Screening of Lactobionic Acid Producing Microorganisms

Abstract

Lactobionic acid (LA) is derived from lactose and expected to be a versatile material for grow-ing bifidobacterium and forming mineral salts with high solubility in water for supplements. We aimed to develop microbial or enzymatic production systems of LA. To this aim, we screened lactose-oxidizing microorganisms, and obtained a strain of Burkholderia cepacia. The lactose-oxidizing activity existed in the membrane fraction of disrupted cell preparation of the strain. Only oxygen was necessary for lactose-oxidizing activity as a proton acceptor. A crude cell-free enzyme preparation was prepared, and its oxidizing ability and other properties on several saccharides were examined. The cell-free preparation oxidized D-glucose, D-mannose, D-galactose, D-xylose, L-arabinose and D-ribose. It also reacted with lactose, cellobiose, maltose, maltotriose, maltotetaose and maltopentaose. The strain accumulated LA in the culture supernatant with no loss of lactose. The strain is advantageous to production of LA by both fermentation and enzymatic reaction.