Instead, they are chemical alarms, signals that bacteria transmit when they are on the verge of death, known as “death signaling.”. Through the “death signaling” behavior, bacteria can alert their neighbors to the presence of a lethal threat, thus saving most of the bacteria in the colony (that is, the bacteria in motion). When faced with threats such as antibiotics, chemical death screams can provide enough time for surviving bacteria to acquire mutations that transmit antibiotic resistance, scientists write in a new study. < / P > < p > many kinds of bacteria swim at high speed under the action of slender tail like structure “flagella”. Sometimes, bacteria like E. coli have billions of bacteria in clusters that move harmoniously on fixed surfaces in groups. < / P > < p > “bacterial colonies are metabolically active and grow vigorously,” the researchers wrote. For this reason, scientists suspect that clusters may also have their own evolutionary mechanisms for antibiotic resistance. However, this mechanism may be different from the evolution mechanism of drug resistance in a single cell. < / P > < p > previously, researchers had pointed out that about 25% of the bacteria die when they encounter antibiotics. Dead bacteria seem to be protecting the surviving bacteria in some way. After some of the group’s companions died, the surviving cells seemed to stay away from antibiotics. At that time, however, researchers did not know exactly what caused the bacteria to behave like this. < / P > < p > and in this new study, scientists looked at what happens when E.coli colonies encounter antibiotics to reveal how dead cells save the remaining colonies. < / P > < p > the researchers found that the dead E.coli in the colony released a death signal: a protein that binds to the outer membrane of living cells in the cluster. In response to these dying chemical “screams,” dead bacteria can activate mechanisms in living cell membranes and “begin to excrete antibiotics,” said rachica Halsey, co-author of the paper and professor of biological sciences. Research shows that this “scream” compound can transmit a “state of emergency” signal to alert living bacteria to the dangers. < / P > < p > the death signal on gene cascade not only protects the surviving clusters from being chased by antibiotics, but also strengthens the resistance to the compounds that kill their comrades. More importantly, scientists realized that subpopulations of clustered bacteria also had genetic variability; some were more susceptible to antibiotics than others. Different bacterial clusters may co breed different subpopulations as evolutionary survival strategies – if new antibiotics kill the weak members of the colony, their sacrifice will protect the remaining members. The results of this study suggest that exposure to low doses of antibiotics is actually more conducive to the acquisition of antibiotic resistance in dense bacterial populations. This is very enlightening to study how to fight bacterial infection. Global Tech