Improvement in the compatibility of hydrocarbon and water is achieved by surface active agents newly synthesized by mixed microbial populations. Methods for enhancing the microbial production of surface-active agents in hydrocarbon-exposed surface waters can be achieved by supplementing the mixed microbial population with one or more carbon sources, most notably propionate. Hydrocarbon-exposed surface waters having enhanced levels of surface-active agents can be used to improve hydrocarbon recovery from subterranean formations or for remediation of hydrocarbon-contaminated sites.