β-Galactosidase release kinetics during ultrasonic disruption of Lactobacillus acidophilus isolated from fermented Eleusine coracana

The indigenous isolate of Lactobacillus acidophilus obtained from fermented Eleusine coracana was used as the source of intracellular β-galactosidase. Release of this enzyme from the bacterial cells is a challenging step for its recovery and further downstream processing. This paper reports the release kinetics of β-galactosidase by ultrasonication and survival rate of L. acidophilus as a function of acoustic power. A maximum of 360.3 U/g DCW of lactase was recovered with a release rate constant, Ka, of 0.454/min at an acoustic power of 50 W. The experimental data was fitted to Doulah's equation to determine the kinetic constant β and decipher the pattern of lysis during the ultrasonication process. Here we also hypothesize that due to local heat generation during the ultrasonication process, the enzyme was translocated from the cytoplasmic space in to the periplasm.

Research highlights▶ Decreasing β value with increasing power showed early life failure of L.acidophilus. ▶ β-galactosidase and total protein release was directly proportional to the acoustic power. ▶ Heat generation led to translocation of β-galactosidase from cytoplasm to periplasm.