Beneficial microbes in the soil employ a variety of strategies to fortify the soil’s defenses against diseases. For instance, biocontrol bacteria like Bacillus spp. and Pseudomonas spp. are well – known for their production of soluble antibacterial substances. These include antibiotics, cyclic lipopeptides, surfactants, extracellular polyhydroxybutyrate polymerase, and volatile organic compounds. Through antagonism, inhibition, or direct killing of pathogens, these substances act as a front – line defense. For example, certain antibiotics secreted by Bacillus spp. can disrupt the cell walls or metabolic processes of pathogenic bacteria, rendering them unable to cause harm.
Phages, with their “specific hunting” ability, can efficiently lyse pathogenic bacteria. They target specific pathogens, injecting their genetic material into the host bacteria and using the host’s cellular machinery to replicate, ultimately bursting the pathogen and reducing its population. Protozoa, on the other hand, use selective predation to lower the abundance of pathogens. They actively consume pathogenic microorganisms, thus maintaining a balance in the soil microbial community.
The diversity of indigenous microbes and the efficient resource utilization by a wide range of microorganisms are key mechanisms in inhibiting pathogen invasion. A highly competitive microbial community creates a self – regulating environment. Microbes compete for nutrients, space, and other resources, making it difficult for pathogens to establish themselves. This collective resistance effectively reduces the occurrence of soil – borne diseases.
Soil microbes interact to form a complex network. This network influences the composition and function of different interdependent components, having direct or indirect effects on soil and plant health. An example is the interaction between Bacillus and indigenous Pseudomonas populations. They form a symbiotic relationship, synergistically enhancing the colonization of multiple species in the root system. This results in the formation of a beneficial “bacterial consortium” that can effectively resist the invasion of pathogens into plants.
The concept of creating a “biotherapy” for soil immunity, through precise regulation of the soil microbiome, holds great promise. By increasing the abundance of beneficial bacterial communities and reducing the number of pathogens, it offers a new perspective on improving soil biological fertility, constructing an immune defense line, and enhancing soil health. This could involve strategies such as inoculating the soil with specific beneficial microbes or creating conditions that favor their growth.
