What type of genetic material outnumbers human genes by a significant margin?

Microbial genes outnumber human genes by a significant margin because of the vast number of microorganisms that inhabit various environments, including the human body. The human genome contains about 20,000 to 25,000 genes; however, the human microbiome, which consists of trillions of microbes, contains a staggering number of microbial genes—estimates suggest that these can be in the range of 2 to 20 million. This dramatic difference in the number of genes is primarily due to the sheer diversity and abundance of bacteria, archaea, fungi, and viruses present in various ecosystems, particularly within the human gut and on the skin, where these microbes play crucial roles in digestion, immunity, and overall health.

While animal DNA and plant DNA do have their own complexity and richness, they do not come close to matching the vast diversity found in microbial communities. Synthetic genes pertain to laboratory-created sequences and are not naturally occurring in the same sense as the genes found in living organisms. Thus, microbial genes clearly represent an incredibly abundant source of genetic material, highlighting the vast and often overlooked genetic diversity that exists in our surroundings.