References

242 B. Giri et al.
11.6
Interactions Between Arbuscular Mycorrhizal Fungi
and Soil-Borne Pathogens
Many studies have demonstrated that AM fungi inhibit growth of the soilborne
pathogens (Al-Raddad and Adhmad 1995; Azcon-Aguilar and Barea
1996; Mukerji et al. 1997; Sharma et al. 1998; Sharma and Mukerji 1999;
Mukerji 1999; Joseph and Sivaprasad 2000; Singh et al. 2000). Since AM
fungi are established in the roots of host plants, research on the mycorrhizae
and disease incidence has been concentrated on disease caused by
soil-borne pathogens only. In the rhizosphere AM fungi occupy a unique
ecological position as they are partly inside and partly outside the host
thus, root-borne pathogens could directly interact with AM fungi in the
mycorrhizosphere. A summary of the AM fungi and soil-borne pathogens
is given in the Tables 8 and 9.
12
Conclusion
Microbialsurvivalandreproductivesuccessinmanysystemsrequirecolonization
of a surface and/or integration into a biofilm community. Success
in a community context requires morphological, physiological, and geneticattributesthathaveonlyrecentlybeenexplored.Thedevelopmentof
multicellular biofilm communities represents the interplay of many factors
including specific cell–cell interactions and, in many cases, metabolic communications.
Microbial interactions enable a variety of microorganisms
to coexist in environments in which individual organisms cannot survive.
Typically, these communities consist of various microbial aspects with
different metabolic activities and nutritional requirements. Particularly
within a biofilm, temporal and spatial formation of chemical microzones,
positioning of syntrophic partners and establishment of complimentary
metabolic pathways may all occur. Interaction between different species
and populations is often characterized by close but, in general, poorly
understood interdependencies.
Predation may also affect microbial activity. The role of protozoa in
regulating population numbers in the microbial community is well recognized.
This leads to increased mineralization of carbon, phosphorus, and
nitrogenasaresultofpredation.Collembolaareestablishedmycophagous
and after mites and nematodes they are among the soil’s most abundant
microfauna. They distribute the mycorrhizosphere flora.
Currently,thereisconsiderableresistancetotheuseofchemicalinsecticides,
pesticides, herbicides, weedicides and fungicides and fertilizers, be-