A reverse transcriptase controls prophage genome reduction to promote phage dissemination in Pseudomonas aeruginosa biofilms.

Filamentous bacteriophages play a critical role in biofilm formation and virulence in the opportunistic pathogen Pseudomonas aeruginosa. Here, studies of the filamentous Pf4 prophage life cycle within P. aeruginosa biofilms revealed that the prophage-encoded reverse transcriptase (RT) regulates phage genome dynamics.

High temperatures increase the virulence of Vibrio bacteria towards their coral host and competing bacteria via type VI secretion systems.

The bacterial pathogen Vibrio coralliilyticus induces severe coral diseases in warming oceans. A study in PLOS Biology reveals that high temperatures activate 2 type VI secretion systems in V. coralliilyticus, enhancing pathogenicity by deploying toxic effectors against competing bacteria and coral cells.

A nuclease domain fused to the Snf2 helicase confers antiphage defence in coral-associated Halomonas meridiana.

The coral reef microbiome plays a vital role in the health and resilience of reefs. Previous studies have examined phage therapy for coral pathogens and for modifying the coral reef microbiome, but defence systems against coral-associated bacteria have received limited attention. Phage defence systems play a crucial role in helping bacteria fight phage infections.

Active prophages in coral-associated Halomonas capable of lateral transduction.

Temperate phages can interact with bacterial hosts through lytic and lysogenic cycles via different mechanisms. Lysogeny has been identified as the major form of bacteria-phage interaction in the coral-associated microbiome. However, the lysogenic-to-lytic switch of temperate phages in ecologically important coral-associated bacteria and its ecological impact have not been extensively investigated.

Combining CRISPR/Cas9 and natural excision for the precise and complete removal of mobile genetic elements in bacteria.

Horizontal gene transfer, facilitated by mobile genetic elements (MGEs), is an adaptive evolutionary process that contributes to the evolution of bacterial populations and infectious diseases. A variety of MGEs not only can integrate into the bacterial genome but also can survive or even replicate like plasmids in the cytoplasm, thus requiring precise and complete removal for studying their strategies in benefiting host cells. Existing methods for MGE removal, such as homologous recombination-based deletion and excisionase-based methods, have limitations in effectively eliminating certain MGEs.

Genomic Island-Encoded Diguanylate Cyclase from Regulates Biofilm Formation and Motility in .

Many bacteria use the second messenger c-di-GMP to regulate exopolysaccharide production, biofilm formation, motility, virulence, and other phenotypes. The c-di-GMP level is controlled by the complex network of diguanylate cyclases (DGCs) and phosphodiesterases (PDEs) that synthesize and degrade c-di-GMP. In addition to chromosomally encoded DGCs, increasing numbers of DGCs were found to be located on mobile genetic elements.

Minimized antibiotic-free plasmid vector for gene therapy utilizing a new toxin-antitoxin system.

Approaches to improve plasmid-mediated transgene expression are needed for gene therapy and genetic immunization applications. The backbone sequences needed for the production of plasmids in bacterial hosts and the use of antibiotic resistance genes as selection markers represent biological safety risks. Here, we report the development of an antibiotic-free expression plasmid vector with a minimized backbone utilizing a new toxin-antitoxin (TA) system.

Comparative Genomic Analysis of Cold-Water Coral-Derived : Insights into Their Habitat Adaptation and Metabolism.

is one of the major sulfite-oxidizing alphaproteobacterial groups and is often associated with marine algae and corals. Their association with the eukaryotic host cell may have important ecological contexts due to their complex lifestyle and metabolism. However, the role of in cold-water corals remains largely unexplored.

Comparative genomic insights into habitat adaptation of coral-associated .

Green sulfur bacteria (GSB) are a distinct group of anoxygenic phototrophic bacteria that are found in many ecological niches. , a marine representative genus of GSB, was found to be dominant in some coral skeletons. However, how coral-associated (CAP) adapts to diurnal changing microenvironments in coral skeletons is still poorly understood.

Applications of toxin-antitoxin systems in synthetic biology.

Toxin-antitoxin (TA) systems are ubiquitous in bacteria and archaea. Most are composed of two neighboring genetic elements, a stable toxin capable of inhibiting crucial cellular processes, including replication, transcription, translation, cell division and membrane integrity, and an unstable antitoxin to counteract the toxicity of the toxin. Many new discoveries regarding the biochemical properties of the toxin and antitoxin components have been made since the first TA system was reported nearly four decades ago.

The coral pathogen Vibrio coralliilyticus kills non-pathogenic holobiont competitors by triggering prophage induction.

The coral reef microbiome is central to reef health and resilience. Competitive interactions between opportunistic coral pathogens and other commensal microbes affect the health of coral. Despite great advances over the years in sequencing-based microbial profiling of healthy and diseased coral, the molecular mechanism underlying colonization competition has been much less explored.

Mobile genetic elements used by competing coral microbial populations increase genomic plasticity.

Intraspecies diversification and niche adaptation by members of the Vibrio genus, one of the most diverse bacterial genera, is thought to be driven by horizontal gene transfer. However, the intrinsic driving force of Vibrio species diversification is much less explored. Here, by studying two dominant and competing cohabitants of the gastric cavity of corals, we found that a phenotype influencing island (named VPII) in Vibrio alginolyticus was eliminated upon coculturing with Pseudoalteromonas.

Filamentous prophage capsid proteins contribute to superinfection exclusion and phage defence in Pseudomonas aeruginosa.

Filamentous prophages in Pseudomonas aeruginosa PAO1 are converted to superinfective phage virions during biofilm development. Superinfection exclusion is necessary for the development of resistance against superinfective phage virions in host cells. However, the molecular mechanisms underlying the exclusion of superinfective Pf phages are unknown.

Prophage Tracer: precisely tracing prophages in prokaryotic genomes using overlapping split-read alignment.

The life cycle of temperate phages includes a lysogenic cycle stage when the phage integrates into the host genome and becomes a prophage. However, the identification of prophages that are highly divergent from known phages remains challenging. In this study, by taking advantage of the lysis-lysogeny switch of temperate phages, we designed Prophage Tracer, a tool for recognizing active prophages in prokaryotic genomes using short-read sequencing data, independent of phage gene similarity searching.

Xenogeneic silencing relies on temperature-dependent phosphorylation of the host H-NS protein in Shewanella.

Lateral gene transfer (LGT) plays a key role in shaping the genome evolution and environmental adaptation of bacteria. Xenogeneic silencing is crucial to ensure the safe acquisition of LGT genes into host pre-existing regulatory networks. We previously found that the host nucleoid structuring protein (H-NS) silences prophage CP4So at warm temperatures yet enables this prophage to excise at cold temperatures in Shewanella oneidensis.

Conjugative plasmid-encoded toxin-antitoxin system PrpT/PrpA directly controls plasmid copy number.

Toxin-antitoxin (TA) loci were initially identified on conjugative plasmids, and one function of plasmid-encoded TA systems is to stabilize plasmids or increase plasmid competition via postsegregational killing. Here, we discovered that the type II TA system, plasmid toxin-antitoxin PrpT/PrpA, on a low-copy-number conjugative plasmid, directly controls plasmid replication. Toxin PrpT resembles ParE of plasmid RK2 while antitoxin PrpA (PF03693) shares no similarity with previously characterized antitoxins.

Novel polyadenylylation-dependent neutralization mechanism of the HEPN/MNT toxin/antitoxin system.

The two-gene module HEPN/MNT is predicted to be the most abundant toxin/antitoxin (TA) system in prokaryotes. However, its physiological function and neutralization mechanism remains obscure. Here, we discovered that the MntA antitoxin (MNT-domain protein) acts as an adenylyltransferase and chemically modifies the HepT toxin (HEPN-domain protein) to block its toxicity as an RNase.

Prophage encoding toxin/antitoxin system PfiT/PfiA inhibits Pf4 production in Pseudomonas aeruginosa.

Pf prophages are ssDNA filamentous prophages that are prevalent among various Pseudomonas aeruginosa strains. The genomes of Pf prophages contain not only core genes encoding functions involved in phage replication, structure and assembly but also accessory genes. By studying the accessory genes in the Pf4 prophage in P.

Symbiosis of a P2-family phage and deep-sea Shewanella putrefaciens.

Almost all bacterial genomes harbour prophages, yet it remains unknown why prophages integrate into tRNA-related genes. Approximately 1/3 of Shewanella isolates harbour a prophage at the tmRNA (ssrA) gene. Here, we discovered a P2-family prophage integrated at the 3'-end of ssrA in the deep-sea bacterium S.

Digital Approach to Rotational Speed Measurement Using an Electrostatic Sensor.

In industrial production processes, rotational speed is a key parameter for equipment condition monitoring and fault diagnosis. To achieve rotational speed measurement of rotational equipment under a condition of high temperature and heavy dust, this article proposes a digital approach using an electrostatic sensor. The proposed method utilizes a strip of a predetermined material stuck on the rotational shaft which will accumulate a charge because of the relative motion with the air.

Biofilm formation in Pseudoalteromonas lipolytica is related to IS5-like insertions in the capsular polysaccharide operon.

Bacterial capsular polysaccharides (CPSs) participate in environmental adaptation in diverse bacteria species. However, the role and regulation of CPS production in marine bacteria have remained largely unexplored. We previously reported that both wrinkled and translucent Pseudoalteromonas lipolytica variants with altered polysaccharide production were generated in pellicle biofilm-associated cells.

Characterization of Two Toxin-Antitoxin Systems in Deep-Sea sp. SCSIO 02999.

Toxin-antitoxin (TA) systems are ubiquitous and abundant genetic elements in bacteria and archaea. Most previous TA studies have focused on commensal and pathogenic bacteria, but have rarely focused on marine bacteria, especially those isolated from the deep sea. Here, we identified and characterized three putative TA pairs in the deep-sea-derived sp.

Antitoxin HigA inhibits virulence gene mvfR expression in Pseudomonas aeruginosa.

Toxin/antitoxin (TA) systems are ubiquitous in bacteria and archaea and participate in biofilm formation and stress responses. The higBA locus of the opportunistic pathogen Pseudomonas aeruginosa encodes a type II TA system. Previous work found that the higBA operon is cotranscribed and that HigB toxin regulates biofilm formation and virulence expression.

Quorum Sensing System of Rm01 Controls Lipase and Biofilm Formation.

Quorum sensing (QS) promotes extracellular enzyme (EE) activity via the exogenous signal -acylhomoserine lactone (AHL), which facilitates marine particle degradation, but the species that engage in this regulatory mechanism remain unclear. Here, we obtained AHL-producing and AHL-degrading strains from marine particles. The strain Rm01 of the group (RBG), which was capable of both AHL producing and degrading, was chosen to represent these strains.