A psychrotolerant extracellular phosphatase from Krossfjorden sediment bacterium Bacillus cereus KR_O9: purification and functional characterization.

Abstract

This study reports the identification of a phosphatase-producing psychrotolerant bacterium, Bacillus cereus KR_O9, isolated from Arctic Krossfjorden sediments. The extracellular KR_O9 phosphatase was purified to homogeneity through acetone precipitation and ion exchange chromatography, achieving a specific activity of 12.51 U mg⁻¹ min⁻¹, a 17.3-fold purification, and a 64.94% yield. The molecular mass of the enzyme was estimated as 37 kDa by SDS-PAGE. K_m, and V_max for KR_O9 phosphatase towards substrate p-NPP were determined as 0.033 M L^-1, 1.67 mg^-1 min^-1. The enzyme exhibited optimal activity at 40 °C and pH 6.0, with stability up to ≤ 40 °C and at pH levels ≤ 7.0, highlighting its thermolability and sensitivity to alkaline pH. At 10 mM level, Cu²⁺, Hg²⁺, Co²⁺, Pb²⁺, urea, EDTA, and GSH significantly stimulated the enzyme, and Ca²⁺, Zn²⁺, Mn²⁺, SDS, and CTAB were, strong inhibitors. The kinetic efficiency, resilience to low to neutral pH, and tolerance to various metal ions, including heavy metals, underscore the potential of B. cereus KR_O9 phosphatase for bioremediation and biofertilizer applications, paving the way for industrial exploration.