Fluorescent bioassays for toxic metals in milk and yoghurt

BMC Biotechnology

Methodology Article

Mohammad Shohel Rana Siddiki¹  Isamu Maeda²  Shunsaku Ueda² 

[1] United Graduate School of Agricultural Science, Tokyo University of Agriculture and Technology, 3-5-8 Saiwaicho, 183-8509, Fuchu, Japan;United Graduate School of Agricultural Science, Tokyo University of Agriculture and Technology, 3-5-8 Saiwaicho, 183-8509, Fuchu, Japan;Faculty of Agriculture, Utsunomiya University, 350 Minemachi, 321-8505, Utsunomiya, Japan;

关键词: Inductively Couple Plasma Mass Spectrometry;    Toxic Metal;    Inductively Couple Plasma Atomic Emission Spectroscopy;    Inductively Couple Plasma Atomic Emission Spectroscopy;    Flame Atomic Absorption Spectrometry;   

DOI  :  10.1186/1472-6750-12-76

 received in 2012-04-22, accepted in 2012-10-16,  发布年份 2012

来源: Springer

【 摘 要 】

BackgroundFrom a human health viewpoint, contaminated milk and its products could be a source of long-term exposure to toxic metals. Simple, inexpensive, and on-site assays would enable constant monitoring of their contents. Bioassays that can measure toxic metals in milk or yoghurt might reduce the risk. For this purpose, the green fluorescent protein (GFP)-tagged trans factors, ArsR-GFP and CadC-GFP, together with their cis elements were used to develop such bioassays.ResultsArsR-GFP or CadC-GFP, which binds either toxic metal or DNA fragment including cis element, was directly mixed with cow’s milk or yoghurt within a neutral pH range. The fluorescence of GFP, which is reflected by the association/dissociation ratio between cis element and trans factor, significantly changed with increasing externally added As (III) or Cd (II) whereas smaller responses to externally added Pb (II) and Zn (II) were found. Preparation and dilution of whey fraction at low pH were essential to intrinsic zinc quantification using CadC-GFP. Using the extraction procedure and bioassay, intrinsic Zn (II) concentrations ranging from 1.4 to 4.8 mg/l for milk brands and from 1.2 to 2.9 mg/kg for yoghurt brands were determined, which correlated to those determined using inductively coupled plasma atomic emission spectroscopy.ConclusionsGFP-tagged bacterial trans factors and cis elements can work in the neutralized whole composition and diluted whey fraction of milk and yoghurt. The feature of regulatory elements is advantageous for establishment of simple and rapid assays of toxic metals in dairy products.

【 授权许可】

Unknown   
© Siddiki et al.; licensee BioMed Central Ltd. 2012. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.