Nanobiosensors and their role in detection of adulterants and contaminants in food products.

Nanotechnology is a multifaceted technical and scientific field undergoing a fast expansion. Nanoparticles, quantum dots, nanotubes, nanorods, nanowires, nanochips and many more are being increasingly used for fabrication of nanosensors and nanobiosensors to increase the sensitivity and selectivity of reactions. Food safety is an extremely important concern in food industries since it is directly associated with effect of food on human health. Here in our review, we have not only described the newest information regarding methods and use of nanomaterials for construction of nanosensors but also their detection range, limit of detection (LOD) and applications for food safety. Precise nanosensors having improved sensitivity and low limit of detection were discussed in brief. Review is primarily focused on nanosensors employed for detection of adulterants and contaminants in food products such as meat products, milk, fruit juices and water samples.

Chicken Feather Waste Hydrolysate as a Superior Biofertilizer in Agroindustry.

Billions of tons of keratinous waste in the form of feathers, antlers, bristles, claws, hair, hoofs, horns, and wool are generated by different industries and their demolition causes environmental deterioration. Chicken feathers have 92% keratin that can be a good source of peptides, amino acids, and minerals. Traditional methods of feather hydrolysis require large energy inputs, and also reduce the content of amino acids and net protein utilization values. Biological treatment of feathers with keratinolytic microbes is a feasible and environmental favorable preference for the formulation of hydrolysate that can be used as bioactive peptides, protein supplement, livestock feed, biofertilizer, etc. The presence of amino acids, soluble proteins, and peptides in hydrolysate facilitates the growth of microbes in rhizosphere that promotes the uptake and utilization of nutrients from soil. Application of hydrolysate enhances water holding capacity, C/N ratio, and mineral content of soil. The plant growth promoting activities of hydrolysate potentiates its possible use in organic farming, and improves soil ecosystem and microbiota. This paper reviews the current scenario on the methods available for management of keratinous waste, nutritional quality of hydrolysate generated using keratinolytic microbes, and its possible application as plant growth promoter in agroindustry.

Nutritional Enhancement of Chicken Feather Waste by Bacillus aerius NSMk2.

Keratinous waste is the bulk by-product of various livestock industries. Slow natural degradation of keratin and less efficient chemical hydrolysis imposes challenge for the search of alternative recycling methods. Keratin degrading microbes hydrolyse keratin to soluble peptides and amino acids. Bacillus aerius NSMk2 showed great potential for hydrolysis of chicken feather waste. Bacillus aerius NSMk2 cells grown in phosphate buffer supplemented with chicken feathers showed high disulfide reductase activity and release of sulfhydryl groups. The release of proteins and amino acids were statistically optimized at varied pH (4.0-11.0), temperature (30.0-45.0 °C) and agitation (100-250 rpm), and maximum release was recorded at pH 7.5, temperature 37 °C and shaking (175 rpm). FTIR and SEM showed sulfitolysis and extensive keratinolysis of feathers resulting in complete hydrolysis of white chicken feathers after 84 h. MALDI-TOF mass spectrometry confirmed the release of low molecular weight peptides in the range of 399 to 3289.4 m/z. The present study demonstrates management of otherwise hard-to-degrade keratinous waste and simultaneous nutritional enhancement of waste chicken feathers to value-added hydrolysate that can be used in livestock feed formulations or biofertilizer in agro-industry.

Thermostable and halotolerant keratinase from Bacillus aerius NSMk2 with remarkable dehairing and laundary applications.

Keratinases hydrolyze structural protein called keratin into constituent peptides. The present study reports excellent washing efficiency and dehairing properties of thermostable and halotolerant keratinase from Bacillus aerius NSMk2. Alkaline keratinase with molecular mass of 9 kDa displayed remarkable thermostability. K+ , Na+ , Ca2+ , Mn2+ , ß-mercaptoethanol, sodium sulfite, dithiothreitol, ethanol, isopropanol, Tween-20, and Tween-80 stimulated keratinase activity, while Hg2+ and Ba2+ were found to be inhibitory. The enzyme efficiently hydrolyzed a variety of complex protein substrates and exhibited high catalytic efficiency toward keratin-rich substrates and least toward collagen. Keratinase showed exceptional stability to salinity and was found to be compatible with most of the commercial detergents. Efficient removal of chocolate, blood, and egg albumin stains from clothes and tolerance to elevated temperature and salinity potentiated the suitability of keratinase from B. aerius NSMk2 as laundary additive. Keratinase could efficiently dehair goat skin after 15 hr of incubation without damaging the grain structure and collagen layers that assures its use as a promising contender for leather industry.

Lectin activity in mycelial extracts of Fusarium species

ABSTRACT Lectins are non-immunogenic carbohydrate-recognizing proteins that bind to glycoproteins, glycolipids, or polysaccharides with high affinity and exhibit remarkable ability to agglutinate erythrocytes and other cells. In the present study, ten Fusarium species previously not explored for lectins were screened for the presence of lectin activity. Mycelial extracts of F. fujikuroi, F. beomiformii, F. begoniae, F. nisikadoi, F. anthophilum, F. incarnatum, and F. tabacinum manifested agglutination of rabbit erythrocytes. Neuraminidase treatment of rabbit erythrocytes increased lectin titers of F. nisikadoi and F. tabacinum extracts, whereas the protease treatment resulted in a significant decline in agglutination by most of the lectins. Results of hapten inhibition studies demonstrated unique carbohydrate specificity of Fusarium lectins toward O-acetyl sialic acids. Activity of the majority of Fusarium lectins exhibited binding affinity to D-ribose, L-fucose, D-glucose, L-arabinose, D-mannitol, D-galactosamine hydrochloride, D-galacturonic acid, N-acetyl-d-galactosamine, N-acetyl-neuraminic acid, 2-deoxy-D-ribose, fetuin, asialofetuin, and bovine submaxillary mucin. Melibiose and N-glycolyl neuraminic acid did not inhibit the activity of any of the Fusarium lectins. Mycelial extracts of F. begoniae, F. nisikadoi, F. anthophilum, and F. incarnatum interacted with most of the carbohydrates tested. F. fujikuroi and F. anthophilum extracts displayed strong interaction with starch. The expression of lectin activity as a function of culture age was investigated. Most species displayed lectin activity on the 7th day of cultivation, and it varied with progressing of culture age.

Lectin activity in mycelial extracts of Fusarium species.

Lectins are non-immunogenic carbohydrate-recognizing proteins that bind to glycoproteins, glycolipids, or polysaccharides with high affinity and exhibit remarkable ability to agglutinate erythrocytes and other cells. In the present study, ten Fusarium species previously not explored for lectins were screened for the presence of lectin activity. Mycelial extracts of F. fujikuroi, F. beomiformii, F. begoniae, F. nisikadoi, F. anthophilum, F. incarnatum, and F. tabacinum manifested agglutination of rabbit erythrocytes. Neuraminidase treatment of rabbit erythrocytes increased lectin titers of F. nisikadoi and F. tabacinum extracts, whereas the protease treatment resulted in a significant decline in agglutination by most of the lectins. Results of hapten inhibition studies demonstrated unique carbohydrate specificity of Fusarium lectins toward O-acetyl sialic acids. Activity of the majority of Fusarium lectins exhibited binding affinity to d-ribose, l-fucose, d-glucose, l-arabinose, d-mannitol, d-galactosamine hydrochloride, d-galacturonic acid, N-acetyl-d-galactosamine, N-acetyl-neuraminic acid, 2-deoxy-d-ribose, fetuin, asialofetuin, and bovine submaxillary mucin. Melibiose and N-glycolyl neuraminic acid did not inhibit the activity of any of the Fusarium lectins. Mycelial extracts of F. begoniae, F. nisikadoi, F. anthophilum, and F. incarnatum interacted with most of the carbohydrates tested. F. fujikuroi and F. anthophilum extracts displayed strong interaction with starch. The expression of lectin activity as a function of culture age was investigated. Most species displayed lectin activity on the 7th day of cultivation, and it varied with progressing of culture age.

Purification, characterization, and mitogenic potential of a mucin-specific mycelial lectin from Aspergillus sparsus.

Lectins are carbohydrate binding proteins or glycoproteins that bind reversibly to specific carbohydrates present on the apposing cells, which is responsible for their ability to agglutinate red blood cells, lymphocytes, fibroblasts, etc. Due to their carbohydrate specificity, lectins have been used for purification and characterization of glycoproteins like antibodies, cytokines, tumor-associated glycoproteins, hormones, inhibitors, growth factors, various enzymes, membrane proteins (receptors), or even toxins and viruses. In the present study, a mycelial lectin from Aspergillus sparsus was purified, characterized, and evaluated for its mitogenic potential. Lectin could be effectively purified 17.8-fold in a single-step using affinity chromatography on mucin-sepharose column. Lectin migrated as a single band in sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) with an apparent molecular mass of 100.2 kDa. Lectin showed pH optima of 6.5-8.0, and optimum temperature was determined to be 20-30 °C. Lectin was stable within a pH range of 5.5-10.0 and showed fairly good thermostability. Lectin activity was unaffected in the presence of EDTA, while activity reduced upon interaction with denaturants. MTT assay revealed strong mitogenic potential of A. sparsus lectin at a concentration up to 100 µg/ml.

Characteristics of yeast lectins and their role in cell-cell interactions.

Lectins are ubiquitous proteins with the ability to induce cell agglutination and, mediate cellular and molecular recognition processes in a variety of biological interactions. Fungi display exquisite specificity for target tissues and attach to host glycoconjugates via these sugar-binding proteins. Although only few reports are available on lectin activity of yeasts, these sugar binding proteins have been embraced for their role in cell flocculation, a commercially beneficial property, that simplifies downstream recovery operations in yeast fermentations. The lectins bind to cell wall mannans of the neighboring cells via hydrogen bonds leading to the formation of cell aggregates which get interrupted in the presence of specific sugars. Attachment of pathogenic yeasts to host cell surface is also a consequence of lectin-mediated recognition process. This review provides a brief overview of yeast lectins, with an insight to lectin-mediated cellular recognition phenomenon in yeasts.

Immunomodulatory and therapeutic potential of a mycelial lectin from Aspergillus nidulans.

Lectins bind to surface receptors on target cells, and activate a cascade of events, eventually leading to altered immune status of host. The immunomodulatory potential of purified lectin from Aspergillus nidulans was evaluated in Swiss albino mice treated intraperitoneally with seven different doses of purified lectin. Lectin prevented BSA-induced Arthus reaction and systemic anaphylaxis. The enhanced functional ability of macrophages was evident from respiratory burst activity and nitric oxide production in splenocyte cultures. Interferon-gamma and interleukin-6 levels were significantly up-regulated in treated groups. Maximum stimulatory effect was observed at the dose of 1.5 mg/kg body weight. Therapeutic potential of A. nidulans lectin was assessed against trinitrobenzene sulfonic acid-induced ulcerative colitis in male Wistar rats. Rats pre-treated with 80 mg/kg body weight of purified lectin intraperitoneally prior to colitis induction showed lesser disease severity and recovery within 7 days, while rats post-treated with the same dose showed recovery in 11 days. The results demonstrate immunomodulatory effects of A. nidulans lectin in Swiss albino mice, resulting in improved immune status of the animals and unfold its curative effect against ulcerative colitis in rat model. This is the first report on immunomodulatory and therapeutic potential of a lectin from microfungi.

Current trends of lectins from microfungi.

Lectins are widespread in nature and have been isolated from plants, animals, microorganisms, and viruses. Although several lectins have been reported from microfungi, many more genera still remain unexplored and their physiological role is also uncertain. Microfungal lectins show wide disparity regarding their specificity to erythrocytes. Only a few lectins display specificity to particular human blood types. In addition, they also show agglutination to various animal erythrocytes. Many lectins from microfungi exhibit stringent specificity to animal glycoproteins, while a few have much more simplified sugar binding properties. The role of few microfungal lectins in host-parasite interactions, as storage proteins, and in growth and morphogenesis has been proposed. The current review focuses on an overview of lectins from microfungi, their specificity towards erythrocytes and carbohydrates, physicochemical characteristics, and their possible role and applications.

Further screening of Aspergillus species for occurrence of lectins and their partial characterization.

Fifteen species of Aspergillus were screened for occurrence of lectins. Nine of them (A. sydowii, A. candidus, A. allahabadi, A. terricola, A. ficuum, A. sparsus, A. carneus, A. pulvinus and A. aculeatus) were found to possess lectin activity. None of the species elaborated lectin in culture supernatant. All the lectins agglutinated rat, pig and rabbit erythrocytes. A. sydowii, A. candidus, A. allahabadi, A. terricola, A. ficuum, A. sparsus, A. carneus and A. aculeatus lectins agglutinated all human type erythrocytes equally, while A. pulvinus lectin specifically agglutinated human type A and O erythrocytes. Neuraminidase and protease treatment to erythrocytes substantially augmented lectin titres manyfold. Lectins showed specificity to mucin and asialofetuin and all of them were specific to L-arabinose except that of A. carneus. Lectins from A. sydowii, A. ficuum, A. sparsus and A. carneus displayed remarkable specificities to D-xylose. Maximum lectin activity was expressed by 11 day old cultures of A. sydowii (titre 32), A. ficuum (titre 64) and A. sparsus (titre 1024). Lectins from A. aculeatus, A. candidus and A. terricola were expressed by 7-10 days, 6-9 days and 5-11 days old cultures, respectively. A. allahabadi cultures exhibited maximum lectin activity (titre 32) after 8-10 days of cultivation. A. carneus and A. pulvinus expressed optimal titres of 32 and 8, respectively on the 9th day.

Purification and characterization of a novel thermostable mycelial lectin from Aspergillus terricola.

Lectin has been isolated from mycelia of Aspergillus terricola by single step purification on porcine stomach mucin-Sepharose 4B affinity column. Lectin could be effectively purified with 75% recovery and 4.47-fold increase in specific activity. Lectin migrated as a single band on SDS-PAGE with an apparent molecular mass of 32.5 kDa. Sugar inhibition assay revealed that the lectin did not strongly interact with most carbohydrates and their derivatives tested while strong binding affinity to D-glucose, D-sucrose, N-acetyl-D-galactosamine, asialofetuin, porcine stomach mucin, and bovine submaxillary mucin was indicated. Neuraminidase and protease treatment to erythrocytes enhanced lectin titre. Lectin activity was stable within the pH range of 7.0-10.5. A. terricola lectin displayed remarkable thermostability and remained unaffected upon incubation at 70 degrees C for 2.5 h. Lectin did not require metal ions for its activity. Incubation with denaturants (urea, thiourea, and guanidine-HCl) substantially reduced lectin activity. Carbohydrate analysis revealed that it is a glycoprotein with 9.76% total sugars.

Mushroom lectins: current status and future perspectives.

Lectins are nonimmune proteins or glycoproteins that bind specifically to cell surface carbohydrates, culminating in cell agglutination. These are known to play key roles in host defense system and also in metastasis. Many new sources have been explored for the occurrence of lectins during the last few years. Numerous novel lectins with unique specificities and exploitable properties have been discovered. Mushrooms have attracted a number of researchers in food and pharmaceuticals. Many species have long been used in traditional Chinese medicines or functional foods in Japan and other Asian countries. A number of bioactive constituents have been isolated from mushrooms including polysaccharides, polysaccharopeptides, polysaccharide-protein complexes, proteases, ribonucleases, ribosome inactivating proteins, antifungal proteins, immunomodulatory proteins, enzymes, lectins, etc. Mushroom lectins are endowed with mitogenic, antiproliferative, antitumor, antiviral, and immune stimulating potential. In this review, an attempt has been made to collate the information on mushroom lectins, their blood group and sugar specificities, with an emphasis on their biomedical potential and future perspectives.

Screening of Penicillium species for occurrence of lectins and their characterization.

Out of 15 Penicillium species screened for lectin activities, P. griseofulvum and P. thomii were found to possess mycelial lectin activity. None of the species displayed extracellular or cell surface-bound lectin activity. Both species agglutinated rabbit erythrocytes. P. griseofulvum lectin showed specificity to human type O erythrocytes. While P. thomii lectin specifically agglutinated human type A erythrocytes. Highest lectin activities from P. thomii and P. griseofulvum were expressed after 8 and 7 days of growth, respectively. Lectins from both the species displayed a high binding affinity to chondroitin-6-sulphate, mucin, asialofetuin, D-sucrose, and D-trehalose. Ammonium sulphate at 50% saturation yielded 80% of the total lectin activity. Dialysis and ultrafiltration of the precipitates resulted in 1.79 and 3.46 fold purification of P. griseofulvum and P. thomii lectins, respectively. Both lectins showed pH optima between 7.0-8.0 and were stable near the neutral pH after 2 h. P. thomii lectin exhibited optimal activity at 35-40 degrees C, and P. griseofulvum lectin at 30-40 degrees C. P. thomii lectin showed a complete loss of activity above 40 degrees C, P. griseofulvum lectin was stable at or below 35 degrees C.

Optimization of culture conditions and characterization of a new lectin from Aspergillus niger.

Lectin activity was determined on solidified medium containing agar and in broth cultures of Aspergillus niger. The fungus was found to express 16 times higher activity in broth cultures, when grown in a medium adjusted to pH 5.5 at 30°C under stationary condition. Lectin activity was found to be expressed by 6-day-old mycelial cultures with maximum activity being expressed on 9th day of incubation. The crude lectin (total titer 1280) was found to be precipitated at 50% saturation of ammonium sulphate with 2.4-fold purifi cation and 83% yield in the precipitate. The partially purifi ed lectin was found to agglutinate all human, rat, mice and pig erythrocytes. It was found to have a strong binding affinity to mucin, asialofetuin and inulin.

Screening of Aspergillus species for occurrence of lectins and their characterization.

Ten species of Aspergillus were screened for occurrence of lectins. Each of the species was investigated for the occurrence of extracellular, surface-bound and intracellular lectin activities. As many as four species namely, Aspergillus niger, Aspergillus versicolor, Aspergillus rugulosus and Aspergillus nidulans, were found to possess intracellular lectin activities, while none of the species showed extracellular or surface-bound lectin activities. Each of the lectin was characterized with respect to blood group and carbohydrate specificities. All the lectins were found to agglutinate human erythrocytes, irrespective of their blood group and pig erythrocytes. However, they did not show agglutination with sheep or goat erythrocytes. Of the various carbohydrates tested, all lectins were found to be specific for inulin, mucin, asialofetuin, N-acetyl galactosamine, melibiose, D-ribose, L-fucose, D-arabinose, D-sucrose and D-mannitol. The minimum inhibitory concentration of each of the specific sugars was also determined. The lectins were partially purified using ammonium sulfate precipitation technique. Each of the lectin was found to be precipitated at 40-50% saturation of ammonium sulfate, yielding about 80% of lectin activity.