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The kinetic basis of the role of Ca++ ions for higher yield of citric acid in a repeated-batch cultivation system

Authors
  • Ikram-ul-Haq,1
  • Ali, Sikander1
  • Qadeer, M.A.2
  • Iqbal, Javed3
  • 1 Government College University Lahore, Biotechnology Research Laboratories, Department of Botany, Pakistan; E-mails:
  • 2 University of the Punjab, National Centre of Excellence in Molecular Biology, Thokar Niaz Baig, C/B Road, Lahore, Pakistan , Lahore
  • 3 School of Biological Sciences, University of the Punjab, Quaid-e-Azam Campus, Lahore, Pakistan , Lahore
Type
Published Article
Journal
World Journal of Microbiology and Biotechnology
Publisher
Kluwer Academic Publishers
Publication Date
Nov 01, 2003
Volume
19
Issue
8
Pages
817–823
Identifiers
DOI: 10.1023/A:1026098631152
Source
Springer Nature
Keywords
License
Yellow

Abstract

The present investigation deals with role of Ca++ ions in increasing the yield of citric acid in a repeated-batch cultivation system (working volume 9-1) and its kinetic basis. Five different hyper-producing strains of Aspergillus niger were evaluated for citric acid production using clarified cane-molasses as basal substrate. Among the cultures, NGGCB101 (developed by u.v./chemical mutation in our labs) gave maximum production of citric acid i.e., 87.98 g/1, 6 days after mycelial inoculation. The addition of CaCl2 to the culture medium promoted the formation of small rounded fluffy pellets (1.55 mm, diameter), which were desirable for citric acid productivity. CaCl2 at a level of 2.0 μM, added during inoculation time, was optimized for commercial exploitation of molasses. During repeated-batch culturing, a yield of citric acid monohydrate of 128.68 g/1 was obtained when the sampling vs. substrate feeding was maintained at 4-1 (44.50% working volume). The incubation period was reduced from 6 to only 2 days. The values of kinetic parameters such as substrate consumption and product formation rates revealed the hyperproducibility of citric acid by the selected Aspergillus niger NGGCB101 (LSD = 0.456a, HS). Case studies are highly economical because of higher yield of product, lower energy consumption and the use of raw substrate without any additional supplementation.

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