NCBI Taxonomy identifier for the source organism.
In this context, the source organism is the source of the gene
for samples that are isolated from a genetically manipulated source
(e.g. recombinant expression), or which are chemically synthesized.
The organism name is for both the source of the gene and/or the entity
if sample is isolated from a natural source.
Reference:
Wheeler DL, Chappey C, Lash AE, Leipe DD, Madden TL, Schuler GD,
Tatusova TA, Rapp BA (2000). Database resources of the National
Center for Biotechnology Information. Nucleic Acids Res 2000 Jan
1;28(1):10-4
Benson DA, Karsch-Mizrachi I, Lipman DJ, Ostell J, Rapp BA,
Wheeler DL (2000). GenBank. Nucleic Acids Res 2000 Jan 1;28(1):15-18.