Final answer:
The collective genome for a habitat sequenced from its microbial communities is known as a metagenome, and the related field of study is called metagenomics.
Step-by-step explanation:
The rapidity and cost-efficiency of DNA sequencing has allowed for the sequencing of genomic fragments from entire microbial communities within a given habitat. This collective genome for that habitat is called a metagenome.
The term metagenomics refers to the study of these collective genomes of multiple species that grow and interact in an environmental niche.
It enables researchers to study genes from a plethora of species, many of which may be unculturable in the laboratory, and analyze environmental impacts, such as the effect of pollutants or the identification of new species.
As technology progresses, the methodologies of metagenomics and metatranscriptomics continue to provide more in-depth and rapid insights into microbial communities and their gene expression profiles.