The methods included in Environmental Microbiology: Methods and Pro- cols can be placed in the categories ?Communities and Biofilms,? ?Fermented Milks,? ?Recovery and Determination of Nucleic Acids,? and the review s- tion, containing chapters on the endophytic bacterium, Bacillus mojavensis, the engineering of bacteria to enhance their ability to carry out bioremediation of aromatic compounds, using the hemoglobin gene from a strain of Vitreoscilla 23 spp., and the use of chemical shift reagents and Na NMR to study sodium gradients in microorganisms, all of which should be of interest to investigators in these fields. The subjects treated within the different categories also cover a wide range, with methods ranging from those for the study of marine organisms, through those for the investigation of microorganisms occurring in ground waters, including subsurface ground waters, to other types of environmental waters, to as varied subjects as the biodiversity of yeasts found in northwest Argentina. The range of topics described in the Fermented Milks section is smaller, but significant for investigators in areas concerned with milk as an item of foods for infants, small children, and even adults.