When spiked into an unknown sample, this product will serve as an in situ positive control for DNAsequencing-based (e.g. NGS-based) microbiome measurements. These two bacteria, Imtechella halotolerans (Gram-negative) and Allobacillus halotolerans (Gram-positive) represent different cell recalcitrance and can expose potential bias during DNA extraction. Moreover, with accurately quantified cell numbers, this standard enables absolute cell number quantification in microbiome measurements.