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An Ipomoea batatas extract obtained by enzymatic hydrolysis with alpha amylase was characterized to be used as nutrient basis. Among its quality indicators, it had a content of over 50% whole carbohydrates with respect to the nominal mass, estimated by phenol-sulphur method. The same content of aminonitrogen detected and quantified by potentiometric titration using formaldehyde and of total nitrogen (0,23%) by Kjeldahl method were detected. The content of necessary mineral elements for microbial culture was determined by the atom absorption method. The study of biological reactivity of the vegetal extract showed the existence of essential aminoacids such as triptophane, cystine and cysteine for microorganisms. It was proved that the vegetal extract, when used as the only source of nutrients at various concentration levels (2, 4 and 10%), is capable of stimulating the growth of bacteriae and yeasts. The increase of two Candida albicans biomass, determined in a specially designed medium (SIGMA, USA), was significantly higher to that of other nutrient bases like soy peptone, yeast extract, triptone and micological peptone. It was evinced that the vegetal extract as a culture medium component did not have antimicrobial effect compounds since at 15-30 g/L concentrations, this extract did stimulate the microbial growth up to values (UFC/mL) similar to those of the reference media called agar triptone soy.

A soy peptone obtained with enzyme papain as a hydrolyzing agent was characterized. The physicochemical evaluation of the nutritive base attained at pilot and industrial scale showed the following characteristics: loss due to desiccation, 1.93%; aminic nitrogen, 1.71%; total nitrogen, 8.63%; chlorides (as NaCl), 5.45%; and pH, 6.94. For the functional evaluation of the pilot and industrial batches (3), developed soy peptone and another one taken as a reference from the Biotécnica Internacional firm (México), was incorporated to a mixture of bases. There were no significant differences (p < 0.05) in the absorbance values at 640 nm obtained in the promotion of the growth between the developed product and that of reference for Staphylococcus aureus ATCC 25923. For Streptococcus pyogenes ATCC 19615, it was observed a mild superiority (significant difference for p < 0.05) starting from the 5th hour of incubation in favor of the industrial batches compared with the reference soy peptone. It was proved that the promotion of the growth in the soy triptone agar and broth media and in malt extract agar for the evaluated microorganisms was similar or higher (significant differences for p < 0.05) in those prepared with the experimental soy peptone, in comparison with the formulated with the reference base.