ABSTRACT
ObjectiveTo screen and validate key enzyme genes affecting the polysaccharide content in different Polygonatum species and perform in-depth amino acid sequence analysis by transcriptomic analysis of P. zanlanscianense， P. kingianum， and P. cyrtonema rhizomes to enrich the transcriptome data of Polygonatum plants and provide references for polysaccharide biosynthesis mechanism and genetic improvement. MethodThe Polygonatum transcriptome was sequenced and analyzed using the Illumina NovaSeq high-throughput sequencing platform， and the differences in the transcriptomes of the three Polygonatum species were compared and according to the annotations of Nr， Gene Ontology （GO）， and Kyoto Encyclopedia of Genes and Genomes （KEGG） databases. The key enzymes in the polysaccharide metabolism pathway were screened， and the expression of key enzyme genes was clustered and correlated with the polysaccharide content. Finally， Real-time polymerase chain reaction （Real-time PCR） was performed to validate the eight key enzyme genes， and the key genes of polysaccharide biosynthesis were further screened for homologous gene sequence analysis in combination with sequencing results， followed by constructing phylogenetic trees， predicting motifs， conserved structural domains， protein sequence isoelectric points， and molecular weights， and constructing 3D protein structures by using homology modeling method. ResultThe annotation of the Nr database revealed that three Polygonatum species had the highest gene homology with Asparagus officinalis. GO database annotation results showed that three Polygonatum species differed significantly in binding， catalytic activity， metabolic processes， and cellular components， while the KEGG pathway annotation results indicated that three Polygonatum species differed significantly in the starch and sucrose metabolic pathway and galactose metabolic pathway. According to clustering analysis， correlation analysis， Real-time PCR， expression profiles， and structural and functional predictions of amino acid sequences， the key enzyme significantly affecting the polysaccharide content in different Polygonatum species was inferred to be β-fructofuranosidase （sacA）. ConclusionSacA may be the main influencing factor for the difference in polysaccharide content of Polygonatum， and is also an important reason why Polygonatum polysaccharides are mainly fructans.
ABSTRACT
This present study focuses on the microbial production of Fructosyl Transferase (FTase) and the production of Fructooligosaccharides(FOS) by transfructosylation using this enzyme. Fructooligosaccharides are industrially produced from sucrose by microbial enzymes with transfructosylating activity. Fructosyltransferase is produced intracellulraly by fungi. In the present study fungus Aureobasidium pullulans was used to produce FOS and effect of different physical and chemical parameters on FOS production were studied. The analysis of the product was performed by High Pressure Liquid Chromatography (HPLC).
ABSTRACT
Aspergillus oryzae IPT-301, previously reported as a ¥â-fructofuranosidase producing microorganism, was successfully mutated using UV irradiation at 253.7 nm followed by the screening of survivors resistant to certain stress conditions. Strains were first subjected to the ¥â-fructofuranosidase activity assay using a portion from the colony grown in Petri dish as the enzyme source. Seven mutants with fructofuranosidase activity values relative to the parent culture between 140 -190 percent were selected from survivors grown at temperature of 40¨¬C or 0.018 percent (w/v) sodium dodecyl sulfate concentration. They were cultivated on a rotary shaker to characterize mycelium and extracellular fructosyltransferase activities. Three mutants named IPT-745, IPT-746 and IPT-748 showed the highest amount of mycelium activity whose values increased 1.5 -1.8 fold, compared with the parent strain. It was found that more than 55 percent of total enzyme activity (mycelium- plus extracellular- activity) from these strains was detected in the mycelium fraction. Only one mutant, IPT-747, exceeded the amount of extracellular enzyme exhibited by the parent strain (1.5 times). This mutant also showed the highest value of total fructosyltransferase activity.