Complete Genome Sequence of Vibrio campbellii DS40M4

Environmental Microbiology

Petersen

Haas

et al. 2021

Self Cite

Vibrio campbellii BB120 (previously classified as Vibrio harveyi) is a fundamental model strain for studying quorum sensing in vibrios. A phylogenetic evaluation of sequenced Vibrio strains in Genbank revealed that BB120 is closely related to the environmental isolate V. campbellii DS40M4. We exploited DS40M4's competence for exogenous DNA uptake to rapidly generate greater than 30 isogenic strains with deletions of genes encoding BB120 quorum-sensing system homologues. Our results show that the quorum-sensing circuit of DS40M4 is distinct from BB120 in three ways: (i) DS40M4 does not produce an acyl homoserine lactone autoinducer but encodes an active orphan LuxN receptor, (ii) the quorum regulatory small RNAs (Qrrs) are not solely regulated by autoinducer signalling through the response regulator LuxO and (iii) the DS40M4 quorum-sensing regulon is much smaller than BB120 (~100 genes vs.~400 genes, respectively). Using comparative genomics to expand our understanding of quorumsensing circuit diversity, we observe that conservation of LuxM/LuxN proteins differs widely both between and within Vibrio species. These strains are also phenotypically distinct: DS40M4 exhibits stronger interbacterial cell killing, whereas BB120 forms more robust biofilms and is bioluminescent. These results underscore the need to examine wild isolates for a broader view of bacterial diversity in the marine ecosystem.

Section: Discussionmentioning

confidence: 93%

The quorum‐sensing systems of Vibrio campbellii DS40M4 and BB120 are genetically and functionally distinct

Environmental Microbiology

Petersen

Haas

et al. 2021

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“…cholerae exhibit differing natural transformation frequencies (15, 16), we hypothesized that the absence of competence in BB120 may not be indicative of competence in other V. campbellii isolates. We therefore assayed natural transformation in three V. campbellii environmental isolates with sequenced genomes: DS40M4, NBRC 15631, and HY01 (21, 23–26). DS40M4 was isolated from the Atlantic Ocean near the west coast of Africa (26), HY01 was isolated from a bioluminescent shrimp in Thailand (24), and NBRC 15631 (also called CAIM 519 and ATCC 25920) was isolated from seawater in Hawaii (21).…”

Section: Resultsmentioning

confidence: 99%

Diversity in Natural Transformation Frequencies and Regulation across Vibrio Species

Podicheti

Rusch

et al. 2019

mBio

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Naturally transformable, or competent, bacteria are able to take up DNA from their environment, a key method of horizontal gene transfer for acquisition of new DNA sequences. Our research shows that Vibrio species that inhabit marine environments exhibit a wide diversity in natural transformation capability ranging from nontransformability to high transformation rates in which 10% of cells measurably incorporate new DNA. We show that the role of regulatory systems controlling the expression of competence genes (e.g., quorum sensing) differs throughout both the species and strain levels. We explore natural transformation capabilities of Vibrio campbellii species which have been thus far uncharacterized and find novel regulation of competence. Expression of two key transcription factors, TfoX and QstR, is necessary to stimulate high levels of transformation in Vibrio campbellii and recover low rates of transformation in Vibrio vulnificus.

“…However, while it is understood and accepted that strains of the same bacterial species can vary widely in nature, it isn't often investigated how the canonical models diverge amongst these strains. Although BB120 and DS40M4 are very closely related (Colston et al, 2019), we have shown that these two strains differ widely from one another in natural transformation, quorum-sensing pathways, and various other phenotypes. It is important to consider strain to strain variations and how bacteria in the environment may differ from the models established from laboratory strains.…”

Section: Discussionmentioning

confidence: 84%

“…We hypothesized that these environmental V. campbellii strains may exhibit differences in other behaviors such as growth and quorum sensing-controlled phenotypes. Here, we show that the recently sequenced environmental isolate V. campbellii DS40M4 (16–18) exhibits several advantages as a model organism compared to BB120. Using natural transformation to rapidly construct mutants, we tested differences in quorum sensing-controlled phenotypes between DS40M4 and BB120, including biofilm formation, T6SS-mediated cell killing, protease activity, and bioluminescence.…”

Section: Introductionmentioning

confidence: 91%

The quorum-sensing systems ofVibrio campbelliiDS40M4 and BB120 are genetically and functionally distinct

Petersen

Haas

et al. 2020

Preprint

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Vibrio campbellii DS40M4 is a tractable model strain that diverges from the canonical quorum-1 sensing regulatory circuit in vibrios 2 3 4 5 Abstract 33 Vibrio campbellii BB120 (previously designated as Vibrio harveyi) is a fundamental 34 model strain for studying population density-based cell-to-cell communication, known as quorum 35 sensing. In V. campbellii BB120, sensing of autoinducers at high cell densities activates the 36 expression of the master transcriptional regulator, LuxR, which controls the expression of genes 37 involved in group behaviors. The environmental isolate Vibrio campbellii DS40M4 was recently 38 shown to be capable of natural transformation, a process by which bacteria take up exogenous 39 DNA and incorporate it into their genome via homologous recombination. In contrast, BB120 is 40 not naturally transformable. Here, we compare additional phenotypes between these two V. 41 campbellii strains. DS40M4 has a faster growth rate and stronger type VI secretion-mediated 42 cell killing, whereas BB120 forms more robust biofilms and is bioluminescent. To explore the 43 function of DS40M4-encoded homologs of the BB120 quorum-sensing system, we exploited the 44 power of natural transformation to rapidly generate >30 mutant strains. Our results show that 45 DS40M4 has a similar quorum-sensing circuit to BB120 but with three distinct differences: 1) 46DS40M4 lacks the canonical HAI-1 autoinducer LuxM synthase but has an active LuxN 47 receptor, 2) the quorum regulatory small RNAs (Qrrs) are not solely regulated by autoinducer 48 signaling through the response regulator LuxO, and 3) the DS40M4 LuxR regulon is <100 49 genes, which is relatively small compared to the >400 genes regulated in BB120. This work 50 illustrates that DS40M4 is a tractable and relevant model strain for studying quorum-sensing 51 phenotypes in Vibrio campbellii. 52 53 Importance 54 Wild isolates of bacterial type strains can yield important information about traits that 55 vary within species. Here, we compare the recently sequenced isolate of Vibrio campbellii 56 DS40M4 to the canonical lab type strain BB120 and examine several phenotypes that define 57 this species, including quorum sensing, bioluminescence, and biofilm formation. Importantly, 58DS40M4 is naturally transformable with exogenous DNA, which allows for the rapid generation 59 of mutants in a laboratory setting. By exploiting natural transformation, we genetically dissected 60 the functions of BB120 quorum-sensing system homologs in the DS40M4 strain, including two-61 component signaling systems, transcriptional regulators, and small RNAs. Our results show 62 important distinctions between the quorum-sensing circuits of these two strains that underscore 63 the need to examine wild isolates alongside type strains. 64 65 66 3 Introduction 67 Quorum sensing is a form of cell-cell communication between bacteria in which 68 individual cells synthesize and respond to signaling molecules called autoinducers. High 69 concentrations of autoinducers trigger changes in gene...