Isolation And Characterization Of Marine Actinomycetes For Anti-Infective Activity Towards Pseudomonas aeruginosa PA14

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Date
2018-05
Authors
Ahmad Kamal, Siti Nur Fatin
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Publisher
Universiti Sains Malaysia
Abstract
Marine environment serve as reservoir of vast useful secondary metabolites and at the same time, new anti-infective agents are required to combat antibiotic resistant pathogenic bacteria.Therefore, this research was carried out to screen for anti-infective agents from the environment that are capable of overcoming Pseudomonas aeruginosa infection through anti-virulence or boosting of host immunity activities. Marine soil sediments were collected from Songsong Island, Yan, Kedah, Malaysia and a total of 18 actinomycetes with different morphology were successfully isolated. Secondary metabolites from all isolates were extracted out using solid-liquid extraction method and were screened for anti-infective activity using Caenorhabditis elegans infection model. Only extract from isolate A5 showed significant life-span promotion of the host. Thus, it was used for further characterization and screening. Isolate A5 showed 99.7% molecular sequence similarity to Streptomyces sundarbansensis MS1/7 and was designated as Streptomyces sundarbansensis CCB-PSK207 due to morphological difference observed under the same culture condition. It can withstand up to 10% (w/v) NaCl concentration and it showed highest growth (referring to cell dry weight) at pH7 after ten days of cultivation compared to pH4, pH5, pH6, pH8, pH 9 and pH10. Methanolic extract A5 was further partitioned by using liquid-liquid extraction method. n-hexane partition was found to exhibit the best hit in survival assay. Dose response assay revealed that 400μg/mL was the best concentration with survivability rate change of 69.65±4.50% as compared to controlled worms 96-hours post PA14 infection. Therefore, all screening assays were progressed using that concentration.
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Keywords
Anti-infective agents from the environment , capable of overcoming Pseudomonas aeruginosa infection
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