E. coli survive predatory bacteria by playing hide and seek

To understand how E. coli is able to survive in the presence of such an effective predator, the researchers created two different environments for the bacteria – open and fragmented.

A sample bottle containing E. coli bacteria is seen at the Health Protection Agency in north London (photo credit: REUTERS)
A sample bottle containing E. coli bacteria is seen at the Health Protection Agency in north London
(photo credit: REUTERS)
Most of the body’s disease-causing bacteria are made harmless by the protective effects of the immune system. Those that manage to evade the immune system can be killed by antibiotics, but bacteria are becoming more and more resistant to a growing number of antibiotics.
But Hebrew University of Jerusalem researchers, who published their findings in Proceedings of the Royal Society B, say that studying the struggle between bacterial predator and prey could generate alternatives to these drugs.
Consider Bdellovibrio bacteriovorus, a bacterial predator that is an efficient killer of gram-negative bacteria (those that don’t retain the crystal violet stain used to make positive identification possible), such as the prevalent E. coli bacterium. It is present in soil and, just like E. coli, it grows in the human gut, where a complex ecosystem of bacterial inhabitants exists.
This ferocious bacterial predator enters its prey and devours it from the inside while dividing into four or six offspring and then explodes its prey and starts its hunt for the next. B. bacteriovorus is a formidable opponent because it is not only an efficient killer, but also very fast. Although the bacterium itself is less than one micrometer long, it can reach speeds of 160 micrometers per second, making it the “world champion” in speed swimming and 10 times faster than E. coli.
“Knowledge of defense and attack mechanisms in bacteria is crucial for future development of potential alternatives to antibiotics,” explained Dr. Daniel Koster, from the university’s department of ecology, evolution and behavior.
“B. bacteriovorus kills bacteria by a whole different mechanism of action than classical antibiotics, and as such, predatory bacteria might in the future constitute a viable alternative to these antibiotics,” said Koster, who led the research along with scientists from the Kavli Institute of Nanoscience at in the Netherlands.
To understand how E. coli is able to survive in the presence of such an effective predator, the researchers created two different environments for the bacteria – open and fragmented. In the open environment, which can be compared to a bare open surface, E. coli had no chance of surviving, as most of the population was eliminated within a couple of hours. But it proved surprisingly able to maintain a healthy population in an environment with many small chambers.
But E. coli was able to survive in the fragmented environment: “It seems that groups of them ‘hide’ in the many corners of the fragmented environment, where they readily stick as biofilms that probably protect them against B. bacteriovorus. Our findings provide important information because in natural environments, such as our gut, the bacterium also lives in fragmented spaces.”
It is not yet known precisely how E. coli is able to defend itself against predatory bacteria, but the research contributes to the understanding of their behavior, and this could become an alternative to antibiotics in the future. “In the future, predatory bacteria could be genetically modified to specifically target harmful bacteria, while leaving benign bacteria untouched. As such, B. bacteriovorus might be more selective than the antibiotics currently in use, and anti-bacterial treatment might not require the widespread extermination of the gut flora that is of importance to human health, he concluded.
SMS FROM BEERSHEBA HOSPITAL Soroka University Medical Center in Beersheba has introduced a new service that will calm patients and relieve tension and uncertainty. Hundreds of people arrive at the emergency department every day, and all of them want to speak to doctors or nurses about their condition. Now they can receive SMS messages in their cellular phone with information on the stages of their treatment until they are discharged.
There are five types of messages: one sent after reaching the reception desk; what doctor will see them; the name of the nurse in charge, the arrival of blood tests at the lab and the doctor’s decision whether the patient will be hospitalized or sent home. The SMS also provides data from a number of computerized hospitalized systems in the hospital.
GREEN TEA COMPOUND BLOCKS RHEUMATOID ARTHRITIS Researchers at Washington State University have identified a potential new approach to combating the joint pain, inflammation and tissue damage caused by rheumatoid arthritis.
Their discovery was recently featured on the cover of Arthritis and Rheumatology, a journal of the American College of Rheumatology.
Rheumatoid arthritis is a debilitating autoimmune disorder that affects the small joints of the hands and feet, causing painful swelling that progresses into cartilage damage, bone erosion and joint deformity.
“Existing drugs for rheumatoid arthritis are expensive, immunosuppressive and sometimes unsuitable for long-term use,” said Salah-uddin Ahmed, the lead researcher.
His team evaluated a phytochemical called epigallocatechin-3-gallate (EGCG) with the anti-inflammatory properties found in green tea. Their study suggests that EGCG has high potential as a treatment for rheumatoid arthritis because of how effectively the molecule blocks the effects of the disease without blocking other cellular functions.
“This study has opened the field of research into using EGCG for targeting TAK1 - an important signaling protein - through which proinflammatory cytokines transmit their signals to cause inflammation and tissue destruction in rheumatoid arthritis,” said Ahmed. The researchers confirmed their findings in a pre-clinical animal model of human rheumatoid arthritis, where they observed that ankle swelling in animals given EGCG in a 10-day treatment plan was markedly reduced.