Radical scavenging activity and stability of betalains from Beta vulgaris hairy root culture in simulated conditions of human gastrointestinal tract.

Stability and radical scavenging activity of betalains, biosynthesized by Beta vulgaris hairy root culture were investigated at different pH values, bile salts concentration, as well as at the in vitro conditions of gastrointestinal tract. It was established that pH below 3 and concentrations of the bile salts up to 4% had no great influence on betalains stability. At the in vitro conditions of gastrointestinal tract betalains are relatively stable, as their radical scavenging activity decrease from 75% inhibition of 2,2-diphenyl-1-picrylhydrazyl (DPPH*) to about 38%.

Mutant Hansenula polymorpha strain with constitutive alcohol oxidase and peroxisome biosynthesis.

A mutant of the methylotrophic yeast Hansenula polymorpha with constitutive alcohol oxidase (AOX) and peroxisome biosynthesis was obtained after UV treatment followed by cell plating on a medium containing methanol and 2-deoxy-D-glucose (DOG). DOG-resistant colonies of mutants were insensitive to catabolic repression by glucose and methanol. A selection procedure is described that allows the isolation of a mutant exhibiting a constitutive phenotype of AOX involved in methanol utilization.