THE GERM IC IDAL EFF ICACY OF POTASS IUM FERRATE ( K2FeO4)AGA INST SEVERAL F ISH2PATHOGENIC BACTERIA

It has been well documented that potassium ferrate is a strong and environmental friendly oxidant. Under thecidic conditions,the redox potential of ferrate (Ⅳ) ions is higher than that ofmolecular ozone. The product of the ferrate Ⅳ) oxidation reactions is considered to be the ferric hydroxide,which is a useful coagulant and can enhance the wateremediation performance. Additionally,others disinfectant chemicals including chlorine and ozone,which are powerfulnd successful to combat the harmful micro-organism-causing problems,but such disinfectants have been confirmed to bef health concern. So,as a healthy potential alternative,potassium ferrate has been widely used in the fields of drinkingater and wastewater treatmenti; however,there is no available report of its app lication to aquaculture. The purpose ofhis study is to investigate whether potassium ferrate can be used as an aquacultural disinfectant. Prior to this study,theoncentration of potassium ferrate was determined by spectrophotometry. The equation of concentrations of Fe2+ againstODalues was obtained: OD = 0. 005 + 1--41. 071 C2+Fe (r = 0. 9985),and then through transformation,the purity of potassi-m ferrate was -9. 75%. In this study,eight kinds of fishpathogenic bacteria were selected (Aeromonas sobria,Yersiniauckeri,Aeromonas hydrophila,V ibrioflurialis,Aeromonas punctata subsp. Punctata,Pseudomonas fluorescent,V ibrioroup I freshwater subgroup,Aeromonas punctata f. intedtinalis),the MIC (minimal inhibitory concentration,MIC<>) andBC (minimal bactericidal concentration,MBC) of potassium ferrate against them were obtained,and the effect of potassim ferrate solution in different concentrations to sterilize these test germswere mensurated. The results showed that potasium ferrate had a better effect on inhibiting Aeromonas sobria,V ibrioflurialis,and V ibrio group I freshwater subgroup,nd theirMIC values were 1.2mg/L. At the same time,theMBC values of these eight kinds of fish-pathogenic bacteriaere obtained,theywere 9. 6 mg/L,19.2mg/L,9. 6 mg/L,9. 6 mg/L,19.2mg/L,19.2mg/L,9. 6 mg/L,> 19.2mg/L,respectively. When the test pathogens density was regulated approximately to 105 cfu/mL,the germicidal efficacy of otassium ferrate solution in different concentrations against the pathogens was determined after an hour. Exhilaratingly,he vibrio were sterilized completely by potassium ferrates solution in lower concentrations than others. When the concen-ration of potassium ferrate solution were adjusted to 2. 4 mg/L and 7.2mg/L,their bactericidal coefficients were 4. 21%,100% and 95. 45%,100%,respectively. Based on the above results,the growth trends of these two kinds of ibrio were constructed. The figure showed that with higher concentration of potassium ferrate solution,the quantity of ibrioflurialis and V ibrio group I freshwater subgroup were larger. It was clear that potassium ferrate could be used as anquatic disinfectant for both bath treatment of fish and splash treatment of the whole pond,aswell as potassium ferrate cane used to prevent the fish vibriosis. However,the mechanism of potassium ferrate sterilizing germs remains unknown,andeed to make further investigation.