Permeabilization of Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus with Ethanol

Abstract

Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus cultures were treated with ethanol and tested for viability and beta-galactosidase activity. Exposure of the biomass of test cultures to 30%-55% ethanol (vol/vol) caused a 100% loss of viability and up to 15-fold increase in measurable beta-galactosidase activity in both streptococci and lactobacilli. Ethanol-treated cell suspensions could be stored for up to 6 months without loss of enzyme activity. The nonviable permeabilized biomass of the more active S. thermophilus was used to achieve up to 80% hydrolysis of lactose in aqueous solutions and non-fat milk.

Production of Food Grade β-Galactosidase from Artisanal Yogurt Strains

“…In order to encourage the growth and product formation in lactic acid bacteria in whey, complex nutrients such as, malt sprouts, corn step liquor, yeast extract, meat extract or hydrolyzed whey proteins were recommended in many studies (Aeschlimann and von Stockor, 1989;Bury et al, 1999;Ghaly et al, 2004). The highest b-galactosidase activity level obtained in this study using St 95/2 and St 77a strains especially using medium M2 under static conditions was comparable to many studies in the literature (Greenberg and Mahoney, 1982;Somkuti et al, 1996;Somkuti et al, 1998) and very promising for many industrial applications with respect to its low cost media composition. Strain St 95/2, besides having the high potential as b-galactosidase producer was also determined to be a high lactic acid producer and as starter culture to be used in many dairy applications.…”

“…As mentioned previously, b-galactosidase enzyme in Lactobacillus bulgaricus and Streptococcus thermophilus cultures is a cytoplasmic enzyme whose expression of activity is achieved through the perturbation of cell integrity by means of either sonication, mechanical, enzymatic, or chemical treatments (Somkuti et al, 1998). The disruption of cells is the first and important stage in the isolation and preparation of intracellular products such as b-galactosidase.…”

Transgalactosylating β-galactosidase from probiotic Lactobacillus plantarum MCC2156: production and permeabilization for use as whole cell biocatalyst

“…The process of permeabilization is useful in facilitating the utilization of intracellular enzymes or transforming microbial cells into biocatalysts (Somkuti et al 1998). Surfactants, detergents or organic solvents such as toluene, ethanol, acetone, CTAB and SDS are the most commonly used permeabilizing agents (Kumari et al 2012;Panesar et al 2007;Krishnan et al 2000;Sekhar et al 1999;Somkuti et al 1998).…”

Production of β-galactosidase from streptococcus thermophilus for galactooligosaccharides synthesis

“…In this study five different disruption methods such as SDS-Chloroform, lysozyme treatment, glass bead extraction, microfluidizer and sonication were applied. Initially all the 62 characterized strains were used for the enzyme extraction by the use of SDS-chloroform method which was reported as the most effective detergent for disruption of S. thermophilus cells (Somkuti and Dominiecki 1998). Thirty higher enzyme producing strains were selected and further subjected to remaining four techniques for cell disruption.…”