They are introduced into various agricultural soils which may harbour pollutants. Biocontrol agents have metal-chelating and nutrient-solubilizing properties. This is further escalated by the discovery of metal-tolerant species as biocontrol agents. As such, this approach promotes the use of biocontrol agents as bioremediation agents as well, to manage disease and bioremediate soils at the same time. This chapter will describe microbial biocontrol agents and their potential, mechanisms, and applications for the remediation of polluted soils.