Grow faster, die sooner

August 06, 2020

Bacteria are survival artists: When they get nutrition, they multiply rapidly, albeit they can also survive periods of hunger. But, when they grow too quickly, their ability to survive is hampered, as studies by a research team at the Technical University of Munich (TUM) on E. coli bacteria show. The results could help increase the effectiveness of antibiotics.

"The fitness of bacteria is more complex than expected," explains Ulrich Gerland, professor for the theory of complex biosystems at the Technical University of Munich. The physicist has been studying the survival strategies of E. coli bacteria for several years.

The unicellular organisms, which go by the Latin name Escherichia coli and support digestion in the large intestine of mammals, are a popular model organism. They facilitate investigations into the way living beings can adapt to changing environmental conditions.

Surviving hard times

"We have known for some time that biological fitness depends on two things: the growth rate when food is available and the ability to survive periods of nutrient deficiency," explains the scientist. "What was not clear is how these two factors are related."

For the first time, Gerland and his team have now systematically investigated the extent to which fast or slow growth influences the survivability of E. coli bacteria: "It turns out that changes in growth conditions have a direct impact on death rates. These follow a simple law: The best-nourished and fastest-growing bacteria are the first to die when deprived of food."

Fat bacteria - poor fitness

So, a good diet is bad for the fitness of bacteria. But why? To find an answer to this question, the TUM researchers carried out a number of experiments: First, cultures of E. coli bacteria were provided nutrient solutions with different compositions.

In the second step, the unicellular organisms were put on a zero diet. Throughout the entire period, the scientists examined whether and how quickly the cells multiplied, and how long they survived.

The fight for survival

The research showed that regardless of how well or poorly they were previously fed, bacteria stopped reproducing when they were deprived of food. In this "maintenance phase," organisms struggle for bare survival. All available energy sources - for example, the cellular remains of dead bacteria - are used to sustain the metabolism.

In this extreme situation, many cells die of starvation within a few days. However, the death rate is particularly high among rapidly growing E. coli bacteria. "They are primed for rapid growth and waste energy resources. This leads to their demise during the hunger phase," explains Gerland.

As it turns out, the abundantly fed bacteria have an increased need for energy, as further experiments prove. Surviving times of scarcity is more difficult for organisms with a high energy consumption. "We now understand why evolution doesn't favor the fastest possible reproduction," says Gerland. "The biological fitness that is crucial for the survival of a species builds on a balance between growth and survivability."

Antibiotic therapy with a carrot and a stick

The research results may find application in the future, for example, to improve the effect of antibiotics: "Applying a carrot and stick principle, intestinal bacteria growth could be stimulated by consuming a sweet dish. This would weaken the bacteria if an antibiotic against an intestinal infection is then administered," explains Gerland. However, it is still too early for concrete recommendations. More research will be necessary.
-end-
The research was funded by the German Research Foundation (DFG; SPP1617 and SFB / Transregio 174), a DFG research grant as part of the Graduate School of Quantitative Biosciences Munich (QBM) and a research grant from the European Molecular Biology Organization (EMBO). The investigations were done at the Chair for Physics of Complex Biosystems and in the TUM Research Center for Industrial Biotechnology.

Publication:

Elena Biselli, Severin Josef Schink, Ulrich Gerland:

Slower growth of Escherichia coli leads to longer survival in carbon starvation due to a decrease in the maintenance rate

Molecular Systems Biology, (2020) 16:e9478 - DOI: 10.15252/msb.20209478

Technical University of Munich (TUM)

Related Bacteria Articles from Brightsurf:

Siblings can also differ from one another in bacteria
A research team from the University of Tübingen and the German Center for Infection Research (DZIF) is investigating how pathogens influence the immune response of their host with genetic variation.

How bacteria fertilize soya
Soya and clover have their very own fertiliser factories in their roots, where bacteria manufacture ammonium, which is crucial for plant growth.

Bacteria might help other bacteria to tolerate antibiotics better
A new paper by the Dynamical Systems Biology lab at UPF shows that the response by bacteria to antibiotics may depend on other species of bacteria they live with, in such a way that some bacteria may make others more tolerant to antibiotics.

Two-faced bacteria
The gut microbiome, which is a collection of numerous beneficial bacteria species, is key to our overall well-being and good health.

Microcensus in bacteria
Bacillus subtilis can determine proportions of different groups within a mixed population.

Right beneath the skin we all have the same bacteria
In the dermis skin layer, the same bacteria are found across age and gender.

Bacteria must be 'stressed out' to divide
Bacterial cell division is controlled by both enzymatic activity and mechanical forces, which work together to control its timing and location, a new study from EPFL finds.

How bees live with bacteria
More than 90 percent of all bee species are not organized in colonies, but fight their way through life alone.

The bacteria building your baby
Australian researchers have laid to rest a longstanding controversy: is the womb sterile?

Hopping bacteria
Scientists have long known that key models of bacterial movement in real-world conditions are flawed.

Read More: Bacteria News and Bacteria Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.