ITURin

Iturin is a family of cyclic lipopeptide antibiotics produced by certain Bacillus species, most notably Bacillus subtilis and Bacillus amyloliquefaciens. Members include iturin A, iturin B, iturin C, as well as related bacillomycins and mycosubtilins. These compounds occur as mixtures of homologues that vary in amino acid sequence and in the length of their fatty acid side chains. They are characterized by an amphiphilic structure, with a cyclic heptapeptide ring linked to a beta-amino fatty acid tail, giving them strong surface-active properties.

Mechanism and activity: Iturins exert pronounced antifungal activity by interacting with fungal cell membranes. They preferentially target membranes containing sterols, assembling to form ion-permeable channels that disrupt membrane integrity, leading to leakage of cytoplasmic contents and cell death. They show broad activity against filamentous fungi and some yeasts, while generally having limited antibacterial activity. The antifungal effects are often enhanced when iturins are part of a broader suite of Bacillus lipopeptides, such as fengycins and surfactins.

Production and applications: Iturin compounds are produced by fermentation of Bacillus strains and are used in agricultural biocontrol formulations to protect crops from fungal pathogens, including Fusarium, Botrytis, and related diseases. As biosurfactants, they can aid in root colonization and biofilm interactions, contributing to the biocontrol efficiency of Bacillus-based products. They are typically deployed as part of integrated pest management and organic farming strategies.

Safety and considerations: Formulations of iturin-containing products are subject to regulatory safety assessments to evaluate effects on non-target organisms, soil microbiota, and environmental fate. Their surfactant activity may influence application conditions and compatibility with other agrochemicals.