Fatty acid elongase with strict substrate specificity for monounsaturated fatty acids, in particular 16:1 (delta-9) to produce the unusual 18:1 (delta-11) fatty acid. a very-long-chain acyl-CoA + H(+) + malonyl-CoA = a very-long-chain 3-oxoacyl-CoA + CO2 + CoA Down-regulated by Pseudomonas aeruginosa, PAO1 strain and PA14 strain infection. Belongs to the ELO family.