Bioemulsifier (BE-AM1) produced by <i>Solibacillus silvestris</i> AM1 is a functional amyloid that modulates bacterial cell-surface properties

A novel estuarine bacterial strain, <i>Solibacillus silvestris</i> AM1, produces an extracellular, thermostable and fibrous, glycoprotein bioemulsifier (BE-AM1). The amyloid nature of the bioemulsifier (BE-AM1) was confirmed by biophysical techniques (Congo red based polarization microscopy, ThioflavinS based fluorescent microscopy, fibrous arrangement in transmission electron microscopy and secondary structure measurement by FTIR and CD spectrum analysis). Cell-bound BE-AM1 production by <i>S. silvestris</i> AM1 during the mid-logarithmic phase of growth coincided with a decrease in cell surface hydrophobicity, and an increase in cell autoaggregation and biofilm formation. It was observed that the total interfacial interaction energy () for the surface of the bioemulsifier producing <i>S. silvestris</i> AM1 and different derivatized surfaces of polystyrene (silanized and sulfonated) was found to support biofilm formation. This study has revealed that the BE-AM1, a bacterial bioemulsifier, is a functional amyloid and has a role in biofilm formation and cell surface modulation in <i>S. silvestris</i> AM1.