So how far can we push this analogy? Genome has two meanings: the complete genetic material of a living organism, and the idealized genome of a species. With millions of species, there are millions of genomes in the second sense and many quadrillions in the first sense. Genomics is the study of all of these.
So is the lexome the (potential) vocabulary of an individual, of a language, or of a species? Individuals can speak more than one language, so do they have more than one lexome? (They have more than one genome: mitochondrial and nuclear.)
Does the lexisphere contain multiple lexomes or only one? Is the lexisphere the set of things describable by a (the) lexome, or are lexisphere and lexome synonyms? Interestingly, the word genosphere, most broadly defined as "the genetic content of the universe at anytime" has been around for at least a dozen years.
I'm a biologist too, adoarns. Lexome is a great analogy, given how words and languages evolve and recombine and memes compete for prominence. (For non-biologists, the reference is to genome, proteome, metabolome, transcriptome etc.)