ABSTRACT
Probiotics due to their multifaceted health promoting attributes have gained immense research impetus in recent years. The current study reports the hypocholesterolemic potential of lactic acid bacteria (LAB) isolated from indigenous sources. LAB may use several mechanisms for lowering serum cholesterol level viz. cholesterol assimilation, bile salt deconjugation, and cholesterol adsorption on cell surface of live, resting and dead probiotic cells. Cholesterol lowering is generally a strain dependent phenomenon, and different LAB isolates exhibited varying level of hypocholesterolemic effects. Among the LAB isolates, K2 i.e. Enterococcus faecalis K2 showed the highest in vitro cholesterol lowering ability (82.32%), and strong bile salt deconjugation potential, and released about 128.43 µM/mL of cholic acid upon bile salt deconjugation. Furthermore, cholesterol removal by live, resting and dead E. faecalis K2 probiotic cells was shown to the extent of 72.46, 44.93, and 45.88%, respectively. Scanning electron microscopy displayed appreciable adherence of cholesterol on to the cellular surfaces of E. faecalis K2 cells. The antioxidant potential of the cell free cultural fluid of LAB isolates was quite variable. LAB isolate E. faecalis K2 showed appreciable DPPH radical scavenging activity (37.36%), hydroxyl radical scavenging ability (26.35%), and superoxide radical scavenging ability (42.67%). Most of the LAB probiotic isolates were susceptible to conventionally used antibiotics, and lacked biogenic amine producing ability and haemolytic activity. The probiotic isolate E. faecalis K2 may have potential for application for management of hypercholesterolemia related coronary heart diseases, however, after thorough in vivo investigation.
ABSTRACT
The aim of this work was to study the production of fibrinolytic protease by Bacillus subtilis I-2 on agricultural residues. Molasses substantially enhanced (63%) protease production (652.32 U/mL) than control (398.64 U/mL). Soybean meal supported maximum protease production (797.28 U/mL), followed by malt extract (770.1 U/mL), cotton cake (761.04 U/mL), gelatin (742.92 U/mL) and beef extract (724.8 U/mL). Based on the Plackett-Burman designed experiments, incubation time, soybean meal, mustard cake and molasses were identified as the significant fermentation parameters. Ammonium sulfate precipitation and DEAE sephadex chromatography resulted 4.8-fold purification of protease. Zymography showed the presence of three iso-forms in the partially purified protease preparation, which was confirmed by the SDS-PAGE analysis (42, 48, 60 kDa). Protease exhibited maximum activity at 50oC and at pH 8.0. Significant stability was observed at 30-50oC and at pH 7.0-10.0. Mg2+, Zn2+, Co2+, Ca2+, Mn2+ and Cu2+,EGTA, EDTA and aprotinin severely decreased the enzyme activity.