A novel, symbiotic bacterium isolated from marine shipworm secretes proteolytic activity

Greene, Richard V.; Cotta, Michael A.; Griffin, H. L.

doi:10.1007/bf01570881

Cited by 25 publications

(19 citation statements)

References 10 publications

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“…To determine total protease activity, cultures of PA14 were stab inoculated on medium containing 0.8% nutrient broth (Luria) and 1.5% powdered skim milk amended with 1 mM or 5 mM SA and were incubated at 37°C for 12 to 24 h before visual inspection for a zone of clearing. The same procedure was followed for elastase activity except that 0.5% elastin (Sigma, St. Louis, MO) was incorporated into the medium in place of 1.5% skim milk and cultures were incubated for 48 h. Protease activity was quantified using a modification of the method described by Greene et al (22). Bacterial cultures were grown with and without added SA in 50 ml of 5% peptone and 0.25% tryptic soy broth (PTSB) at 37°C for 24 h. The supernatants were collected and filter purified using a 0.22-m nylon filter.…”

Section: Methodsmentioning

confidence: 99%

Down Regulation of Virulence Factors of Pseudomonas aeruginosa by Salicylic Acid Attenuates Its Virulence on Arabidopsis thaliana and Caenorhabditis elegans

et al. 2005

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Salicylic acid (SA) is a phenolic metabolite produced by plants and is known to play an important role in several physiological processes, such as the induction of plant defense responses against pathogen attack. Here, using the Arabidopsis thaliana-Pseudomonas aeruginosa pathosystem, we provide evidence that SA acts directly on the pathogen, down regulating fitness and virulence factor production of the bacteria. Pseudomonas aeruginosa PA14 showed reduced attachment and biofilm formation on the roots of the Arabidopsis mutants lox2 and cpr5-2, which produce elevated amounts of SA, as well as on wild-type Arabidopsis plants primed with exogenous SA, a treatment known to enhance endogenous SA concentration. Salicylic acid at a concentration that did not inhibit PA14 growth was sufficient to significantly affect the ability of the bacteria to attach and form biofilm communities on abiotic surfaces. Furthermore, SA down regulated three known virulence factors of PA14: pyocyanin, protease, and elastase. Interestingly, P. aeruginosa produced more pyocyanin when infiltrated into leaves of the Arabidopsis transgenic line NahG, which accumulates less SA than wild-type plants. This finding suggests that endogenous SA plays a role in down regulating the synthesis and secretion of pyocyanin in vivo. To further test if SA directly affects the virulence of P. aeruginosa, we used the Caenorhabiditis elegans-P. aeruginosa infection model. The addition of SA to P. aeruginosa lawns significantly diminished the bacterium's ability to kill the worms, without affecting the accumulation of bacteria inside the nematodes' guts, suggesting that SA negatively affects factors that influence the virulence of P. aeruginosa. We employed microarray technology to identify SA target genes. These analyses showed that SA treatment affected expression of 331 genes. It selectively repressed transcription of exoproteins and other virulence factors, while it had no effect on expression of housekeeping genes. Our results indicate that in addition to its role as a signal molecule in plant defense responses, SA works as an anti-infective compound by affecting the physiology of P. aeruginosa and ultimately attenuating its virulence.Pseudomonas aeruginosa is a prevalent opportunistic pathogen in humans, causing chronic lung infections in cystic fibrosis patients, burn victims, and other immunocompromised people (61, 62). Pathogenesis of P. aeruginosa is mediated by a suite of cell-associated and excreted virulence factors. The cell-associated factors include flagella that aid in motility, systems that are involved in the delivery of effector proteins into the host cells (67), and lipopolysaccharide that suppresses host immune responses as well as being involved in the establishment of persistent infections (13). Secreted factors such as elastase and protease cause the degradation of host proteins such as elastin, collagen, and transferrins, destroying the integrity of the host tissues (2, 34), while low-molecular-weight toxins such as pyocyanin affect mu...

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Section: Methodsmentioning

confidence: 99%

Down Regulation of Virulence Factors of Pseudomonas aeruginosa by Salicylic Acid Attenuates Its Virulence on Arabidopsis thaliana and Caenorhabditis elegans

et al. 2005

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“…Symbionts isolated from seven shipworm host species are currently maintained in culture (this study and reference 35). In vitro gill isolates synthesize both cellulolytic and proteolytic enzymes for digestion, as well as nitrogenase for atmospheric nitrogen fixation (14,15,16). It has been suggested that these microbially derived enzymes provide the bivalve host with the ability to thrive on a diet of wood alone.…”

mentioning

confidence: 99%

Bacterial Symbiont Transmission in the Wood-Boring Shipworm Bankia setacea (Bivalvia: Teredinidae)

Sipe

Wilbur

Cary

2000

Appl Environ Microbiol

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The Teredinidae (shipworms) are a morphologically diverse group of marine wood-boring bivalves that are responsible each year for millions of dollars of damage to wooden structures in estuarine and marine habitats worldwide. They exist in a symbiosis with cellulolytic nitrogen-fixing bacteria that provide the host with the necessary enzymes for survival on a diet of wood cellulose. These symbiotic bacteria reside in distinct structures lining the interlamellar junctions of the gill. This study investigated the mode by which these nutritionally essential bacterial symbionts are acquired in the teredinid Bankia setacea. Through 16S ribosomal DNA (rDNA) sequencing, the symbiont residing within the B. setacea gill was phylogenetically characterized and shown to be distinct from previously described shipworm symbionts. In situ hybridization using symbiontspecific 16S rRNA-directed probes bound to bacterial ribosome targets located within the host gill coincident with the known location of the gill symbionts. These specific probes were then used as primers in a PCR-based assay which consistently detected bacterial rDNA in host gill (symbiont containing), gonad tissue, and recently spawned eggs, demonstrating the presence of symbiont cells in host ovary and offspring. These results suggest that B. setacea ensures successful inoculation of offspring through a vertical mode of symbiont transmission and thereby enables a broad distribution of larval settlement.

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“…One enzymatic activity unity was arbitrarily defined as the amount of enzyme that increments OD 440 nm in 0.001 unity of absorbance per min of digestion 15 . The proportional enzymatic activities were estimated as the enzymatic unities per reduced XTT absorbances 14 .…”

Section: Planktonic Growthmentioning

confidence: 99%

Modulatory Effects of Dexamethasone upon Virulence Attributes of Pseudomonas Aeruginosa ATCC® 27853™

Ferreir¹,

Gregi²,

Alani³

et al. 2015

Insight Microbiology

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Background: Pseudomonas aeruginosa is a versatile and opportunistic human pathogen whose virulence derives from several factors as extracellular proteases, pyocyanin and pyoverdin and biofilm formation, among others. Dexamethasone is a glucocorticoid widely used as anti-inflammatory. Despite its immunosuppressive role, the interplay between dexamethasone and bacterial virulence remains uncovered. Objectives: In this study, the dexamethasone modulatory effects on planktonic growth, surface adhesion, cell surface hydrophobicity, biofilm formation and pyocyanin and protease secretion by P. aeruginosa ATCC®27853TM was evaluated. Results and Conclusion: The results showed that dexamethasone decreases planktonic cell growth rate and biofilm development. In other hand, the medicine increases proportional pyocyanin secretion and, in high concentrations, collaborates with the bacterial adherence.

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A novel, symbiotic bacterium isolated from marine shipworm secretes proteolytic activity

Cited by 25 publications

References 10 publications

Down Regulation of Virulence Factors of Pseudomonas aeruginosa by Salicylic Acid Attenuates Its Virulence on Arabidopsis thaliana and Caenorhabditis elegans

Down Regulation of Virulence Factors of Pseudomonas aeruginosa by Salicylic Acid Attenuates Its Virulence on Arabidopsis thaliana and Caenorhabditis elegans

Bacterial Symbiont Transmission in the Wood-Boring Shipworm Bankia setacea (Bivalvia: Teredinidae)

Modulatory Effects of Dexamethasone upon Virulence Attributes of Pseudomonas Aeruginosa ATCC® 27853™

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