Determination of the specific growth of molds on semi-solid cultures [Aspergillus niger, cassava flour, Manihot esculenta]

The determination of growth constant of Aspergillus niger were obtained for semisolid cultures on cassava flour, Manihot esculenta, as a sole carbon source. As a consequence, a technique was developed that consisted of the use of a packed‐bed microfermentor with a working volume of 16 cm3. The bed c...

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Published in:Biotechnology and bioengineering 1981-02, Vol.23 (2), p.321-333
Main Authors: Carrizalez V, Rodriguez H, Sardina I
Format: Article
Language:English
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Summary:The determination of growth constant of Aspergillus niger were obtained for semisolid cultures on cassava flour, Manihot esculenta, as a sole carbon source. As a consequence, a technique was developed that consisted of the use of a packed‐bed microfermentor with a working volume of 16 cm3. The bed consisted of gelatinized and granulated cassava flour containing mineral nutrients and mold spores. The carbon dioxide produced during the respiration was drawn off with a current of air and then absorbed in a solution of sodium hydroxide. The absorption of CO2, P, was correlated with the specific growth rate μ, by means of the equation P=Keμt, where t is time and K is a constant. Ammonium nitrogen was used as a limiting substrate and its concentration was varied from 0.039 to 2.5% in dry base. The maximum growth rate, μmax, and the saturation constant, Ks, were 0.31 hr−1 and 0.065 mmol (NH4)2SO4/g total dry solids. Substrate inhibition was presented and the constant ki gave a value of 1.5 mmol (NH4)2SO4/g total dry solids. The proposed method is highly recommended for the evaluation of the semisolid fermentation of molds and for strictly aerobic bacteria and yeasts. It can be used especially in the evaluation of the growth of microorganisms on peanut shells, coffee residues, sugar cane bagasse, and other agricultural wastes.
ISSN:0006-3592
1097-0290
DOI:10.1002/bit.260230207