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Nanotechnology in Functional Foods and Their Packaging
Published in Alok Dhawan, Sanjay Singh, Ashutosh Kumar, Rishi Shanker, Nanobiotechnology, 2018
Satnam Singh, Shivendu Ranjan, Nandita Dasgupta, Chidambaram Ramalingam
Another role of nanosenors is the detection of pathogens and toxins in food products when incorporated into food packaging (Bhattacharya et al. 2007). The fluorescent nanoparticles method is the one of the methods to detect pathogens and toxins in food (Burris and Stewart 2012). Foodborne pathogenic bacteria species (such as Salmonella typhimurium, Shigella flexneri, and E. coli O157:H7) can be detected by quantum dots coupled with immunomagnetic (Fe2O3 magnetic nanoparticles) separation in milk and apple juice (Zhao et al. 2008). Another technique that is used in detecting of E. coli in food samples is based on light scattering by cell mitochondria; measurement of the light scattering confirms the presence of E. coli. The basic principle behind this technique is that a protein of a known and characterized bacterium set on a silicon chip can bind with any other E. coli bacteria present in the food sample and result in nanosized light scattering that will be detected by analyzing the digital image (Horner et al. 2006). Fu et al. (2008) developed a technique for detection of Salmonella present in food products. Silicon/gold nanorods are incorporated with anti-Salmonella antibodies and fluorescent dye, which become visible when they attach to the bacteria (Fu et al. 2008).
Mechanisms of Bacterial Heavy Metal Resistance and Homeostasis
Published in Edgardo R. Donati, Heavy Metals in the Environment, 2018
Pallavee Srivastava, Meenal Kowshik
The MerR family of regulators are exclusive transcriptional activators that have similar N-terminal helix-turn-helix DNA binding regions and C-terminal effector binding regions that are specific to the effector. The first 100 amino acids of the N-terminal region are conserved and is the signature of this family of regulators (Brown et al., 2003). Within the family, the Hg2+ resistance regulator, MerR was the first metalloregulatory protein identified in transposons Tn501 from P. aeruginosa 278 and Tn21 from Shigella flexneri R100 plasmid (Barkay et al., 2003). Subsequently, various regulators belonging to this family were identified that recognised other metal ions such as ZntR for Zn2+, CueR for Cu+, GolS for Au+, CadR for Cd2+, and PbrR for Pb+ (Ma et al., 2009).
Dendrimers: Emerging Anti-Infective Nanomedicines
Published in Bhupinder Singh, Rodney J. Y. Ho, Jagat R. Kanwar, NanoBioMaterials, 2018
The antibacterial activity of PAMAM dendrimers with surface amino group is limited by its considerable toxicity towards mammalian cells. Hence, to explore the antibacterial properties of PAMAM dendrimers without affecting normal cells, Xue et al. (2015) designed LED209-conjugated PAMAM dendrimers to develop a multifunctional antibacterial agent to combat the challenge of multidrug-resistant (MDR), gram-negative bacteria. LED209 was used in this study to increase specificity of PAMAM dendrimers towards gram-negative pathogens. It is a specific inhibitor of QseC (conserved histidine sensor kinase found in minimum of 21 MDR gram-negative bacteria infecting humans) of MDR gram-negative bacteria and nontoxic to human cells. It does not inhibit growth of bacteria and it is anticipated that it will exert least survival pressure on bacteria to develop resistance that can inhibit the virulence of these pathogens. The results according to the anticipated hypothesis revealed low cytotoxicity towards human cells and selectivity towards gram-negative bacteria, with promising antibacterial activity against many pathogenic gram-negative bacteria including E. coli, P. aeruginosa, Klebsiella pneumoniae, Salmonella paratyphi, Salmonella typhimurium, MDR-Acinetobacter baumannii, MDR-E. coli, MDR-Shigella flexneri, Extended Spectrum Beta-Lactamases (ESBLs)-E. coli.
Molecular epidemiology of virulent E. coli among rural small scale dairy herds and shops: Efficacy of selected marine algal extracts and disinfectants
Published in International Journal of Environmental Health Research, 2022
Ahmed S. Ahmed, Hassan M. Diab, Mohammed A. Alkahtani, Mohammed A. Alshehri, Hani Saber, Heba Badr, Mohamed K. Dandrawy, Ahmed A. El-Mansi, Ali A. Shati, Ahmed Ezzat Ahmed
Various studies evaluated the antimicrobial activities of marine seaweeds, i.e. C. racemosa, J. rubens and Turbinaria Species. Different solvents viz., methanol, ethanol, chloroform, diethyl ether, hexane, chloroform, ethyl acetate and water were used for seaweed extraction to investigate the antibacterial activity against gram-negative and gram-positive bacteria including E.coli, Enterobacter aerogenes, Klebsiella pneumonia, Proteus vulgaris, Pseudomonas aeruginosa, Salmonella typhi, Shigella flexneri, Enterococcus faecalis and Staphylococcus aureus (Vijayabaskar and Shiyamala 2011; Karthikeyan et al. 2015; Ward and Deyab 2016; Sasikala and Geetha Ramani 2017). Some Egyptian researches evaluated the potential antibacterial activities of Turbinaria species against E. coli showing that the inhibitory effects were 0.05–0.3 of ethanolic extracts (Ward and Deyab 2016) and 14.75 ± 1.3 mm of isopropyl alcohol extracts (Madkour et al. 2019). Globally, Turbinaria species exhibited the highest activity against the growth of E. coli with 16 ± 0.58 mm inhibition zone (Vijayabaskar and Shiyamala 2011). In addition, the diethyl ether extract of C. racemosa generated maximum zone of inhibition against E. coli (21 ± 0.25 mm) followed by chloroform, ethanol and methanol (Karthikeyan et al. 2015). Also, it was reported that J. rubens exhibited significant inhibition against E. coli (09.00 ± 0.81 mm) (Sasikala and Geetha Ramani 2017).
Silver nanoparticles biosynthesis by Elaeodendron croceum stem bark and leaves extracts, their anti-bacterial and cytotoxicity activities
Published in Inorganic and Nano-Metal Chemistry, 2020
Samuel Wale Odeyemi, Emmanuel O. Ajayi, Gloria A. Otunola, Anthony Jide Afolayan
The four reference strains of bacteria used in this study were chosen based on their pathological effects on human and deterioration of food products. Gram positive bacteria Streptococcus faecalis (ATCC: 29212), Bacillus cereus (ATCC: 10702), and Gram negative bacteria Escherichia coli (ATCC: 25922), and Shigella flexneri (KZN) were obtained from the Microbiology Unit of MPED Research Center, Botany Department, University of Fort Hare. The bacteria isolates were sub-cultured on nutrient agar (SAARCHEM, Gauteng SA) plates and incubated at 37 °C for 24 h. A loopful of bacterial cells from the nutrient agar plates was inoculated into 50 mL of a nutrient broth (DIFCO, California, USA) in a Erlenmeyer flask and incubated at 37 °C for 16 h with vigorous shaking in orbital incubator (S150, UK). After incubation, the culture was diluted with fresh media to give an OD600 nm of 0.1. 100 μL of the culture cells was added onto the plate and spread into agar lawn using a sterile glass spreader.
Exploring the therapeutic potentials of phyto-mediated silver nanoparticles formed via Calotropis procera (Ait.) R. Br. root extract
Published in Journal of Experimental Nanoscience, 2020
Suresh Sagadevan, Selvaraj Vennila, Lakshmipathy Muthukrishnan, K. Gurunathan, Won Chun Oh, Suriati Paiman, Faruq Mohammad, Hamad A. Al-Lohedan, Ainil Hawa Jasni, Is Fatimah, Kuppan Sivaranjan, Prasanna Kumar Obulapuram
The antibacterial efficacy of AgNPs was determined using the agar diffusion method [14] against clincally significant bacteria namely Salmonella typhi, Shigella flexneri, Bacillus subtilis, E. coli, S. aureus, Enterococcus sp., K. pneumoniae, P. aeruginosa, Staphylococcus epidermidis, and E. faecalis. The strains used are typical representatives of two large bacterial taxonomical lineages and were obtained from a private clinical laboratory in India. Prior to the assay, each bacterium was refreshed on nutrient agar stocks and fresh overnight grown suspensions in nutrient broth were preferred. The inoculum size of each strain from overnight suspensions was prepared using 0.8% NaCl and the turbidity adjusted to OD600 = 0.1. Sterile disks were loaded with 5, 102, 550, 100 µL of AgNPs (1 mg/mL) and control disk with the 1 mM solution of AgNO3. The inoculated plates were incubated at 37 °C for 24 h for any inhibitory effect and at the same visualised and measured the extent of inhibition using the calipers.