Researchers have developed a device that swiftly analyzes microbes in oceans and other aquatic environments, revealing the health of these organisms — too tiny to be seen by the naked eye —and their response to threats to their ecosystems. The portable device could be used to assess microbes, screen for antibiotic-resistant bacteria, and analyze algae that live in coral reefs.
The tool, developed initially to assess algae, can determine in the field or in laboratories how microbes and cells respond to environmental stresses such as pollution and changes in temperature or water salinity. Being able to assess and understand the status of cells, without having to send samples back to a lab, can allow the identification of threatened ecosystems based on a “stress index” for their inhabitants.
The research focused on a well-studied green microalga, Picochlorum. The tool can quickly reveal whether a cell is stressed, robust, or unaffected by environmental conditions. Microbes pass one by one through a microchannel, thinner than the diameter of a human hair. Impedance, or the amount an electrical field in the tool is perturbed when a cell passes through the channel, is measured. Impedance varies among cells in a population, reflecting their size and physiological state, both of which provide important readouts of health.
The electrical impedance measurements can be applied at the single-cell and population levels. The scientists plan to use the tool to screen for antibiotic resistance in different bacteria and algae that live in symbiosis with coral reefs, which will help give them a better idea of coral health.