Microbiosensor developed to detect probiotics

Mexican researchers have developed a microbiosensor that detects beneficial bacteria in food. The micromechanical device is the first of its kind manufactured in the country and has been used to evaluate the growth of L. plantarum 299vm - a probiotic microorganism useful in the development of fermented dairy products.

The biosensor can monitor the growth of 400 cells in just 30 minutes, compared with traditional methods that require at least 24 hours’ incubation.

“We have built the microbiosensor as a pilot to evaluate its potential in biosensing bacteria; the device is based on the resonance advantage of a lever or beam (holder chip) of micron size, to evaluate small changes in mass of the order of nanograms (which is the approximate weight of a bacterium),” said Jorge Perez Chanona, researcher at the National School of Biological Sciences at the National Polytechnic Institute.

The microbiosensor was built with a holder chip supporting a fabricated silicon beam 125 µm long by 50 wide and 4 thick.

The holder chip is chemically and biologically modified and microcapillaries were used to coat the substrate with a specific growth of lactic acid bacteria, then inoculated with the ‘problem’ sample, and the beam was vibrated at a specific resonance frequency matching the atomic scanner microscope, which allows monitoring the damping experienced by the holder chip due to small mass changes that occur when microorganisms grow on its surface, similar to the behaviour of a trampoline when more weight is added, thus detecting possible bacterial growth dynamics within minutes of inoculation.

Aside from probiotics, micro- and nano-biosensors can detect other microorganisms such as pathogens, fungi, yeast, viruses, toxins, pollution particles and biomolecules, Perez Chanona says.