Nonlinear regression application in Aspergillus flavus radial mycelial growth inhibition by essential oils of Piper guineense Schum and Thonn., Zingiber officinale roscoe and Monodora myristica (Gaertn) Dunal

Abstract

The objective pursued by the present study is to contribute to application of nonlinear regression in Aspergillus flavus radial mycelial growth inhibition by essential oils extracted from three plants: Piper guineense, Zingiber officinale and Monodora myristica. The techniques of hydrodistillation, poisoning and microdilution followed by seeding in an agar medium free of essential oil were used. The analysis of the dynamics of the diameters obtained under the effect of three essential oils in increasing concentrations was carried out by the nlm () function of the R software. It made it possible to establish the sigmoidal curves characterized by three growth simulation parameters: Asym, the asymptotic diameter, Xmid, the time at Asym/2 and Scal, the spread over time. It also made it possible to simulate growth beyond the incubation time. Partial inhibition is marked by the non-zero values of these simulated parameters and total inhibition by their zero value. These zero values correspond to the minimum inhibitory concentration. The essential oil of Piper guineense exerts a fungistatic power with partial inhibition over the entire range of concentrations studied. The essential oil of Zingiber officinale exerts a fungicidal power with partial inhibition at concentrations less than 0.25% and total inhibition at concentrations greater than 0.5% and the essential oil of Monodora myristica exerts a fungistatic power with growth stimulation at concentrations less than 0.1%, partial inhibition between 0.25 and 1.5% and total inhibition above 1.5%.