Journal of Microbiology

Research Support, Non-U.S. Gov't

Isolation, Characterization, and Investigation of Surface and Hemolytic Activities of a Lipopeptide Biosurfactant Produced by Bacillus subtilis ATCC 6633: Gholamreza Dehghan-Noudeh , Mohammadreza Housaindokht , Bibi Sedigeh Fazly Bazzaz; J. Microbiol. 2005;43(3):272-276.; DOI: https://doi.org/2213 [pii]

Abstract: Bacillus subtilis ATCC 6633 was grown in BHIB medium supplemented with Mn^2^+ for 96 h at 37^oC in a shaker incubator. After removing the microbial biomass, a lipopeptide biosurfactant was extracted from the supernatant. Its structure was established by chemical and spectroscopy methods. The structure was confirmed by physical properties, such as Hydrophile-Lipophile Balance (HLB), surface activity and erythrocyte hemolytic capacity. The critical micelle concentration (cmc) and erythrocyte hemolytic capacity of the biosurfactant were compared to those of surfactants such as SDS, BC (benzalkonium chloride), TTAB (tetradecyltrimethylammonium bromide) and HTAB (hexadecyltrimethylammonium bromide). The maximum hemolytic effect for all surfactants mentioned was observed at concentrations above cmc. The maximum hemolytic effect of synthetic surfactants was more than that of the biosurfactant produced by B. subtilis ATCC 6633. Therefore, biosurfactant would be considered a suitable surface-active agent due to low toxicity to the membrane.

Structure-antifungal activity relationships of cecropin a hybrid peptides against trichoderma sp.: Shin, Song Yub , Lee, Dong Gun , Lee, Sung gu , Kim, Kil Lyong , Lee, Myung Kyu , Hahm, Kyung Soo; J. Microbiol. 1997;35(1):21-24.

Abstract: The hybrid peptides, CA-ME, CA-MA and CA-BO, with the N-terminal sequence 1-8 of cecropin A and the N-terminal sequences 1-12 of melittin, magainin 2 and bombinin, respectively, have more improved antibacterial activities. CA-MA was found to have stronger antifungal activity against Trichoderma sp than other hybrid peptides and their parental peptides. In order to elucidate the relationships between the peptide structure and antifungal activity, several analogues of CA-MA or CA-BO were also designed and synthesized by the solid phase method. Antifungal activity was measured against T. reesei and T. viride, and hemolytic activity was measured by a solution method against human red blood cells. The residue 16 of CA-MA, Ser, was found to be important for antifungal activity. When the residue was substituted with Leu, showed powerful antifungal activity was dramatically decreased. CA-MA, P1, P4 and P5 designed in this study showed powerful antifungal activity against T. reesei and T. viride with low hemolytic activity against human red blood cells. These hybrid peptides will be potentially useful model to further design peptides with powerful antifungal activity for the effective therepy of fungal infection and understand the mechanisms of antifungal actions of hybrid peptides.

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