Involvement of thehapgene (mucinase) in the survival ofVibrio choleraeO1 in association with the blue-green alga,Anabaenasp.

Islam, Mohammad Shafiqul; Goldar, Md. Muniruzzaman; Morshed, Muhammad; Khan, MA; Sack, R. Bradley

doi:10.1139/w02-073

Cited by 21 publications

(19 citation statements)

References 28 publications

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“…cholerae and many related Gram-negative bacteria have been shown to become nonculturable under specific experimental conditions, although the time required for these cells to become nonculturable is variable (8,9,(19)(20)(21). In this study, V. cholerae O1 cells in all microcosms became nonculturable on TCBS agar within 10-15 days, as has been reported by other investigators (19)(20)(21).…”

Section: Discussionsupporting

confidence: 81%

Viable but nonculturable Vibrio cholerae O1 in biofilms in the aquatic environment and their role in cholera transmission

Alam

Sultana

Nair

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

209

175

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Vibrio cholerae persists in aquatic environments predominantly in a nonculturable state. In this study coccoid, nonculturable V. cholerae O1 in biofilms maintained for 495 days in Mathbaria, Bangladesh, pond water became culturable upon animal passage. Culturability, biofilm formation, and the wbe, ctxA, and rstR2 genes were monitored by culture, direct fluorescent antibody (DFA), and multiplex PCR. DFA counts were not possible after formation of biofilm. Furthermore, wbe, but not ctxA, were amplifiable, even after incubation for 54 and 68 days at room temperature (Ϸ25°C) and 4°C, respectively, when no growth was detectable. Slower biofilm formation and extended culturability were observed for cultures incubated at 4°C, compared with Ϸ25°C, suggesting biofilm production to be temperature dependent and linked to loss of culturability. Small colonies appearing after incubation in microcosms for 54 and 68 days at 25°C and 4°C, respectively, were wbe positive and ctxA and rstR2 negative, indicating loss of bacteriophage CTX⌽. The coccoid V. cholerae O1 observed as free cells in microcosms incubated for 495 days could not be cultured, but biofilms in the same microcosms yielded culturable cells. It is concluded that biofilms can act as a reservoir for V. cholerae O1 between epidemics because of its long-term viability in biofilms. In contrast to biofilms produced in Mathbaria pond water, V. cholerae O1 in biofilms present in cholera stools and incubated under identical conditions as the Mathbaria pond water biofilms could not be cultured after 2 months, indicating that those V. cholerae cells freshly discharged into the environment are significantly less robust than cells adapted to environmental conditions. Bangladesh ͉ bacteriophage CTX⌽ ͉ DFA ͉ multiplex-PCR ͉ ctxA C holera continues to pose a serious health threat globally, notably in those countries where clean drinking water is not available to local populations. Vibrio cholerae serogroups O1 and O139 are associated with epidemic and pandemic cholera. Cholera is endemic in the Ganges delta, occurring twice yearly in epidemic form (1). It is also a major health problem for countries of Africa, Latin America, and Asia (2). V. cholerae O1 is native to both marine and fresh water environments and exists in association with plankton (3). In general, it can be isolated from only 1% of water samples collected during epidemic periods and rarely, if ever, between epidemics (4). However, fluorescent antibody-based studies show that V. cholerae O1 is, nevertheless, present in aquatic environments throughout the year (5). Furthermore, the presence of nonculturable V. cholerae O1 is confirmed by molecular methods (6). The question of whether such nonculturable cells in aquatic environments are capable of returning to an actively growing state to initiate cholera epidemics has been debated.Extensive studies have shown that V. cholerae O1 becomes coccoid and enters into a nonculturable state in the environment when conditions are not conducive to active growth (5, 7). Some of...

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Section: Discussionsupporting

confidence: 81%

Viable but nonculturable Vibrio cholerae O1 in biofilms in the aquatic environment and their role in cholera transmission

Alam

Sultana

Nair

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

209

175

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“…cholerae O139 strains were cultured on taurocholate tellurite gelatine agar (TTGA ) plates at 37°C for 18-24 hrs by following small modification of previously published method [1] . In previous method, inoculum was prepared in 7 mL 0.1% NaCl solution (pH 7.0) but in this experiment prepared by mixing properly a loopful of culture in 5 mL 0.1% NaCl (pH 7.0) saline water.…”

Section: Methodsmentioning

confidence: 99%

“…The samples were cultured in two TTGA media [21] seperately. The steps of this experiment were followed by the procedures described by Islam et al [1] with few changes in amount. In brief, 0.05 gm wet weight of algae were collected with the help of a sterile spatula and then gently squeezed on the glass walls of the flasks to remove the excess water.…”

Section: Methodsmentioning

confidence: 99%

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Survival of Vibrio cholerae O139 in Association with Anabaena variabilis in Four Different Microcosoms

Ferdous¹

2009

American J. of Applied Sciences

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Investigation was carried out to see the association of Vibrio cholerae O139 with Anabaena variabilis, in four different types of water. Conventional media were used to count culturable bacteria while epi fluorescence microscopy to count the viable but non culturable (VBNC) V. cholerae O139. It was found that the culturable form of V. cholerae O139 found 9 days in the control artificial sea water and 4 days in river water and BOD dilution water. However, in association with A. variabilis, culturable form was found for 6 days in artificial sea water, 4 days in distilled water, 1 day in BOD dilution water, 4 days in river water. The bacterial count of surrounding water decreased inversely with the bacterial count in association with algae. Among these four microcosm water, associations of V. cholerae O139 with algae was higher in artificial sea water. In control water of four microcosms, direct viable count (DVC) gradually decreased with time. In association with algae the DVC increased after some time then reached a peak in 4-8 days depending on the types of water. The epi fluorescence microscopy indicated that V. cholerae O139 survived for more than one month in association with algae. Present study demonstrated that survival of V. cholerae O139 appears to get advantages in association with A. variabilis in different types of water.

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“…A number of genes have been previously implicated in environmental survival, and this has already led to a better understanding of the genetic basis for V. cholerae adaptations. Genes have been uncovered which are important for biofilm formation (for examples, see references 68 and 73), zooplankton association (9), survival with filamentous blue cyanobacteria (28), and the degradation of nonbiting midge (Chironomos sp.) egg masses (24).…”

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confidence: 99%

A Glimpse into the Expanded Genome Content of Vibrio cholerae through Identification of Genes Present in Environmental Strains

et al. 2005

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Vibrio cholerae has multiple survival strategies which are reflected both in its broad distribution in many aquatic environments and its high genotypic diversity. To obtain additional information regarding the content of the V. cholerae genome, suppression subtractive hybridization (SSH) was used to prepare libraries of DNA sequences from two southern California coastal isolates which are divergent or absent in the clinical strain V. cholerae O1 El Tor N16961. More than 1,400 subtracted clones were sequenced. This revealed the presence of novel sequences encoding functions related to cell surface structures, transport, metabolism, signal transduction, luminescence, mobile elements, stress resistance, and virulence. Flanking sequence information was determined for loci of interest, and the distribution of these sequences was assessed for a collection of V. cholerae strains obtained from southern California and Mexican environments. This led to the surprising observation that sequences related to the toxin genes toxA, cnf1, and exoY are widespread and more common in these strains than those of the cholera toxin genes which are a hallmark of the pandemic strains of V. cholerae. Gene transfer among these strains could be facilitated by a 4.9-kbp plasmid discovered in one isolate, which possesses similarity to plasmids from other environmental vibrios. By investigating some of the nucleotide sequence basis for V. cholerae genotypic diversity, DNA fragments have been uncovered which could promote survival in coastal environments. Furthermore, a set of genes has been described which could be involved in as yet undiscovered interactions between V. cholerae and eukaryotic organisms.Although it is best known as the causative agent of the human disease cholera, Vibrio cholerae is also an autochthonous inhabitant of many aquatic environments, including estuarine and coastal waters (13). Indeed, the great majority of its more than 200 serogroups, excluding O1 and O139, are not associated with epidemic disease. V. cholerae has been isolated routinely from many aquatic environments throughout the world, often in association with plankton, plants, invertebrates, and fish, and there are some reports of its presence in water birds, seals, and diseased farm animals (2,26,27,33,43,56,66). The prevalence of V. cholerae in the environment is influenced by temperature and salinity (reviewed in reference 42) as well concentrations of dissolved organic carbon (44). A number of genes have been previously implicated in environmental survival, and this has already led to a better understanding of the genetic basis for V. cholerae adaptations. Genes have been uncovered which are important for biofilm formation (for examples, see references 68 and 73), zooplankton association (9), survival with filamentous blue cyanobacteria (28), and the degradation of nonbiting midge (Chironomos sp.) egg masses (24). These genes clearly provide V. cholerae with mechanisms to avoid environmental stresses and obtain nutrients in aquatic environments.The evol...

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Involvement of thehapgene (mucinase) in the survival ofVibrio choleraeO1 in association with the blue-green alga,Anabaenasp.

Cited by 21 publications

References 28 publications

Viable but nonculturable Vibrio cholerae O1 in biofilms in the aquatic environment and their role in cholera transmission

Viable but nonculturable Vibrio cholerae O1 in biofilms in the aquatic environment and their role in cholera transmission

Survival of Vibrio cholerae O139 in Association with Anabaena variabilis in Four Different Microcosoms

A Glimpse into the Expanded Genome Content of Vibrio cholerae through Identification of Genes Present in Environmental Strains

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