Disclosed are compositions for isolating populations of nucleic acids from biological, forensic, and environmental samples. Also disclosed are methods for using these compositions as one-step formulations for killing pathogens, inactivating nucleases, and releasing polynucleotides from other cellular components within the sample, and stabilizing the nucleic acids prior to further processing or assay. The disclosed compositions safely facilitate rapid sample collection, and provide extended storage and transport of the samples at ambient or elevated temperature without contamination of the sample or degradation of the nucleic acids contained therein. This process particularly facilitates the collection of specimens from remote locations, and under conditions previously considered hostile for preserving the integrity of nucleic acids released from lysed biological samples without the need of refrigeration or freezing prior to molecular analysis.