Novel bacterial acid tolerance system sheds light on development of antimicrobials

March 20, 2020

Growth ability at acidic conditions is important to bacteria. Enteric bacteria such as Escherichia coli and Salmonella can colonize and cause disease in the host's intestinal tract, but they have to combat acidic environments during the whole process of invading the host.

The stomach, with pH value as low as 1.5-2.5, is recognized as a natural antibiotic barrier. After entering into the small intestine, E. coli will encounter a less acidic environment (with pH value of 4-6), reproduce rapidly, and cause disease to the host ultimately.

Recently, a research team led by Prof. XIAN Mo and Prof. ZHAO Guang from the Qingdao Institute of Bioenergy and Bioprocess Technology (QIBEBT) of the Chinese Academy of Sciences (CAS) discovered a novel bacterial acid tolerance system, which confers the growth capability to E. coli at pH of 4.2.

Up to now, five acid resistance systems have been reported. These acid resistance systems can enable E. coli to survive in gastric acid for hours, but they play no role in rapid multiplication of E. coli under moderate acidic conditions.

CpxA, the newly discovered system, can sense acidification directly through protonation of histidine residues. It will also activate its cognate regulator protein CpxRx to stimulate the expression of fabA and fabB genes for biosynthesis of unsaturated fatty acids, increasing unsaturated fatty acid contents in membrane lipid.

Changes in membrane lipid composition lower the fluidity and proton permeability of cell membrane, increasing the intracellular pH homeostasis.

Experiment results showed that E. coli mutant deficient in this system cannot grow in mouse intestine. Besides E. coli, this acid tolerance system also exists in pathogenic bacteria including Salmonella, Shigella, Vibrio cholerae, Yersinia pestis and Pseudomonas aeruginosa, which may be a new target for the development of antimicrobials.

The related findings were published in Nature Communications on Mar. 20.
-end-
This work was supported by the National Natural Science Foundation of China and the Natural Science Foundation of Shandong Province.

Chinese Academy of Sciences Headquarters

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.