Production of β-galactosidase from new actinobacterial species

Streptomyces himalayensis 3K401, Jiangella aurantiaca 8K307T, and Jiangella ureilytica KC603T isolates were identified as potential β-galactosidase producers. The specific activities of the partially purified enzyme preparations were measured as 3.588 ± 0.00 U/mg protein, 1.320 ± 0.09 U/mg protein, and 1.262 ± 0.02 U/mg protein, respectively. The optimal operating conditions for β-galactosidase derived from S. himalayensis 3K401, J. aurantiaca 8K307T, and J. ureilytica KC603T were determined to be 40°C at pH 7.0, 50°C at pH 7.0, and 50°C at pH 9.0, respectively. Notably, all enzyme solutions retained activity at elevated temperatures (60–70°C). Comparative analysis revealed that β-galactosidases from Jiangella isolates exhibited greater thermal stability at 50°C and 60°C than the enzyme from S. himalayensis 3K401. This suggests that these enzymes could remain active following pasteurization at relatively high temperatures. Furthermore, enzyme solutions from Jiangella isolates demonstrated activity across a broad pH range, including acidic conditions (pH 4.0 and 5.0), which aligns with their potential application in the production of drinking milk. Additionally, the operational pH profiles of these enzymes, particularly their activity under neutral and alkaline conditions, highlight their potential utility in pharmacological applications beyond the food industry.