A chitosanase-producing strain was isolated and identified as Bacillus cereus C-01. The purification and characterization of two chitosanases were studied. The purification assay was accomplished by ion exchange expanded-bed chromatography. Experiments were carried out in the presence and in the absence of cells through different expansion degree to evaluate the process performance. The adsorption experiments demonstrated that the biomass does not affect substantially the adsorption capacity of the matrix. The enzyme bound to the resin with the same extent using clarified and unclarified broth (0.32 and 0.30 U/g adsorbent, respectively). The fraction recovered exhibited 31% of the yield with a 1.26-fold increase on the specific activity concerned to the initial broth. Two chitosanases from different elution steps were recovery. Chit A and Chit B were stable at 30-60°C, pH 5.5-8.0 and 5.5-7.5, respectively. The highest activity was found at 55°C, pH 5.5 to Chit A and 50°C, pH 6.5 to Chit B. The ions Cu(2+), Fe(2+) and Zn(2+) indicated inhibitory effect on chitosanases activities that were significantly activated by Mn(2+). The methodology applied in this study enables the partial purification of a stable chitosanase using a feedstock without any pre-treatment using a single-step purification.
Keywords: B. cereus; Bioseparation; Chitosan; Chitosanase; Expanded bed adsorption; Ion exchange.
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