Screening and characterization of in-vitro probiotic criteria of Saccharomyces and Kluyveromyces strains.

BACKGROUND AND OBJECTIVES: Probiotics are defined as live micro-organisms conferring a health benefit on the host. Although most probiotics are bacteria, some yeasts such as Saccharomyces and Kluyveromyces, has been found to have effective probiotic properties. The objective of this study was to isolate and identify indigenous Saccharomyces and Kluyveromyces yeast strains and to compare some probiotic characteristics between these two strains in vitro. MATERIALS AND METHODS: Strains were isolated on yeast glucose chloramphenicol agar medium from 205 samples and identified by morphological, physiological and biochemical assays. The effects of different conditions such as pH and temperature on the survival and growth of the isolates were studied. In addition, resistance to acidic pH (1.5, 2, 3 and 5), pepsin and different concentrations of bile salts (1%, 3% and 5%), as well as proteolytic, lipolytic and hemolytic activity of selected isolates were assessed. Finally, the best isolates were selected for investigation of their viability in samples of dairy products. RESULTS: 126 isolates were identified using biochemical and molecular techniques as yeast strains. Five isolates were found to have effective probiotic properties, belonging to Kluyveromyces marxianus (S97, S101 and S106) and Saccharomyces cerevisiae (S28, S34). These isolates were able to grow at 37°C, pH=1.5, withstand to concentration of 5% oxbile and pepsin and exhibit the proteolytic activity. The isolates of K. marxianus showed better viability in dairy (yogurt). CONCLUSION: In the in-vitro comparative experiments, the isolates of K. marxianus showed better probiotic potentials.

Isolation of indigenous Glutathione producing Saccharomyces cerevisiae strains.

BACKGROUND: Glutathione (GSH) is a non-protein thiol compound, which plays an important role in the response to oxidative stress and nutritional stress. The aim of this study was to isolate indigenous S. cerevisiae strains capable of effectively produce GSH. METHODS: One hundred-twenty sweet fruit samples were collected. The strains were isolated on yeast glucose chloramphenicol (YGC) agar medium and identified. The isolates were evaluated for GSH producing on yeast malt (YM) medium. Concentration of glutathione was investigated by recording absorbance of all samples at wavelength 412 nm (Ellman's method). In addition, optimization of glucose and peptone concentration in culture medium and the effects of various environmental conditions such as temperature (20-35 °C), agitation rate (150-250 rpm), and initial pH (4.0-6.0) were assessed on producing of GSH. RESULTS: From 120 samples, 80 isolates were identified by morphological, biochemical and molecular tests as S. cerevisiae. Five isolates were capable to produce effectively GSH. The optimal culture conditions were agitation rate, 200 rpm; temperature, 30 °C; initial pH, 6; glucose, 30 g/l; and peptone concentration, 5 g/l. In optimal conditions, the amount of derived glutathione was improved compared to YM basal medium and highest GSH concentration (296.8 mg/l) was obtained after cultivation with shaking for 72 h. CONCLUSION: The possibility of obtaining S. cerevisiae cells with a high GSH intracellular content can be considered an interesting opportunity of furthering the range of application and utilization of this molecule.

Effects of Hydroalcoholic Extract of Watercress (Nasturtium Officinale) Leaves on Serum Glucose and Lipid Levels in Diabetic Rats.

OBJECTIVE: Hyperlipidemia is a known complication of diabetes mellitus and predisposes to coronary heart disease. The lowering of total cholesterol and low density lipoprotein (LDL)-cholesterol should reduce the incidence of coronary disease. The aim of the present study was to examine the antihyperlipidemic and antidiabetic effects of the hydroalcoholic extract of watercress (Nasturtium officinale) leaves in streptozotocin-induced diabetic rats. METHODS: Female Wistar rats were randomly divided into 4 groups: control, diabetic and diabetic rats treated with the extract of watercress (Nasturtium officinale) at doses of 100 and 200 mg/kg. Diabetic rats received the watercress extract daily in drinking water for 4 weeks since the day after diabetes confirmation. The levels of serum glucose and lipids were spectrophotometrically measured in all groups at weeks 0 (before diabetes induction), 2 and 4. RESULTS: There was a significant increase in serum glucose, triglycerides, total cholesterol, and LDL-cholesterol in streptozotocin-induced diabetic rats, accompanied by a decrease in high density lipoprotein (HDL)-cholesterol. The treatment of diabetic rats with hydroalcoholic extract of watercress (Nasturtium officinale) leaves over a 4-week period significantly reduced serum glucose, total cholesterol and LDL- cholesterol in comparison with diabetic untreated rats. CONCLUSION: Our findings demonstrated that a 4-week treatment with watercress extract at a dose of 200 mg/kg has hypoglycemic and hypolipidemic effects in streptozotocin-diabetic rats. This implies that the consumption of watercress leaves can be helpful in reducing the complications of hyperglycemia and dyslipidemia associated with diabetes.

Antihyperglycemic and antihyperlipidemic effects of hydroalcoholic extract of Securigera securidaca seeds in streptozotocin-induced diabetic rats.

BACKGROUND: Hyperlipidemia is an associated complication of diabetes mellitus. Lowering of serum lipid levels seems to be associated with a decrease in the risk of vascular disease and related complications. The purpose of the current study was to evaluate the antihyperglycemic and antihyperlipidemic effects of the hydroalcoholic extract of Securigera securidaca seeds in streptozotocin-induced diabetic rats. MATERIALS AND METHODS: Female Wistar rats were randomly divided into four groups as follows: Control, diabetic, and diabetic rats treated with the Securigera extract at doses of 100 and 200 mg/kg. The animals were rendered diabetic by a single intraperitoneal injection of 55 mg/kg streptozotocin. Diabetic rats received the Securigera extract daily in drinking water from the day on which diabetes was confirmed for 4 weeks. The levels of serum glucose and lipids were spectrophotometrically measured in all groups at weeks 0 (before diabetes induction), 2, and 4. RESULTS: The results showed that there was a significant increase in serum glucose, triglycerides, total cholesterol, and low density lipoprotein (LDL)-cholesterol in streptozotocin-induced diabetic rats, accompanied by a decrease in high density lipoprotein (HDL)-cholesterol. Treatment of diabetic rats with S. securidaca seed extract at a dose of 200 mg/kg over a 4-week period significantly reduced the levels of serum glucose, total cholesterol, and LDL-cholesterol and increased the level of HDL-cholesterol, compared to diabetic untreated rats. CONCLUSIONS: Securigera extract at a dose of 200 mg/kg exhibited hypoglycemic and hypolipidemic activities in streptozotocin-diabetic rats during the 4-week treatment period. This provides a valid scientific basis for using it in the treatment of diabetes in Iranian folk medicine.