Expression and characterization of a recombinant stevioside hydrolyzing β-glycosidase from Enterococcus casseliflavus.

The demand for steviol glycosides, non-caloric sweet components of Stevia rebaudiana Bertoni (stevia) leaves, has increased considerably as a benefit to enhance human health. However, the supply has remained challenging due to limited production, with the lack of a specific steviol glycoside hydrolyzing enzyme. In this study, a novel β-glucosidase (EcBgl) from Enterococcus casseliflavus was cloned and expressed in Escherichia coli.

Three novel mutations in α-galactosidase gene involving in galactomannan degradation in endosperm of curd coconut.

The deficiency of α-galactosidase activity in coconut endosperm has been reported to cause a disability to hydrolyze oligogalactomannan in endosperm resulting in curd coconut phenotype. However, neither the α-galactosidase encoding gene in coconut nor the mutation type has been identified and characterized in normal and curd coconuts. In this study, cDNA and genomic DNA encoding α-galactosidase gene alleles from a normal and two curd coconuts were successfully cloned and characterized.

The plasmid vectors, pBS2ndd and pBS3ndd, for versatile cloning with low background in Escherichia coli.

For decades, diverse plasmid vectors have been continuously developed for molecular cloning of DNA fragment in the bacterial host cell Escherichia coli. Even with deliberate performances in vector preparation, the cloning approaches still face inevitable background colonies, or false positive clones, that may be arisen from intact or self-ligated plasmid molecules. To assist in such problem, two plasmids, pBS2ndd and pBS3ndd, which resistant to ampicillin and kanamycin respectively, were developed in this study as more advantageous cloning vector.

Development and Validation of an Enzymatic Method To Determine Stevioside Content from Stevia rebaudiana.

An enzymatic method for specific determination of stevioside content was established. Recombinant β-glucosidase BT_3567 (rBT_3567) from Bacteroides thetaiotaomicron HB-13 exhibited selective hydrolysis of stevioside at β-1,2-glycosidic bond to yield rubusoside and glucose. Coupling of this enzyme with glucose oxidase and peroxidase allowed for quantitation of stevioside content in Stevia samples by using a colorimetric-based approach.

Sap phytochemical compositions of some bananas in Thailand.

Banana sap has some special properties relating to various phenomena such as browning of fruits after harvesting, permanent staining of cloth and fibers, and antioxidant and antibleeding properties. Analysis of banana sap using high-performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS) indicated the presence of phenolic and aromatic amino compounds of interest due to their special properties. With the online positive electrospray ionization mode (ESI), the possible structures of specific compounds were determined from the fragmentation patterns of each particular ion appearing in the mass spectra.

Anthocyanin composition of wild bananas in Thailand.

Anthocyanins were isolated from male bracts of 10 wild species of bananas (Musa spp. and Ensete spp.) distributed in Thailand.