Microorganisms are one of the first living organisms that populated Earth. Microbial life is exceptionally diverse and microorganisms have inhabited various environments such as soil, water, air, sediments, and also include the plants and animals. Till recent past, conventional approaches were taken into consideration to study the isolation and characterization of selected microbes in defined communities. However, molecular biology approach has transformed the field. It has ameliorated our knowledge of the microbial communities and this modern approach can be deployed to analyse microorganisms in the environment without much hassle. The present molecular biology approach incorporates analysis of DNA, RNA and proteins obtained from environmental samples. At present, the identity and functions of microbes is determined by applying `omics’ approach.

Microorganisms have exceptional influence on the whole ecosystem. Chemosynthetic bacteria help other organisms in light devoid zones by providing them carbon and energy. Few microbes have the potential to recycle the nutrients. Microorganisms are of prime importance for on-site remediation of agricultural and industrial wastes and subsurface pollution. Each microorganism is capable of degrading toxic waste depending on the nature of each contaminant. Special effects of microbe symbiotic relationship (either good or bad) on the biosphere make it significant.

The initiatives to eradicate the environmental problems highlight the need for collating significant published research work of different scientists across the world to help young researchers in accomplishing their ambitious goals. The significance and role of bacteria in natural environments is described in Chapter 1. Chapters 2-4 focus on the analyses of microorganisms in soil. Study of microbial community in marine environment is discussed in Chapters 5-7. A study of airborne microbial communities is reported in Chapter 8. The analysis of bacterial communities in sediment is described in Chapters 9-12. Isolation and characterization of bacteria of cattle is reported in Chapter 13. Chapter 14 describes the characterization of tomato-associated Rhizobacteria. The last three Chapters of the book describe the assessment of microbial species in an artificial environment.

I hope that this book will serve as assistance to students, researchers, teachers, environmental organizations and industries.