The editors (of the Planta Piloto de Procesos Industriales Microbiologicos-Consejo Nacional de Investigaciones Cientificas y Tecnicas, Argentina) present 38 contributions describing step-by-step protocols for investigating the interactions of microorganisms with their environment. The protocols follow the same format as other volumes in the series, including laboratory instructions, a summary of the principle of the technique, lists of equipment and reagents, and discussions of pitfalls. The protocols are grouped into sections on communities and biofilms; fermented milks; nucleic acids, recovery, and determination; and reviews. Review articles discuss the endophytic bacterium Bacillus mojavensis, the engineering of bacteria to enhance bioremediation of aromatic compounds, and the use of chemical shift reagents and Na-NMR to study sodium gradients in microorganisms.