Estudio fisiológico de la producción de ácido cítrico por Aspergillus niger O-5

Abstract

Due to an increasing demand for valuable metals, there is a
great interest in looking for alternative technologies that improve the
environmental impact caused by mining industry. Biological leaching
could be an alternative for processing nickel laterite ores. The organic
acids from fungi are used for dissolving metals from ore. Citric acid producer
strains of A. niger are the most employed bioleaching. Therefore it
is important determining the best culture conditions for higher productions
of this organic acid. In this work the influence of incubating time
of inoculums (72, 96, 112, 120 and 140 h), inoculums volume (2,5; 5 and 7 %),
culture media volume (20 and 40 %) and aeration (superficial and submerged
culture) on citric acid production of A. niger O-5, a Cuban strain isolated
of acidic media was studied. The highest production of citric acid was
obtained with inoculums of 112 h, 20 % of culture media volume and 5 %
of inoculums volume. On the other hand the fungal growth in submerged
culture was increased and was obtained almost 5 g/L of citric acid, more
than on superficial cultures. Nevertheless, the product/biomass yield was
higher using superficial cultures than submerged cultures. According to
the relation between product and biomass, it can classify citric acid production
by A. niger O-5 as fermentation type I (associated).