Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10884502 | Biocatalysis and Agricultural Biotechnology | 2014 | 33 Pages |
Abstract
Rhizobium spp. produce a variety of commercially important polymers during free living growth, which includes polyhydroxyalkanoate (PHA), exopolysaccharides (EPS), β-(1,2)-glucan, etc. Shake flask cultivation of Sinorhizobium meliloti CFR 14 for 72 h with ammonium sulfate (0.318 g/L of N) and sucrose (12.64 g/L of C) resulted in 3.5 g/L of biomass with 1.7 g/L of PHA and 1.5 g/L of EPS. Corresponding yields enhanced to 5.0, 2.5 and 2 g/L, in a 48 h batch fermentation process at 30 °C, pH 7.0 and 40% air saturation level. Fed batch fermentation process with ammonium sulfate and sucrose as feed nutrients supported the production of 34.5 g/L of biomass with 17.2 g/L of PHA and 3.5 g/L of EPS. Concentration of glycogen, cellular and excreted β-(1,2)-glucan were about 0.3 g/L each under this condition. Fed batch process operated using ammonium hydroxide for dual purpose as a nitrogen source and for pH adjustment, lead to decreased biomass (29.6 g/L) and PHA yields (9.4 g/L). However, higher synthesis of EPS, glycogen, cellular and excreted β-(1,2)-glucan amounting to 9.0, 1.1, 1.3 and 2.0 g/L, respectively, were obtained indicating that the fermentation conditions like pH, dissolved oxygen level, amount of carbon and nitrogen play a significant role in the synthesis of intra- and extra-cellular polymers by the free living cells of S. meliloti.
Keywords
Related Topics
Life Sciences
Agricultural and Biological Sciences
Agricultural and Biological Sciences (General)
Authors
T.R. Shamala, Y.S. Rohinishree, S.V.N. Vijayendra,