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Glycomacropeptide (GMP) is a C-terminal part (f 106–169) of kappa-casein which is released in whey during cheese making by the action of chymosin. GMP being a biologically active component has gained much attention in the past decade. It also has unique chemical and functional properties. Many of the biological properties have been ascribed to the carbohydrate moieties attached to the peptide. The unique set of amino acids in GMP makes it a sought-after ingredient with nutraceutical properties. Besides its biological activity, GMP has several interesting techno-functional properties such as wide pH range solubility, emulsifying properties as well as foaming abilities which are shown to be promising for applications in food and nutrition industry. These properties of GMP have given new dimension for the profitable utilization of cheese whey to the dairy industry. A number of protocols for isolation of GMP from cheese whey have been reported. Moreover, its role in detection of sweet/rennet whey adulteration in milk and milk products has also attracted attention of various researchers, and many GMP-specific analytical methods have been proposed. This review discusses the chemico-functional properties of GMP and its role in the detection methods for checking cheese or sweet whey adulteration in milk. Recent concepts used in the isolation of GMP from cheese whey have also been discussed.

To understand the role of cell membrane phospholipids during resistance development to cationic antimicrobial peptides (CAMPs) in Enterococcus faecalis, gradual dose-dependent single exposure pediocin-resistant (Pedr) mutants of E. faecalis (Efv2.1, Efv3.1, Efv3.2, Efv4.1, Efv4.2, Efv5.1, Efv5.2 and Efv5.3), conferring simultaneous resistance to other CAMPs, selected in previous study were characterized for cell membrane phospholipid head-groups and fatty acid composition. The involvement of phospholipids in resistance acquisition was confirmed by in vitro colorimetric assay using PDA (polydiacetylene)-biomimetic membranes. Estimation of ratio of amino-containing phospholipids to amino-lacking phospholipids suggests that phospholipids in cell membrane of Pedr mutants loose anionic character. At moderate level of resistance, the cell-membrane becomes neutralized while at further higher level of resistance, the cell-surface acquired positive charge. Increased expression of mprF gene (responsible for lysinylation of phospholipids) was also observed on acquiring resistance to pediocin in PedrE. faecalis. Decreased level of branched chain fatty acids in Pedr mutants might have contributed in enhancing rigidification of cell membrane and contributing towards resistance. The interaction of pediocin with PDA-biomimetic membranes prepared from wild-type and Pedr mutants was monitored by measuring percent colorimetric response (%CR). Increased %CR of pediocin against PDA-biomimetic membranes prepared from Pedr mutants confirmed that cell membrane phospholipids are involved in the interactions of pore formation by CAMPs. There was a direct linear relationship between percent colorimetric response and IC50 of CAMPs for wild-type and Pedr mutants. This relationship further reveals that in vitro colorimetric assay can be used effectively for quantification of resistance to CAMPs.

In the present work, aptamers against aflatoxin M1 and aflatoxin B1 were generated and tested for creating proof of principle of recognition of aflatoxin M1 by generated aptamers. The aptamers were selected through the process referred as systematic evolution of ligands by exponential enrichment. A total of 41 different aptamer (36 aptamers for aflatoxin M1 and 5 for aflatoxin B1) sequences were obtained. The determination of dissociation constant (Kd ) values revealed that aptamers generated against aflatoxin M1 exhibited Kd values in the range of 35-1515 nM. Selected aptamers were grouped on the basis of the presence of common motifs or G-quadruplex. We find it interesting that one aptamer with no conserved motif or G-quadruplex had lowest Kd value (Kd = 35 nM). This structural motif is very distinct from motifs present in other aptamers. The Kd values of selected aptamers for aflatoxin B1 were in the range of 96-221 nM. One aptamer from each group was further tested for its ability to be used in aptasensor. The aptamer recognized aflatoxin M1 as indicated by color change (red to purple or blue) of aptamer-coated gold nanoparticles in the presence of 250-500 nM aflatoxin M1. The aptamers can be used in developing methods for detection/estimation/separation of aflatoxin or antidote for aflatoxin toxicity.

Background & objectives:Adherence of bacteria to epithelial cells and mucosal surfaces is a key criterion for selection of probiotic. We assessed the adhesion property of selected indigenous probiotic Lactobacillus strains based on their hydrophobicity and ability to adhere to human epithelial cells.Methods:Five human faecal Lactobacillus isolates, one from buffalo milk and one from cheese were assessed for hydrophobicity following the microbial adhesion to hydrocarbons (MATH) method and colonization potentials based on their adherence to Caco2 and HT-29 colonic adenocarcinomal human intestinal epithelial cell lines. Lactobacillus strains that adhered to Caco2 and HT-29 cell lines were quantified by plating after trypsinization and simultaneously the adhered bacteria were also examined microscopically after staining with Geimsa stain and counted in different fields.Results:Among the tested faecal isolates, L. plantarum Lp91 showed maximum percentage hydrophobicity (35.73±0.40 for n-hexadecane and 34.26±0.63 for toluene) closely followed by L. plantarum Lp9 (35.53±0.29 for n-hexadecane and 33.00±0.57 for toluene). Based on direct adhesion to epithelial cells, L. plantarum Lp91 was the most adhesive strain to HT-29 and Caco2 cell lines with per cent adhesion values of 12.8 ± 1.56 and 10.2 ± 1.09, respectively. L. delbrukeii CH4, was the least adhesive with corresponding figures of 2.5 ± 0.37 and 2.6 ± 0.20 per cent on HT-29 and Caco2 cell lines. Adhesion of the six isolated Lactobacillus strain to HT-29 cell and Caco2 lines as recorded under microscope varied between 131.0 ± 13.9 (Lp75) to 342.7 ± 50.52 (Lp91) and 44.7 ± 9.29 (CH4) to 315.7± 35.4 (Lp91), respectively.Interpretation & conclusions:Two Indigenous probiotic Lactobacillus strains (Lp9, Lp91) demonstrated their ability to adhere to epithelial cell and exhibited strong hydrophobicity under in vitro conditions, and thus could have better prospects to colonize the gut with extended transit