In this work we measure the time it takes for predatory Bdellovibrio bacteriovorus to attach to prey bacteria. B. bacteriovorus preys on Gram-negative bacteria such as E. coli. Some Gram-negative bacteria, including strains of E. coli, are resistant to antibiotics, so it is important to look for new ways to prevent its reproduction and spread, such as with predatory bacteria. The predation cycle includes an attack phase, during which B. bacteriovorus identifies and then attaches to its prey, followed by a growth phase, when it burrows into the periplasmic membrane of the prey cell, consumes its nutrients, and forms several bacteria that emerge, leaving the husk of the host cell behind. The attachment to the host is made with long fibers called type IV pili. The goal of this research is to measure the likelihood of B. bacteriovorus forming an attachment to its prey after different lengths of time. We optically trap a single B. bacteriovorus and position it against an E. coli bacterium fixed to a microscope slide. After a length of time from 15 seconds to three minutes, we release the B. bacteriovorus and observe whether the bacterium remains attached to the E. coli or moves away. Our results show an increase after 15 seconds in the percent of trials that result in attachments, with a percentage approaching 50% after two minutes. This investigation improves understanding of the time needed for secure attachment and informs how these bacteria use their type IV pili.
|