| Animals(including humans)and microorganisms are interdependent and in a state of long-term micro-ecological equilibrium.The imbalance of micro-ecology due to host infection with pathogenic microorganisms and subsequent health problems in animals is of great concern.In addition to pathogenic bacteria that resided on the animal’s epidermis for long periods of time,the diseases caused by foodborne pathogenic bacteria would also threaten animal life and health.In recent years,ozone has been used to treat more than 50 skin diseases caused by pathogenic bacterial infections,but the feasibility of using trace ozone as a substitute for common toiletries has scarcely been reported.The inactivation effects and mechanisms of UV and chlorine on intestinal and foodborne pathogenic bacteria in animals(e.g.,aquatic animals)is lacking in previous studies.Therefore,this paper assesses the feasibility of replacing common toiletries with trace ozone to address the issue of skin health risks caused by epidermal pathogenic bacteria in animals,and investigate the inactivation effects and mechanisms of UV and chlorine on the problem of common inflammatory enteritis diseases caused by intestinal and foodborne pathogenic bacteria in animals.The main conclusions are as follows:(1)Feasibility analysis of replacing common toiletries with trace ozone.The results revealed that at a 10:1 ratio of ozonated water to bacterial suspension,the inactivation ratios of Malassezia,Candida albicans(C.albicans),and Staphylococcus epidermidis(S.epidermidis)reached99.63%,83.47%,and 100%,respectively.The scanning electron microscope(SEM)observation and washing ratio analysis showed that ozone could remove sebum and carbon black from simulated animal hair and epidermis,and the cleaning performance of an ozone solution(0.4mg/L)for simulated animal skin contaminated with carbon black and sebum could reach 95.89%and 95.63%,respectively,with 5 min of washing.The average scores were 0.40 and 0.37 after 5 min and 10 min of ozone treatments,respectively,further indicating that trace ozone does not significantly damage simulated human hair.Meanwhile,the quantification of organic pollutants in common toiletries revealed that the total emissions of COD,TP and TN would be reduced by 1.29×10~6,3.55×10~3,and3.63×10~3 mg/(household·year),respectively,by using trace ozone instead of common toiletries.Therefore,replacing common toiletries with trace ozone can reduce carbon emissions.(2)Inactivation effects and mechanisms of UV and chlorine disinfection on enteric and foodborne pathogenic bacteria.The results showed that the inactivation efficiencies for Escherichia coli(E.coli),Vibrio vulnificus(V.vulnificus),and Enterococcus faecalis(E.faecalis)were 4.44,4.90,and 7.39 logs at the UV irradiation dose of 369 m J/cm~2,respectively.Therefore,the susceptibility of the three pathogenic bacteria to UV irradiation followed the sequence of E.faecalis>V.vulnificus>E.coli.The metabolic activities of the pathogenic bacteria were detected by Biolog-ECO plate method,and it was found that the metabolic activities of E.coli(UV:AWCD=1.87-2.10;CK:AWCD=1.71-1.99),V.vulnificus(UV:AWCD=1.54-1.86;CK:AWCD=1.69-2.00),and E.faecalis(UV:AWCD=0.40-0.49;CK:AWCD=0.59-0.72)were not significantly different after UV disinfection compared to the control group,indicating that the pathogenic bacteria still maintained high metabolic activity after UV disinfection.Meanwhile,when the three pathogenic bacteria were treated with chlorine,the metabolic activities of E.coli(Cl:AWCD=0.32-0.45),V.vulnificus(Cl:AWCD=0.26-0.27),and E.faecalis(Cl:AWCD=0.22-0.24)were found to be significantly reduced compared to the control group,indicating that chlorine disinfection was effective in inhibiting metabolic activity of the pathogenic bacteria.In addition,a comparative analysis of the changes in extracellular protein and total nitrogen concentrations of pathogenic bacteria during UV and chlorine inactivation was conducted.The results showed that UV treatment had no significant effect on the changes in extracellular protein concentrations of the three pathogenic bacteria(P=0.167-0.7),while the concentrations of extracellular protein and total nitrogen increased significantly after chlorine treatment(P=0-0.002).The results of SEM further showed that UV treatment resulted in contraction of the cellular morphology,while chlorine treatment resulted in severe rupture or even mutilation of the bacterial morphology,which led to leakage of intracellular material.Therefore,although UV treatment could reduce the culturable number of pathogenic bacteria,the cell integrity was still maintained and there was no significant change in metabolic activity compared with the untreated group,while chlorine treatment could not only reduce the culturability of bacteria,but also destroy the cell morphological structure and even inhibit the metabolic activity of bacteria.The above findings suggest that trace ozone can replace common toiletries to reduce chemical contamination and improve the ecological environment;secondly,there are serious microbiological safety risks when UV is used to disinfect intestinal and foodborne pathogens,while chlorine disinfection can mitigate the safety risks caused by pathogenic microorganisms. |
