Deeplina Das

A food additive with prebiotic properties of an α-d-glucan from lactobacillus plantarum DM5.

An α-d-glucan produced by Lactobacillus plantarum DM5 was explored for in vitro prebiotic activities. Glucan-DM5 demonstrated 21.6% solubility, 316.9% water holding capacity, 86.2% flocculation activity, 71.4% emulsification activity and a degradation temperature (Td) of 292.2°C. Glucan-DM5 exhibited lowest digestibility of 0.54% by artificial gastric juice, 0.21% by intestinal fluid and 0.32% by α-amylase whereas the standard prebiotic inulin, showed 25.23%, 5.97% and 19.13%, hydrolysis, respectively. Prebiotic activity assay of glucan-DM5 displayed increased growth of probiotic bacteria such as Bifidobacterium infantis and Lactobacillus acidophilus, but did not support the growth of non-probiotic bacteria such as Escherichia coli and Enterobacter aerogenes. The overall findings indicated that glucan from L. plantarum DM5 can serve as a potential prebiotic additive for food products.

Characterization and biocompatibility of glucan: a safe food additive from probiotic Lactobacillus plantarum DM5

BACKGROUND Exopolysaccharide produced by lactic acid bacteria are the subject of an increasing number of studies for their potential applications in the food industry as stabilizing, bio-thickening and immunostimulating agents. In this regard, the authors isolated an exopolysaccharide producing probiotic lactic acid bacterium from fermented beverage Marcha of north eastern Himalayas. RESULTS The isolate Lactobacillus plantarum DM5 showed extracellular glucansucrase activity of 0.48 U mg⁻¹ by synthesizing natural exopolysaccharide glucan (1.87 mg mL⁻¹) from sucrose. Zymogram analysis of purified enzyme confirms the presence of glucosyltransferase of approximately 148 kDa with optimal activity of 18.7 U mg⁻¹ at 30 °C and pH 5.4. The exopolysaccharide was purified by gel permeation chromatography and had an average molecular weight of 1.11 × 10⁶ Da. Acid hydrolysis and structural characterization of exopolysaccharide revealed that it was composed of d-glucose residues, containing 86.5% of α-(1→6) and 13.5% of α-(1→3) linkages. Rheological study exhibited a shear thinning effect of glucan appropriate for food additives. A cytotoxicity test of glucan on human embryonic kidney 293 (HEK 293) and human cervical cancer (HeLa) cell lines revealed its nontoxic biocompatible nature. CONCLUSION This is the first report on the structure and biocompatibility of homopolysaccharide α-D-glucan (dextran) from probiotic Lactobacillus plantarum strain and its unique physical and rheological properties that facilitate its application in the food industry as viscosifying and gelling agent.

Potential probiotic attributes and antagonistic activity of an indigenous isolate Lactobacillus plantarum DM5 from an ethnic fermented beverage “Marcha” of North Eastern Himalayas

Abstract A novel isolate DM5 identified as Lactobacillus plantarum displayed in vitro probiotic properties as well as antimicrobial activity. It showed adequate level of survival to the harsh conditions of the gastrointestinal tract and survived low acidic pH 2.5 for 5 h. Artificial gastric juice and intestinal fluidic environment decreased the initial viable cell population of isolate DM5 only by 7% and 13%, respectively, while lysozyme (200 µg/ml) and bile salt (0.5%) enhanced its growth. It was found to deconjugate taurodeoxycholic acid, indicating its potential to reduce hypercholesterolemia. Isolate DM5 demonstrated cell surface hydrophobicity of 53% and autoaggregation of 54% which are the prerequisite for adhesion to epithelial cells and colonization to host. Bacteriocin activity of isolate was found to be 6400 AU/ml as it inhibited the growth of food borne pathogens Escherichia coli, Staphylococcus aureus, and Alcaligenes faecalis. The bactericidal action of bacteriocin from isolate was analyzed by flow cytometry, rendering its use as prospective probiotic and starter culture in food industry.

Heteropolysaccharides from Lactic Acid Bacteria: Current Trends and Applications

Exopolysaccharides produced by lactic acid bacteria have tremendous value in the development of new functional foods. Different types of exopolysaccharides produced vary in monomer composition, molecular weight and structure. This review focuses on the heteropolysaccharides produced by lactic acid bacteria. The huge diversity of heteropolysaccharides presents several applications in food industry. Here we report heteropolysaccharides produced by lactic acid bacteria along with their characteristics and applications.

Purification and characterization of fructan and fructansucrase from Lactobacillus fermentum AKJ15 isolated from Kodo ko jaanr, a fermented beverage from north-eastern Himalayas

Fructansucrase and fructan produced from Lactobacillus fermentum AKJ15 were isolated from seeds of Kodo ko jaanr, a fermented mild-alcoholic beverage prepared in North East India. The strain was identified by 16S rRNA gene sequence analysis and biochemical characterization. The strain displayed maximum fructansucrase activity of 4.3 U/ml (1.02 U/mg) at 28°C at 180 rpm. The enzyme purified by polyethylene glycol-400 gave specific activity of 5 U/mg and showed 90 kDa band on non-denaturing Sodium Dodecyl Sulphate-Poly Acrylamide Gel Electrophoresis (SDS-PAGE). The purified enzyme confirmed the presence of fructan by periodic acid Schiffs staining which showed magenta colour bands with both sucrose and raffinose. The strain produced 10.2 mg/ml fructan in broth under optimized culture conditions. The purified fructansucrase displayed Vmax of 5.42 U/mg and Km of 16.65 mM. The enzyme showed maximum activity at 30°C and at pH 5. The structure of fructan was analysed by 1H and 13C NMR spectra confirming β-(2-1) and β-(2-6) linkages.