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In the present study, the synergism of the lipopeptide bacillomycin D in combination with the polyene amphotericin B against pathogenic Candida species is described along with their potential cytotoxicity against mammalian cells. Bacillomycin D inhibited the growth of various Candida species at minimal concentrations from 12.5 to 25μg ml-1. Furthermore, it showed a synergistic effect with the antifungal drug amphotericin B in inhibiting the growth of Candida strains, with fractional inhibitory concentration indices ranging from 0.28 to 0.5. Time killing studies revealed a >2-log reduction in the viability of Candida albicans ATCC 10231 cells after 3 h incubation with the combination amphotericin B plus bacillomycin D, at their subinhibitory concentration. Interestingly, when the two drugs were used together at those dosages displaying a synergism in the anti-Candida activity, no cytotoxic effect was observed against mammalian cells. Therefore, the combination bacillomycin D/amphotericin B may represent a valid alternative to conventional antifungals for topical treatment of C. albicans infections. To the best of our knowledge, this is the first report describing the in vitro interaction between the antifungal drug amphotericin B and bacillomycin D against pathogenic Candida species. [ABSTRACT FROM AUTHOR]

A protease-producing strain CT2 isolated from Tunisian potatoes, exhibiting a potent protease activity (prot CT2), was identified as Bacillus halotolerans according to 16S ribosomal DNA sequence analysis. Maximum prot CT2 production was obtained in medium supplemented with bean seed proteins. Proteolytic activity was purified by ammonium sulphate precipitation, Sephacryl S-200 gel filtration and SP-sepharose cation-exchange chromatography. Optimal enzyme activity was reached at pH 9 and temperature of 50 °C. Proteolytic activity was enhanced by Ca 2+ and Mn 2+ ions, completely inhibited by PMSF suggesting a serine protease nature and exhibited high stability in the presence of commercial detergents. Prot CT2 showed broad substrate specificity towards both synthetic and natural substrates, with a high capacity to hydrolyze legume seed proteins. Using electrophoretic analysis, its molecular weight was around 250 kDa with two major subunit showing important homologies with serine proteases belonging to the subtilisin-like serine proteases. Based on the Lineweaver–Burk plots K m and V max values were 10 mg/ml and 50,000 U/mg respectively. This newly described prot CT2 displays relevant properties which highlight its potential use in various industrial and biotechnological applications. [ABSTRACT FROM AUTHOR]