Amyloid protein produced by B. cereus CR4 possesses bioflocculant activity and has potential application in microalgae harvest

Bacillus cereus CR4 from the flocs of activated sludge was found to produce an extracellular bioflocculant, which was characterized as amyloid protein and demonstrated to have potential application in microalgae recovery. Cell surface amyloid production was demonstrated by fluorescence, confocal and scanning electron microscopy. Birefringence, spectral shift assay, TEM, FTIR and CD spectra confirmed the amyloid nature of the purified protein that demonstrated flocculation. The gene for amyloid protein of B. cereus CR4 was found to be related to tas A gene of amyloid protein produced by Bacillus subtilis. The results demonstrated that the amyloid protein produced by B. cereus CR4 possessed a novel bioflocculant activity which at pH below 4.5 reached to a maximum of 86.87%. The amyloid bioflocculant producing B. cereus CR4 has a potential in biotechnological application like Scenedesmus biomass recovery.