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1.
Biofouling ; 36(1): 1-13, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31997661

RESUMO

This work aimed to evaluate the action of materials with different copper content (0, 57, 96 and 100%) on biofilm formation and control by chlorination and mechanical stress. Stenotrophomonas maltophilia isolated from drinking water was used as a model microorganism and biofilms were developed in a rotating cylinder reactor using realism-based shear stress conditions. Biofilms were characterized phenotypically and exposed to three control strategies: 10 mg l-1 of free chlorine for 10 min, an increased shear stress (a fluid velocity of 1.5 m s-1 for 30s), and a combination of both treatments. These shock treatments were not effective in biofilm control. The benefits from the use of copper surfaces was found essentially in reducing the numbers of non-damaged cells. Copper materials demonstrated better performance in biofilm prevention than chlorine. In general, copper alloys may have a positive public health impact by reducing the number of non-damaged cells in the water delivered after chlorine exposure.


Assuntos
Biofilmes/efeitos dos fármacos , Cloro/farmacologia , Cobre/farmacologia , Stenotrophomonas maltophilia/efeitos dos fármacos , Estresse Mecânico , Biofilmes/crescimento & desenvolvimento , Halogenação , Modelos Teóricos , Stenotrophomonas maltophilia/crescimento & desenvolvimento , Propriedades de Superfície , Microbiologia da Água , Purificação da Água
2.
Chemosphere ; 242: 125310, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31896192

RESUMO

The bacterial composition of biofilms in drinking water distribution systems is significantly impacted by the disinfection regime and substrate material. However, studies that have addressed the changes in the biofilm community during the early stage of formation (less than 10 weeks) were not yet adequate. Here, we explore the effects of the substrate materials (cast iron, stainless steel, copper, polyvinyl chloride, and high density polyethylene) and different disinfectants (chlorine and chloramine) on the community composition and function of young biofilm by using 16S rDNA sequencing. The results showed that Alphaproteobacteria (39.14%-80.87%) and Actinobacteria (5.90%-40.03%) were the dominant classes in chlorine-disinfection samples, while Alphaproteobacteria (17.46%-74.18%) and Betaproteobacteria (3.79%-68.50%) became dominant in a chloraminated group. The infrequently discussed genus Phreatobacter became predominant in the chlorinated samples, but it was inhibited by chloramine and copper ions. The key driver of the community composition was indicated as different disinfectants according to principle coordination analysis (PCoA) and Permutational multivariate analysis of variance (Adonis test), and the bacterial community changed significantly over time. Communities of biofilms grown on cast iron showed a great distance from the other materials according to Bray-Curtis dissimilarity, and they had a unique dominant genus, Dechloromonas. A metagenomics prediction based on 16S rDNA was used to detect the functional pathways of antibiotic biosynthesis and beta-lactam resistance, and it revealed that several pathways were significantly different in terms of their chlorinated and chloraminated groups.


Assuntos
Biofilmes/efeitos dos fármacos , Cloraminas/farmacologia , Cloro/farmacologia , Desinfetantes/farmacologia , Água Potável/microbiologia , Microbiota/efeitos dos fármacos , Materiais de Construção/microbiologia , Desinfecção/métodos , Água Potável/química , Ferro , Microbiota/genética , RNA Ribossômico 16S/genética , Aço Inoxidável , Microbiologia da Água/normas
3.
Chemosphere ; 243: 125453, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31995893

RESUMO

Fungal contamination in drinking water has been becoming a hot topic. The routine enumeration method of fungal spores is heterotrophic plate counts (HPC). However, this method is time-consuming and labor-intensive and there is also the difficulty of enumerating viable but non-culturable cells. In this study, a rapid, simple and accurate method for quantifying fungal spores and discriminating their viability in water was established using flow cytometry (FCM) combined with fluorescence dyes. The optimal staining conditions are as follows: spores suspensions are sonicated at 495 W for 5 min as pretreatment, and then 10 µL of SYBR Green I (100×) and 30 mM Ethylene diamine tetraacetic acid are added to a 500 µL water sample, which incubate at 35 °C for 20 min in dark. The concentration of fungal spores measured by FCM was highly correlated with HPC results and microscope observations, with correlation coefficient of 0.996 and 0.988, respectively. This staining method can be widely applied to the enumeration and viability evaluation of fungal spores. In addition, chlorine-based inactivation of three genera of fungal spores was assessed by plating and FCM. The result showed that all three genera of fungal spores lost culturability firstly and then membrane integrity decreased, preliminarily revealing the inactivation mechanism. The inactivation rate constants of membrane damage varied in the following order: chlorine dioxide > chlorine > chloramine. This study concluded that FCM is an appropriate and alternative tool to detect fungal spores' viability and can be used for evaluating the fungal inactivation by disinfectants.


Assuntos
Desinfecção/métodos , Citometria de Fluxo/métodos , Esporos Fúngicos/crescimento & desenvolvimento , Cloraminas/farmacologia , Cloro/farmacologia , Compostos Clorados/farmacologia , Desinfetantes/farmacologia , Corantes Fluorescentes , Fungos/citologia , Fungos/efeitos dos fármacos , Compostos Orgânicos , Óxidos/farmacologia , Esporos Fúngicos/citologia , Coloração e Rotulagem/métodos
4.
Food Microbiol ; 87: 103359, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31948614

RESUMO

Washing in chlorinated water is widely practiced for commercial fresh produce processing. While known as an effective tool for mitigating food safety risks, chlorine washing could also represent an opportunity for spreading microbial contaminations under sub-optimal operating conditions. This study evaluated Salmonella inactivation and cross-contamination in a simulated washing process of cherry and grape tomatoes. Commercially harvested tomatoes and the associated inedible plant matter (debris) were differentially inoculated with kanamycin resistant (KanR) or rifampin resistant (RifR) Salmonella strains, and washed together with uninoculated tomatoes in simulated packinghouse dump tank (flume) wash water. Washing in chlorinated water resulted in significantly higher Salmonella reduction on tomatoes than on debris, achieving 2-3 log reduction on tomatoes and about 1 log reduction on debris. Cross-contamination by Salmonella on tomatoes was significantly reduced in the presence of 25-150 mg/L free chlorine, although sporadic cross-contamination on tomatoes was detected when tomatoes and debris were inoculated at high population density. The majority of the sporadic cross-contaminations originated from Salmonella inoculated on debris. These findings suggested that debris could be a potentially significant source of contamination during commercial tomato washing.


Assuntos
Contaminação de Alimentos/análise , Lycopersicon esculentum/microbiologia , Prunus avium/microbiologia , Salmonella/crescimento & desenvolvimento , Cloro/farmacologia , Manipulação de Alimentos , Microbiologia de Alimentos , Inocuidade dos Alimentos , Salmonella/efeitos dos fármacos
5.
Food Microbiol ; 86: 103308, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31703866

RESUMO

The aim of this study was to use chlorine dioxide (ClO2) gas to inactivate Aspergillus flavus on green coffee beans. Green coffee beans inoculated with A. flavus were exposed to ClO2 gas generated from 0.75, 1, 1.25, or 1.5 mL of ClO2 solution in a sealed container at 25 or 50 °C (100% relative humidity [RH]) for up to 10 h. Numbers of A. flavus on beans treated at 25 °C decreased by 1.1-2.2 log cfu/bean within 1 h of exposure to ClO2 and decreased to below the detection limit (≤1.0 log cfu/bean) at all ClO2 concentrations after 10 h. At 50 °C, the microbial population reached the detection limit within 0.5 h regardless of the ClO2 solution concentration. Beans exposed to gas for 10 h at 25 °C were stored for 14 days under conditions of 43, 75, or 100% RH and 4, 12, or 25 °C. At 4 °C, visible mold growth was not established regardless of RH. After 12 days, mold was observed only at 25 °C. At 100% RH, beans stored under the same conditions without ClO2 gas treatment showed mold formation at 13 and 4 days at 12 and 25 °C, respectively.


Assuntos
Aspergillus flavus/efeitos dos fármacos , Compostos Clorados/farmacologia , Cloro/farmacologia , Coffea/microbiologia , Conservação de Alimentos/métodos , Óxidos/farmacologia , Aspergillus flavus/crescimento & desenvolvimento , Compostos Clorados/química , Contagem de Colônia Microbiana , Óxidos/química , Sementes/microbiologia
6.
Food Microbiol ; 86: 103346, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31703876

RESUMO

This work aimed to study the effect of the combination of Sodium hypochlorite, the most used disinfectant by the vegetable industry, with a natural antimicrobial, benzyl-isothiocyanate (BITC), considering cutting surface and contact time, on the reduction of Salmonella in fresh-cut produce in washing operations under typical industrial conditions. Overall, the combinations of disinfectant and process parameters resulted in a mean reduction of Salmonella of 2.5 log CFU/g. According to statistical analysis, free chlorine and BITC concentrations, contact time and cut size exerted a significant effect on the Salmonella reduction (p ≤ 0.05). The optimum combination of process parameter values yielding the highest Salmonella reduction was a lettuce cut size of 15 cm2 washed for 110 s in industrial water containing 160 mg/L free chlorine and 40 mg/L BITC. A predictive model was also derived, which, as illustrated, could be applied to optimize industrial disinfection and develop probabilistic Exposure Assessments considering the effect of washing process parameters on the levels of Salmonella contamination in leafy green products. The present study demonstrated the efficacy of chlorine to reduce Salmonella populations in fresh-cut lettuce while highlighting the importance of controlling the washing process parameters, such as, contact time, cut size and concentration of the disinfectant to increase disinfectant efficacy and improve food safety.


Assuntos
Cloro/farmacologia , Desinfecção/métodos , Manipulação de Alimentos/métodos , Isotiocianatos/farmacologia , Alface/microbiologia , Salmonella/efeitos dos fármacos , Desinfetantes/farmacologia , Contaminação de Alimentos/análise , Microbiologia de Alimentos , Inocuidade dos Alimentos , Alface/crescimento & desenvolvimento , Salmonella/crescimento & desenvolvimento , Hipoclorito de Sódio/farmacologia , Fatores de Tempo , Verduras/crescimento & desenvolvimento , Verduras/microbiologia
7.
Chemosphere ; 239: 124714, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31499309

RESUMO

Enhanced mineralization of phenol in brines with high chloride content was investigated by employing an electrochemical advanced oxidation treatment that couples anodic oxidation, electrochlorination and electro-Fenton in a single process. Experimental work was carried out in a pilot scale unit with an undivided plate-and-frame cell equipped with a boron-doped diamond anode and a carbon-PTFE gas diffusion electrode as cathode, in batch recirculation mode. The effects of operating conditions on phenol degradation, including current density, air flow rate, water feed flow rate, Fe2+ dosage and pH as well as of the water matrix, were evaluated. Applied current exhibited the greatest effect on phenol degradation/mineralization efficiency. Complete degradation of phenol (of initial concentration 50 mg L-1) was achieved under the near-optimum operating conditions (40 mA cm-2, pH 7, 0.4 m3 h-1 water circulation rate) within 30 min. Both air flow rate and Fe2+ dosage did not show a measurable impact on phenol removal. However, increasing the chloride content of water significantly improved the efficiency of treatment due to the enhanced indirect oxidation by the electrogenerated chlorine. Several trihalomethane intermediates (chloroform, bromodichloromethane) and chlorinated/brominated phenol byproducts forming during treatment, were eliminated after 60 min of processing time.


Assuntos
Técnicas Eletroquímicas/métodos , Fenol/isolamento & purificação , Salinidade , Poluentes Químicos da Água , Cloro/farmacologia , Eletrodos , Peróxido de Hidrogênio/química , Oxirredução , Projetos Piloto , Águas Salinas , Poluentes Químicos da Água/isolamento & purificação
8.
Food Microbiol ; 85: 103282, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31500713

RESUMO

Two biopreservation approaches for fresh lettuce, rocket salad, parsley and spinach were studied. The potential of Pediococcus pentosaceus DT016, as a protective culture, to suppress Listeria monocytogenes in vegetables during storage was evaluated. The pathogen numbers in the vegetables inoculated with P. pentosaceus DT016 were significantly (p < 0.01) lower throughout the storage period and, at the last storage day, a minimum difference of 1.4 log CFU/g was reported when compared with the vegetables without the protective culture. Moreover, by using two levels of L. monocytogenes (about 6 and 4 log CFU/g), it was observed that the antagonist effect of P. pentosaceus was higher for the lower pathogen numbers. The second approach evaluated a pediocin DT016 solution to inactivate and control L. monocytogenes proliferation. The pathogen load was studied after washing with: water, chlorine and the pediocin solution and along storage at 4  °C. Comparing the various washing solutions, the vegetables washed with pediocin presented significantly (p < 0.01) lower pathogen numbers throughout storage, by a minimum of 3.2 and 2.7 log CFU/g, than in vegetables washed with water and chlorine, respectively. The proposed methodologies are promising alternatives to maintain the safety of fresh vegetables during extended storage at refrigeration temperature.


Assuntos
Antibiose , Microbiologia de Alimentos/métodos , Conservação de Alimentos/métodos , Listeria monocytogenes/fisiologia , Verduras/microbiologia , Carga Bacteriana , Cloro/farmacologia , Temperatura Baixa , Qualidade de Produtos para o Consumidor , Manipulação de Alimentos/métodos , Alface/microbiologia , Listeria monocytogenes/efeitos dos fármacos , Listeria monocytogenes/crescimento & desenvolvimento , Pediocinas/farmacologia , Pediococcus pentosaceus/fisiologia , Petroselinum/microbiologia , Refrigeração , Spinacia oleracea/microbiologia , Água
9.
Chemosphere ; 235: 1172-1179, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31561308

RESUMO

Rice (Oryza sativa L.) was cultivated in a Cd-contaminated soils with rice straw biochar (BC) and water-washed rice straw biochar (W-BC) were applied to investigate the underlying mechanisms and possible reasons for biochar's weakening effects on the immobilization of Cd in soil-rice system. The results indicated that W-BC reduced the Cd concentration in pore water as well as in the roots and shoots of rice by 26.24%, 53.23% and 62.47% respectively. On the contrary, there was an increase in Cd contents by 50.27% in pore water, 2.32% in the roots, and 12.80% in the shoots of rice under BC treatment. Furthermore, Cd content in rice shoot was significantly and positively correlated with Cl- addition to the soil (P < 0.01). This phenomenon could be attributed to several combined effects: (1) the increase of Cl- in the soil decreased the soil pH, enhanced the dissolved organic carbon in soil pore water and increased the complexes of Cd2+ and Cl-, resulting in the release of Cd from solid phase into solution phase, (2) the chloride in the soil increased the uptake of CdCl+ instead of Cd2+ by the roots, thereby causing an increase of Cd in rice tissues. These results demonstrate for the first time that biochar with high chloride content could weaken its immobilization effects on soil Cd and even enhance Cd uptake by rice.


Assuntos
Cádmio/farmacocinética , Carvão Vegetal/farmacologia , Cloro/farmacologia , Oryza/metabolismo , Solo/química , Carvão Vegetal/química , Poluição Ambiental , Poluentes do Solo/análise , Distribuição Tecidual
10.
Food Microbiol ; 84: 103226, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31421764

RESUMO

Atmospheric cold plasma (ACP) is an effective method for microbiological decontamination. This study evaluated an alternative water-based decontamination approach for inactivation of bacterial population from fresh produce and in the wash water generated from fresh produce washing. The study characterised ACP inactivation of attached Listeria innocua and Pseudomonas fluorescens inoculated on lettuce in comparison to chlorine treatment. P. fluorescens was sensitive to ACP treatment and was reduced below detection limit within 3 min of treatment. L. innocua population was reduced by ∼2.4 Log10 CFU/g after 5 min of treatment; showing similar inactivation efficacy to chlorine treatment. The microbial load in wash water was continuously decreased and was below detection limits after 10 min of ACP treatment. Micro-bubbling along with agitation assisted the bacterial detachment and distribution of reactive species, thus increasing bacterial inactivation efficacy from fresh produce and wash water. A shift in pH of plasma functionalised water was observed along with high concentration of nitrate and ozone with a relative amount of nitrites which increased with plasma exposure time. Further, L. innocua treated at different independent pH conditions showed minimal or no effect of pH on ACP bacterial inactivation efficacy. Aqueous ACP treatment poses a promising alternative for decontamination of fresh produce and the associated wash-waters which could be applied in the food industry to replace continuous chlorine dosing of process waters.


Assuntos
Cloro/farmacologia , Desinfetantes/farmacologia , Microbiologia de Alimentos/métodos , Alface/microbiologia , Gases em Plasma , Aderência Bacteriana/efeitos dos fármacos , Contagem de Colônia Microbiana , Descontaminação/métodos , Contaminação de Alimentos/análise , Manipulação de Alimentos , Alface/efeitos dos fármacos , Listeria monocytogenes/efeitos dos fármacos , Pseudomonas fluorescens/efeitos dos fármacos , Água/análise
11.
mSphere ; 4(4)2019 07 03.
Artigo em Inglês | MEDLINE | ID: mdl-31270167

RESUMO

Infections by nontuberculous mycobacteria (NTM) are primarily acquired from environmental sources, including exposure to municipally treated drinking water. Higher levels of NTM have been reported in drinking water disinfected with monochloramine than in that disinfected with chlorine. However, the relationships between water treatment practices and NTM infection are unclear. The objective of this study was to examine a possible relationship between residual disinfectant used for municipal drinking water treatment (monochloramine or chlorine) and NTM infection. We retrospectively reviewed NTM diagnostic tests performed at a single health care center during a 15-year period. Information on municipal water treatment practices, including disinfectant and primary source water type, was obtained for 140 cities. Based on a logistic regression model, municipal drinking water disinfection with monochloramine compared to chlorine was not associated with NTM infection (P = 0.24). An additional model variable examining water source showed that the likelihood of having an NTM infection was 1.46 times higher for patients residing in cities with drinking water derived from surface water than for those residing in cities with drinking water derived from groundwater (odds ratio [OR], 1.46; 95% confidence interval [CI], 1.03 to 2.08; P = 0.04). In an inverse propensity score weighted regression, monochloramine disinfection was also not associated with NTM infection. A moderate effect on NTM infection rates was observed in the weighted regression for municipal drinking water derived from surface water, though the results were not statistically significant (OR, 1.24; 95% CI, 0.92 to 1.69; P = 0.17).IMPORTANCE Infections by nontuberculous mycobacteria (NTM) result in significant morbidity, mortality, and health care costs. NTM are primarily acquired from environmental sources, including exposure to municipally treated drinking water. Higher levels of NTM have been reported in drinking water disinfected with monochloramine than in drinking water disinfected with chlorine. Our results suggest that municipal drinking water disinfection with monochloramine compared to chlorine is not associated with higher risk of NTM infection. This is important given that regulations that limit drinking water concentrations of disinfection by-products, which are formed primarily when chlorine disinfection is used, incentivize drinking water utilities to change from chlorine disinfection to monochloramine disinfection.


Assuntos
Cloraminas/farmacologia , Desinfetantes/farmacologia , Água Potável/microbiologia , Infecções por Mycobacterium não Tuberculosas/etiologia , Micobactérias não Tuberculosas/efeitos dos fármacos , Adulto , Idoso , Cloro/farmacologia , Desinfecção/métodos , Feminino , Humanos , Masculino , Michigan/epidemiologia , Pessoa de Meia-Idade , Infecções por Mycobacterium não Tuberculosas/epidemiologia , Estudos Retrospectivos , Purificação da Água/métodos , Purificação da Água/normas
12.
Zebrafish ; 16(5): 460-468, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31216245

RESUMO

Pseudocapillaria tomentosa is an important pathogen in zebrafish facilities. We investigated heat, ultraviolet (UV) light, chlorine, iodine, and dessciation for killing the parasite's eggs. Eggs released with feces larvate in about 5-10 days, and treatments were evaluated by exposing fresh eggs and subsequently comparing larvation to untreated eggs as an indication of survival. Collectively, untreated eggs in all trials showed high levels of survival. Eggs were exposed to elevated temperatures (40°C, 45°C and 50°C) for 1, 8, or 24 h, which resulted in substantial reduction in viability of eggs. UV radiation was effective, with no larvation at 50-300 mWs/cm2 and <2% at 20 mWs/cm2. Three chlorine products (JT Baker, Clorox®, and Bi-Mart) were tested at 25, 50, 100, 500, and 3,000 ppm (pH 7.0-7.3) with 10 min exposure. All were effective at 500 or 1,000 ppm. There was variability between three products and trials at lower concentrations, but overall chlorine was not very effective at 25-100 ppm except for Bi-Mart brand at 100 ppm. Povidone-iodine was not effective at 25 or 50 ppm for 10 min, but was effective at 200 ppm for 1 h. Desiccation was effective, and no eggs larvated after 2 h drying.


Assuntos
Cloro/farmacologia , Iodo/farmacologia , Nematoides/efeitos dos fármacos , Nematoides/efeitos da radiação , Óvulo/efeitos dos fármacos , Óvulo/efeitos da radiação , Animais , Sobrevivência Celular/efeitos dos fármacos , Desinfetantes/farmacologia , Temperatura Alta , Raios Ultravioleta , Água , Peixe-Zebra
13.
PLoS One ; 14(5): e0216040, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31083664

RESUMO

Wastewater from different sources is contaminated by protozoan parasites including Cryptosporidium and Giardia. Many protozoan parasites are becoming resistant to chemical treatment. The challenge of finding alternatives is presented to researchers by exploring other methods of eliminating protozoan parasites from wastewater. The aim of this study was to assess the speciation and the viability of Cryptosporidium and Giardia in environmental samples with the specific objective of evaluating if effluent chlorination and UV affect the viability. Different doses of chlorine with different exposure times were experimented with both distilled water and waste water spiked with (oo)cysts derived from environmental samples. UV irradiation at different doses was also experimented using the same spiked samples. Two methods of quantification and detection, namely, microscopy and flow cytometry, were used in the experiment. Two vital dyes, Syto-9+PI and DAPI+PI, were the used for staining the collected wastewater samples. It was found that the (oo)cysts responded to chlorination and UV treatments with Giardia responding better than Cryptosporidium. Giardia responded very well to UV irradiations with almost 0 percent remaining viable after a low dose of UV. Cryptosporidium was found to be resistant to chlorination even at high doses but responded well to high UV doses. DAPI+PI dye gave a lower mean percentage viability values than Syto-9+PI. Flow cytometry gave higher mean percentage than microscopy from the results. It is concluded that UV is a promising alternative to Chlorine in removing Cryptosporidium and Giardia from waste water. Appropriate treatment method for wastewater is necessary to minimize water resources pollution when wastewater is released into water systems.


Assuntos
Cloro/farmacologia , Cryptosporidium/efeitos dos fármacos , Giardia/efeitos dos fármacos , Águas Residuárias/parasitologia , Água/parasitologia , Corantes/farmacologia , Criptosporidiose/prevenção & controle , Giardíase/prevenção & controle , Oocistos/efeitos dos fármacos , Raios Ultravioleta , Poluição da Água
14.
Food Microbiol ; 82: 371-377, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31027796

RESUMO

The aim of this study was to determine the microbial quality of mung bean sprouts produced in Italy. The presence of pathogenic microorganisms (Shiga toxin-producing Escherichia coli (STEC), Salmonella spp. and Listeria monocytogenes), total coliforms, and total viable counts (TVCs) were determined. The study covered five years of sprout production. The results demonstrated that no pathogenic microorganisms were present, and the microbial load was less than 6 log CFU/g. The mung bean sprouts currently produced in Italy were found to be acceptable for consumption. An additional aim was to determine the fate of different strains of STEC, L. monocytogenes and Salmonella spp. by intentionally inoculating mung bean seeds during sprouting and by using chlorinated water to reduce the concentration of these strains in seeds and sprouts. The data demonstrated that these strains increased over 5-6 log CFU/g within 3 days from inocula. The chlorinated washing solution reduced the concentration of the investigated strains in seeds and sprouts by approximately 3 and 7 log CFU/g, respectively. However, it was not possible to completely eliminate the pathogens from either the mung bean seeds or sprouts. Despite these encouraging results, the producer's attention to hygienic quality should not be reduced when attempting to produce safe-to-consume mung bean sprouts.


Assuntos
Bactérias/isolamento & purificação , Microbiologia de Alimentos , Plântula/microbiologia , Vigna , Bactérias/classificação , Bactérias/efeitos dos fármacos , Bactérias/crescimento & desenvolvimento , Cloro/farmacologia , Contagem de Colônia Microbiana , Desinfecção , Itália , Sementes/microbiologia
15.
ACS Appl Mater Interfaces ; 11(19): 17204-17214, 2019 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-30997985

RESUMO

Biofilms can persist in food-processing environments because of their relatively higher tolerance and resistance to antimicrobials including sanitizers. In this study, a novel biobased sanitizer composition was developed to effectively target biofilms and deliver chlorine-based sanitizers to inactivate bacterial and fungal biofilms. The biobased composition was developed by encapsulating a chlorine-binding polymer in a biobased yeast cell wall particle (YCWP) microcarrier. This study demonstrates the high affinity of biobased compositions to bind target bacterial and fungal cells and inactivate 5 logs of model pathogenic bacteria and fungi in wash water without and with high organic load (chemical oxygen demand = 2000 mg/L) in 30 s and 5 min, respectively. For the sanitation of biofilms, this biobased sanitizer can inactivate 7 logs of pathogenic bacteria and 3 logs of fungi after 1 h treatment, whereas the 1 h treatment using conventional chlorine-based sanitizer can only achieve 2-3 log reduction for bacterial biofilms and 1-2 log reduction for fungal biofilms, respectively. The enhanced antimicrobial activity can be attributed to three factors: (a) localized high concentration of chlorine bound on the YCWPs; (b) high affinity of YCWPs to bind diverse microbes; and (c) improved stability in an organic-rich aqueous environment. In summary, these unique attributes of biobased carriers will significantly enhance the sanitation efficacy of biofilms, reduce the persistence and transmission of antimicrobial resistant microbes, limit the use of antimicrobial chemicals, and improve the cost-effectiveness of sanitizers.


Assuntos
Infecções Bacterianas/microbiologia , Biofilmes/efeitos dos fármacos , Desinfetantes/farmacologia , Fungos/efeitos dos fármacos , Infecções Bacterianas/prevenção & controle , Biofilmes/crescimento & desenvolvimento , Cloro/farmacologia , Contagem de Colônia Microbiana , Contaminação de Alimentos , Manipulação de Alimentos , Fungos/patogenicidade , Humanos , Listeria monocytogenes/efeitos dos fármacos , Listeria monocytogenes/patogenicidade , Saneamento
16.
Food Environ Virol ; 11(3): 205-213, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-30903597

RESUMO

This study investigated the synergistic effects of combined chlorine (200, 500, 700, and 1000 ppm) and vitamin B1 (1000, 2000, and 3000 ppm) on the murine norovirus-1 (MNV-1), a human norovirus (NoV) surrogate, on oyster surface. Vitamin B1 slightly reduced MNV-1 (0.04-0.3 log-reduction), whereas chlorine significantly reduced MNV-1 (0.4-1.0 log-reduction). The combined chlorine and vitamin B1 resulted in a 0.52-1.97 log-reduction of MNV-1. The synergistic reduction in the MNV titer was not dependent on the concentrations of chlorine and vitamin B1, and it ranged between 0.08 and 1.03 log10 PFU/mL. The largest synergistic reduction observed was for the combined 700 ppm chlorine and 1000 ppm vitamin B1. The pH and mechanical texture of the oysters were not significantly changed by the combined 0-1000 ppm chlorine and 3000 ppm vitamin B1. The overall sensory acceptability were significantly (P < 0.05) reduced in oysters treated with 1000 ppm chlorine and 3000 ppm vitamin B1 than in those treated with 0-700 ppm chlorine and 3000 ppm vitamin B1. This study suggests that the combined 700 ppm chlorine and 3000 ppm vitamin B1 could potentially be used to reduce NoV on oyster surface without causing concomitant changes in the mechanical texture, pH, or sensory qualities of the oysters.


Assuntos
Cloro/farmacologia , Crassostrea/virologia , Desinfetantes/farmacologia , Contaminação de Alimentos/prevenção & controle , Conservação de Alimentos/métodos , Norovirus/efeitos dos fármacos , Frutos do Mar/virologia , Tiamina/farmacologia , Animais , Sinergismo Farmacológico , Humanos , Norovirus/genética , Norovirus/crescimento & desenvolvimento , Paladar
17.
Food Res Int ; 116: 157-167, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30716932

RESUMO

Bacillus cereus can exist as vegetative cells, spores, and biofilms in food-processing environment, posing a big challenge for the food industry. The objective of this study was to examine the inactivation efficacy of slightly acidic electrolyzed water (SAEW) in combination with benzalkonium chloride (BAC) and mild heat treatment (50 and 60 °C) on B. cereus strains (ATCC 10987 and ATCC 14579). The inactivation efficacy of SAEW was found to be largely dependent on available chlorine concentration (ACC) level and exposure time as well as B. cereus strains and growth conditions. SAEW with ACC of 40 ppm reduced ATCC 10987 and ATCC 14579 vegetative cells to the non-detection limit within 30 s. and 1 min, respectively. Combination treatment with SAEW+60 °C for 10 min resulted in reductions of ATCC 10987 spores, ATCC 14579 spores, and ATCC 10987 biofilms at 0.76 logCFU/ml, 0.59 logCFU/ml, and 1.28 logCFU/cm2, respectively. While, treatment with SAEW+BAC + 60 °C for 10 min resulted in reductions of ATCC 10987 spores, ATCC 14579 spores, and ATCC 10987 biofilms at 1.91 logCFU/ml, 1.98 logCFU/ml, and 2.62 logCFU/cm2, respectively. The inactivation kinetics under different ACC of SAEW and in combination with BAC and mild treatment were determined by Weibull model. The calculated adjusted correlation coefficients (R2adj) and root mean sum of squared error (RMSE) values for all curves were found to be ranges from 0.95-0.99 and 0.04-0.23, respectively, indicating that the Weibull model precisely predicted the inactivation kinetics of B. cereus during SAEW in combination with BAC and mild heat treatments. These results suggest that SAEW in combination with BAC and mild heat may be used as an effective cleaning strategy against B. cereus in the food contact surfaces.


Assuntos
Bacillus cereus/efeitos dos fármacos , Compostos de Benzalcônio/química , Biofilmes/efeitos dos fármacos , Eletrólise , Temperatura Alta , Água/química , Ácidos , Bacillus cereus/crescimento & desenvolvimento , Bacillus cereus/fisiologia , Compostos de Benzalcônio/farmacologia , Cloro/farmacologia , Contagem de Colônia Microbiana , Desinfetantes , Desinfecção/métodos , Manipulação de Alimentos , Indústria Alimentícia , Concentração de Íons de Hidrogênio , Cinética , Viabilidade Microbiana/efeitos dos fármacos , Esporos Bacterianos/efeitos dos fármacos , Aço Inoxidável
18.
Food Res Int ; 116: 778-785, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30717007

RESUMO

In this study, we evaluated the performance of a large-scale decontamination system based on a washing process in combination with pulsed light (PL) exposure and H2O2/chlorine. In order to identify optimum processing condition, we first evaluated the effect of single and combined PL treatments on the inactivation of Salmonella on grape tomatoes using a small sample size of 50 g. Two inoculation methods, spot and dip, were used to simulate different contamination scenarios and two wash water quality, clear tap water and turbid tap water with extremely high levels of organic load and soil, were used to represent clean and very dirty wash water. In general, the combined PL-Chlorine and PL-H2O2 treatments were more or as effective as chlorine washing in killing Salmonella on grape tomatoes and were able to keep residual Salmonella in wash water below the detection limit of 2 CFU/mL. The PL alone and combined PL-H2O2 treatments were chosen and further tested for their decontamination efficacy under turbid wash water condition using large sample sizes, 300, 1000 and 2000 g. Sample size did not negatively affect the single and combined PL treatments on the inactivation of Salmonella on grape tomatoes. The combined PL-H2O2 treatment in general showed better inactivation effect of Salmonella on tomatoes than the PL alone treatment. Additionally, the combined PL-H2O2 treatment reduced Salmonella in turbid wash water below the detection limit of 2 CFU/mL in the majority of cases. In conclusion, the combined PL-H2O2 treatment could potentially be used as an environmentally friendly alternative to chlorine washing for tomato decontamination and cleaning.


Assuntos
Cloro/farmacologia , Descontaminação/métodos , Desinfetantes/farmacologia , Manipulação de Alimentos/métodos , Microbiologia de Alimentos , Frutas/microbiologia , Peróxido de Hidrogênio/farmacologia , Luz , Lycopersicon esculentum/microbiologia , Salmonella enterica , Água , Intoxicação Alimentar por Salmonella/microbiologia , Intoxicação Alimentar por Salmonella/prevenção & controle , Salmonella enterica/efeitos dos fármacos , Salmonella enterica/crescimento & desenvolvimento , Salmonella enterica/efeitos da radiação , Saneamento
19.
Artigo em Inglês | MEDLINE | ID: mdl-30686111

RESUMO

Contamination events and biofilms can decrease the amount of free chlorine available in drinking water systems. The efficacy of 100 µg/L silver and 400 µg/L copper, individually and combined, were evaluated as secondary, longer-lasting residual disinfectants against Salmonella enterica serovar Typhimurium, Escherichia coli, Listeria monocytogenes, and Mycobacterium fortuitum at 24 °C and 4 °C. A >5.0-log10 reduction was observed in E. coli and L. monocytogenes after three hours and S. Typhimurium following seven hours of exposure to silver. M. fortuitum was the most resistant species to silver (1.11-log10 after seven hours). Copper did not significantly reduce S. Typhimurium and E. coli at 24 °C; ≥2.80-log10 reductions were observed in the Gram-positive L. monocytogenes and M. fortuitum. Longer exposure times were required at 4 °C to achieve significant reductions in all species. A synergistic effect was observed when silver and copper were combined at 24 °C. In addition, silver was not affected by the presence of organic matter at concentrations that completely inhibited 0.2 mg/L chlorine. The results of this study suggest that combinations of silver and copper show promise as secondary residual disinfectants. They may also be used in conjunction with low chlorine levels or other disinfectants to provide additional, long-lasting residuals in distribution systems.


Assuntos
Cobre/farmacologia , Desinfetantes/farmacologia , Água Potável/análise , Contaminação de Alimentos/análise , Prata/farmacologia , Antibacterianos/farmacologia , Biofilmes/efeitos dos fármacos , Cloro/farmacologia , Contagem de Colônia Microbiana , Escherichia coli/efeitos dos fármacos , Escherichia coli/isolamento & purificação , Microbiologia de Alimentos , Listeria monocytogenes/efeitos dos fármacos , Listeria monocytogenes/isolamento & purificação , Mycobacterium fortuitum/efeitos dos fármacos , Mycobacterium fortuitum/isolamento & purificação , Salmonella typhimurium/efeitos dos fármacos , Salmonella typhimurium/isolamento & purificação
20.
BMC Plant Biol ; 19(1): 18, 2019 Jan 09.
Artigo em Inglês | MEDLINE | ID: mdl-30626334

RESUMO

BACKGROUND: Algal biofuel has a potential for reducing dependence on fossil fuel while curbing CO2 emissions. Despite these potential benefits, a scalable, sustainable, and commercially viable system has not yet been developed. One of the key barriers is the lack of viable methods for disrupting algal biomass for the separation and extraction of bioproducts. This study experimentally investigated the feasibility of using chlorine as an agent for algal biomass disruption. RESULTS: Chlorine was an effective agent for disrupting algal cell, as demonstrated with cell viability and SEM analyses. For disruption studies conducted using algal suspension at 0.02% solids (0.2 g/L), 90% of the algal cells were disrupted in 6 min at 10 mg/L chlorine dose. Moreover, the results demonstrated that the estimated specific energy requirement, specific cost, and GWP for chlorine were lower than those of the existing methods. The energy requirement for chlorine was 3.73 MJ/ kg of dry algae disrupted, while the requirements for the existing methods ranged from 33 to 860 MJ/ kg of dry algae. The GWP for chlorine was 0.3 kg CO2-eq./kg dry algae, while for the existing methods it varied from 5.9 to 369.8 CO2-eq./kg dry algae. Despite these advantages, it was observed that residual chlorine reacted with and mineralized the cell contents, which is undesirable. CONCLUSIONS: Future research efforts must be focused on eliminating or reducing the reaction of residual chlorine with cell contents. If this challenge is addressed, chlorine has a potential to be developed into an energy-efficient, cost-effective, and sustainable method for algal biomass disruption. This will in turn will overcome one of the technical bottlenecks, and ultimately increase algal biofuel production and reduce dependence on fossil fuel and curb CO2 emissions.


Assuntos
Cloro/farmacologia , Microalgas/metabolismo , Biocombustíveis , Biomassa , Microalgas/efeitos dos fármacos
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