News Chemistry

Bacteria staining method has long been misexplained

Gram technique works, but not the way scientists thought

gram staining bacteria

COLOR CODED  An old lab technique for differentiating bacteria as either gram-positive (left) or gram-negative (right) has been incorrectly explained for decades.

From left: Riraq25/Wikimedia (CC-BY-SA-3.0); CDC

By Beth Mole

- More than 2 years ago

With delicate hues of purple and pink, a lab technique called gram staining has reliably characterized bacteria for more than a century.