The antioxidant and antibacterial activities of the phytochemical constituents of the pericarp, mesocarp and segment membrane crude ethanolic extracts of Pummelo (Citrus maxima (Burm.)) fruit were were tested against ...The antioxidant and antibacterial activities of the phytochemical constituents of the pericarp, mesocarp and segment membrane crude ethanolic extracts of Pummelo (Citrus maxima (Burm.)) fruit were were tested against Escherichia coli and Salmonella typhimurium. Preliminary phytochemical test revealed the presence of phenols, tannins, saponins expressed as catechine quivalent (CE)/100ml and flavonoid expressed as gallic acid equivalent (GAE)/100ml. The order of which was as follows pericarp > segment membrane > mesocarp. The strongest antioxidant activity was obtained by the pericarp extract (29.64 expressed as % lipid peroxidation). The differences in the measured amount of phytochemicals and antioxidant activity among the three sample extracts were found to be significant. In terms of antimicrobial activity, the pericarp, mesocarp and segment membrane extracts generated zone of inhibitions measuring 17.10, 18.00 and 17.03 mm for S. typhimurium, respectively at 100% concentration. E. coli was noted to be inactive in all three sample extracts at 100% concentration. The capacity of E. coli to counteract the inhibitory effect of the phytochemicals contained in the pummelo extracts may be attributed to its rough corrugated cell wall and thick periplasmic space as opposed to the smooth curved and barely seen periplasmic space of S. typhimurium. However, no significant correlation was detected among the phytochemical content, antioxidant and in vitro antimicrobial activities of the sample extracts against S. typhimurium.展开更多
Organically modified silica (ORMOSILS) thin films produced by sol-gel method were imprinted with two bacterial strains as whole cells in order to develop an easy, fast and specific probe to detect and specifically ide...Organically modified silica (ORMOSILS) thin films produced by sol-gel method were imprinted with two bacterial strains as whole cells in order to develop an easy, fast and specific probe to detect and specifically identify these micro-organisms when present in water samples. An important feature of the imprinting process was the molecular finger-prints left by these microorganisms alongside morphology, into imprinted film cavities. The films also showed high selectivity toward the imprinted template and were able to discriminate between two very close bacterial species (E. coli and S. typhimurium). In addition, several central physical parameters of the experimental water solution were examined (i.e., pH, ionic strength and the organic load exemplified by NaCl and TOC concentration, respectively). The method sensitivity to different bacterial concentrations was studied by confocal microscopy (CLSM) and quartz crystal microbalance (QCM) tools. Results showed that increased bacterial concentrations favor rapid adsorption onto imprinted sol-gel films with high affinity, while low pH, increased organic load and high ionic concentrations (i.e., seawater) interfere with bacteria re-adsorption, reducing detection capability. Under average drinking water chemical composition the method proved to be highly efficient.展开更多
The absence of efficient tools for preventing bacterial contamination in the meat processing industry as well as for detecting Salmonella positive samples in real time is a matter of concern. Impedance technology has ...The absence of efficient tools for preventing bacterial contamination in the meat processing industry as well as for detecting Salmonella positive samples in real time is a matter of concern. Impedance technology has proved its effectiveness as a bacterial quantification tool for research purposes instead of laborious standard plate count, and as a detection tool to substitute tedious current horizontal method ISO 6579：2002. Calibration curves were carded out for S. enteritidis and S. typhimurium in raw pork matrix （R2 〉 0.90）. Calibrations of mixtures of both strains at different ratio were prepared, showing a high efficiency to differentiate bacterial metabolism. Impediometry was also validated against standard plate count in raw pork samples treated by UV-C illumination to inactivate Salmonella. Even, damaged but still viable bacteria were recorded. Detection of Salmonella by impediometry led to a decrease in false positives, obtaining results within 30 h compared to 72 h in case of conventional method.展开更多
基金The authors acknowledge the Department of Science and Technology,Philippines,for the financial support through a PhD scholarship for A.S.A.Barrion.
文摘The antioxidant and antibacterial activities of the phytochemical constituents of the pericarp, mesocarp and segment membrane crude ethanolic extracts of Pummelo (Citrus maxima (Burm.)) fruit were were tested against Escherichia coli and Salmonella typhimurium. Preliminary phytochemical test revealed the presence of phenols, tannins, saponins expressed as catechine quivalent (CE)/100ml and flavonoid expressed as gallic acid equivalent (GAE)/100ml. The order of which was as follows pericarp > segment membrane > mesocarp. The strongest antioxidant activity was obtained by the pericarp extract (29.64 expressed as % lipid peroxidation). The differences in the measured amount of phytochemicals and antioxidant activity among the three sample extracts were found to be significant. In terms of antimicrobial activity, the pericarp, mesocarp and segment membrane extracts generated zone of inhibitions measuring 17.10, 18.00 and 17.03 mm for S. typhimurium, respectively at 100% concentration. E. coli was noted to be inactive in all three sample extracts at 100% concentration. The capacity of E. coli to counteract the inhibitory effect of the phytochemicals contained in the pummelo extracts may be attributed to its rough corrugated cell wall and thick periplasmic space as opposed to the smooth curved and barely seen periplasmic space of S. typhimurium. However, no significant correlation was detected among the phytochemical content, antioxidant and in vitro antimicrobial activities of the sample extracts against S. typhimurium.
文摘Organically modified silica (ORMOSILS) thin films produced by sol-gel method were imprinted with two bacterial strains as whole cells in order to develop an easy, fast and specific probe to detect and specifically identify these micro-organisms when present in water samples. An important feature of the imprinting process was the molecular finger-prints left by these microorganisms alongside morphology, into imprinted film cavities. The films also showed high selectivity toward the imprinted template and were able to discriminate between two very close bacterial species (E. coli and S. typhimurium). In addition, several central physical parameters of the experimental water solution were examined (i.e., pH, ionic strength and the organic load exemplified by NaCl and TOC concentration, respectively). The method sensitivity to different bacterial concentrations was studied by confocal microscopy (CLSM) and quartz crystal microbalance (QCM) tools. Results showed that increased bacterial concentrations favor rapid adsorption onto imprinted sol-gel films with high affinity, while low pH, increased organic load and high ionic concentrations (i.e., seawater) interfere with bacteria re-adsorption, reducing detection capability. Under average drinking water chemical composition the method proved to be highly efficient.
文摘The absence of efficient tools for preventing bacterial contamination in the meat processing industry as well as for detecting Salmonella positive samples in real time is a matter of concern. Impedance technology has proved its effectiveness as a bacterial quantification tool for research purposes instead of laborious standard plate count, and as a detection tool to substitute tedious current horizontal method ISO 6579：2002. Calibration curves were carded out for S. enteritidis and S. typhimurium in raw pork matrix （R2 〉 0.90）. Calibrations of mixtures of both strains at different ratio were prepared, showing a high efficiency to differentiate bacterial metabolism. Impediometry was also validated against standard plate count in raw pork samples treated by UV-C illumination to inactivate Salmonella. Even, damaged but still viable bacteria were recorded. Detection of Salmonella by impediometry led to a decrease in false positives, obtaining results within 30 h compared to 72 h in case of conventional method.
