scholarly journals Transcriptional Profile during Deoxycholate-Induced Sporulation in a Clostridium perfringens Isolate Causing Foodborne Illness

2016 ◽  
Vol 82 (10) ◽  
pp. 2929-2942 ◽  
Author(s):  
Mayo Yasugi ◽  
Daisuke Okuzaki ◽  
Ritsuko Kuwana ◽  
Hiromu Takamatsu ◽  
Masaya Fujita ◽  
...  
Keyword(s):  
Bile Salt ◽  
Clostridium Perfringens ◽  
Bile Salts ◽  
Intestinal Tract ◽  
Critical Role ◽  
Type A ◽  
Foodborne Illness ◽  
Common Source ◽  
Content Type ◽  
Small Intestinal

ABSTRACTClostridium perfringenstype A is a common source of foodborne illness (FBI) in humans. Vegetative cells sporulate in the small intestinal tract and produce the major pathogenic factorC. perfringensenterotoxin. Although sporulation plays a critical role in the pathogenesis of FBI, the mechanisms inducing sporulation remain unclear. Bile salts were shown previously to induce sporulation, and we confirmed deoxycholate (DCA)-induced sporulation inC. perfringensstrain NCTC8239 cocultured with human intestinal epithelial Caco-2 cells. In the present study, we performed transcriptome analyses of strain NCTC8239 in order to elucidate the mechanism underlying DCA-induced sporulation. Of the 2,761 genes analyzed, 333 were up- or downregulated during DCA-induced sporulation and included genes for cell division, nutrient metabolism, signal transduction, and defense mechanisms. In contrast, the virulence-associated transcriptional regulators (the VirR/VirS system, theagrsystem,codY, andabrB) were not activated by DCA. DCA markedly increased the expression of signaling molecules controlled by Spo0A, the master regulator of the sporulation process, whereas the expression ofspo0Aitself was not altered in the presence or absence of DCA. The phosphorylation of Spo0A was enhanced in the presence of DCA. Collectively, these results demonstrated that DCA induced sporulation, at least partially, by facilitating the phosphorylation of Spo0A and activating Spo0A-regulated genes in strain NCTC8239 while altering the expression of various genes.IMPORTANCEDisease caused byClostridium perfringenstype A consistently ranks among the most common bacterial foodborne illnesses in humans in developed countries. The sporulation ofC. perfringensin the small intestinal tract is a key event for its pathogenesis, but the factors and underlying mechanisms by whichC. perfringenssporulatesin vivocurrently remain unclear. Bile salts, major components of bile, which is secreted from the liver for the emulsification of lipids, were shown to induce sporulation. However, the mechanisms underlying bile salt-induced sporulation have not yet been clarified. In the present study, we demonstrate that deoxycholate (one of the bile salts) induces sporulation by facilitating the phosphorylation of Spo0A and activating Spo0A-regulated genes using a transcriptome analysis. Thus, this study enhances our understanding of the mechanisms underlying sporulation, particularly that of bile salt-induced sporulation, inC. perfringens.

scholarly journals Genotypic and Phenotypic Characterization of Clostridium perfringens Isolates from Darmbrand Cases in Post-World War II Germany

2012 ◽  
Vol 80 (12) ◽  
pp. 4354-4363 ◽  
Author(s):  
Menglin Ma ◽  
Jihong Li ◽  
Bruce A. McClane
Keyword(s):  
World War Ii ◽  
Heat Resistance ◽  
Clostridium Perfringens ◽  
Type A ◽  
World War ◽  
Content Type ◽  
Post World War Ii ◽  
Heat Resistant ◽  
Type C ◽  
Beta Toxin

ABSTRACTClostridium perfringenstype C strains are the only non-type-A isolates that cause human disease. They are responsible for enteritis necroticans, which was termed Darmbrand when occurring in post-World War II Germany. Darmbrand strains were initially classified as type F because of their exceptional heat resistance but later identified as type C strains. Since only limited information exists regarding Darmbrand strains, this study genetically and phenotypically characterized seven 1940s era Darmbrand-associated strains. Results obtained indicated the following. (i) Five of these Darmbrand isolates belong to type C, carry beta-toxin (cpb) and enterotoxin (cpe) genes on large plasmids, and express both beta-toxin and enterotoxin. The other two isolates arecpe-negative type A. (ii) All seven isolates produce highly heat-resistant spores withD100values (the time that a culture must be kept at 100°C to reduce its viability by 90%) of 7 to 40 min. (iii) All of the isolates surveyed produce the same variant small acid-soluble protein 4 (Ssp4) made by type A food poisoning isolates with a chromosomalcpegene that also produce extremely heat-resistant spores. (iv) The Darmbrand isolates share a genetic background with type A chromosomal-cpe-bearing isolates. Finally, it was shown that both thecpeandcpbgenes can be mobilized in Darmbrand isolates. These results suggest thatC. perfringenstype A and C strains that cause human food-borne illness share a spore heat resistance mechanism that likely favors their survival in temperature-abused food. They also suggest possible evolutionary relationships between Darmbrand strains and type A strains carrying a chromosomalcpegene.

scholarly journals Molecular basis of bile-salt- and iron-induced enterohaemorrhagic E. coli resistance to cationic antimicrobial peptides

Microbiology ◽  
2020 ◽  
Vol 166 (12) ◽  
pp. 1149-1159
Author(s):  
Chhatra B. Kunwar ◽  
Sarah Birstonas ◽  
Joseph B. McPhee ◽  
Debora Barnett Foster
Keyword(s):  
Gastrointestinal Tract ◽  
Bile Salt ◽  
Bile Salts ◽  
Type Species ◽  
Two Component System ◽  
Component System ◽  
Content Type ◽  
Link Type ◽  
Two Component ◽  
Mild Acid

Colonization of the gastrointestinal tract by enterohaemorrhagic Escherichia coli (EHEC) is critically dependent on its ability to sense and respond to various microenvironments within the host. EHEC exposure to physiologically relevant levels of bile salts upregulates the two-component system, pmrAB, and the arnBCADTEF operon, resulting in lipopolysaccharide modification and increased resistance to the cationic antimicrobial peptide, polymyxin B (PMB). A similar pmrAB- and arn-dependent PMB resistance has been observed in Salmonella enterica in the presence of ferric iron. Limiting magnesium levels and mild acid can also induce Salmonella resistance to PMB through another two-component system, PhoPQ and the connector protein, PmrD. This study aims to evaluate the relative contributions of a bile-salt mix (BSM), iron, limiting magnesium as well as the roles of pmrAB, phoPQ and pmrD to EHEC’s resistance to PMB. Killing assays show that EHEC treatment with the BSM or iron under excess magnesium and neutral pH conditions induces a pmrAB-dependent, phoP-independent PMB resistance. By contrast, exposure to limiting magnesium triggers a pmrB-, phoP- and pmrD-dependent PMB resistance. The iron-induced PMB resistance is independent of phoP and pmrD under limiting magnesium conditions while the bile-salt-induced PMB resistance is independent of pmrD only under non-PhoP-inducing conditions. GFP-pmrD transcriptional reporter studies reveal that the limiting magnesium enhances pmrD expression, which is repressed upon additional exposure to either BSM or iron. Our results also show that exposure to mild acid enhances PMB resistance in a pmrD-independent manner and GFP reporter results confirm minimal expression of pmrD at this pH regardless of the magnesium level. This study provides novel insights into how EHEC differentially employs PmrAB, PhoPQ and PmrD to monitor and respond to bile salts, iron, acidic pH and magnesium typically encountered within the gastrointestinal tract in order to modulate its survival against cationic antimicrobial peptides.

scholarly journals The MarR Family Regulator BmrR Is Involved in Bile Tolerance ofBifidobacterium longumBBMN68 via Controlling the Expression of an ABC Transporter

2018 ◽  
Vol 85 (3) ◽  
Author(s):  
Qi Xu ◽  
Zhengyuan Zhai ◽  
Haoran An ◽  
Yang Yang ◽  
Jia Yin ◽  
...  
Keyword(s):  
Gastrointestinal Tract ◽  
Stress Response ◽  
Heterologous Expression ◽  
Bile Salts ◽  
Intestinal Tract ◽  
Bifidobacterium Longum ◽  
Transcriptional Regulator ◽  
Mobility Shift ◽  
Content Type ◽  
Bile Tolerance

ABSTRACTIn order to colonize the human gastrointestinal tract and exert their beneficial effects, bifidobacteria must effectively cope with toxic bile salts in the intestine; however, the molecular mechanism underlying bile tolerance is poorly understood. In this study, heterologous expression of a MarR family transcriptional regulator, BmrR, significantly reduced the ox bile resistance ofLactococcus lactisNZ9000, suggesting that BmrR might play a role in the bile stress response.In silicoanalysis combined with reverse transcription-PCR assays demonstrated thatbmrRwas cotranscribed withbmrAandbmrB, which encoded multidrug resistance (MDR) ABC transporters. Promoter prediction and electrophoretic mobility shift assays revealed that BmrR could autoregulate thebmrRABoperon by binding to thebmrbox (ATTGTTG-6nt-CAACAAT) in the promoter region. Moreover, heterologous expression ofbmrAandbmrBinL. lactisyielded 20.77-fold higher tolerance to 0.10% ox bile, compared to the wild-type strain. In addition, ox bile could disrupt the DNA binding activity of BmrR as a ligand. Taken together, our findings indicate that thebmrRABoperon is autoregulated by the transcriptional regulator BmrR and ox bile serves as an inducer to activate the bile efflux transporter BmrAB in response to bile stress inBifidobacterium longumBBMN68.IMPORTANCEBifidobacteria are natural inhabitants of the human intestinal tract. Some bifidobacterial strains are used as probiotics in fermented dairy production because of their health-promoting effects. Following consumption, bifidobacteria colonize the lower intestinal tract, where the concentrations of bile salts remain nearly 0.05% to 2.0%. Bile salts, as detergent-like antimicrobial compounds, can cause cellular membrane disruption, protein misfolding, and DNA damage. Therefore, tolerance to physiological bile stress is indeed essential for bifidobacteria to survive and to exert probiotic effects in the gastrointestinal tract. InB. longumBBMN68, the MarR-type regulator BmrR was involved in the bile stress response by autoregulating thebmrRABoperon, and ox bile as an inducer could increase the expression of the BmrAB transporter to enhance the bile tolerance of BBMN68. Our study represents a functional analysis of thebmrRABoperon in the bile stress response, which will provide new insights into bile tolerance mechanisms inBifidobacteriumand other bacteria.

scholarly journals Calcium Enhances Bile Salt-Dependent Virulence Activation in Vibrio cholerae

2016 ◽  
Vol 85 (1) ◽  
Author(s):  
Amanda J. Hay ◽  
Menghua Yang ◽  
Xiaoyun Xia ◽  
Zhi Liu ◽  
Justin Hammons ◽  
...  
Keyword(s):  
Bile Salt ◽  
Vibrio Cholerae ◽  
Bile Salts ◽  
Diarrheal Disease ◽  
Content Type ◽  
Inner Membrane Protein ◽  
Virulence Regulator ◽  
Host Signals

ABSTRACT Vibrio cholerae is the causative bacteria of the diarrheal disease cholera, but it also persists in aquatic environments, where it displays an expression profile that is distinct from that during infection. Upon entry into the host, a tightly regulated circuit coordinates the induction of two major virulence factors: cholera toxin and a toxin-coregulated pilus (TCP). It has been shown that a set of bile salts, including taurocholate, serve as host signals to activate V. cholerae virulence through inducing the activity of the transmembrane virulence regulator TcpP. In this study, we investigated the role of calcium, an abundant mental ion in the gut, in the regulation of virulence. We show that whereas Ca2+ alone does not affect virulence, Ca2+ enhances bile salt-dependent virulence activation for V. cholerae. The induction of TCP by murine intestinal contents is counteracted when Ca2+ is depleted by the high-affinity calcium chelator EGTA, suggesting that the calcium present in the gut is a relevant signal for V. cholerae virulence induction in vivo. We further show that Ca2+ enhances virulence by promoting bile salt-induced TcpP-TcpP interaction. Moreover, fluorescence recovery after photobleaching (FRAP) analysis demonstrated that exposure to bile salts and Ca2+ together decreases the recovery rate for fluorescently labeled TcpP, but not for another inner membrane protein (TatA). Together, these data support a model in which physiological levels of Ca2+ may result in altered bile salt-induced TcpP protein movement and activity, ultimately leading to an increased expression of virulence.

scholarly journals Synergistic Effects of Clostridium perfringens Enterotoxin and Beta Toxin in Rabbit Small Intestinal Loops

2014 ◽  
Vol 82 (7) ◽  
pp. 2958-2970 ◽  
Author(s):  
Menglin Ma ◽  
Abhijit Gurjar ◽  
James R. Theoret ◽  
Jorge P. Garcia ◽  
Juliann Beingesser ◽  
...  
Keyword(s):  
Clostridium Perfringens ◽  
Synergistic Effects ◽  
Fluid Accumulation ◽  
Content Type ◽  
Positive Type ◽  
Intestinal Infections ◽  
Type C ◽  
Small Intestinal ◽  
Beta Toxin ◽  
Enteritis Necroticans

ABSTRACTThe ability ofClostridium perfringenstype C to cause human enteritis necroticans (EN) is attributed to beta toxin (CPB). However, many EN strains also expressC. perfringensenterotoxin (CPE), suggesting that CPE could be another contributor to EN. Supporting this possibility, lysate supernatants from modified Duncan-Strong sporulation (MDS) medium cultures of three CPE-positive type C EN strains caused enteropathogenic effects in rabbit small intestinal loops, which is significant since CPE is produced only during sporulation and sinceC. perfringenscan sporulate in the intestines. Consequently, CPE and CPB contributions to the enteropathogenic effects of MDS lysate supernatants of CPE-positive type C EN strain CN3758 were evaluated using isogeniccpbandcpenull mutants. While supernatants of wild-type CN3758 MDS lysates induced significant hemorrhagic lesions and luminal fluid accumulation, MDS lysate supernatants of thecpbandcpemutants caused neither significant damage nor fluid accumulation. This attenuation was attributable to inactivating these toxin genes since complementing thecpemutant or reversing thecpbmutation restored the enteropathogenic effects of MDS lysate supernatants. Confirming that both CPB and CPE are needed for the enteropathogenic effects of CN3758 MDS lysate supernatants, purified CPB and CPE at the same concentrations found in CN3758 MDS lysates also acted together synergistically in rabbit small intestinal loops; however, only higher doses of either purified toxin independently caused enteropathogenic effects. These findings provide the first evidence for potential synergistic toxin interactions duringC. perfringensintestinal infections and support a possible role for CPE, as well as CPB, in some EN cases.

scholarly journals NanR Regulates Sporulation and Enterotoxin Production byClostridium perfringensType F Strain F4969

2018 ◽  
Vol 86 (10) ◽  
Author(s):  
Eric Mi ◽  
Jihong Li ◽  
Bruce A. McClane
Keyword(s):  
Sialic Acid ◽  
Clostridium Perfringens ◽  
Vegetative Growth ◽  
Foodborne Illness ◽  
Null Mutant ◽  
Wild Type ◽  
Gastrointestinal Infections ◽  
Content Type ◽  
Antibiotic Associated Diarrhea ◽  
Uptake And Metabolism

ABSTRACTClostridium perfringenstype F strains, which produceC. perfringensenterotoxin (CPE), are a major cause of gastrointestinal infections, including the second most prevalent bacterial foodborne illness and 5 to 10% cases of antibiotic-associated diarrhea. Virulence of type F strains is primarily ascribable to CPE, which is synthesized only during sporulation. Many type F strains also produce NanI sialidase and carry ananoperon that likely facilitates uptake and metabolism of sialic acid liberated from glycoconjugates by NanI. During vegetative growth of type F strain F4969, NanR can regulate expression ofnanI. Given their importance for type F disease, the current study investigated whether NanR can also influence sporulation and CPE production when F4969 or isogenic derivatives are cultured in modified Duncan-Strong sporulation (MDS) medium. An isogenic F4969nanRnull mutant displayed much less sporulation and CPE production but more NanI production than wild-type F4969, indicating that NanR positively regulates sporulation and CPE production but represses NanI production in MDS. Results for thenanRmutant also demonstrated that NanR regulates expression of thenanoperon. AnanI nanRdouble null mutant mirrored the outcome of thenanRnull mutant strain but with a stronger inhibition of sporulation and CPE production, even after overnight incubation. Coupled with results using ananInull mutant, which had no impairment of sporulation or CPE production, NanR appears to carefully modulate the availability of NanI,nanoperon-encoded proteins and sialic acid to provide sufficient nutrients to sustain sporulation and CPE production when F4969 is cultured in MDS medium.

scholarly journals Draft Genome Sequence of a New Methanobacterium Strain Potentially Resistant to Bile Salts, Isolated from Deer Feces

2020 ◽  
Vol 9 (32) ◽  
Author(s):  
Heleen T. Ouboter ◽  
Stefanie Berger ◽  
Erbil Güngör ◽  
Mike S. M. Jetten ◽  
Cornelia U. Welte
Keyword(s):  
Salt Tolerance ◽  
Bile Salt ◽  
Genome Sequence ◽  
Bile Salts ◽  
Draft Genome ◽  
Draft Genome Sequence ◽  
Bile Salt Hydrolase ◽  
High Quality ◽  
Content Type ◽  
Hydrogenotrophic Methanogen

ABSTRACT We present the high-quality draft genome of Methanobacterium subterraneum DF, a hydrogenotrophic methanogen that was isolated from deer feces. This organism has potentially been overlooked in previous studies. Interestingly, its genome encoded bile salt hydrolase, a crucial enzyme for bile salt tolerance that is found in gut organisms.

scholarly journals A Synthetic Peptide Corresponding to the Extracellular Loop 2 Region of Claudin-4 Protects against Clostridium perfringens EnterotoxinIn VitroandIn Vivo

2014 ◽  
Vol 82 (11) ◽  
pp. 4778-4788 ◽  
Author(s):  
Archana Shrestha ◽  
Susan L. Robertson ◽  
Jorge Garcia ◽  
Juliann Beingasser ◽  
Bruce A. McClane ◽  
...  
Keyword(s):  
Clostridium Perfringens ◽  
Synthetic Peptide ◽  
Inhibitory Effect ◽  
Intestinal Loop ◽  
Extracellular Loop ◽  
Content Type ◽  
Potential Therapeutic Application ◽  
Small Intestinal

ABSTRACTClostridium perfringensenterotoxin (CPE) action starts when the toxin binds to claudin receptors. Claudins contain two extracellular loop domains, with the second loop (ECL-2) being slightly smaller than the first. CPE has been shown to bind to ECL-2 in receptor claudins. We recently demonstrated that Caco-2 cells (a naturally CPE-sensitive enterocyte-like cell line) can be protected from CPE-induced cytotoxicity by preincubating the enterotoxin with soluble full-length recombinant claudin-4 (rclaudin-4), which is a CPE receptor, but not with recombinant nonreceptor claudins, such asrclaudin-1. The current study evaluated whether a synthetic peptide corresponding to the claudin-4 ECL-2 sequence can similarly inhibit CPE actionin vitroandin vivo. Significant protection of Caco-2 cells was also observed using eitherrclaudin-4 or the claudin-4 ECL-2 peptide in both a preincubation assay and a coincubation assay. This inhibitory effect was specific, sincerclaudin-1 and a synthetic peptide based on the claudin-1 ECL-2 offered no protection to Caco-2 cells. However, the claudin-4 ECL-2 peptide was unable to neutralize cytotoxicity if CPE had already bound to Caco-2 cells. When the study was repeatedin vivousing a rabbit small intestinal loop assay, preincubation or coincubation of CPE with the claudin-4 ECL-2 peptide significantly and specifically inhibited the development of CPE-induced luminal fluid accumulation and histologic lesions in rabbit small intestinal loops. No similarin vivoprotection from CPE was afforded by the claudin-1 ECL-2 peptide. These results suggest that claudin-4 ECL-2 peptides should be further investigated for their potential therapeutic application against CPE-associated disease.

scholarly journals The Agr-Like Quorum-Sensing System Is Important for Clostridium perfringens Type A Strain ATCC 3624 To Cause Gas Gangrene in a Mouse Model

mSphere ◽  
2020 ◽  
Vol 5 (3) ◽  
Author(s):  
Mauricio A. Navarro ◽  
Jihong Li ◽  
Juliann Beingesser ◽  
Bruce A. McClane ◽  
Francisco A. Uzal
Keyword(s):  
Quorum Sensing ◽  
Mouse Model ◽  
Clostridium Perfringens ◽  
Regulatory System ◽  
Type A ◽  
Gas Gangrene ◽  
Null Mutant ◽  
Wild Type ◽  
Content Type

ABSTRACT Clostridium perfringens type A is involved in gas gangrene in humans and animals. Following a traumatic injury, rapid bacterial proliferation and exotoxin production result in severe myonecrosis. C. perfringens alpha toxin (CPA) and perfringolysin (PFO) are the main virulence factors responsible for the disease. Recent in vitro studies have identified an Agr-like quorum-sensing (QS) system in C. perfringens that regulates the production of both toxins. The system is composed of an AgrB membrane transporter and an AgrD peptide that interacts with a two-component regulatory system in response to fluctuations in the cell population density. In addition, a synthetic peptide named 6-R has been shown to interfere with this signaling mechanism, affecting the function of the Agr-like QS system in vitro. In the present study, C. perfringens type A strain ATCC 3624 and an isogenic agrB-null mutant were tested in a mouse model of gas gangrene. When mice were intramuscularly challenged with 106 CFU of wild-type ATCC 3624, severe myonecrosis and leukocyte aggregation occurred by 4 h. Similar numbers of an agrB-null mutant strain produced significantly less severe changes in the skeletal muscle of challenged mice. Complementation of the mutant to regain agrB expression restored virulence to wild-type levels. The burdens of all three C. perfringens strains in infected muscle were similar. In addition, animals injected intramuscularly with wild-type ATCC 3624 coincubated with the 6-R peptide developed less severe microscopic changes. This study provides the first in vivo evidence that the Agr-like QS system is important for C. perfringens type A-mediated gas gangrene. IMPORTANCE Clostridium perfringens type A strains produce toxins that are responsible for clostridial myonecrosis, also known as gas gangrene. Toxin production is regulated by an Agr-like quorum-sensing (QS) system that responds to changes in cell population density. In this study, we investigated the importance of this QS system in a mouse model of gas gangrene. Mice challenged with a C. perfringens strain with a nonfunctional regulatory system developed less severe changes in the injected skeletal muscle compared to animals receiving the wild-type strain. In addition, a synthetic peptide was able to decrease the effects of the QS in this disease model. These studies provide new understanding of the pathogenesis of gas gangrene and identified a potential therapeutic target to prevent the disease.

scholarly journals CodY Promotes Sporulation and Enterotoxin Production by Clostridium perfringens Type A Strain SM101

2017 ◽  
Vol 85 (3) ◽  
Author(s):  
Jihong Li ◽  
John C. Freedman ◽  
Daniel R. Evans ◽  
Bruce A. McClane
Keyword(s):  
Gene Expression ◽  
Clostridium Perfringens ◽  
Food Poisoning ◽  
Type A ◽  
Toxin Production ◽  
Null Mutant ◽  
Wild Type ◽  
Content Type ◽  
Type D ◽  
Epsilon Toxin

ABSTRACT Clostridium perfringens type D strains cause enterotoxemia and enteritis in livestock via epsilon toxin production. In type D strain CN3718, CodY was previously shown to increase the level of epsilon toxin production and repress sporulation. C. perfringens type A strains producing C. perfringens enterotoxin (CPE) cause human food poisoning and antibiotic-associated diarrhea. Sporulation is critical for C. perfringens type A food poisoning since spores contribute to transmission and resistance in the harsh food environment and sporulation is essential for CPE production. Therefore, the current study asked whether CodY also regulates sporulation and CPE production in SM101, a derivative of C. perfringens type A food-poisoning strain NCTC8798. An isogenic codY-null mutant of SM101 showed decreased levels of spore formation, along with lower levels of CPE production. A complemented strain recovered wild-type levels of both sporulation and CPE production. When this result was coupled with the earlier results obtained with CN3718, it became apparent that CodY regulation of sporulation varies among different C. perfringens strains. Results from quantitative reverse transcriptase PCR analysis clearly demonstrated that, during sporulation, codY transcript levels remained high in SM101 but rapidly declined in CN3718. In addition, abrB gene expression patterns varied significantly between codY-null mutants of SM101 and CN3718. Compared to the levels in their wild-type parents, the level of abrB gene expression decreased in the CN3718 codY-null mutant strain but significantly increased in the SM101 codY-null mutant strain, demonstrating CodY-dependent regulation differences in abrB expression between these two strains. This difference appears to be important since overexpression of the abrB gene in SM101 reduced the levels of sporulation and enterotoxin production, supporting the involvement of AbrB repression in regulating C. perfringens sporulation.

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