Removal Of Listeria Monocytogenes Research Articles

Selective Photocatalytic Disinfection by Coupling StrepMiniSog to the Antibody Catalyzed Water Oxidation Pathway.

For several decades reactive oxygen species have been applied to water quality engineering and efficient disinfection strategies; however, these methods are limited by disinfection byproduct and catalyst-derived toxicity concerns which could be improved by selectively targeting contaminants of interest. Here we present a targeted photocatalytic system based on the fusion protein StrepMiniSOG that uses light within the visible spectrum to produce reactive oxygen species at a greater efficiency than current photosensitizers, allowing for shorter irradiation times from a fully biodegradable photocatalyst. The StrepMiniSOG photodisinfection system is unable to cross cell membranes and like other consumed proteins, can be degraded by endogenous digestive enzymes in the human gut, thereby reducing the consumption risks typically associated with other disinfection agents. We demonstrate specific, multi-log removal of Listeria monocytogenes from a mixed population of bacteria, establishing the StrepMiniSOG disinfection system as a valuable tool for targeted pathogen removal, while maintaining existing microbial biodiversity.

Performance of the municipal wastewater treatment plant for removal of Listeria monocytogenes

Aims: The aim of present study was determination of occurrence of Listeria Listeria spp. in various point of a municipal wastewater treatment plant. Materials and Methods: The samples were collected of influent, effluent, raw sludge, stabilized sludge and dried sludge from north wastewater treatment plant Isfahan, Iran. The presence of Listeria spp. was determined using USDA procedure and enumerated by a three-tube most probable number assay using Fraser enrichment broth. Then, biochemically identified Listeria monocytogenes was further confirmed by PCR amplification. Results: L. monocytogenes, L. innocua and L. seeligeri were isolated from 76.9%, 23.1% and 23.1% of influent, 38.5%, 46.2% and 7.7% of effluent, 84.6%, 69.2% and 46.2% of raw sludge, 69.2%, 76.9% and 0% of stabilized sludge and 46.2%, 7.7% and 0% of dried sludge samples, respectively. The efficiency of wastewater treatment processes, digester tank and drying bed in removal of L. monocytogenes were 69.6%, 64.7% and 73.4%, respectively. All phenotypically identified L. monocytogenes were further confirmed by PCR method. Conclusion: Application of sewage sludge in agricultural farms as fertilizer may result in bacteria spreading in agriculture fields and contaminated foods with plant origin. This may cause a risk of spreading disease to human and animals. Using parameters such as BOD 5 is not sufficient standard for the elimination of pathogenic microorganisms.

Effects of sewage treatment on the removal of Listeria monocytogenes

Two sewage treatment plants in Baghdad, Iraq, were investigated to assess the effects of the different treatment stages on the removal of Listeria monocytogenes. The bacteria were severely affected after the activation and digestion stages at both plants. A dramatic decrease in numbers of listerias after each of these two stages was noticed during the cold months (September-January). The organisms were able to survive these treatments and were present in the final effluent and even in low numbers in the sewage sludge cake. Sufficient dewatering of sewage sludge is recommended to obtain sewage free of listerias. Improvements in the isolation procedure of L. monocytogenes from such heavily contaminated material is also discussed.