Memory is usually associated with higher organisms. However, a recent study conducted by scientists at the University of Texas at Austin found that despite lacking neurons, synapses and nervous systems, when millions of bacteria gather on the same surface, they can form something similar to a memory. Such as when to swim together, when to form biofilms, etc., and bacteria can at least pass these “memories” to their “great-grandchildren.” Further analysis revealed that seemingly ordinary iron was responsible for the bacteria forming this “memory.” Relevant papers were published in the Proceedings of the National Academy of Sciences.
So, can bacteria really form a “memory” and pass it on to future generations? Fu Yu, a researcher at the State Key Laboratory of Preliminary Development of Microbial Resources at the Institute of Microbiology, Chinese Academy of Sciences, told a reporter from Science and Technology Daily: “Strictly speaking, the bacterial ‘memory’ described in this study conducted by scientists at the University of Texas at Austin is not memory in the biological sense. , but the response of bacteria to external stimuli based on changes in iron concentration. This allows bacteria to survive and reproduce better in complex environments.”
“The latest research is instructive for us to deal with bacterial resistance. For example, we can artificially adjust the concentration of iron to reduce the attachment of bacteria to the infection site, reduce the bacterial tolerance to antibiotics, facilitate the immune system to clear pathogenic bacteria and enhance the effectiveness of antibiotics. Curative effect.” Fu Yu further emphasized.
Tie is one of the heroes behind the scenes
Higher animals, including humans, have the ability to remember, which allows higher animals to continuously adapt to changes in the environment and make correct responses quickly. Research shows that this memory ability originates from neural tissue. Nervous tissue will form nerve impulses after receiving external stimulation. The nerve impulses form conditioned reflexes for specific stimuli and can respond accordingly when encountering the same stimuli in the future.
Fu Yu said: “Although bacteria do not have brains and cannot remember information like higher animals, in a sense, they do have a ‘memory’ mechanism. This mechanism is mainly reflected in their adaptability to environmental changes and their genetic on the transmission of information and chemical substances.”
Bacteria can collect information from the environment. If they encounter this environment frequently, it can be to their advantage to store information and access it quickly later.
The latest study, conducted by a team led by Suvik Bhattacharya, a scientist at the University of Texas at Austin, found that bacteria can not only form “memories” but also pass “memories” to their offspring.
Scientists have previously observed that bacteria with experience in swarming motility (the rapid movement of many bacteria driven by flagella) are more willing and able to move in groups. Bhattacharya and others hope to clarify the underlying reasons for this phenomenon. To this end, they designed an experimental setup that can monitor the movement of swarms consisting of more than 10,000 E. coli cells. A series of analysis results showed that these E. coli can retain the “memory” of forming swarming movements for at least four generations, which is passed to their “great-grandchildren”, and will not completely disappear until the seventh generation.
So, how is this “memory” retained and passed on? The answer points to iron. Iron is one of the most abundant elements on earth. Before oxygen appeared in the early Earth’s atmosphere, iron played a key role in many cellular processes in early life and was crucial to the evolution of life.
Bhattacharya explained that the above-mentioned “memory” mechanism of E. coli stems from changes in the iron content within the E. coli cells. Their observations showed that different bacteria contain different levels of iron, which is important for their cellular metabolism. E. coli with lower iron content are more likely to move in groups. Bacteria with higher intracellular iron content tend to stay put and form biofilms. The descendants of these E. coli cells will inherit the materials in the cells of their “parents”, thereby inheriting the “memory” of swarm movements.
The researchers speculate that when iron levels are low, bacteria quickly assemble into fast-moving swarms that search for iron in the environment. When iron levels are high, bacteria can attach in situ and form biofilms.
Their latest research also found that artificially raising or lowering the iron content in E. coli cells can shorten or extend the storage time of “memory”.
Fu Yu believes that iron, as an important element in life activities, plays an important role in various biochemical reactions of bacteria. Therefore, it is not surprising that changes in iron concentration can regulate the way bacteria respond to the external environment.
Helping fight antibiotic resistance
Bhattacharya said the bacteria have a “memory” of when to form swarms and when to form biofilms. This characteristic may also play an important role in its infection of humans. Therefore, these findings have important implications for the treatment and prevention of bacterial infections and can help combat antibiotic resistance. Bhattacharya emphasized that iron concentration is definitely one of the targets for treating bacterial infections because iron is an important factor in determining bacterial virulence.
Fu Yu explained: “When the concentration of iron in E. coli is high, E. coli tends to stop moving and form biofilm. The formation of biofilm can improve the resistance of bacteria. When the concentration of iron in E. coli is low, the bacteria are resistant to Antibiotic resistance is poor. These are instructive for us to deal with bacterial resistance. For example, we can change the concentration of iron to make it difficult for bacteria to form biofilms and reduce their resistance to antibiotics, thereby effectively treating infections. .”
“The ‘memory’ displayed by microorganisms may be based on various mechanisms, but in the final analysis, all of these are rapid responses to changes in the external environment formed by microorganisms during their long-term evolution. Small bacteria possess great wisdom, and countless interesting phenomena are waiting for scientists. Analyze them one by one.” Fu Yu concluded.