New publication in Environmental Science & Technology finds that chemical structure controls lipopeptide biotransformation in soil

Bacillus lipopeptides - including surfactins, iturins and fengycins - are emerging biopesticides, yet their fate in agricultural soils is still not well understood. This study examined how chemical structure influences biotransformation by combining laboratory soil-incubation experiments with high-performance liquid chromatography coupled to high-resolution mass spectrometry.

The authors found strong differences between families and structures. Iturins degraded fastest, with half-lives of one to eight days, followed by fengycins at five to fifteen days and surfactins at six to sixty-seven days. In one of the three soils tested, surfactins showed biphasic removal, and about one fifth of the added amount remained after more than one hundred days, suggesting the formation of a poorly bioavailable fraction. The study also showed that each additional methylene unit in the alkyl chain could increase half-life by up to about forty-five percent for iturins and about one hundred and ten percent for surfactins. Linearised surfactins were transformed substantially faster than cyclic surfactins. Together, these results help explain why some lipopeptides persist longer in soil and may support the selection and redesign of biopesticides with improved biodegradability. 

The study was co-led by Richard Gruseck, Thilo Hofmann and Michael Zumstein, all from EDGE | CeMESS, University of Vienna.