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In vitro Antibiofilm Potential of Halophilic/Halotolerant Strains from the Mangrove Soil of Mauritius against Pseudomonas aeruginosa.

S. Parboteeah^1,3, M.G. Bhowon^2,3, S. Jhaumeer Laulloo^2,3, S. Jawaheer^1,3, S.D. Dyall^1,3

¹Department of Biosciences and Ocean Studies, University of Mauritius, Réduit, Mauritius

²Department of Chemistry, University of Mauritius, Réduit, Mauritius

³ Molecular Life Sciences Pole of Research Excellence, Faculty of Science, University of Mauritius, Réduit, Mauritius

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Aim:

Evaluate antibacterial metabolites derived from mangrove associated bacteria of Mauritius.

Specific objectives:

Isolate halophilic/halotolerant bacteria from mangrove soils with high salinity

Evaluate isolates for antibiofilm activities against E. coli and P.aeruginosa.

Aim and Specific Objectives

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Antimicrobial Resistance

According to the World Health Organisation (2022):

‘Antimicrobial resistance (AMR) occurs when bacteria, viruses, fungi and parasites change over time and no longer respond to medicines, making infections harder to treat and increasing the risk of disease spread, severe illness and death. As a result of drug resistance, antibiotics and other antimicrobial medicines become ineffective and infections become increasingly difficult or impossible to treat.’

Statement of Problem

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Source: Tuon et al., 2022

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Research Strategy

Antibiotic resistance

Lack of antibiotic with novel mode of action

Overexploitation of available resources (E.g Cultivable soil)

Unexplored ecosystem with biotechnological prospective

Mangrove ecosystem

Untapped source of halophilic microorganisms

Isolation of halophiles with antimicrobial/antibiofilm properties

Extraction and testing of the metabolites

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Isolation of halophilic/halotolerant bacterial strains from mangrove soil of a north eastern mangrove setting of Mauritius.

Experimental strategy

Determination of the antibiofilm disruption potential of ethyl acetate extracts of four isolates Z3RZ3, Z3PZ1, Z3RZ1 and Z5PZ2 against Escherichia coli (ATCC 25922), and Pseudomonas aeruginosa (ATCC 27853).

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Sampling Site

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Four mangrove soil bacterial isolates previously screened for antibacterial activity by:

Disc diffusion assay

Agar overlay assay

Broth macrodilution assay

Ethyl acetate extracts

Antibiofilm inhibition assay by the crystal violet staining method

Identification of strains through sequencing and bioinformatic analyses of 16S rRNA gene fragments.

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Inhibition of Escherichia coli ATCC 25922 biofilm formation by the Z3RZ3, Z3PZ1, Z3RZ1 and Z5PZ2 ethyl acetate extracts. C+: 50 µg/ml ampicillin (positive control); C- : pure ethyl acetate (negative control).

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Inhibition of Pseudomonas aeruginosa ATCC 27853 biofilm formation by the Z3RZ3, Z3PZ1, Z3RZ1 and Z5PZ2 ethyl acetate extracts. C- : pure ethyl acetate (negative control).

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Summary of main findings

Ethyl acetate extract of isolates Z3RZ3 and Z3RZ1 exhibited the highest antibiofilm activity against P. aeruginosa and E. coli respectively

The 16S rRNA phylogenetic analyses showed the closest sequence matches to Globicatella sanguinis (Z3RZ3), Shewanella chilikensis (Z3PZ1), Micrococcus luteus (Z3RZ1) and Shewanella algae (Z5PZ2)

Mauritian mangrove soil microbiota could be a source of bioactives of potential pharmaceutical interest

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Acknowledgements

Supervisors:

Assoc. Prof. Sabrina Devi Dyall
Dr. Shobha Jawaheer
Prof. Minu Bhowon
Prof. Sabina Jhaumeer Laulloo

Technical Staff (Department of Biosciences and Ocean Studies/ Department of Chemistry)

University of Mauritius for research funding and logistical support

Ministry of Blue Economy, Marine Resources, Fisheries and Shipping for permit

Higher Education Commission for the MPhil/ PhD Scholarship