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Improvement on citric acid production in solid-state fermentation by Aspergillus niger LPB BC mutant using citric
Cristine Rodrigues1, Luciana Porto de Souza Vandenberghe, Juliana Teodoro
1Bioprocess Engineering and Biotechnology Division, Chemical Engineering Department, Federal University of Paraná (UFPR), Curitiba, PR, Brazil.
Abstract:
Citric acid (CA) production has been conducted through a careful strain selection, physical-chemical optimization and mutation. The aim of this work was to optimize the physical-chemical conditions of CA production by solid-state fermentation (SSF) using the Aspergillus niger LPB BC strain, which was isolated in our laboratory. The parental and mutant strain showed a good production of CA using citric pulp (CP) as a substrate. The physical-chemical parameters were optimized and the best production was reached at 65% moisture, 30 degrees C and pH 5.5. The influence of the addition of commercial and alternative sugars, nitrogen sources, salts, and alcohols was also studied. The best results (445.4 g of CA/kg of CP) were obtained with sugarcane molasses and 4% methanol (v/w). The mutagenesis induction of LPB BC was performed with UV irradiation. Eleven mutant strains were tested in SSF where two mutants showed a higher CA production when compared to the parental strain. A. niger LPB B3 produced 537.6 g of CA/kg of CP on the sixth day of fermentation, while A. niger LPB B6 produced 616.5 g of CA/kg of CP on the fourth day of fermentation, representing a 19.5% and 37% gain, respectively.
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