In a parallel control test, a non-sterilized (without the use of membrane)
organic medium was added into the same volume of solution
(100 ml sterile mineral medium). Then, these flasks were incubated
at 25 °C for 7 days and inspected daily. By direct microbiological techniques,
the assessment of the two used media (the sterilized and nonsterilized
samples) was performed by visual observation of the variation
(color, form) on the surface of the medium every day