Detection of Escherichia coli in meat with an electrochemical biochip.

Detection of foodborne pathogenic and spoilage bacteria by RNA-DNA hybridization is an alternative to traditional microbiological procedures. To achieve high sensitivity with RNA-DNA-based methods, efficient bacterial lysis and release of nucleic acids from bacteria are needed. Here we report the specific detection of the hygiene indicator microorganism Escherichia coli in meat by use of electrochemical biochips.

Rapid, specific and sensitive electrochemical detection of foodborne bacteria.

Electrochemical biochips are an emerging tool for point-of-care diagnostic systems in medicine, food and environmental monitoring. In the current study, a thermostable reporter enzyme, esterase 2 (EST2) from Alicyclobacillus acidocaldarius, is used for specific and sensitive detection of bacteria by one-step rRNA/DNA hybridization between a bacterium-specific capture oligodeoxynucleotide (ODN), bacterial 16S rRNA and an uniform EST2-ODN reporter conjugate. The detection limit corresponds to approximately 500 colony forming units (cfu) Escherichia coli.

Ozone-induced gene expression occurs via ethylene-dependent and -independent signalling.

Recent studies suggest that ethylene is involved in signalling ozone-induced gene expression. We show here that application of ozone increased glucuronidase (GUS) expression of chimeric reporter genes regulated by the promoters of the tobacco class I beta-1,3-glucanases (GLB and Gln2) and the grapevine resveratrol synthase (Vst1) genes in transgenic tobacco leaves. 5'-deletion analysis of the class I beta-1,3-glucanase promoter revealed that ozone-induced gene regulation is mainly mediated by the distal enhancer region containing the positively acting ethylene-responsive element (ERE).