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Characterization of Bioactive Actinomycetes Isolated from Kadolkele Mangrove Sediments, Sri Lanka Cover

Characterization of Bioactive Actinomycetes Isolated from Kadolkele Mangrove Sediments, Sri Lanka

Polish Journal of Microbiology
Volume 71 (2022): Issue 2 (June 2022)
By: Kishani N. Naligama,  Kavindi E. Weerasinghe and  Anupama P. Halmillawewa  
Open Access
|Jun 2022

Figures & Tables

Fig. 1

Colony morphologies of actinomycete isolates. The view of the aerial mass and reverse-side pigment colors of isolates Ac-1 (A), Ac-2 (B), Ac-6 (C), Ac-7 (D), Ac-9 (E), and Ac-10 (F) on modified-starch casein agar after 1–2 weeks of incubation at 28°C.
Colony morphologies of actinomycete isolates. The view of the aerial mass and reverse-side pigment colors of isolates Ac-1 (A), Ac-2 (B), Ac-6 (C), Ac-7 (D), Ac-9 (E), and Ac-10 (F) on modified-starch casein agar after 1–2 weeks of incubation at 28°C.

Fig. 2

Spore chain morphologies of actinomycete isolates. Spore chain morphologies of actinomycetes Ac-1 (A), Ac-2 (B), Ac-6 (C), and Ac-9 (D) as observed under a light microscope (magnification 100×).
Spore chain morphologies of actinomycete isolates. Spore chain morphologies of actinomycetes Ac-1 (A), Ac-2 (B), Ac-6 (C), and Ac-9 (D) as observed under a light microscope (magnification 100×).

Fig. 3

Extracellular enzyme production of actinomycete isolates. Actinomycete isolates were tested for the production of cellulase (A), amylase (B), protease (C), and lipase (D)separately on solid agar media. The ‘Enzymatic Index’ for each enzyme assay was expressed using the ratio between the average diameter of the halo/clear zone around the colony and the average diameter of the colony. Error bars represent the standard error of the mean (n = 3). The bars indicated with the same lower case letter are not significantly different from those in the same graph (Tukey’s test, p < 0.05). * – no visible enzymatic activity
Extracellular enzyme production of actinomycete isolates. Actinomycete isolates were tested for the production of cellulase (A), amylase (B), protease (C), and lipase (D)separately on solid agar media. The ‘Enzymatic Index’ for each enzyme assay was expressed using the ratio between the average diameter of the halo/clear zone around the colony and the average diameter of the colony. Error bars represent the standard error of the mean (n = 3). The bars indicated with the same lower case letter are not significantly different from those in the same graph (Tukey’s test, p < 0.05). * – no visible enzymatic activity

Fig. 4

Antibacterial activity of selected actinomycete isolates against test strains. The cell-free supernatants of selected actinomycete isolates were tested against selected test bacterial pathogens using a standard well-diffusion assay. The average diameter of the zones of inhibition for each cell-free supernatant was calculated using three independent replicates. Error bars indicate the standard error of the mean (A). Plates show the inhibition zones given by cell-free supernatants of Ac-1, Ac-2, and Ac-9 against Salmonella Typhimurium (B) and Pseudomonas aeruginosa (C) on Mueller-Hinton agar after the incubation.
Antibacterial activity of selected actinomycete isolates against test strains. The cell-free supernatants of selected actinomycete isolates were tested against selected test bacterial pathogens using a standard well-diffusion assay. The average diameter of the zones of inhibition for each cell-free supernatant was calculated using three independent replicates. Error bars indicate the standard error of the mean (A). Plates show the inhibition zones given by cell-free supernatants of Ac-1, Ac-2, and Ac-9 against Salmonella Typhimurium (B) and Pseudomonas aeruginosa (C) on Mueller-Hinton agar after the incubation.

Fig. 5

Phylogenetic relationship based on the partial 16s rRNA gene sequences. The evolutionary relationships of Streptomyces isolates (Ac-1, Ac-2, and Ac-9) were inferred via a neighbor-joining method. Strains isolated in this study are indicated with a red diamond (). Bootstrap support values from 1,000 replicates are shown next to the branches. Gordonia rubripertincta was used as the out-group of the analysis. The scale bar represents 0.005 nucleotide substitutions per character.
Phylogenetic relationship based on the partial 16s rRNA gene sequences. The evolutionary relationships of Streptomyces isolates (Ac-1, Ac-2, and Ac-9) were inferred via a neighbor-joining method. Strains isolated in this study are indicated with a red diamond (). Bootstrap support values from 1,000 replicates are shown next to the branches. Gordonia rubripertincta was used as the out-group of the analysis. The scale bar represents 0.005 nucleotide substitutions per character.

Fig. 6

Effect of salt concentration of the medium for the growth of actinomycete isolates. Isolates Ac-1 and Ac-2 were grown in modified-starch casein broth (SCB) supplemented with different NaCl concentrations, and the dry weight of the resulting biomass was measured after the incubation. Values represent the mean of three independent replicates (n = 3) , and error bars represent the standard error of the mean (A). The biomass of Ac-1 (B) and Ac-2 (C) grown in modified-SCB supplemented with (i) 0%, (ii) 2%, (iii) 4%, (iv) 6%, and (v) 8% NaCl were filtered and dried on a sterile filter paper.
Effect of salt concentration of the medium for the growth of actinomycete isolates. Isolates Ac-1 and Ac-2 were grown in modified-starch casein broth (SCB) supplemented with different NaCl concentrations, and the dry weight of the resulting biomass was measured after the incubation. Values represent the mean of three independent replicates (n = 3) , and error bars represent the standard error of the mean (A). The biomass of Ac-1 (B) and Ac-2 (C) grown in modified-SCB supplemented with (i) 0%, (ii) 2%, (iii) 4%, (iv) 6%, and (v) 8% NaCl were filtered and dried on a sterile filter paper.

Fig. 7

Effect of initial pH of the medium for the growth of actinomycete isolates. Isolates Ac-1 and Ac-2 were grown in modified-starch casein broth (SCB) adjusted to different initial pH, and the dry weight of the resulting biomass was measured after the incubation. Values represent the mean of three independent replicates (n = 3) and error bars represent the standard error of the mean (A). The biomass of Ac-1 (B) and Ac-2 (C) grown in modified-SCB with different initial pH values (3, 5, 7, and 9) were filtered and dried on sterile filter paper.
Effect of initial pH of the medium for the growth of actinomycete isolates. Isolates Ac-1 and Ac-2 were grown in modified-starch casein broth (SCB) adjusted to different initial pH, and the dry weight of the resulting biomass was measured after the incubation. Values represent the mean of three independent replicates (n = 3) and error bars represent the standard error of the mean (A). The biomass of Ac-1 (B) and Ac-2 (C) grown in modified-SCB with different initial pH values (3, 5, 7, and 9) were filtered and dried on sterile filter paper.

Fig. 8

Application of yellow-colored pigment of Ac-1 as a fabric colorant. Six different commercially available fabric types, ‘Kushbu’, silk-cotton blend fabric, polyester, satin, poplin, and terrine, were dyed using acetone-extracted crude pigments of Streptomyces spp. Ac-1.
Application of yellow-colored pigment of Ac-1 as a fabric colorant. Six different commercially available fabric types, ‘Kushbu’, silk-cotton blend fabric, polyester, satin, poplin, and terrine, were dyed using acetone-extracted crude pigments of Streptomyces spp. Ac-1.

Antibacterial activity of actinomycete isolates against the test strains in the cross-streak assay_

Strain IDTest strain
Staphylococcus aureusEscherichia coliBacillus cereusListeria monocytogenes
Ac-1+++++–
Ac-2++++–
Ac-6––––
Ac-7––––
Ac-9+++–
Ac-10––––

Comparison of growth of actinomycete isolates Ac-1 and Ac-2 under shaking and non-shaking conditions_

Growth conditionDry weight of the biomass (g)#
Ac-1Ac-2
With shaking (at 100 rpm)0.023 ± 0.003**0.043 ± 0.006*
Without shaking0.000**0.057 ± 0.006*

Characteristics of actinomycete isolates_

Isolate nameColony morphologyGram’s reactionSpore chain morphologyCatalase production
Aerial mass colorReverse side pigment color
Ac-1greyish whiteyellowish green+open spirals+
Ac-2greyish whiteyellowish orange+biverticillate with spirals+
Ac-6white–+flexuous+
Ac-7white–+flexuous+
Ac-9greyish whiteyellowish grey+open spirals+
Ac-10white–+pleomorphic bacilli+

Antibacterial activity of actinomycete crude pigment extracts against test strains in well-diffusion assay_

Test organismAverage diameter of the zone of inhibition (mm) ± SEM*
Ac-1Ac-2
Escherichia coli–21.0 ± 0.5774
Pseudomonas aeruginosa–18.0 ± 0.0
Staphylococcus aureus–22.5 ± 0.2881
DOI: https://doi.org/10.33073/pjm-2022-017 | Journal eISSN: 2544-4646 | Journal ISSN: 1733-1331
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Language: English
Page range: 191 - 204
Submitted on: Dec 21, 2021
Accepted on: Mar 9, 2022
Published on: Jun 11, 2022
Published by: Polish Society of Microbiologists
In partnership with: Paradigm Publishing Services
Publication frequency: 4 issues per year
Keywords:
mangrove sediment bacteria,
bioactive actinomycetes,
extracellular enzymes,
bacterial pigments
Related subjects:
Life sciences,
Microbiology and virology

© 2022 Kishani N. Naligama, Kavindi E. Weerasinghe, Anupama P. Halmillawewa, published by Polish Society of Microbiologists
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

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