Influence of molasses and aqueous soybean extract concentrations on the specific growth rate of Bradyrhizobium elkanii ICA 8001

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Gretel Gómez

Abstract

The strain ICA 8001 from Bradyrhizobium
elkanii is broadly used in Cuba for soybean inoculant
production. One culture medium designed to multiply this
microorganism contains molasses and aqueous soybean
extract, which are elements of a variable composition and origin
providing considerable amounts of carbonated substrates.
Therefore, concentrations of total soluble carbohydrates and
reducing carbohydrates as well as N, P, K, Ca, Mg and Na
contents were determined, to get a partial nutritional
characterization of these components. Analyses showed
substantial quantities of these bacterium-absorbing elements
within cell growth. The influence of molasses and aqueous
soybean extract concentrations on the specific strain growth
rate ? (h-1) was estimated by varying molasses concentrations
in Bradyfact medium from 3 to 20 g.L-1 and aqueous soybean
extract from 5 to 20 g.L-1. Growth dynamics were recorded for
each variant, besides calculating ?. Results proved that higher
than 10 and 12,5 g.L-1 molasses and aqueous soybean extract
concentrations, respectively, inhibit Bradyrhizobium elkanii
ICA 8001 growth. This phenomenon could be mathematically
and physiologically explained through two new kinetic models.
This research work contributes to Bradyrhizobium
physiological knowledge, since it makes evident the
relationship between culture medium composition and
microorganism nutritional requirements, also how culture
medium design may ensure more effective inoculants
containing high cell concentrations.

Article Details

How to Cite
Gómez, G. (2012). Influence of molasses and aqueous soybean extract concentrations on the specific growth rate of Bradyrhizobium elkanii ICA 8001. Cultivos Tropicales, 29(4), 21–26. Retrieved from https://ediciones.inca.edu.cu/index.php/ediciones/article/view/206
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Original Article