XANTHAN LYASE OF BACILLUS SP. STRAIN GL1 LIBERATES PYRUVYLATED MANNOSE FROM XANTHAN SIDE-CHAINS

When the bacterium Bacillus sp. strain GL1 was grown in a medium conta ining xanthan as the carbon source, the viscosity of the medium decrea sed in association with growth, showing that the bacterium had xanthan -depolymerizing enzymes. One of the xanthan-depolymerizing enzymes (xa nthan lyase) was present in the medium and was found to be induced by xanthan. The xanthan lyase purified from the culture fluid was a monom er with a molecular mass of 75 kDa, and was most active at pH 5.5 and 50 degrees C. The enzyme was highly specific for xanthan and produced pyruvylated mannose. The result indicates that the enzyme cleaved the linkage between the terminal pyruvylated mannosyl and glucuronyl resid ues in the side chain of xanthan.