Bacterial defense systems

Microbial evolution is driven by a dynamic interaction between bacteria and viruses (bacteriophages). Bacteria and archaea are frequently threated by bacteriophages and plasmids, also known as ‘mobile genetic elements’ (MGEs). To avoid cell death or genomic invasion, bacteria have developed several sophisticated defense strategies, like preventing cell entry (e.g. via receptor masking or variation) and infection (e.g. altruistic suicide and/or dormancy of infected cells to protect the clonal population), or activating cellular immunity comprising both innate mechanisms (e.g. restriction-modification systems) and adaptive mechanisms (e.g. the CRISPR-Cas systems). Conversely, bacteriophages have evolved strategies to evade or counteract many of these defense systems, e.g. anti-CRISPR and anti-restriction proteins.
 
Bacterial defense systems are under constant selective pressure by bacteriophage attack, and they rapidly evolve to combat phage infection and parasitism. Many types of defense systems encoded in bacterial and archaeal genomes are therefore likely to be still unknown. Understanding the diversity of bacterial defense system is therefore relevant for fundamental and applicative reasons. For instance, it has paramount importance to reveal bacterial mechanisms underlying antibiotic resistance, or promising approaches for targeted phage therapies against infectious diseases, or novel applications of CRISPR-Cas systems for genome editing and gene therapy.
 
By acknowledging that research on bacterial defense mechanisms, as well as their potential applications, is rapidly evolving and fundamentally changing the way we understand microbial ecology and evolution, and possibly treat human diseases, BMC Microbiology presents a collection on ‘Bacterial defense systems’. The overall goal of the collection is to explore the diverse strategies employed by bacteria to combat challenges such as phage attacks, antimicrobial agents, environmental stresses, and interactions with other microorganisms.

The scope of this collection covers a broad range of topics including, but not limited to:

• Mechanisms of bacterial defense systems
• Molecular and ecological interactions between bacteria and bacteriophages, and microbial evolution
• Regulatory cross-talk between bacteriophages, mobile genetic elements (MGEs) and bacterial hosts
• Bacterial abortive infection
• Bacterial innate and adaptive immunity mechanisms
• Evolutionary ecology of prokaryotic innate and adaptive immune systems and their interplay in microbial communities
• CRISPR-Cas systems in bacteria and archaea
• Mobile genetic elements (MGEs), chromosome hotspots and ‘defense island systems’
• Phage receptor binding proteins
• Investigating bacterial defense strategies against antimicrobial agents to explore the potential of antimicrobial alternatives
• Targeting bacterial immune systems for novel therapeutic approaches
• Phage therapies against antibiotic-resistant bacteria
• The response of bacteria against ROS stress
• Mechanisms of bacterial dormancy and resuscitation induction
• Bacterial persister cell formation and dormancy, and strategies for removing bacterial persisters
• In silico and molecular tools to study bacterial defense systems

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