Cited by 17Fluoride Effects and RemovalMicrobial Community Ecology and PhysiologyFecal contamination and water quality

The DOI matches its Crossref record; 33 of the 34 references it cites were found in a registry or an index; 2 of the 37 sources its claims cite were checked for support.

Isolation and identification of high fluoride resistant bacteria from water samples of Dindigul district, Tamil Nadu, South India

Open access
Chellaiah, Edward Raja, Ravi, Pandeeswari, Uthandakalaipandian, Ramesh·2021·Current Research in Microbial Sciences

Abstract

Fluoride (F − ) pollution is one of the major issues in India and worldwide. Water samples were collected, and analyse the physicochemical characteristics. From the results, acceptable limit pH ranges, low and high electrical conductivity (EC) values, high-level of TDS (total dissolved solids) and chloride (Cl − ) values, less than desirable and higher than permissible F − concentrations (4.7 and 11 ppm) were found. At first, ninety-three colonies were screened using rapid hicoliform agar plates. After that, sixty-six F − resistant colonies were picked up from 50 mM NaF (Sodium fluoride) containing LB agar plates. Finally, eight isolates were showing a high degree of F − resistance (200–-300 mM NaF) and selected for further studies. High F − resistance isolates exhibited β and γ-haemolytic activities were determined in blood agar plates. F − resistant isolates showed their salt tolerances ranged from 4% to 7% NaCl and resistant to multiple antibiotics. Biochemical and 16S rRNA sequencing results showed that the F − resistant isolates were identified as Enterobacter cloacae strain 3, E. hormaechei strain 14, Enterobacter sp. strain 21, E. hormaechei strain 22, E . coli strain S2-9, Aeromonas caviae strain 31, A. caviae strain 32, A. caviae strain 34. All strains were submitted in the NCBI database with the accession numbers (MW131637, MW131639; MW131650-655). The F − resistant gene ‘crcB ’ gene was successfully amplified from the resistant isolates using gene-specific primers. These results have demonstrated that fluoride resistant bacteria would be useful for bacterial fluoride bioremediation near future.

Overview

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Written from the paper’s full text.

TL;DR

Eight high fluoride-resistant bacteria (200–300 mM NaF) were isolated from groundwater in Natham taluk, Dindigul district, Tamil Nadu, where two villages had 4.7 and 11 ppm fluoride. Isolates included *Aeromonas caviae*, *E. coli*, and *Enterobacter* spp.; *crcB* was amplified from *Aeromonas*, *E. coli*, and *Enterobacter*, and *Aeromonas* strains showed β-haemolysis and virulence genes lipase/elastase.

Key findings

  • Water fluoride ranged from 0.409 to 11 ppm; high F− was detected at Odukampatty (4.7 ppm) and Chellapanaikenpatti (11 ppm). pH ranged 6.13–6.94 (average 6.42), EC 2.13–1918 μS/cm, highest TDS 994 mg/L, and Cl− 50–800 mg/L.
  • Eight F−-resistant isolates were identified: *Enterobacter cloacae* strain 3, *E. hormaechei* strain 14, *Enterobacter* sp. strain 21, *E. hormaechei* strain 22, *E. coli* strain S2-9, and *A. caviae* strains 31, 32, and 34. Strains 31, 32, and 34 tolerated 300 mM NaF; strains 3, 14, 21, 22, and S2-9 tolerated up to 250 mM.
  • Salt tolerance ranged from 4% to 7% NaCl: isolates 3, 14, 21, and 22 grew at 7%; S2-9 at 5%; high F−-resistant *Aeromonas* isolates up to 4%. Isolates 3, 14, 21, 22, and S2-9 were γ-haemolytic; 31, 32, and 34 were β-haemolytic. All isolates were resistant to methicillin, rifampicin, penicillin, and vancomycin.
  • *crcB* was amplified from *E. coli* S2-9 (384 bp), *Aeromonas* (375 bp), and *Enterobacter* (375 bp). *Aeromonas* strains 31, 32, and 34 carried lipase (381 bp) and elastase (513 bp) genes; aerolysin, Act, and Ast were not detected.

Methods

  • Water samples were collected from boreholes and handpumps in selected villages of Natham taluk, Dindigul district, Tamil Nadu, South India. Physicochemical parameters measured included pH, EC, TDS, salinity, Cl−, and F−.
  • Bacteria were screened on rapid hicoliform agar, patched on LB agar with 50 mM NaF, and tested for maximum F− tolerance on LB agar containing 50–300 mM NaF. Further characterization used biochemical kits, blood agar, 26-antibiotic disc diffusion, and salt tolerance from 0% to 10% NaCl.
  • Genomic DNA was extracted; 16S rRNA was amplified, sequenced, and compared by BLAST. Specific PCR assays identified *Aeromonas* (16S rRNA, AER8/AER9, AluI restriction), *E. coli* (16E1/16E2, *lacZ*, *uidA*), virulence genes, and *crcB*.

Limitations

  • Stated limitations: Not stated in the paper.
  • Evident from the text: the study is limited to Natham taluk, Dindigul district, and characterizes only eight isolates.
  • Evident from the text: no quantitative fluoride removal or bioremediation experiments were performed, despite the conclusion suggesting future bioremoval use; antibiotic susceptibility tests were performed in duplicate with no statistical analysis described.

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Integrity signals

Registry

Crossref · 10.1016/j.crmicr.2021.100038

Cites

33 of 33 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Figures

Fig. 1 (a) β-Haemolytic activities of Aeromonas isolates estimated by blood agar plates, (b) Identification of Aeromonas species by using Aeromonas isolation medium base.
Fig. 1 (a) β-Haemolytic activities of Aeromonas isolates estimated by blood agar plates, (b) Identification of Aeromonas species by using Aeromonas isolation medium base.CC BY-NC-ND · PubMed Central
Fig. 2 (a) The isolate S2-9 producing metallic sheen on EMB agar, and (b) blue-green colonies on rapid hicoliform agar, hicrome coliform agar. E. coli 0157-H7 ATCC 43888 not formed metallic sheen colonies on EMB agar and used as a standard strain.
Fig. 2 (a) The isolate S2-9 producing metallic sheen on EMB agar, and (b) blue-green colonies on rapid hicoliform agar, hicrome coliform agar. E. coli 0157-H7 ATCC 43888 not formed metallic sheen colonies on EMB agar and used as a standard strain.CC BY-NC-ND · PubMed Central
Fig. 3 The growth prformances of Enterobacter isolates (3, 14, 21 and 22) on rapid hicoliform agar as well as hicrome coliform agar. E. aerogenes ATCC 13048 act as a reference strain.
Fig. 3 The growth prformances of Enterobacter isolates (3, 14, 21 and 22) on rapid hicoliform agar as well as hicrome coliform agar. E. aerogenes ATCC 13048 act as a reference strain.CC BY-NC-ND · PubMed Central
Fig. 4 Salt tolerance of fluoride resistant isolates determined by plate assay.
Fig. 4 Salt tolerance of fluoride resistant isolates determined by plate assay.CC BY-NC-ND · PubMed Central
Fig. 5 (a) The 16S rRNA PCR using Aeromonas universal primers. lane (+): A. hydrophila ATCC 7966 used as a positive control, lane (–): negative control without template DNA; lanes 31, 32 and 34: PCR products of Aeromonas isolates. (b) The confirmation of A. caviae by PCR using AER8 and AER9 primers. lanes 31, 32, and 34: amplified PCR products (260 bp) of Aeromonas isolates. (c) Restriction analysis of AluI against AER8 and AER9 PCR. lanes 31, 32 and 34: restricted fragments (180 and 80 bp) releasing by Aeromonas strains and confirmed as A. caviae. lanes M: 100 bp DNA ladder.
Fig. 5 (a) The 16S rRNA PCR using Aeromonas universal primers. lane (+): A. hydrophila ATCC 7966 used as a positive control, lane (–): negative control without template DNA; lanes 31, 32 and 34: PCR products of Aeromonas isolates. (b) The confirmation of A. caviae by PCR using AER8 and AER9 primers. lanes 31, 32, and 34: amplified PCR products (260 bp) of Aeromonas isolates. (c) Restriction analysis of AluI against AER8 and AER9 PCR. lanes 31, 32 and 34: restricted fragments (180 and 80 bp) releasing by Aeromonas strains and confirmed as A. caviae. lanes M: 100 bp DNA ladder.CC BY-NC-ND · PubMed Central
Fig. 6 Molecular detection of E. coli by PCR (a, b, c). lanes M: 100bp DNA ladder; lanes S2-9: amplified PCR products of E. coli S2-9 using 16E1/16E2, lacZ and uidA gene primers. lanes ATCC: PCR amplification by E. coli ATCC 43888 (+ control); lanes (–): negative control with out template DNA.
Fig. 6 Molecular detection of E. coli by PCR (a, b, c). lanes M: 100bp DNA ladder; lanes S2-9: amplified PCR products of E. coli S2-9 using 16E1/16E2, lacZ and uidA gene primers. lanes ATCC: PCR amplification by E. coli ATCC 43888 (+ control); lanes (–): negative control with out template DNA.CC BY-NC-ND · PubMed Central
Fig. 7 Virulence analysis of fluoride resistant Aeromonas species. lanes (–): negative control with out template DNA, lanes (+): A. hydrophila ATCC 7966 act as a reference strain, lanes 31, 32 and 34: virulence genes (lipase, elastase) amplified by Aeromonas isolates.
Fig. 7 Virulence analysis of fluoride resistant Aeromonas species. lanes (–): negative control with out template DNA, lanes (+): A. hydrophila ATCC 7966 act as a reference strain, lanes 31, 32 and 34: virulence genes (lipase, elastase) amplified by Aeromonas isolates.CC BY-NC-ND · PubMed Central
Fig. 8 Fluoride resistance gene (crcB) amplification using gene specific primers. (a) lane M: 100 bp DNA ladder; lane (–): negative control; lane S2-9: crcB gene amplification by strain S2-9. (b) lane M: 100 bp DNA ladder; lanes 31, 32 and 34: amplification of crcB by Aeromonas isolates. lane (–): negative control.
Fig. 8 Fluoride resistance gene (crcB) amplification using gene specific primers. (a) lane M: 100 bp DNA ladder; lane (–): negative control; lane S2-9: crcB gene amplification by strain S2-9. (b) lane M: 100 bp DNA ladder; lanes 31, 32 and 34: amplification of crcB by Aeromonas isolates. lane (–): negative control.CC BY-NC-ND · PubMed Central
Fig. 9 The amplification of ‘crcB’ by Enterobacter isolates. lane (–): negative control; lanes 2, 3 and 4: gene amplification by strains 22, 21 and 14 using EAF and EAR primers. lane 5: 100 bp ladder; lane 6: negative control; lane 7: gene amplification by strain 3 using ERF and ERR primers.
Fig. 9 The amplification of ‘crcB’ by Enterobacter isolates. lane (–): negative control; lanes 2, 3 and 4: gene amplification by strains 22, 21 and 14 using EAF and EAR primers. lane 5: 100 bp ladder; lane 6: negative control; lane 7: gene amplification by strain 3 using ERF and ERR primers.CC BY-NC-ND · PubMed Central

Verification

Claims the paper makes

62 Own result · 13 No full text of the sources · 8 Sources not found · 8 Not checked yet · 6 Own interpretation · 5 Own method · 2 Supported

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  • The quote only partly states this claim. 3
  • Probably not a substantial claim. 27
  • It may state two separate claims as one. 18
46 of 46
  • The paper relies on this without support.

    No study has been conducted for the isolation of F− resistance bacteria from Natham taluk, Dindigul district, South India.

    “However, no such study has been conducted for the isolation of F− resistance bacteria from Natham taluk, Dindigul district, South India.”
  • The paper relies on this without support.

    This is the first report identifying fluoride-resistant bacteria from Natham taluk, southern Tamil Nadu.

    “To our knowledge, this is the first report identifying fluoride resistant bacteria especially from Natham taluk, southern part of Tamilnadu.”
2 of 2

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Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

9 of 9

Citations

Cites

Show all 34 references

Research works printed but not linked: 3

  1. Banerjee, 2016, Isolation and characterization of fluoride resistant bacterial strains from fluoride endemic areas of West Bengal, India: assessment of their fluoride absorption efficiency, Fluoride, 49, 429
  2. Sankpal, 2012, Physiochemical analysis of effluent discharge of fish processing industries in Ratnagiri, India, Biosci. Discov., 3, 107
  3. Shobana, 2012, Ground water quality of five villages in Natham city, Dindigul District Tamil Nadu (India), Interface J. Currt Sci., 68

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Metadata

Authors
Chellaiah, E. R., Ravi, P., & Uthandakalaipandian, R.
Affiliations
Madurai Kamaraj University (IN)
Venue
Current Research in Microbial Sciences
Publisher
Elsevier BV
Published
2021-12
Volume
2
Pages
100038
ISSN
2666-5174 (ISSN-L)
OpenAlex
W3161143346
Cited by
17
References
34
Citations by year
2026: 1 · 2025: 6 · 2024: 5 · 2023: 4 · 2022: 1
FWCI
0.76
Type
journal article
Language
en
Open access
Locations
  • Current Research in Microbial Sciences (publishedVersion, cc-by-nc-nd)
  • PubMed Central (publishedVersion, cc-by-nc-nd)
  • PubMed (publishedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
Funders
  • Department of Science and Technology, Ministry of Science and Technology, India (SB/S2/RJN-009/2016)
  • Science and Engineering Research Board
  • Madurai Kamaraj University
Topics
  • Physical Sciences › Environmental Science › Water Science and Technology › Fluoride Effects and Removal
  • Physical Sciences › Environmental Science › Ecology › Microbial Community Ecology and Physiology
  • Physical Sciences › Environmental Science › Water Science and Technology › Fecal contamination and water quality
Keywords
fluoride contamination, drinking water quality, Enterobacter cloacae, Enterobacter hormaechei, Aeromonas caviae, bacterial bioremediation, Dindigul district

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