Cells of the ten microbes were mixed to create log-distributed abundance, which allows one to easily assess the detection limit of a microbiomics workflow. 75 l of the standard contains about ~100 cells of the Staphylococcus aureus, the organism of lowest abundance. If needed, the standard can be spiked into a sample matrix (e.g. soil and blood) to mimic real samples of interest. The microbial standard is accurately characterized and contains negligible impurity (< 0.01%). It was constructed by pooling cells from pure cultures of ten microbial strains. The cells from each pure culture were quantified before pooling. After mixing, the microbial composition was confirmed using NGS-based sequencing.