Purification, characterization, and gene cloning of a new cold-adapted β-galactosidase from Erwinia sp. E602 isolated in northeast China

Abstract

β-Galactosidases are widely used in industry for elimination of lactose from milk products. A new β-galactosidase was obtained from bacterial strain Erwinia sp. E602, newly isolated in northeast China. The enzyme was purified with the methods of ammonium sulfate fractionation, ion exchange, and gel filtration chromatography for further study of the enzymatic characteristics. The purified enzyme had a molecular weight of near 110 kDa. The optimum reaction temperature and pH of this enzyme was determined to be 40°C and 7.0, respectively, indicating that this enzyme was a mesophilic neutral β-galactosidase. Furthermore, the enzyme retained near 10% of the activity at 0°C, which also suggested its cold-adapted property. Kinetics of the β-galactosidase was studied, and the K (Michaelis constant) and V (maximum enzymatic reaction rate) of this enzyme were 0.21 mmol/L and 263.16 µmol/mg per minute, respectively. The effects of metal ions on the enzymatic activity and the lactose hydrolysis efficiency in milk, as well as its trans-glycosylation activity, were studied in this work. The β-galactosidase coding gene was cloned to be a 3-kb length fragment, which shared at most 81% of identity with the published sequences in NCBI Blast database (https://blast.ncbi.nlm.nih.gov). Results in this work suggested it is a new β-galactosidase and it has potential to be used in dairy and food processing.

Characterization and Application of a New β-Galactosidase Gal42 From Marine Bacterium Bacillus sp. BY02

“…The β-galactosidase obtained from bacterial strain Erwinia sp. E602 ( Xia et al, 2018 ) was also obviously inactivated by Cu 2+ with about 5% activity. Mg 2+ and Na + are both required to achieve the maximal activity of the β-galactosidase ( Juers et al, 2001 ).…”

Cloning, expression, and characteristic analysis of the novel β‐galactosidase from silkworm, Bombyx mori

“…Therefore, we expressed it in the baculovirus expression system, and high enzyme activity was detected. The optimal pH and temperature for β‐galactosidase of many bacteria and fungi were found in the range of 6.5–4.5 and 40–60 °C, respectively (Carneiro, Yu, Dupree, & Ward, 2018; Li et al, 2020; Xia et al, 2018; Yang et al, 2018). However, the optimum pH and temperature of some β‐galactosidase are not in this range, for example, β‐galactosidase from Aspergillus lacticoffeatus (Cardoso, Silverio, Abrunhosa, Teixeira, & Rodrigues, 2017).…”

Cloning, Expression, and Characteristic Analysis of the Novel β-Galactosidase from Silkworm,Bombyx Mori

“…Therefore, we expressed it in the silkworm expression system, and high enzyme activity was detected. The optimal pH and temperature for β-galactosidase of many bacteria and fungi were found in the range of 6.5-4.5 and 40-60 ºC, respectively [3,7,28,29]. However, the optimum pH and temperature of some β-galactosidase are not in this range, for example, β-galactosidase from Aspergillus lacticoffeatus [30].…”