Cold adaptation regulated by cryptic prophage excision in Shewanella oneidensis

Area of Science:

• Microbiology
• Bacterial Physiology
• Genomics

Background:

• Bacterial cold tolerance is crucial for survival in changing environments.
• Previous research focused on membrane, RNA, and protein level adaptations.
• Genomic changes in bacterial cold adaptation remain largely unexplored.

Purpose of the Study:

• To investigate novel cold adaptation mechanisms in bacteria at the DNA level.
• To explore the role of cryptic prophage excision in bacterial survival under cold stress.
• To elucidate the regulatory pathways governing cold adaptation.

Main Methods:

• Whole-genome deep sequencing of a psychrotrophic bacteria strain.
• Analysis of cryptic prophage excision rates at different temperatures.
• Investigation of gene expression and protein-DNA interactions.

Main Results:

• A 10,000-fold increase in novel P4-like cryptic prophage excision was observed upon temperature downshift.
• Prophage excision facilitated biofilm formation and enhanced population survival.
• Excision disrupted transfer-messenger RNA (tmRNA) gene activity.
• Histone-like nucleoid-structuring protein (H-NS) repressed prophage excision at warm temperatures, with reduced levels at cold temperatures.

Conclusions:

• Cryptic prophage excision is a novel DNA-level cold adaptation mechanism in bacteria.
• This process is regulated by H-NS and impacts tmRNA activity and biofilm formation.
• Prophage excision acts as a regulatory switch for bacterial survival at low temperatures.