Improvement on Citric Acid Production in Solid-state Fermentation by Aspergillus niger LPB BC Mutant Using Citric Pulp

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.

Utilization of different agro-industrial wastes for sustainable bioproduction of citric acid by Aspergillus niger

“…Tran et al [27] obtained higher citric acid concentration with 3% MeOH by solid-state fermentation of pineapple waste. The increased citric acid production from citric pulp by A. niger was observed with the addition of 4% MeOH [28]. They observed the drastic increase in citric acid production from 261.2 g/kg to 380.9 g/kg of citric pulp.…”

Biotechnological production of citric acid

“…The same stimulating effect of methanol was observed by Kumar et al (48, 49) using a mixture of different fruit wastes and bagasse for A. niger DS1 solid-state fermentation. The use of 4% methanol (v/w) was also reported for the submerged fermentation of orange peel hydrolysates (84) and the solid-state fermentation of sugarcane molasses (85), that led to citric acid productions of 9.2 g/l and 445.4 g/kg, respectively. Roukas (88) observed an increase in citric production from 176 to 264 g/kg when the concentration of methanol was increased up to 6% (w/w) in dry pod solid-state fermentation.…”

Citric acid production from orange peel wastes by solid-state fermentation

“…However, because of several advantages over the submerged fermentations such as solid waste management, biomass energy Citric acid production by solid-state fermentation conservation, production of high value products and little risk of bacterial contamination (44), the SSF methods have recently gained attention using agroresidues like sugarcane or cassava bagasse (29,30,38,46), carob pod (44), areca husk (36), beet molasses (1), soy residues (27), sugar cane bagasse, coffee husk and cassava bagasse (55) and waste of food processing industries including pineapple wastes (6,11,18,22,52,53), apple pomace (20,48), grape pomace (19), or different fruit peels, including kiwi (17), orange (43) or prickly pear (12).…”