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Determination of the specific growth of molds on semi‐solid cultures
Author(s) -
Carrizalez V.,
Rodríguez H.,
Sardiña I.
Publication year - 1981
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.260230207
Subject(s) - bagasse , chemistry , starch , fermentation , aspergillus niger , sodium hydroxide , substrate (aquarium) , nitrogen , ammonium , food science , botany , organic chemistry , microbiology and biotechnology , biology , ecology
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 cm 3 . 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 CO 2 , P , was correlated with the specific growth rate μ, by means of the equation P = Ke μt , 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, μ max , and the saturation constant, K s , were 0.31 hr −1 and 0.065 mmol (NH 4 ) 2 SO 4 /g total dry solids. Substrate inhibition was presented and the constant k i gave a value of 1.5 mmol (NH 4 ) 2 SO 4 /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.