Now, a new study is revealing that they can survive without food. The study was conducted by Indiana University professor Jay T. Lennon and it saw about 100 populations of different bacteria in closed systems be denied food for 1,000 days.
The team followed how long they could survive while starved and found that most of them lived on.
"The larger question of how bacteria survive long periods of energy limitation is relevant to understanding chronic infections in humans and other hosts, and is related to how some pathogens tolerate drugs like antibiotics," said in a statement Lennon, a professor in the Department of Biology in the College of Arts and Sciences.
Bacterial infections are so difficult to treat, in part, because bacteria can often enter a quiescent or dormant, state (an energy-limited state) that makes them less sensitive to drug treatments. In this state, they can also develop antibiotic resistance.
In the study, Lennon and his team, including former Indiana University doctoral student William Shoemaker, discovered that energy-limited bacteria can have lifespans that can last up to 100,000 years.
"Obviously, these predictions extend far beyond what can be measured," Lennon added. But the researcher did specify that the numbers comply with the ages of viable bacteria that have been recovered and resuscitated from ancient materials, such as amber, halite crystals, permafrost, and sediments at the bottom of the deepest oceans.
Lennon and Shoemaker presume that bacteria have many energy-preserving mechanisms such as dormancy. Some bacteria could even "scavenge" their dead relatives in order to survive.
What does this all mean for humans? It means that bacterial infections are more dangerous than ever and with climate change bringing some of these ancient bacteria back to life, we may soon have something to worry about.