A hydroxy fatty acid; predominant monomer in PHA polymers produced by P. putida CA-3; present in LPS from the H. pylori strain SS1 and in the lipid A component of clinical isolates of P. aeruginosa isolated from patients with cystic fibrosis; inhibits mitotic progression of O. virens pollens via impairment of plasma membrane function; induces a reversible shape change of the membrane crenation in human erythrocytes