Preparation of the culture media
The concentrated soybean molasses received from local industries with 550–650 g L-1 of soluble solids was diluted with distilled water to produce the culture media with the desired sugar concentration, without any supplementation of other nitrogen or carbon sources, or salts. The total soluble solids concentration was determined with the aid of a saccharimeter. The pH was adjusted to the desired value with 1000 mol.m-3 HCl or 3000 mol.m-3 NaOH, depending on the case. The material was sterilized at 121 °C during 15 min.