Characterization of a Haloalkaline Nocardiopsis sp. Strain S10 Isolated from Wastewater and Optimization of Culture Medium for Improving Production of Antifungal Compounds

Abstract

The emerging antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) are a pressing global concern. Furthermore, the limited number of available antifungal agents requires the discovery of new antimicrobials. Introduction: This paper focused on the isolation and characterization of an actinobacterium designated S10, the study of its antimicrobial activity, on the one hand, and the optimization of antifungal production using statistical methods, on the other hand. In this study, the actinobacteria was isolated from the wastewater plant of Souk-El-Tenine in the Bejaia region (Algeria) with antimicrobial activity, Nocardiopsis sp. S10 strain was screened for biological activities and the optimization of antifungal metabolites (against C. albicans) production was carried out through statistical methods using CCD and RSM. A haloalkaliphilic actinobacterium designated S10 was isolated from a wastewater treatment plant in the Souk-El-Tenine region (Bejaia, Algeria). This strain showed a broad spectrum of activity against bacteria (B. subtilis, L. innocua, M. luteus, S. aureus, MRSA, E. coli, P. aeruginosa, S. Typhi, and V. cholerae), molds (A. niger, G. geotricum, and F. oxysporum) and a pathogenic yeast (C. albicans). The extracellular enzymes producer Nocardiopsis sp. S10 was identified based on morphological, chemical, and 16S rRNA gene sequencing analysis. The best antimicrobial production was achieved on Mincer-Sea-Water (MSW) solid medium, and the antibiotics produced were extracted with ethyl acetate. For antifungal production, central composite design (CCD) and response surface methodology (RSM) were used to optimize the culture medium formulation. Improvement of antifungal production by a strain of Nocardiopsis. sp strain S10. Optimal antifungal activity was achieved using a mixture of 2 g. L-1 starch, 2 g. L-1 of yeast extract and 2.75 g. L-1 of peptone at pH = 9.2. The application of the statistical approach stimulated a good yield of anti-C. albicans activity, corresponding to an increase of 72.22% compared to the non-optimized conditions. Strain Isolation; Screening for antagonistic activity; 2.3 Characterization of the selected S10 strain ; 2.5 Strain fermentation and antimicrobials Production; Kinetics of growth and active metabolite synthesis; Determination of Minimum Inhibitory Concentration (MIC) values and 2.8 Optimization of anti- Candida albicans metabolites production by CCD and RSM. A haloalkaliphilic actinobacterium designated S10 was isolated from a wastewater treatment plant in the Souk-El-Tenine region (Bejaia, Algeria). This strain showed a broad spectrum of activity against bacteria, phytopathogenic molds and a pathogenic yeast (C. albicans). The isolate also produces extracellular enzymes, Nocardiopsis sp. S10 was identified based on morphological, chemical, and 16S rRNA gene sequencing analysis. For antifungal production, central composite design (CCD) and response surface methodology (RSM) were used to optimize the culture medium formulation. Optimal antifungal activity was achieved using a mixture of 2 g. L-1 starch, 2 g. L-1 of yeast extract and 2.75 g. L-1 of peptone at pH = 9.2 Isolation of active actinobacteria from a wastewater treatment plant in the Bejaia region (Algeria)