Woven around the global perceptions of microbial diversity in its different facets. Diversity perspectives are discussed in the context of ecosystem dynamics, taking into consideration environments that are unique to microorganisms. Considerable thrust is placed on the role that microorganisms play in sustainable production systems. Microbe-plant interaction arena is highlighted through the discussion of mycorrhizal partners, on which depends not only the plant community structure but also abatement of abiotic and biotic stresses. Other mutualist, rhizobia gets its due coverage whereas plant disease component carries examples from both, fungal and viral disease point of view. Considerable emphasis is placed on a discussion of the environmental issues such as the approaches that will lead to newer bioremediation technologies. This volume also carries a fair number of articles on commercial microbiology.