How Dead Bacteria Return To Life





Science, 07 Oct - 2016 ,

How Dead Bacteria Return To Life
Cutting off the nitrogen supply: A cyanobacteria culture prior to nitrogen removal (left), after several days (middle), and after more than three weeks (right). Credit: Alexander Klotz

Many bacteria - including dangerous pathogens - can make radical changes to their metabolism, switching into a dormant state which allows them to survive periods

Many bacteria - including dangerous pathogens - can make radical changes to their metabolism, switching into a dormant state which allows them to survive periods in which no growth is possible. Such dormancy occurs for instance when the microbes do not have enough food.

International researchers working with Professor Karl Forchhammer and Alexander Klotz at University of Tübingen's Interfaculty Institute of Microbiology and Infection Medicine have become the first to analyze the awakening process of cyanobacteria. They found that the cells' revival process followed a strict genetic timetable. The results of their study have been published in the latest issue of Current Biology. The findings provide insight into a previously unknown survival strategy of bacteria and enable the researchers to draw key conclusions about cell aging processes.

The blue-green photosynthesizing cyanobacteria belong to the oldest group of bacteria; traces of them go back more than three billion years. Their activity released oxygen into the atmosphere, enabling life on Earth in its current forms. Cyanobacteria continue to play an important role in environmental cycles. When nitrogen as major nutrient is lacking, many cyanobacteria cease growing and go into a dormant state. They dismantle their photosynthesis apparatus and lose their color. In this way they can survive long periods without nutrients. Yet when exposed to an accessible supply of nitrogen, they return to normal life within 48 hours. The cells only appear dead. Their vital functions reappear out of nowhere.

The researchers' observations indicate that important switches in the awakening process are located in sections of uncoded RNA. They are copies of DNA which are not translated into proteins; they have regulatory functions. This genetically coded program of dormancy and revival allows cyanobacteria to colonize environments in which the nitrogen supply is inconstant. It is one of the ways how they can survive environmental stress and were thus able to survive for more than three billion years of evolution.

The dormancy phenomenon is also found in many other bacteria, particularly those which colonize environments which face frequent shortages of nutrients


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