International Journal of Biotechnology Applications

55-71

Authors: MAHIMA DUBEY, RAKESH MENNA, GIRISH CHANDEL

Genes in the YSL gene family encode for the metal transporter in plants. In this study, a comprehensive and comparative computational analysis of identified 18 and 8 YSL family genes in rice and Arabidopsis respectively have been carried out presenting a complete overview on gene structures, phylogeny, conserved motifs their distribution and relatedness, intron/ exon distribution and expression. The analysis in all indicated that YSL genes are relatively conserved gene family showing similarity on the basis of evolution and indicates their common ancestral origin. The multi-sequence alignment showed primary and secondary level of conservation at sequence level of YSLs in both rice Arabidopsis. YSL gene intron/ exon structure and domains were also found to be conserved during the evolution. Characterization of YSLs by sequence tag based methods of expression profiling viz ESTs and MPPS signatures showed a total of 833 ESTs and 382 MPSS tags co-localizing with the OsYSLs and 269 ESTs and 219 MPSS tags with AtYSLs. The expression pattern further analyzed digitally, by in silico microarrays in 22 tissues libraries, 8 stages of development and under different stimuli revealed assorted and preferential patterns of expression and provide an evidence for spatiotemporal regulation of these genes throughout plant development. OsYSL6 gene of rice showed very high as well as tissue specific expression under iron and phosphorous interaction by digital microarrays which were equally supported by ESTs and MPSS abundance. Similarly in Arabidopsis AtYSL1, 3 and 6 showed prominent expression in senescent leaves indicating their role in remobilization of metals.

80-88

Authors: MARCIN SKOWRONEK, JAN FIEDUREK, MARIUSZ TRYTEK

A system for the production of extracellular inulinase with the use of Aspergillus niger 20 Osm mycelium immobilized on several polyurethane foam disks in a 2-liter bioreactor was developed. Because the application of the disks reduced the efficiency of the conventional aeration system initially employed in the study and caused difficulties in maintaining sufficient concentrations of dissolved oxygen, an alternative culture oxygenation method based on O2 generation by decomposition of sequential doses of hydrogen peroxide introduced into a bioreactor medium was used. The application of the alternative oxygenation system during repeated batch culture made it possible to maintain adequate concentrations of dissolved oxygen (50 – 99%) and a proper level of inulinase biosynthesis for a long time (up to 22 days). In the optimized conditions, the immobilized mycelium produced 86 321 units of inulinase activity during a 7-cycle process.