The Determination Method Of Toxic Pollutants In Farm Food By Using Luminiscent Bacteria

Relative data has been collected by National Agriculture Department showing that the residues of Pesticide, Heavy-metals and Nitrite went beyond the standard greatly in major farm product(like grain,fruit,vegetable,meat, egg and milk,etc).The export of farm products in China was only 1%of total and the reason for that is the unqualified result of hygienic standard and high residues of medicine.The hygiene and safety of farm food have become the non-tariff barriers of export.The time-saving method of toxicity determination of farm food has aroused great interest among scientists.The traditional biological toxicity assessment methods adopt Mammalian,fishes as trial objects,which are much complicated,lengthy and is only suitable in laboratory.Due to the need for monitory, domestic and international researchers had devoted years of efforts in finding new methods.On the basis of principles of luminescent bacteria and biological statistics a way of rapid determination of farm food toxicity has been established.Based on the lab scale research of single and binary toxicity experiments on pollutants of agricultural products such as heavy metal,pesticide and animal medicine had been conducted using Vibro qinghaiensls on the basis of luminescent principle.The biotoxicity of single heavy metal and integrated biotoxicity of the mixture of heavy metal by mixing up two or three or four kinds of heavy metal are determined using photobacterium phosphoreum.The concentration of each kind of heavy metal in mixture is determined by one of statistical method called general regression circumrotate experimental design.The regression model which explained the correlation between the concentration of heavy metal and the relative intensity of luminescence is constructed for each mixture on the analysis of the total toxicity,interaction and main elements effect of it.The interaction effect and integrate biotoxicity of multi-pollutants had been opened out by which a set of mathematical model had been established including the rapid evaluation system on farm products such as fresh milk,fresh pork,fresh beef and foliate vegetable using luminescent bacteria.The evaluation system considers being rapid and comprehensive which consummates the pre-alarming system and monitoring system for farm products.The main conclusions are drawn as followings:1.Experiments had been conducted with materials including four kinds of heavy metals,eighteen kinds of pesticides and six kinds of veterinary drugs by which reveal that the rapid toxicity effects to luminescent bacteria vary. from the species of pollutants and testing bacteria.Within certain rang of concentrations the relative luminescent intensity has positive correlation with concentration of pollutants.The correlation coefficients are all above 0.9.2.The toxicity of heavy meal towards Vibro qinghaiensls varies according to concentrations.Based on experiment results,seven regression models between relative luminescent intensity and concentration had been drawn out,which had been tested with high significance and fine goodness of fit.The experiment results demonstrate that the most effective element is Cd⁶⁺in mixture,the interaction effect between Cr²⁺and Cd²⁺is synergistic,implying that the actual toxicity of mixture is higher than the sum of toxicities.The mixture of Cr⁺⁶and Pb²⁺is negative effect to luminescent bacteria and the more effective one is Cr⁶⁺and the interaction of Cr⁶⁺and Pb²⁺is antagonistic.In the negative effect of Cr⁶⁺and Hg²⁺,Cr⁶⁺is more effective and the significant interaction is antagonistic.The co-effect of Pb²⁺and Cd²⁺can be determined by concentrations and the adverse effect of Cd²⁺is more significant than Hg²⁺in mixture.Cd²⁺,Cr⁶⁺-Cd²⁺and Cr⁶⁺-Pb²⁺are three most effective elements to luminescent,among which Cd²⁺is most significant.The interaction of Cd²⁺,Cr⁶⁺and Pb²⁺is a bit positive.3.Experiments had been conducted using Vibro qinghaiensls with multi-species of veterinary drug mixture in different concentrations.The joined toxicities vary from the concentration rang.The joined toxicity for Sulfamethoxazole and Sulfaquinoxaline is synergistic according to different concentrations.As for the mixture of Oxytetracycline,Olaquindox and Sulfaquinoxaline the interaction of Olaquindox and Sulfaquinoxaline is negative and the interaction of Oxytetracycline and Olaquindox is antagonistic.4.Based on the lab scale research evaluation grading system had been carried out for farm products according to the relative luminescent intensity of 30 minutes which can be applied in the rapid safety evaluation of farm products such as fresh milk,fresh pork and beef and foliate vegetables.5.The determination of joined toxicity of various kinds of mixture of pollutants using luminescent bacteria is a rapid biological method by which the general biotoxicity of farm products can be evaluated and which can be applied in the pre-selection of polluted farm products.The general biotoxicity evaluation system provides quick,simple and cheap access to the on-time discovery and analysis of potential hazards in farm products.It is promising and innovative in food safety detection area with its advantages in the on-site detections.