Mechanism of Bacterial Cell Flocculation by Extracellular Materials from Nocardia Amarae.

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The fact that Nocardia amarae YK1 produced bacterial flocculation-inducing substances (FIX : Flocculation Inducer-X) was discovered. FIX had a function of flocculating the proliferating cells ; FIX-induced flocculation was retarded in resting cell conditions.FIX had a broad spectrum on flocculation induction from gram-negative to -positive bacteria. In the presence of FIX, Achromobacter cycloclastus IAM1013, Acinetobacter calcoaceticus IAM1517, Bacillus subtilis IAM1069, Escherichia coliC600-1, E. coli IAM1239, Flavobacterium lutescens IAM1667, Klebsiella pneumoniae IAM1102, Micrococcus luteus IAM1313 and Pseudomonas putida IAM1002 formed flocs, respectively, though B. cereus IAM1029 exhibited no flocculation.The fractionation of bioflocculant FIX produced by Nocardia amarae YK1 revealed that the flocculant was a mixture of more than three substances. Although individual fractions did not exhibit the ability of flocculant at pH 5 to 7, synergetic flocculation was observed at pH 7 after mixing the fractions. Infrared spectrophotometry suggested that the chief components of the frctions might be peptides. Enzymatic digestion of peptide moiety results in disappearance of flocculation activity.