The purification and characterization of a novel alkali-stable pectate lyase produced by Bacillus subtilis PB1

Pectinase is an important kind of enzyme with many industrial applications, among which pectinases produced by bacteria were scarce compared with fungal sources. In this study, a novel bacterium which produced extracellular pectinase was firstly isolated from flue-cured tobacco leaves and identified as Bacillus subtilis PB1 according to its 16S rRNA gene. The pectinolytic enzyme was purified by ammonium sulfate precipitation, ion-exchange and gel filtration chromatography, after which molecular weight was determined as 43.1 ± 0.5 kDa by SDS–PAGE. Peptide mass fingerprinting of the pectinase by MALDI-TOF MS showed that the purified enzyme shared homology with pectate lyase and was designated as BsPel-PB1. The optimal temperature for BsPel-PB1 was 50 °C. The optimal pH was pH 9.5 for BsPel-PB1 while it had a broad pH stability from 5 to 11. The values of Km and Vmax were 0.312 mg/mL and 1248 U/mL, respectively. Accordingly, the BsPel-PB1 was a novel alkaline pectate lyase which could find potential application as a commercial candidate in the pectinolytic related industries.