Author/Authors :
Oraei, Marjan Bioprocess Engineering Laboratory (BPEL) - Department of Food Science - Engineering and Technology - Faculty of Agricultural Engineering and Technology - University of Tehran, Karaj, Iran , Razavi, Hadi Bioprocess Engineering Laboratory (BPEL) - Department of Food Science - Engineering and Technology - Faculty of Agricultural Engineering and Technology - University of Tehran, Karaj, Iran , Khodaiyan, Faramarz Bioprocess Engineering Laboratory (BPEL) - Department of Food Science - Engineering and Technology - Faculty of Agricultural Engineering and Technology - University of Tehran, Karaj, Iran
Abstract :
Background: Riboflavin (vitamin B2) is an essential component of the basic metabolism,
and an important nutritional and growth factor in humans, animals, plants and
micro-organisms. It has been widely used in the fields of pharmaceuticals, feed and
food additives. The industrial production of riboflavin mostly relies on the microbial
fermentation. Designing an appropriate fermentation medium is of crucial importance
to improve the riboflavin production.
Methods: In this study, sequential methodology combining a screening test of minerals
by Plackett-Burman (PB) and an optimization test by Central Composite Design
(CCD) was applied to enhance riboflavin production by Bacillus subtilis ATCC 6051 in
shake flasks.
Results: Initially, one-factor-at-a-time approach was applied to evaluate the effect
of different carbon sources. The results showed that fructose was significantly most effective
on biomass and riboflavin production. After that, 13 minerals [CaCl2, CuCl,
FeCl3, FeSO4, AlCl3, Na3MoO4, Co(NO3)2, NaCl, KH2PO4, K2HPO4, MgSO4, ZnSO4, and
MnSO4] were studied with the screening test. The results revealed that concentration
of MgSO4, K2HPO4, and FeSO4 had greater influence on riboflavin production (p<
0.05). A CCD with five factors (concentration of fructose, MgSO4, K2HPO4, FeSO4, and
yeast extract) at five levels was then used to determine the maximum riboflavin concentration.
The optimal concentrations (g/l) of these variables determined by Response
Surface Methodology (RSM) were fructose, 38.10; MgSO4, 0.85; K2HPO4, 2.27;
FeSO4, 0.02; and yeast extract, 4.37.
Conclusion: Statistical experimental design offers a practicable approach to the implementation
of medium optimization. From an industrial view point, our optimum
medium, besides fructose and a small amount of yeast extract, is mainly composed of
common and cheap inorganic salts, which are available to the industrial riboflavin
production.
