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Haifa, Israel – Researchers at the Israel Institute of Technology (Technion) have unveiled a groundbreaking mechanism that allows marine bacteria to defend themselves against viral attacks, shedding light on the evolutionary battle between bacteria and phages—viruses that specifically infect bacteria.
The study, recently published in Nature Microbiology, explores how bacteria in marine environments deploy a passive defense strategy to survive viral infections, a process that has significant implications for marine ecosystems and the global carbon cycle.
Marine bacteria, like Synechococcus, play a crucial role in the environment, producing oxygen through photosynthesis and serving as a vital link in the marine food chain. However, they face constant threats from phages, which can decimate bacterial populations. According to Xinhua news agency, this ongoing battle drives the co-evolution of bacteria and viruses, with some bacterial populations developing innovative survival strategies.
A Unique Passive Defense Mechanism
The researchers focused on the interaction between Synechococcus and the phage Syn9. They discovered that Synechococcus employs a passive resistance mechanism by reducing the levels of transfer RNA (tRNA), a molecule essential for protein synthesis during genetic translation.
When tRNA levels are normal, the bacteria are highly susceptible to viral infections. However, lowering tRNA levels disrupts the virus’s ability to replicate inside the bacterial cell, enhancing the bacteria’s resistance.
Interestingly, this strategy does not prevent the virus from entering the bacterial cell. Instead, it stops the formation of new viruses, effectively halting the infection and allowing the bacteria to survive.
Evolutionary Advantage
The researchers noted that this resistance mechanism likely evolved over time due to selective pressure, where bacteria with reduced tRNA levels had a survival advantage. Over generations, this trait became prevalent, enabling the establishment of bacterial lineages better equipped to withstand viral attacks.
“This is a widespread mechanism,” the researchers stated, “not limited to the interaction between Synechococcus and Syn9.” They suggested that similar passive resistance strategies may be present in other bacterial-phage systems, potentially influencing the dynamics of marine microbial ecosystems.
Implications for Marine Ecosystems
This discovery highlights the complex interplay between marine bacteria and viruses and underscores the importance of microbial processes in maintaining marine ecosystems. By understanding these defense mechanisms, scientists can gain insights into how bacterial populations survive and thrive in the face of viral threats, ultimately influencing the balance of marine life and the global environment.
The findings open new avenues for studying microbial resistance mechanisms and their role in ecological and evolutionary processes, offering a deeper understanding of life in the oceans.
