초록
<P><B>Abstract</B></P><P>Terrestrial bacteria, especially actinomycetes, are known to be prolific producers of volatile compounds. We show here that bacteria from ocean sediments can also release complex bouquets of volatiles. The actinomycete <I>Salinispora tropica</I> produces cyclohexenyl compounds not previously known in nature, such as methyl cyclohex‐2‐ene‐1‐carboxylate (<B>9</B>), methyl 2‐(cyclohex‐2‐en‐1‐yl)acetate (<B>10</B>), methyl (<I>E</I>/<I>Z</I>)‐2‐(cyclohex‐2‐en‐1‐ylidene)acetate (<B>11</B>/<B>12</B>), and related alcohols <B>8</B> and <B>13</B>. These compounds were identified by GC/MS and confirmed by synthesis. In addition, rare spiroacetals, aromatic compounds, short‐chain acids and esters, alcohols, and various cyclic compounds were produced by the bacteria. The biosynthesis of the cyclohexenyl compounds is closely coupled to that of cyclohexenylalanine (<B>4</B>), a building block of salinosporamide A, a proteasome inhibitor produced by <I>S. tropi</I>ca. Analysis of <I>S. tropica</I> strains that harbor knockouts of the salinosporamide biosynthetic genes <I>salX</I> and <I>salD,</I> coupled with feeding experiments, revealed that 3‐(cyclohex‐2‐en‐1‐yl)‐2‐oxopropanoic acid (<B>60</B>) and 3‐(cyclohex‐2‐en‐1‐ylidene)‐2‐oxopropanoic acid (isomers <B>61</B> and <B>62</B>) are important intermediates in the biosynthesis of salinosporamide A, <B>4</B>, and <B>8</B>–<B>13</B>.</P>