Clay Mineralogy in Relation to Survival of Soil Bacteria

Although biologists are conscious of the role of different soil properties in the development of and interaction between different plant communities, little critical thought has been devoted to the effects of such soil properties on the development of microbial communities within soil habitats. Soils are an important repository for many plant pathogens, and the survival of these pathogens in the absence of their specific host plants depends on a complex interplay between the physical, chemical, and biological factors in the soil. The situation is made even more complex by the tremendous degree of variability in these factors, both within and between different soil types. Unlike laboratory culture systems, soil is a growth medium consisting predomi­ nantly of particulate matter offering a large, but variable, surface area that may drastically modify the growth and interaction between microbial populations. The broad aspects of interactions between microorganisms and soil particles have been the subject of several recent reviews (14,20,31,40,61). Consequently, this review is restricted to (a) the influence of clay minerals on bacterial survival and (b) the development of a conceptual basis for more realistic future studies on the role of clay minerals in modifying the survival of bacteria in soils. The successful interpreta­ tion of more detailed studies on survival depends on our ability to define the e!ltent and nature of the many solid and other surfaces encountered in soil microhabitats, as well as on our ability to relate such knowledge to the effects of these surfaces on microbial behavior.