Mono-unsaturated fatty acids are components of the cellular membranes of autotrophic bacteria. The specific composition and abundance of membrane fatty acids can be used to identify specific genera of bacterial populations in natural environments (e.g., mining lakes, etc.). cis-7-Hexadecenoic acid methyl ester is a complement to cis-7-hexadecenoic acid. The non-esterified molecule has been isolated from autotrophic bacterial cultures associated with the accumulation of sulfate in biofilters. This indicates they originate from a sulfide-oxidizing autotrophic organism. To date, however, this fatty acid has only been detected in strains of the genera Nitrospira, which are nitrite oxidizing autotrophic bacteria.