Abstract
The aim of this study was to determine the combined effect of fermentation parameters and enhance the production of cellular biomass and antibacterial compounds from Paludifilum halophilum SMBg3 using the response surface methodology (RSM). Eight variables were screened to assess the effects of fermentation parameters on growth and metabolite production by Taguchi experimental design. Among these, the initial pH, temperature, and the percentage of MgSO4·7H2O in the medium were found to be most influential. The Box–Behnken design was applied to derive a statistical model for the optimization of these three fermentation parameters. The optimal parameters were initial pH: 8.3, temperature growth: 44°C, and MgSO4·7H2O: 1.6%, respectively. The maximum yield of biomass and metabolite production were, respectively, 11 mg/mL dry weight and 15.5 mm inhibition zone diameter against Salmonella enterica, which were in agreement with predicted values. The bioactive compounds were separated by the thick-layer chromatography technique and analyzed by GC/MS, NMR (1D and 2D), and Fourier-transform infrared spectroscopy (FT-IR). In addition to several fatty acids, N-(1-carboxy-ethyl)-phthalamic acid was identified as the main antibacterial compound. This element exhibited a potent activity against the ciprofloxacin-resistant Salmonella enterica CIP 8039 and Pseudomonas aeruginosa ATCC 9027 with a minimum inhibitory concentration (MIC) value range of 12.5–25 μg/mL. Results demonstrated that P. halophilum strain SMBg3 is a promising resource for novel antibacterial production due to its high-level yield potential and the capacity for large-scale fermentation.
Highlights
Donyez Frikha-Dammak,1 Jawhar Fakhfakh,2 Dalel Belhaj,1 Emna Bouattour,2 Houda Ayadi,1 Moncef Chaabouni,3 Habib Ayadi,1 and Sami Maalej 1
The initial pH, temperature, and the percentage of MgSO4·7H2O in the medium were found to be most influential. e Box–Behnken design was applied to derive a statistical model for the optimization of these three fermentation parameters. e optimal parameters were initial pH: 8.3, temperature growth: 44°C, and MgSO4·7H2O: 1.6%, respectively. e maximum yield of biomass and metabolite production were, respectively, 11 mg/mL dry weight and 15.5 mm inhibition zone diameter against Salmonella enterica, which were in agreement with predicted values. e bioactive compounds were separated by the thick-layer chromatography technique and analyzed by GC/MS, NMR (1D and 2D), and Fourier-transform infrared spectroscopy (FT-IR)
In addition to several fatty acids, N-(1-carboxy-ethyl)-phthalamic acid was identified as the main antibacterial compound. is element exhibited a potent activity against the ciprofloxacin-resistant Salmonella enterica CIP 8039 and Pseudomonas aeruginosa ATCC 9027 with a minimum inhibitory concentration (MIC) value range of 12.5–25 μg/mL
Summary
Donyez Frikha-Dammak ,1 Jawhar Fakhfakh, Dalel Belhaj, Emna Bouattour, Houda Ayadi, Moncef Chaabouni, Habib Ayadi, and Sami Maalej 1. Results demonstrated that P. halophilum strain SMBg3 is a promising resource for novel antibacterial production due to its high-level yield potential and the capacity for large-scale fermentation. 1. Introduction e increasing request for novel antibiotics is ascribed to the emergence of several multidrug-resistant pathogens around the globe, along with the drastically shrinking number of new potentially detected molecules [1, 2]. Introduction e increasing request for novel antibiotics is ascribed to the emergence of several multidrug-resistant pathogens around the globe, along with the drastically shrinking number of new potentially detected molecules [1, 2] In this respect, Actinobacteria still figure on the list of the most promising biological sources of new natural products due to its unique adaptation characteristics [3, 4]. On the basis of phenotypic, chemotaxonomic, and phylogenetic classification, several genera of these actinomycetes such as Mechercharimyces, Melghirimyces, Croceifilum, and Salinithrix were affiliated to the ermoactinomycetaceae family of the phylum Firmicutes [8,9,10]. is increasing number of nonconventional actinomycetes considerably paves the way for the discovery of new bioactive natural products [11, 12]
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