Functional amyloid BE-AM1 mediates xenobiotic adaptation in Solibacillus silvestris AM1.

Estuarine ecosystems are complex pollutant mixtures where hydrocarbons and pesticides coexist- resulting in microbial adaptation mechanisms with hitherto less studied cross-pollutant interactions. The present study elucidates the adaptive response of Solibacillus silvestris AM1, isolated from Vellar estuary focusing on regulation of an amphipathic functional amyloid protein, BE-AM1 (a bioemulsifier) under mixed xenobiotic stress (aromatic hydrocarbons and water-soluble pesticides) exhibiting ecological implications. The bacterial strain exhibited strong tolerance to benzene, naphthalene and acephate with maintained or enhanced BE-AM1 synthesis, while trichlorobenzene and cypermethrin significantly suppressed production. Acephate induction resulted in increased BE-AM1 production, enhanced cell-surface hydrophobicity, auto-aggregation and biofilm formation. The results thus suggest pesticide exposure-induced mechanisms of amyloid BE-AM1 mediated modulation of pollutant bioavailability, microbial adhesion and potential co-metabolic degradation within microbial consortia. S. silvestris AM1 is known for hydrocarbon and pesticide tolerance, supported by BE-AM1 mediated surface-activity in surface-wetting and alteration of physicochemical interfaces. Thus, amphipathic amyloid BE-AM1 reported previously for surface-active (bio-emulsifier) can act as mediator influencing estuarine pollutant partitioning and microbial interactions in micro-niches. The present study provides evidence for pesticide-induced regulation of functional amyloid production contributing to adaptive responses in S. silvestris AM1.