Gram-negative bacteria protect themselves with an outermost layer containing lipopolysaccharide (LPS). O-antigen-specific bacteriophages use tailspike proteins (TSP) to recognize and cleave the O-polysaccharide part of LPS. However. O-antigen composition and structure can be highly variable depending on the environmental conditions. https://www.roneverhart.com/HGST-Ultrastar-7K6000-HUS726040ALS214-4TB-7-2K-RPM-SAS-12Gb-s-512n-128MB-3-5-SE-Hard-Drive/