Lactobacillus delbrueckii subsp. bulgaricus develops acid tolerance response when subjected to acid stress conditions, such as the induction of enzymes associated with carbohydrate metabolism. In this study, pyk gene encoding pyruvate kinase was over-expressed in heterologous host Lactococcus lactis NZ9000, and SDS-PAGE analysis revealed the successful expression of this gene in NZ9000. The sur...

Development of efficient screening method coupled with cell functionality evaluation is highly needed in contemporary microbiology. The presented novel concept and fast non-destructive method brings in to play the water spectral pattern of the solution as a molecular fingerprint of the cell culture system. To elucidate the concept, NIR spectroscopy with Aquaphotomics were applied to monitor the...

In the presence of 0.15% oxgall, the B-galactosidase activity of whole cells of Lactobacillus bulgaricus was increased. However, higher concentrations of oxgall decreased the enzyme activity. In the absence of oxgall, little or no B-galactosidase was exhibited by the whole cells. When the cells were lysed to obtain cell-free extracts prior to assay, there was some decrease in activity of the en...

Lactic acid bacteria (LAB) are important organisms in food production. Indeed, LAB autolysis is very critical in dairy processing. For example, it influences the development of cheese flavor by releasing intracellular enzymes, and controls cell growth in yogurts and probiotic products. Two component systems (TCS) constitute essential environmental sensors and effectors of signal transduction in...

We identified the proteins synthesized by Lactobacillus delbrueckii subsp. bulgaricus strain LBB.B5 in laboratory culture medium (MRS) at 37°C and milk at 37 and 4°C. Cell-associated proteins were measured by gel-free, shotgun proteomics using high-performance liquid chromatography coupled with tandem mass spectrophotometry. A total of 635 proteins were recovered from all cultures, among which ...

A protoplast transfection system has been developed for Lactobacillus bulgaricus. The procedure involves a polyethylene glycol-mediated fusion of bacteriophage DNA encapsulated in liposomes into mutanolysin-treated cells. With L. bulgaricus B004 and DNA isolated from the phage phi c5004, transfection reached a maximum when at least 95% of the cells were osmotically fragile. The incorporation of...

The antagonistic effect of lactic acid bacteria (LAB, including Lactobacillus acidophilus, L. bulgaricus, L. casei and Streptococcus thermophilus) on Staphylococcus aureus and Escherichia coli was evaluated on MRS agar with the deferred and cross-streaking techniques, and in milk with the plate counting method. All LAB were repressive to S aureus and E coli on the agar medium. However, their su...

The viability of Lactobacillus bulgaricus in freeze-drying is of significant commercial interest to dairy industries. In the study, L.bulgaricus demonstrated a significantly improved (p < 0.05) survival rate during freeze-drying when subjected to a pre-stressed period under the conditions of 2% (w/v) NaCl for 2 h in the late growth phase. The main energy source for the life activity of lactic a...

The present study was designed to determine the physicochemical properties of yam (Dioscorea) solution fermented by L. bulgaricus, the protective effect of fermented Dioscorea opposita Thunb. on stomach lesions, and the possibility of its application to fermented dairy products. When the concentration of yam increased, the pH increased in raw powder samples but not in extracted powder samples. ...

Lactobacillus bulgaricus prevents intestinal epithelial cell injury caused by Cronobacter 1 (Enterobacter) sakazakii-induced nitric oxide both in vitro and in the newborn rat model of 2 necrotizing enterocolitis. 3 Catherine J. Hunter 1 , Monica Williams 1 , Mikael Petrosyan 1 , Yigit Guner 1 , Rahul Mittal 2 , Dennis 4 Mock 3 , Jeffrey S. Upperman 1, 4 , Henri R. Ford 1, 4 and Nemani V. Prasad...