Paulraj Kanmani

Production and purification of a novel exopolysaccharide from lactic acid bacterium Streptococcus phocae PI80 and its functional characteristics activity in vitro.

Optimum culture conditions which ease the synthesis of a novel exopolysaccharide (EPS) from a potent marine strain Streptococcus phocae was proposed in this study. The strain grows well at 35 °C, pH 7.0 and NaCl (2%) with lactose and yeast extract as best carbon and nitrogen sources. The maximum yield of EPS (11.75 and 12.14 g/L) was obtained in the presence of lactose and yeast extract at a concentration of 20 g/L respectively. EPS was refined by gel filtration chromatography using phenyl Sepharose column which revealed the presence of arabinose, fructose and galactose sugar units with molecular mass about 2.8 × 10(5) Da. Emulsifying and flocculating stability of EPS compared with three commercial hydrocolloids. EPS exhibited better activities which are similar to that of commercial hydrocolloids. Both crude and purified EPS exhibited strong antioxidant potential by quenching hydroxyl and superoxide anion radicals. Antibiofilm activity by inhibition of Gram positive and Gram negative biofilm forming bacteria was evident in our studies. Potential antioxidant activity and biofilm inhibiting property of EPS may lead to the development of novel food grade adjuncts.

Probiotics and Its Functionally Valuable Products—A Review

During the past two decades probiotic bacteria have been increasingly proposed as health promoting bacteria in variety of food system, because of its safety, functional, and technological characteristics. Commonly, Lactobacillus spp., Bifidobacterium spp., Saccharomyces boulardii, and some other microorganisms have been considered as probiotic strains. Possibly these bacterial strains exerted several beneficial effects into gastrointestinal tract of host while administered with variety of food system. Lactic acid bacteria (LAB) usually produce antimicrobial substances like bacteriocin which have broad spectrum of antagonist effect against closely related Gram positive and Gram negative pathogens. LAB strains often produce polymeric substances such as exopolysaccharides (EPS) which increase the colonization of probiotic bacteria by cell–cell interactions in gastrointestinal tract. LAB also produces biosurfactant which showed that the wide range of antimicrobial activity against bacterial pathogen as well as its antiadhesive properties reduces the adhesion of pathogens into gastric wall membrane. Furthermore, LAB strains have also been reported for production of antioxidants which are ability to scavenge the free radicals such as superoxide anions and hydroxyl radicals. For this sense, this review article is mainly focused on the ecology, biosynthesis, genetics, target sites, and applications of bacteriocins and EPS from LAB strains. Moreover, this review discusses about the production and functions of nutritive essential element folate and iron chelating agent such as siderophores from LAB.

Synthesis and characterization of pullulan-mediated silver nanoparticles and its antimicrobial activities

Synthesis of silver nanoparticles was achieved using pullulan as both a reducing and stabilizing agent. The effect of pullulan and silver nitrate amounts on the synthesis of silver nanoparticles (AgNPs) was investigated. The formation of nanoparticles was first screened by measuring the surface plasmon resonance peak at 420-430 nm using UV-vis spectroscopy. The morphology of the synthesized AgNPs was determined using TEM, which indicated that the AgNPs varied in shape and polydispersed with an average size of 2-30 nm. The presence of elemental silver and the crystalline structure of the AgNPs were confirmed by EDX and XRD analyses. The possible functional groups of pullulan responsible for the reduction and stabilization of AgNPs were evaluated using FT-IR. The pullulan-reduced AgNPs showed excellent antibacterial, antifungal, and antibiofilm activity against food and multidrug resistant bacterial and fungal pathogens. The results showed that pullulan could be used as a reducing as well as a capping agent for synthesizing AgNPs which had potent antimicrobial activity.

Development and characterization of novel probiotic-residing pullulan/starch edible films

An innovative approach was performed to prepare novel pullulan/starch blended edible films by direct incorporation of multiple probiotic bacterial strains. Various starches different in origin were blended into the pullulan solutions with different ratios. The physical and mechanical properties of the films were investigated in the presence and absence of probiotic cells. An increase in the starch content of pullulan films resulted in a substantial decrease in relative cell viabilities and mechanical properties. Moreover, slight changes in the physical and mechanical properties of the films were observed with the addition of probiotic strains. Pullulan and pullulan/potato starch films were found to be the most suitable carrier matrices, with a maximum relative cell viability of 70-80% after 2months of storage at 4°C. The results suggest that pullulan and pullulan/starch films can be used as effective delivery and carrier systems for probiotics.

Lactobacillus plantarum AS1 Isolated from South Indian Fermented Food Kallappam Suppress 1,2-Dimethyl Hydrazine (DMH)-Induced Colorectal Cancer in Male Wistar Rats

The relationship between antioxidant and anticancer properties of probiotic bacterium strain Lactobacillus plantarum AS1 (AS1) in colon cancer induced by 1,2-dimethylhydrazine (DMH) has been studied. In this study, an increased level of lipid peroxide (LPO) products and increased activities of antioxidant enzymes (superoxide dismutase, catalase and glutathione-S transferase) and marker enzymes (alkaline phosphatase and acid phosphatase) in colon and plasma of cancer-bearing animals have been observed. AS1 was supplemented either before initiation or during initiation and selection/promotion phases of colon carcinogenesis and was found to be effective in altering lipid peroxidation and antioxidant enzyme activities and marker enzymes to a statistically significant level measured either in the colon and in the plasma. These alterations inclined towards normal in a time-dependent manner on AS1 supplementation. The mean tumor volume diameter and total number of tumors were found to be statistically decreased in AS1 pre- and post-treated rats. Furthermore, histopathological examination shows remarkable difference between control and treated groups. The in vitro antioxidant assay shows that AS1 has promising antioxidant property. These results demonstrate that AS1 strain can modulate the development of DMH-induced rat colon carcinogenesis through an antioxidant-dependent mechanism.

Lactobacillus plantarum AS1 binds to cultured human intestinal cell line HT‐29 and inhibits cell attachment by enterovirulent bacterium Vibrio parahaemolyticus

Aim:  Lactobacillus plantarum AS1 was incubated with HT‐29 adenocarcinoma cell line to assess its adhesion potency and examined for its inhibitory effect on the cell attachment by an enterovirulent bacterium Vibrio parahaemolyticus.

Traditional Indian fermented foods: a rich source of lactic acid bacteria

This review describes the diversity of Indian fermented food and its significance as a potential source of lactic acid bacteria (LAB). Fermented foods consumed in India are categorized based upon their base material. Fermented foods such as dahi, gundruk, sinki, iniziangsang, iromba, fermented rai, kanjika and handua were reported to have significant medicinal properties. Some fermented products such as koozh, dahi and kanjika are consumed unknowingly as, probiotic drinks, by local people. There are very few reports regarding isolation of LAB from Indian fermented foods available in the past; however, due to growing consciousness about potential health benefits of LAB, we now have scores of reports in this field. There is an abundant opportunity available for food microbiologists to explore the Indian fermented foods for the isolation of new LAB strains for their potential role in probiotic research.

DESIGN AND OPTIMIZATION OF FERMENTATION MEDIUM FOR ENHANCED BACTERIOCIN PRODUCTION BY PROBIOTIC BACTERIUM Enterococcus faecium MC13

Statistics-based experimental designs were used to develop a cost-effective medium for enhanced production of viable cells and bacteriocin by probiotic Enterococcus faecium MC13. Carbon, nitrogen, and mineral sources were first screened by one-variable-at-a-time (OVAT) methods. In order to increase yield production, the selected variables were further statistically optimized using response-surface methodology (RSM) with central composite design (CCD). The maximum and minimum levels of the selected variables were determined and a set of 34 experimental runs was performed. The optimum concentrations of the tested variables for production of viable cells (12.24 log CFU mL−1) and bacteriocin activity (25,600 AU mL−1) were tryptone (10.0 g/L), peptone (6.0 g/L), maltose (3.0 g/L), glucose (9.0 g/L), NaCl (15.0 g/L), sodium citrate (2.5 g/L), sodium acetate (1.0 g/L), and dipotassium PO4 (0.1 g/L). Threefold increased yield of bacteriocin was achieved in optimized medium compared to the unoptimized counterpart, and this was two times less cost than commercial MRS medium.

Seagrass as a potential source of natural antioxidant and anti-inflammatory agents

Context: Halophila spp. is a strong medicine against malaria and skin diseases and is found to be very effective in early stages of leprosy. Seagrasses are nutraceutical in nature and therefore of importance as food supplements. Objective: The antibacterial, antioxidant, and anti-inflammatory activities of Halophila ovalis R. Br. Hooke (Hydrocharitaceae) methanol extract were investigated and the chemical constituents of purified fractions were analyzed. Materials and methods: Plant materials were collected from Pondicherry coastal line, and antimicrobial screening of crude extract, and purified fractions was carried out by the disc diffusion method and the minimum inhibitory concentration (MICs) of the purified fractions and reference antibiotics were determined by microdilution method. Antioxidant and anti-inflammatory activities were investigated in vitro. Chemical constituents of purified fractions V and VI were analyzed by gas chromatography–mass spectrometry (GC–MS), and the phytochemicals were quantitatively determined. Results: Methanol extract inhibited the growth of Bacillus cereus at a minimum inhibitory concentration of 50 µg/mL and other Gram-negative pathogens at 75 µg/ml, except Vibrio vulnificus. Reducing power and total antioxidant level increased with increasing extract concentration. H. ovalis exhibited strong scavenging activity on 2,2-diphenyl-1-picrylhydrazyl (DPPH) and superoxide radicals at IC50 of 0.13 and 0.65 mg/mL, respectively. Methanol extract of H. ovalis showed noticeable anti-inflammatory activity at IC50 of 78.72 µg/mL. The GC–MS analysis of H. ovalis revealed the presence of triacylglycerols as major components in purified fractions. Quantitative analysis of phytochemicals revealed that phenols are rich in seagrass H. ovalis. Discussion and conclusion: These findings demonstrated that the methanol extract of H. ovalis exhibited appreciable antibacterial, noticeable antioxidant, and anti-inflammatory activities, and thus could be use as a potential source for natural health products.

Optimization of media components for enhanced production of streptococcus phocae pi80 and its bacteriocin using response surface methodology

The standard MRS components were optimized using response surface methodology for increasing yield of Streptococcus phocae PI80 viable cells and its bacteriocin. The highest amounts of bacteriocin activity and viable cells were recorded from prediction point of optimized MRS medium and achieved two fold higher (33049.8 AU.mL-1 and 14.05 LogCFU.mL-1) than un-optimized counterpart.