Influence of culture conditions on production of phytase by Zygosaccharomyces baili var. balil.

Microbial phytases are phosphohydrolytic enzymes which are gaining attention for their commercial exploitation in feed and food industry. In the present study, ten yeasts were isolated from different soil samples and screened for their phytase producing capability. Among these isolates, the most promising yeast strain was Zygosaccharomyces bailii var. bailii which produced highest phytase yield (6.36 U ml(-1)) in malt yeast extract glucose peptone (MYGP) medium. In order to improve phytase production by Zygosaccharomyces bailii, different physio-chemical parameters were optimized. The optimal conditions for phytase production was found to be: incubation time-42 hr, temperature-30 degrees C, medium pH-6.0 and substrate (calcium phytate) concentration-0.1%. Glucose at 0.5% concentration supported higher phytase production (13.75 U ml(-1)) than other carbon sources tested. Metal ions (Ca+/+, Na+, K+, Mg++) and additives; ethylene diamine tetraacetate (EDTA), sodium dodecyl sulphate (SDS) and toluene did not affect enzyme production. However, Zn++, Ni++, Ba++, Pb++ and detergents like Triton X-100 and Tweens strongly inhibited (>90%) phytase production. An overall 2.21-fold enhancement in phytase activity (6.36-->14.03 U ml(-1)) was attained after optimization studies.

Genome wide identification of Dof transcription factor gene family in sorghum and its comparative phylogenetic analysis with rice and Arabidopsis.

The Dof (DNA binding with One Finger) family represents a classic zinc-finger transcription factors involved with multifarious roles exclusively in plants. There exists great diversity in terms of number of Dof genes observed in different crops. In current study, a total of 28 putative Dof genes have been predicted in silico from the recently available whole genome shotgun sequence of Sorghum bicolor (L.) Moench (with assigned accession numbers TPA:BK006983-BK007006 and TPA:BK007079-BK007082). The predicted SbDof genes are distributed on nine out of ten chromosomes of sorghum and most of these genes lack introns based on canonical intron/exon structure. Phylogenetic analysis of 28 SbDof proteins resulted in four subgroups constituting six clusters. The comparative phylogenetic analysis of these Dof proteins along with 30 rice and 36 Arabidopsis Dof proteins revealed six major groups similar to what has been observed earlier for rice and Arabidopsis. Motif analysis revealed the presence of conserved 50-52 amino acids Dof domain uniformly distributed across all the 28 Dof proteins of sorghum. The in silico cis-regulatory elements analysis of these SbDof genes suggested its diverse functions associated with light responsiveness, endosperm specific gene expression, hormone responsiveness, meristem specific expression and stress responsiveness.

Phenylpropanoid Metabolism in Ripening Fruits.

Ripening of fleshy fruit is a differentiation process involving biochemical and biophysical changes that lead to the accumulation of sugars and subsequent changes in tissue texture. Also affected are phenolic compounds, which confer color, flavor/aroma, and resistance to pathogen invasion and adverse environmental conditions. These phenolic compounds, which are the products of branches of the phenylpropanoid pathway, appear to be closely linked to fruit ripening processes. Three key enzymes of the phenylpropanoid pathway, namely phenylalanine ammonia lyase, O-methyltransferase, and cinnamyl alcohol dehydrogenase (CAD) have been reported to modulate various end products including lignin and protect plants against adverse conditions. In addition, peroxidase, the enzyme following CAD in the phenylpropanoid pathway, has also been associated with injury, wound repair, and disease resistance. However, the role of these enzymes in fruit ripening is a matter of only recent investigation and information is lacking on the relationships between phenylpropanoid metabolism and fruit ripening processes. Understanding the role of these enzymes in fruit ripening and their manipulation may possibly be valuable for delineating the regulatory network that controls the expression of ripening genes in fruit. This review elucidates the functional characterization of these key phenylpropanoid biosynthetic enzymes/genes during fruit ripening processes.

Down-regulation of lignin biosynthesis in transgenic Leucaena leucocephala harboring O-methyltransferase gene.

In the present study, a 0.47 kb OMT gene construct from aspen, encoding for an enzyme O-methyltransferase (OMT, EC 2.1.1.6), in antisense orientation was used to down-regulate lignin biosynthesis in Leucaena leucocephala. The plants were transformed with Agrobacterium tumefaciens strain harboring the antisense gene, and the transformation was confirmed by PCR amplification of the npt II gene. The integration of a heterologous antisense OMT gene construct in transformed plants led to a maximum of 60% reduction in OMT activity relative to control. The evaluation of total lignin content by the Klason method revealed a maximum of 28% reduction. Histochemical analyses of stem sections depicted a reduction in lignin content and normal xylem development. The results also suggested a probable increase in aldehyde levels and a decrease in syringyl units. Lignin down-regulation was accompanied by an increase in methanol soluble phenolics to an extent that had no impact on wood discoloration, and the plants displayed a normal phenotype. Concomitantly, an increase of up to 9% in cellulose content was also observed. Upon alkali extraction, modified lignin was more extractable as evident from reduced Klason lignin in saponified residue and increased alkali soluble phenolics. The results together suggested that the extent of down-regulation of OMT activity achieved may lead to quality amelioration of Leucaena with respect to its applicability in pulp and paper manufacture as well as nutritive and easily digestible forage production.

Insilico microarray analysis for helicobacter pylori using gene expression data.

Helicobacter pylori is a Gram-negative, microaerophilic bacterium that inhibits various areas of the stomach and duodenum. It causes a chronic low-level inflammation of the stomach lining and is strongly linked to the development of duodenal and gastric ulcers and stomach cancer. To better understand adaptive mechanisms utilized by H.pylori within the context of the host environment, spotted-DNA microarrays was utilized to characterize in a temporal manner, the global changes in gene expression in response to low pH in the pathogenic H. pylori strain G27. Raw data of this microarray work was available in Stanford Microarray Database. Co-regulated genes may share similar expression profiles, may be involved in related functions or regulated by common regulatory elements. There are different approaches to analyse the large-scale gene expression data in which the essence is to identify gene clusters. This approach has allowed us to (i) determine expression profiles of previously described developmentally regulated genes, (ii) identify novel developmentally regulated genes. The Helicobacter pylori is an important human and veterinary pathogen. In this work raw data of Helicobacter pylori is used as a sample to find out the coexpressed gene.