Anticorrosion potential of a bioemulsifier produced by Psychrobacillus antarcticus Val9 isolated from Antarctic soil

Livia Vieira Araujo de CastilhoAline Loureiro BarretoKaren Caroline Ferreira SantarenMariana Barbalho Farias RosenblattIgor TaveiraJefferson CyprianoFernanda AbreuMateus Gomes de GodoyDiogo De Azevedo JureleviciusLUCY SELDIN^*

• Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil

Microbiologically influenced corrosion (MIC) poses a persistent challenge in industrial systems, particularly in oilfield infrastructure, where biofilm-forming microorganisms accelerate metal degradation. In this study, we evaluated the anticorrosive, antibiofilm, and biocidal properties of two bioproducts—a bioemulsifier from Psychrobacillus antarcticus Val9 and a surfactin from Bacillus velezensis H2O-1—using microcosms that simulate water injection header conditions. The bioproducts were produced and characterized through emulsification indices under various conditions, surface tension, and oil displacement assays. Their effects were assessed via carbon steel mass loss, scanning electron microscopy, epifluorescence microscopy, surface roughness analysis, ATP quantification, and molecular profiling of microbial communities. Both compounds demonstrated physicochemical stability under extreme environmental conditions and significantly reduced carbon steel mass loss over 96 hours. Microscopic analyses revealed diminished biofilm roughness and disrupted extracellular matrix cohesion, indicating impaired biofilm maturation. ATP assays and qPCR data revealed selective microbial suppression without triggering metabolic rebound, suggesting the destabilization of biofilm homeostasis. Furthermore, 16S rRNA gene sequencing and absolute quantification revealed a shift in the microbial community structure, with a reduced abundance of corrosion-associated taxa such as sulfate-reducing and metal-oxidizing bacteria. Notably, the treatments enriched less aggressive genera, contributing to a lower biomass and a less corrosive microbial environment. These findings highlight the dual action of the tested bioproducts: direct surface protection and strategic microbial community modulation. By integrating biological control with physicochemical resilience, this approach offers a sustainable alternative to conventional chemical biocides, with potential applications in offshore pipelines and industrial water systems.