Screening and electrochemical detection of an antibiotic producing gene in bacteria on an integrated microchip

We demonstrate the electrochemical determination of a secondary metabolite producing gene on an integrated microfluidic chip. The fabricated microchip was assembled with a continuous channel for polymerase chain reaction (PCR) and an electrochemical detector in order to achieve rapid and sensitive determination of the valC gene. valC is a gene responsible for producing antibiotic validamycin A in Streptomyces hygroscopicus. Biotin-conjugated primers amplified the valC gene. After the PCR, a DNA amplicon was analyzed in the electrochemical cell containing a streptavidin functionalized Au working electrode. The guanosine present in the DNA amplicon released electrons upon electrochemical oxidation at 0.93 V and the peak current linearly increased with the concentration of the captured DNA amplicon. The fabricated chip successfully amplified and detected the valC gene as low as 30 pg μL ^-1 resulting in a sensitive, portable and integrated DNA analysis for a secondary metabolite.