Risk-based assessment and criteria specification of the microbial safety of wastewater reuse in food processing: Managing Listeria monocytogenes contamination in pasteurized fluid milk

Quantitative microbiological risk assessment for the occurrence of listeriosis in Brazil due to the consumption of milk processed by pasteurization or thermosonication

This study aimed to estimate the risk of listeriosis from the consumption of pasteurized milk in Brazil, comparing conventional treatment with the technology of thermosonication. The Quantitative Microbiological Risk Assessment (QMRA) model was developed, covering the entire milk production chain, from milking to the moment of consumption. In general, higher risks were observed in association with higher initial concentrations of the pathogen and the vulnerable population. The highest risk predicted (3.67 × 10-5) was related to the scenario considering the initial concentration range of L. monocytogenes between 4 and 6 log CFU/mL, with conventional treatment and considering the vulnerable population, resulting in one case of listeriosis every 27,248 servings. When considering thermosonication treatment, lower risks have been predicted. The scenario analysis indicated that the steps related to storage conditions in retail and at the consumer's home (post-processing steps) are the most influential in the associated risk, in all scenarios. The predictive parameters of inactivation related to the applied treatment also have a considerable influence on the risk. The results point to the influence of the stages of the dairy production chain and the thermosonication treatment applied in the food safety of milk, subsidizing information for industrial application and for regulatory agencies.

Polydopamine-based nanozyme with dual-recognition strategy-driven fluorescence-colorimetric dual-mode platform for Listeria monocytogenes detection

Development of a simple and efficient dual-mode analytical technique with the built-in cross reference correction feature is benefit to achieve the highly accurate detection of the target pollutants and avoid the false-positive outputs in environmental media. Here, we synthesized a Fe-doped polydopamine (Fe@PDA)-based nanozyme with prominent peroxide-mimetic enzyme activity and high fluorescence emission ability. On this basis, we designed a dual-recognition strategy-driven fluorescence-colorimetric dual-mode detection platform, consisting of Listeria monocytogenes (L. monocytogenes) recognition aptamer-modified Fe@PDA (apt/Fe@PDA) and vancomycin-functionalized Fe₃O₄ (van/Fe₃O₄), for L. monocytogenes. Owing to van/Fe₃O₄-powered magnetic separation, there was a L. monocytogenes concentration-dependent fluorescence enhancement of apt/Fe@PDA for performing fluorescence assay in the precipitate. In this case, the prominent peroxide-mimetic enzyme activity of the residual apt/Fe@PDA in the precipitation could catalyze H₂O₂ to further oxidate colorless 3,3',5,5'-tetramethylbenzidine (TMB) into blue oxTMB, which displayed a L. monocytogenes concentration-dependent absorbance enhancement for carrying out colorimetric assay as well. As a result, a fluorescence-colorimetric dual-mode analytical platform was proposed to successfully detect the residual L. monocytogenes in real environmental media with acceptable results. This work showed the great prospects by integrating dual-recognition strategy into fluorescence nanozyme to develop efficient and reliable dual-mode analytical platforms for safeguarding environmental health.

Visible-light photooxidation of ciprofloxacin utilizing metal oxide incorporated sol-gel processed La-doped NaTaO3 nanoparticles: A comparative study

The supper dissemination of antibiotic waste in water resources has exponentially progressed the vital water and soil pollution that affect human health and the environment. Consequently, there have been several types of research anticipated for the green mineralization of such pollutants. Herein, we intended a surfactant-aided sol-gel formation of lanthanum-doped sodium tantalate (LNTO) nanocrystals. The synthesized 13 nm averaged-size perovskite LNTO nanocrystals were responsive to visible-light irradiation by incorporation of 4.4-5.2 nm oxide nanoparticles, namely Bi₂O₃, CdO, Fe₂O₃, and CuO at 4.0 wt% through coprecipitation. The formed nanomaterials unveiled mesostructured surface textures with specific surface areas of 199-229 m² g^-1. The obtained nanoceramics were employed for the mineralization of 10 ppm of ciprofloxacin antibiotic (CPF) as an emerging antibiotic waste in water under visible light irradiation. The CuO-incorporated LNTO exhibited the best photocatalytic oxidation of CPF after 120 min compared with other oxides with an excellent photoreaction rate of 0.0343 min^-1 which is 49 times higher than the pure LNTO. The 2.0 gL^-1 CuO/LNTO-dose achieved the full photooxidation of CPF at an oxidation speed of 0.0738 min ^-1 within just 1.0 h of visible light irradiation and magnificent regeneration ability. This enhanced activity of CuO/LNTO is regarded as significant light absorption and a bandgap energy reduction to 2.12 eV. Besides that, the heterojunction between CuO and LNTO amended the photogenerated carrier mobility and separation as concluded from the photoluminescence and photocurrent exploration. This comparative work suggests the proper design of low bandgap oxide decoration of solution-based perovskite oxide photocatalysts for promoting the visible-light mineralization of antibiotics in water.

Cobalt ferrite-modified sol-gel synthesized ZnO nanoplatelets for fast and bearable visible light remediation of ciprofloxacin in water

Currently, metal oxide photocatalysts is a green and facile tool for the elimination of emerging pollutants utilizing light illumination. Though, the wide bandgap energy (E_g), rapid recombination of photogenerated carriers, and photostability of these oxides represent critical issues before the actual application. Herein, we familiarise a sol-gel based synthesis of ZnO hexagonal nanoplatelets modified with CoFe₂O₄ (CFO) nanoparticles at minor loading (1.0-4.0 wt %) to yield CFO/ZnO nanoheterojunctions. The CFO/ZnO unveiled mesostructured surfaces at surface areas of 102-120 m² g^-1 and photoactive in the visible region with high. The CFO addition to ZnO reduced its E_g from 3.14 to 2.66 eV. The formed nanoheterojunctions were applied to remediate ciprofloxacin (CPF), as an antibiotic pollutant in wastewater. The 2.4 g L^-1 3.0 wt % CFO-added ZnO exhibited a 100% removal of 10-ppm CPF within 45 min of visible-light irradiation and sustainable recycling ability for five consecutive runs at 97%. The sustainable performance of CFO/ZnO is ascribed to the suppression of photogenerated carriers and reduction of E by p-n nanoheterojunction formation. This study broadens the way for nanoheterojunction oxides for the destruction of pharmaceutical wastes under visible-light illumination.

Prevalence and molecular characterization of Listeria monocytogenes isolated from wastewater of cattle slaughterhouses in Turkey

AIM

The study aimed to investigate the role of cattle slaughterhouse wastewater as a possible source for the environmental distribution of Listeria monocytogenes.

METHODS AND RESULTS

Listeria spp. isolation was performed by collecting 117 wastewater samples from four different cattle slaughterhouses in Turkey. Species-specific identification was performed biochemically, and L. monocytogenes isolates were confirmed with polymerase chain reaction (PCR). In all, 71 (62.2%) of the wastewater samples were found to be positive for Listeria spp., and 17 (14.9%) of these samples were contaminated with L. monocytogenes. Pulsed field gel electrophoresis (PFGE) analysis revealed that all L. monocytogenes isolates were of different pulsotypes and isolates belonged to seven different phylogenetic clusters. Multiplex PCR analysis for genoserotypes and lineage determination showed that the isolates were divided into genoserotypes IVb and IIc in Lineages I and II. Also, it has been investigated with SYBR-Green Real-time PCR whether the L. monocytogenes isolates harboured virulence genes (hly, sigB, plcA, plcB, inlA, inlB, inlC and inlJ), and it was found that all isolates were substantially positive. Antibiotic resistance profiles and MIC values of the isolates were determined, and all L. monocytogenes isolates were found susceptible to ampicillin. In contrast, two isolates were resistant to meropenem and erythromycin, and three isolates were resistant to trimethoprim/sulfamethoxazole.

CONCLUSION

L. monocytogenes, which pose a threat to public health and resists to antibiotics effectively used in treatments, can environmentally spread via wastewater of cattle slaughterhouses. The wastewater of the food industry, which has rich microbiota, should be treated carefully, and possible environmental contamination should be prevented.

SIGNIFICANCE AND IMPACT OF STUDY

This is the first study that investigates the molecular characterization of L. monocytogenes isolated from cattle slaughterhouse wastewater and the findings represent the importance of cattle wastewater in the epidemiology of L. monocytogenes in Turkey.

Quantitative microbial risk assessment of SARS-CoV-2 for workers in wastewater treatment plants

Faecal-oral transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is yet to be validated, but it is a critical issue and additional research is needed to elucidate the risks of the novel coronavirus in sanitation systems. This is the first study that investigates the potential health risks of SARS-CoV-2 in sewage to wastewater treatment plant (WWTP) workers. A quantitative microbial risk assessment (QMRA) is applied for three COVID-19 scenarios (moderate, aggressive and extreme) to study the effects of different stages of the pandemic in terms of percentage of infected population on the probability of infection to WWTP workers. A dose-response model for SARS-CoV-1 (as a surrogate pathogen) is assumed in the QMRA for SARS-CoV-2 using an exponential model with k = 4.1 × 10². Literature data are incorporated to inform assumptions for calculating the viral load, develop the model, and derive a tolerable infection risk. Results reveal that estimates of viral RNA in sewage at the entrance of WWTPs ranged from 4.14 × 10¹ to 5.23 × 10³ GC·mL^-1 (viable virus concentration from 0.04 to 5.23 PFU·mL^-1, respectively). In addition, estimated risks for the aggressive and extreme scenarios (2.6 × 10^-3 and 1.3 × 10^-2, respectively) were likely to be above the derived tolerable infection risk for SARS-CoV-2 of 5.5 × 10^-4 pppy, thus reinforcing the concern of sewage systems as a possible transmission pathway of SARS-CoV-2. These findings are helpful as an early health warning tool and in prioritizing upcoming risk management strategies, such as Emergency Response Plans (ERPs) for water and sanitation operators during the COVID-19 and future pandemics.

Quantitative microbial risk assessment of SARS-CoV-2 for workers in wastewater treatment plants

Faecal-oral transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is yet to be validated, but it is a critical issue and additional research is needed to elucidate the risks of the novel coronavirus in sanitation systems. This is the first study that investigates the potential health risks of SARS-CoV-2 in sewage to wastewater treatment plant (WWTP) workers. A quantitative microbial risk assessment (QMRA) is applied for three COVID-19 scenarios (moderate, aggressive and extreme) to study the effects of different stages of the pandemic in terms of percentage of infected population on the probability of infection to WWTP workers. A dose-response model for SARS-CoV-1 (as a surrogate pathogen) is assumed in the QMRA for SARS-CoV-2 using an exponential model with k = 4.1 × 10². Literature data are incorporated to inform assumptions for calculating the viral load, develop the model, and derive a tolerable infection risk. Results reveal that estimates of viral RNA in sewage at the entrance of WWTPs ranged from 4.14 × 10¹ to 5.23 × 10³ GC·mL^-1 (viable virus concentration from 0.04 to 5.23 PFU·mL^-1, respectively). In addition, estimated risks for the aggressive and extreme scenarios (2.6 × 10^-3 and 1.3 × 10^-2, respectively) were likely to be above the derived tolerable infection risk for SARS-CoV-2 of 5.5 × 10^-4 pppy, thus reinforcing the concern of sewage systems as a possible transmission pathway of SARS-CoV-2. These findings are helpful as an early health warning tool and in prioritizing upcoming risk management strategies, such as Emergency Response Plans (ERPs) for water and sanitation operators during the COVID-19 and future pandemics.

Food-processing wastes

Literature published in 2018 and literature published in 2019 related to food-processing wastes treatment for industrial applications are reviewed. This review is a subsection of the Treatment Systems section of the annual Water Environment Federation literature review and covers the following food-processing industries and applications: general, meat and poultry, fruits and vegetables, dairy and beverage, and miscellaneous treatment of food wastes. PRACTITIONER POINTS: This article summarizes literature reviews published in 2018 and in 2019 related to food processing wastes treatment for industrial applications are reviewed. This review is a subsection of the Treatment Systems section of the annual Water Environment Federation literature review and covers the following food processing industries and applications: general, meat and poultry, fruits and vegetables, dairy and beverage, and miscellaneous treatment of food wastes.