Oxidative Disinfectants Activate Different Responses in Vibrio parahaemolyticus

2019 ◽  
Vol 82 (11) ◽  
pp. 1890-1895
Author(s):  
KAI-MING TSO ◽  
BIN NI ◽  
HIN-CHUNG WONG
Keyword(s):  
Hydrogen Peroxide ◽  
Mutant Strain ◽  
Chlorine Dioxide ◽  
Peracetic Acid ◽  
Vibrio Parahaemolyticus ◽  
Reverse Transcription Pcr ◽  
Rpos Mutant ◽  
Global Concern ◽  
Regulator Genes

ABSTRACT Vibrio parahaemolyticus is a prevalent seafoodborne enteropathogen that has become a global concern since the spread of its pandemic strain in 1996. This study investigates the responses of this pathogen to the oxidative disinfectants hydrogen peroxide, chlorine dioxide, and peracetic acid. Expression of the regulator genes oxyR and rpoS, determined by reverse transcription PCR, in V. parahaemolyticus wild-type, oxyR mutant, and rpoS mutant strains exhibited similar patterns in response to the tested oxidative disinfectants. The transcription of the rpoS gene was markedly enhanced in the oxyR mutant strain in the exponential phase. The expression of catalase KatE1 was tracked by using a LacZ fusion reporter in these strains. The experimental results revealed that KatE1 was a significant scavenger of hydrogen peroxide and peracetic acid in V. parahaemolyticus, and RpoS may partially compensate for the regulatory role of OxyR in the oxyR mutant strain. In contrast to its responses to hydrogen peroxide and paracetic acid, KatE1 was not the primary scavenger of chlorine dioxide in these V. parahaemolyticus strains. This study shows that these disinfectants activated a basic oxidative response in this pathogen with different features.

Role of oxidants and disinfectants on the removal, masking and generation of tastes and odours

2004 ◽  
Vol 49 (9) ◽  
pp. 297-306 ◽  
Author(s):  
A. Bruchet ◽  
J.P. Duguet
Keyword(s):  
Hydrogen Peroxide ◽  
Case Studies ◽  
Potassium Permanganate ◽  
Chlorine Dioxide ◽  
Masking Effect ◽  
Negative Effects ◽  
Anthropogenic Pollutants ◽  
Drinking Waters ◽  
By Products

This paper summarises the positive and negative effects of the most commonly used oxidants and disinfectants: chlorine, chloramines, chlorine dioxide, potassium permanganate ozone, and advanced oxidation with ozone/hydrogen peroxide on tastes and odours present in natural and drinking waters. The case studies reported illustrate the generation of odorous by-products such as chlorophenols, iodoforms, aldehydes, the masking effect between earthy-musty and chlorinous odours, and the removal of odorous algal metabolites or anthropogenic pollutants by ozone alone or by ozone coupled with hydrogen peroxide.

scholarly journals Exploring the potential synergistic effects of chemical disinfectants and UV on the inactivation of free-living bacteria and treatment of biofilms in a pilot-scale system

2011 ◽  
Vol 64 (6) ◽  
pp. 1247-1253 ◽  
Author(s):  
E. Vankerckhoven ◽  
B. Verbessem ◽  
S. Crauwels ◽  
P. Declerck ◽  
K. Muylaert ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Sodium Hypochlorite ◽  
Chlorine Dioxide ◽  
Peracetic Acid ◽  
Synergistic Effects ◽  
Pilot Scale ◽  
Bacterial Suspension ◽  
Additive Effects ◽  
Free Living ◽  
Living Bacteria

The main objective of this study is to explore possible synergistic or additive effects of combinations of chemical disinfectants (sodium hypochlorite, peracetic acid, hydrogen peroxide, chlorine dioxide) and UV in their efficacy in inactivating free-living bacteria and removing biofilms. In contrast to most studies, this study examines disinfection of municipal water in a pilot-scale system using a mixed bacterial suspension, which enables a better simulation of the conditions encountered in actual industrial environments. It was shown that the combination of either hypochlorite, hydrogen peroxide, peracetic acid, or chlorine dioxide with UV yielded additive effects on the inactivation of free-living bacteria. Actual synergy was observed for the combination of UV and 5 ppm hydrogen peroxide. Regarding biofilm treatment, additive effects were observed using the combination of hydrogen peroxide and UV. The promising results obtained in this study indicate that the combination of UV and chemical disinfectants can considerably reduce the amount of chemicals required for the effective disinfection and treatment of biofilms.

scholarly journals Hydrogen Peroxide and Peracetic Acid Oxidizing Potential in the Treatment of Water

2019 ◽  
Vol 70 (6) ◽  
pp. 2036-2039 ◽  
Author(s):  
Elena Madalina Popescu ◽  
Octav Pantea ◽  
Daniela Gologan ◽  
Rami Doukeh
Keyword(s):  
Hydrogen Peroxide ◽  
Chlorine Dioxide ◽  
Peracetic Acid ◽  
Carcinogenic Effect ◽  
Oxidation Efficiency ◽  
Iron Manganese ◽  
Ammonium Compounds ◽  
Nitrite Content

Mixture based on peracetic acid and hydrogen peroxide is a more powerful oxidant than chlorine and chlorine dioxide. The reactivity of this oxidizing mixture with the polluting substances in the water: ammonium compounds, nitrites, iron, manganese, organic proteins is evaluated in this study. The results obtained after tasting this mixture, using various natural groundwater matrices shows an oxidation efficiency of over 90% of ammonium and nitrite content, between 40-70% of iron and 25-50% for manganese forms. The advantage of this oxidation mixture compared to thechlorine substances is that they do not form threehalomethane byproducts that have carcinogenic effect.

Role of the rpoS Gene in the Survival of Vibrio parahaemolyticus in Artificial Seawater and Fish Homogenate

2006 ◽  
Vol 69 (6) ◽  
pp. 1438-1442 ◽  
Author(s):  
PRADEEP VASUDEVAN ◽  
KUMAR VENKITANARAYANAN
Keyword(s):  
Cold Stress ◽  
Vibrio Parahaemolyticus ◽  
Storage Temperature ◽  
Wild Strain ◽  
Gene Cassette ◽  
The United States ◽  
Artificial Seawater ◽  
Rpos Gene ◽  
Rpos Mutant

Vibrio parahaemolyticus is a foodborne pathogen isolated from coastal waters of the United States and from a variety of seafood, including fish. Seawater represents a nutrient-limiting environment for V. parahaemolyticus. During its persistence in seawater, V. parahaemolyticus is exposed to a variety of environmental stresses, including hyperosmolarity, fluctuations in temperature, and cold stress. The alternate sigma factor of RNA polymerase, designated σs (RpoS), encoded by the gene rpoS has been shown to play a major role in bacterial adaptive responses to adverse environmental conditions. The present study was undertaken to investigate the role of rpoS in the survival of V. parahaemolyticus in seawater and fish. A V. parahaemolyticus rpoS mutant was constructed by the insertion of a chloramphenicol acetyltransferase gene cassette within the rpoS gene, and the wild and mutant strains were assayed for their ability to survive in artificial seawater (ASW) at 6 and 18°C and in fish homogenate at 4 and 8°C. The survival of the rpoS mutant of V. parahaemolyticus both in ASW and fish homogenate at either storage temperature was significantly (P <0.05) lower than that of the wild strain. Further, the viability of V. parahaemolyticus, especially the mutant, was significantly reduced at lower storage temperatures of ASW and fish homogenate. Results of this study indicate that rpoS potentially plays an important role in the survival of V. parahaemolyticus under conditions of cold stress and hyperosmolarity.

scholarly journals Inactivation of the Phosphatase CheZ Alters Cell-Surface Properties of Azorhizobium caulinodans ORS571 and Symbiotic Association with Sesbania rostrata

2019 ◽  
Vol 32 (11) ◽  
pp. 1547-1556 ◽  
Author(s):  
Xiaolin Liu ◽  
Zhihong Xie
Keyword(s):  
Host Plant ◽  
Mutant Strain ◽  
Root Surface ◽  
Sesbania Rostrata ◽  
Symbiotic Association ◽  
Azorhizobium Caulinodans ◽  
Reverse Transcription Pcr ◽  
Genes Encoding ◽  
Colonization Process

Azorhizobium caulinodans can form root and stem nodules with the host plant Sesbania rostrata. The role of the CheZ phosphatase in the A. caulinodans chemotaxis pathway was previously explored using the nonchemotactic cheZ mutant strain (AC601). This mutant displayed stronger attachment to the root surface, enhancing early colonization; however, this did not result in increased nodulation efficiency. In this study, we further investigated the role of CheZ in the interaction between strain ORS571 and the roots of its host plant. By tracking long-term colonization dynamic of cheZ mutant marked with LacZ, we found a decrease of colonization of the cheZ mutant during this process. Furthermore, the cheZ mutant could not spread on the root surface freely and was gradually outcompeted by the wild type in original colonization sites. Quantitative reverse-transcription PCR analyses showed that exp genes encoding exopolysaccharides synthesis, including oac3, were highly expressed in the cheZ mutant. Construction of a strain carrying a deletion of both cheZ and oac3 resulted in a mutant strain defective in the colonization process to the same extent as found with the oac3 single-mutant strain. This result suggested that the enhanced colonization of the cheZ mutant may be achieved through regulating the formation of exopolysaccharides. This shows the importance of the chemotactic proteins in the interaction between rhizobia and host plants, and expands our understanding of the symbiosis interaction between rhizobium and host plant.

scholarly journals The Global Regulator ArcA Modulates Expression of Virulence Factors in Vibrio cholerae

2003 ◽  
Vol 71 (10) ◽  
pp. 5583-5589 ◽  
Author(s):  
Nilanjan Sengupta ◽  
Kalidas Paul ◽  
Rukhsana Chowdhury
Keyword(s):  
Vibrio Cholerae ◽  
Mutant Strain ◽  
Virulence Factors ◽  
Response Regulator ◽  
Anaerobic Growth ◽  
Infant Mouse ◽  
Reverse Transcription Pcr ◽  
Concomitant Reduction ◽  
Aerobic And Anaerobic

ABSTRACT A Vibrio cholerae arcA mutant was constructed and used to examine the role of the global anaerobiosis response regulator ArcA in the expression of virulence factors in this important human pathogen. In V. cholerae, expression of the major virulence factors cholera toxin (CT) and toxin-coregulated pilus (TCP) is regulated by the transcriptional activator ToxT. toxT expression, in turn, is controlled by the transmembrane DNA binding proteins ToxR and TcpP. In the V. cholerae arcA mutant, although ToxR and TcpP were unaffected, Northern blot and reverse transcription-PCR analyses indicated that the expression of toxT was significantly decreased with concomitant reduction in the expression of CT and TCP. CT and TCP expression was completely restored in the V. cholerae arcA mutant strain by expressing a cloned toxT gene in the mutant. These results suggest that ArcA functions as a positive regulator of toxT expression under both aerobic and anaerobic conditions, although as expected, the effect was more pronounced during anaerobic growth. This was reflected in a reduction of virulence of the V. cholerae arcA mutant strain in the infant mouse cholera model.

The role of copper ions in hydrogen peroxide bleaching: Their origin, removal, and effect on pulp quality

TAPPI Journal ◽  
2012 ◽  
Vol 11 (7) ◽  
pp. 37-46 ◽  
Author(s):  
PEDRO E.G. LOUREIRO ◽  
SANDRINE DUARTE ◽  
DMITRY V. EVTUGUIN ◽  
M. GRAÇA V.S. CARVALHO
Keyword(s):  
Hydrogen Peroxide ◽  
Copper Ions ◽  
Peroxide Bleaching ◽  
Metals Removal ◽  
Peroxide Decomposition ◽  
Equipment Corrosion ◽  
And Performance ◽  
And Control ◽  
Main Effects

This study puts particular emphasis on the role of copper ions in the performance of hydrogen peroxide bleaching (P-stage). Owing to their variable levels across the bleaching line due to washing filtrates, bleaching reagents, and equipment corrosion, these ions can play a major role in hydrogen peroxide decomposition and be detrimental to polysaccharide integrity. In this study, a Cu-contaminated D0(EOP)D1 prebleached pulp was subjected to an acidic washing (A-stage) or chelation (Q-stage) before the alkaline P-stage. The objective was to understand the isolated and combined role of copper ions in peroxide bleaching performance. By applying an experimental design, it was possible to identify the main effects of the pretreatment variables on the extent of metals removal and performance of the P-stage. The acid treatment was unsuccessful in terms of complete copper removal, magnesium preservation, and control of hydrogen peroxide consumption in the following P-stage. Increasing reaction temperature and time of the acidic A-stage improved the brightness stability of the D0(EOP)D1AP bleached pulp. The optimum conditions for chelation pretreatment to maximize the brightness gains obtained in the subsequent P-stage with the lowest peroxide consumption were 0.4% diethylenetriaminepentaacetic acid (DTPA), 80ºC, and 4.5 pH.

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