<jats:p><jats:bold>Antibiotics from Gliding Bacteria, 45. — Phenalamides, New HIV‐1 Inhibitors from <jats:italic>Myxococcus stipitatus</jats:italic> Mx s40</jats:bold><jats:p>We report on the isolation and structure elucidation of the phenalamides A<jats:sub>1</jats:sub> (<jats:bold>1</jats:bold>), A<jats:sub>2</jats:sub> (<jats:bold>2</jats:bold>), A<jats:sub>3</jats:sub> (<jats:bold>3</jats:bold>), B (<jats:bold>4</jats:bold>), and C (<jats:bold>5</jats:bold>), amides from alaninol and ω‐phenyl‐substituted unsaturated carboxylic acids (a pentaene carboxylic acid in <jats:bold>1</jats:bold> — <jats:bold>4</jats:bold>, and a tetraene carboxylic acid chromophore in <jats:bold>5</jats:bold>). Compounds <jats:bold>1</jats:bold> — <jats:bold>3</jats:bold> are <jats:italic>E/Z</jats:italic> isomers with the configuration: 6Z for <jats:bold>1</jats:bold>, <jats:bold>4</jats:bold> represents 8‐methyl‐<jats:bold>1</jats:bold>, and for <jats:bold>5</jats:bold> we determined the 10,11‐double bond in <jats:bold>2</jats:bold> to be epoxidated. C‐16 in <jats:bold>1</jats:bold> has the <jats:italic>S</jats:italic> configuration, as revealed by ozonisation and isolation of the (2<jats:italic>S</jats:italic>)‐(+)‐2‐methyl‐4‐phenylbutyric acid. By comparison of their respective CD spectra all the other centers of chirality in <jats:bold>1</jats:bold> should have the same stereochemistry as in the related compound myxalamid B. <jats:bold>1</jats:bold> seems to be identical to stipiamide. First results of enrichment experiments show that the biogenesis of <jats:bold>1</jats:bold> starts with phenylalanine, which after transamination and decarboxylation is connected with propionate and acetate units to generate the highly unsaturated fatty acid. The second amino acid unit alanine terminates the biosynthesis.