The name of the chain oriental markets is 99 ranch market. They are good and the price is reasonable. It has a pleasant-tasting, cheesy flavor and can be used directly on vegetables, baked potatoes, popcorn and other foods as a condiment. It is different from brewer's yeast or torula yeast. It can often be used by those sensitive to other yeasts.
Yeasts are part of the group fungii.
They were originally considered to be plants even though they do not produce chlorophyll, now they have their own kingdom. Microbial assays for vitamin B12 are no longer considered reliable due to problems with the cross-reactivity of corrinoids.