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. 2017:2017:2605382.
doi: 10.1155/2017/2605382. Epub 2017 Jul 3.

Production, Characterization, and Antimicrobial Activity of Mycocin Produced by Debaryomyces hansenii DSMZ70238

Safaa A S Al-Qaysi  1 , Halah Al-Haideri  1 , Zaid Akram Thabit  2 , Wijdan Hameed Abd Al-Razzaq Al-Kubaisy  3 , Jamal Abd Al-Rahman Ibrahim  3
Affiliations

Production, Characterization, and Antimicrobial Activity of Mycocin Produced by Debaryomyces hansenii DSMZ70238

Safaa A S Al-Qaysi et al. Int J Microbiol. 2017.

Abstract

The present study was conducted to estimate the antimicrobial activity and the potential biological control of the killer toxin produced by D. hansenii DSMZ70238 against several pathogenic microorganisms. In this study, the effects of NaCl, pH, and temperature, killer toxin production, and antimicrobial activity were studied. The results showed that the optimum inhibitory effect of killer toxin was at 8% NaCl, and the diameters of clear zones were 20, 22, 22, 21, 14, and 13 mm for Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Streptococcus pyogenes, Candida albicans, and Candida neoformans, respectively. The largest inhibition zones were observed at pH 4.5 with inhibition zone of 16, 18, 17, 18, 11, and 12 mm for the same microorganisms. The results also showed that 25°C is the optimal temperature for toxin killing activity against all targeted microorganisms. In addition, the activity of killer toxin significantly inhibited the growth of fungal mycelia for all target pathogenic fungi and the percentages of inhibition were 47.77, 48.88, 52.22, and 61.11% for Trichophyton rubrum, Alternaria alternata, Trichophyton concentricum, and Curvularia lunata, respectively. The results showed the highest growth rate of D. hansenii DSMZ70238 under condition of 8% NaCl concentration, pH 4.5, and 25°C for 72 h.

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Figures

Figure 1
Figure 1
One-dimensional SDS-PAGE of partially purified concentrated killer toxin. 12% SDS-PAGE was performed with the partially purified concentrated killer toxin produced by D. hansenii. The 22 kDa protein is referred to by black arrow. Lane M: the PageRuler™ Plus Unstained Rec. Protein Ladder (Promega), lane: referring to the purified protein under normal conditions. ~15 µg of protein was loaded into the well.
Figure 2
Figure 2
Effect of NaCl concentrations on the production and killing activity of killer toxin produced by D. hansenii against pathogenic bacteria and yeasts. Killer activity was measured by the means of inhibition zone around the wells. The shown data are the means and SD from three independent experiments. Values in the same column followed by the same letter are not statistically different by Duncan's multiple range test at (p < 0.05).
Figure 3
Figure 3
(a) Effect of different pH values on the production and killing activity of killer toxin produced by D. hansenii against pathogenic bacteria and yeasts. (b) Inhibition zone distributed within wells filled with partially purified concentrated killer toxin after 48 h at 37°C. S. aureus was used as sensitive bacteria. (c) C. albicans was used as sensitive yeast. Values in the same column followed by the same letter are not statistically different by Duncan's multiple range test at (p < 0.05).
Figure 4
Figure 4
(a) Effect of different temperatures on the production and killing activity of killer toxin produced by D. hansenii against pathogenic bacteria and yeasts. Killer activity was measured by the means of inhibition zones around the wells filled with partially purified and concentrated killer toxin. (b) C. neoformans, (c) C. albicans, (d) S. pyogenes, and (e) S. aureus. Values in the same column followed by the same letter are not statistically different by Duncan's multiple range test at (p < 0.05).
Figure 5
Figure 5
The antagonistic activity of D. hansenii in vitro. The ability of D. hansenii to decrease the growth of T. rubrum (a) and T. concentricum (b) was examined. D. hansenii was streaked out and either T. rubrum or T. concentrcum was inoculated on the same plate. As a control both T. rubrum and T. concentricum were inoculated separately without D. hansenii. All plates were incubated at 28°C for 7 days. All strains were indicated by black arrows.
Figure 6
Figure 6
Growth curve of D. hansenii DSMZ70238. D. hansenii DSMZ70238 was cultured in growth media under different conditions for 72 h. (a) The growth of D. hansenii DSMZ70238 with different concentrations of NaCl, (b) the growth under different temperatures, and (c) growth of D. hansenii under different pH values.
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