Optimization of Bacillus amyloliquefaciens BLB369 Culture Medium by Response Surface Methodology for Low Cost Production of Antifungal Activity

Imen Zalila-Kolsi; Sameh Kessentini; Slim Tounsi; Kaïs Jamoussi

doi:10.3390/microorganisms10040830

Optimization of Bacillus amyloliquefaciens BLB369 Culture Medium by Response Surface Methodology for Low Cost Production of Antifungal Activity

Microorganisms. 2022 Apr 16;10(4):830. doi: 10.3390/microorganisms10040830.

Authors

Imen Zalila-Kolsi^{1

2}, Sameh Kessentini³, Slim Tounsi¹, Kaïs Jamoussi¹

Affiliations

¹ Laboratory of Biopesticides, Centre of Biotechnology of Sfax, University of Sfax, P.O. Box 1177, Sfax 3018, Tunisia.
² Department of Health and Medical Sciences, Khawarizmi International College, Abu Dhabi P.O. Box 25669, United Arab Emirates.
³ Laboratory of Probability and Statistics, Faculty of Sciences of Sfax, University of Sfax, P.O. Box 1171, Sfax 3000, Tunisia.

Abstract

Bacillus amyloliquefaciens BLB369 is an important plant growth-promoting bacterium, which produces antifungal compounds. A statistics-based experimental design was used to optimize a liquid culture medium using inexpensive substrates for increasing its antifungal activity. A Plackett-Burman design was first applied to elucidate medium components having significant effects on antifungal production. Then the steepest ascent method was employed to approach the experimental design space, followed by an application of central composite design. Three factors were retained (candy waste, peptone, and sodium chloride), and polynomial and original trigonometric models fitted the antifungal activity. The trigonometric model ensured a better fit. The contour and surface plots showed concentric increasing levels pointing out an optimized activity. Hence, the polynomial and trigonometric models showed a maximal antifungal activity of 251.9 (AU/mL) and 255.5 (AU/mL) for (19.17, 19.88, 3.75) (g/L) and (19.61, 20, 3.7) (g/L) of candy waste, peptone, and NaCl, respectively. This study provides a potential strategy for improving the fermentation of B. amyloliquefaciens BLB369 in low-cost media for large-scale industrial production.

Keywords: Plackett–Burman design; antifungal activity; central composite design; polynomial and trigonometric regression models; response surface methodology.