Immunoassay for cadmium detection and quantification / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To detect cadmium in environmental and food samples by graphite furnace atomic absorption spectroscopy (GFAAS) and inductively coupled plasma atomic emission spectroscopy (ICPAES).</p><p><b>METHODS</b>An indirect competitive enzyme-linked immunosorbent assay (IC-ELISA) was developed based on a cadmium-specific monoclonal antibody. IC-ELISA for cadmium in environmental and food samples was evaluated.</p><p><b>RESULTS</b>IC-ELISA showed an IC50 of 45.6 microg/L with a detection limit of 1.95 microg/L for cadmium, and showed a mean recovery ranging 97.67%-107.08%. The coefficient of variations for intra- and interassay was 3.41%-6.61% and 4.70%-9.21%, respectively. The correlation coefficient between IC-ELISA and GFAAS was 0.998.</p><p><b>CONCLUSION</b>IC-ELISA can detect and quantify cadmium residue in environmental or food samples.</p>

Selection of Monascus with High Yellow Pigment Production / 微生物学通报

The Monascus mutant with high yield of yellow pigment was obtained by using conventional relevant mutation techniques, e.g., treating with physical mutagens(such as UV light) and chemical sub- stances (such as N-methyl-N'-nitro-N-nitrosoguanidine). The yellow pigment was scanned from 300 nm to 600 nm with UV spectrometer, the maximal absorption was determined at 410 nm. The growth characteristic of Monascus mutant is stable, the yellow pigment value and colour hue in liquid fermentation can reach 100 U/mL and 3.5 respectively. The yellow pigment is stable from pH 3 to pH 8, but the precipitation appeared as the pH of the pigment solution lower than 3.

Advances in heavy metal ions immunoassay / 生物工程学报

Heavy metal leftover on farm and stock products has become a big threat to human. It is necessary to develop some fast and efficient detection methods. Heavy metal immunoassays are new methods for detection of heavy metal ions. Compared to the traditional chemical methods, immunoassays are not only fast, cheap, simple, but also reasonably portable, highly sensitive and selective. It can be used as preliminary screening for rapid determination of heavy metal ions. Except chemical chelators, phytochelatin and metallothionein can also be used for preparing immunogen, both of them can chelate heavy metal ions to carrier protein. There are two prototype assays: polyclonal antibody immunoassay and monoclonal antibody immunoassay. The former includes fluorescence polarization immunoassay; the latter includes indirectly competitive ELISA, one-step competitive immunoassay and KinExA immunoassay. Among these assays, indirectly competitive ELISA which was used for determining heavy metal ions in the early days was easy to be interfered and showed false positive. Fluorescence polarization immunoassay which used polyclonal antibody for determining heavy metal ions was simple and cheap. KinExA instrument could be functioned as an immunosensor for environmental samples. One-step immunoassay which avoided to the addition of second antibody and chromogenic substrate was simple and sensitive. Colloidal gold enhanced immunochromatography assay is a semi-quantitation for determining heavy metal ions. As an adjunctive way for chemical methods, it has the potential application in rapid determination of heavy metal ions.

CLONING OF NATTOKINASE GENE AND EXPRESSION IN E. COLI / 微生物学通报

In this study, nattokinase gene was amplified by PCR using bacillus subtilis chromosomal DNA as template and cloned into expressed vector pBV220. After transforming recombinant plasmid into E.coli HB101, the recombinant strain was yielded. It was proved that expression products was secretive and expression protein was 12% of total cell protein by SDS-PAGE. Optimum culture time and inducing time was determined as 6h and 5h respectively. The plasmid stability studies showed that recombinant plasmid has excellent segregational stability but the structural stability was not good in the host cell.