جستجوی مقالات مرتبط با کلیدواژه "صنایع غذایی" در نشریات گروه "زیست شناسی"

Sorbitol is a 6- carbon polyol, which is used in food industries as a precursor for production of many products due to its sweetness and high solubility. The application of microbial process for sorbitol production has recently been becoming of point of interest because of requirement for suitable fermentative conditions, being cost effective and less environmental pollutions. The purpose of this study was to produce sorbitol from sucrose by Debaryomyces hansenii isolated from the nature.
The sorbitol producing yeast strain was isolated in a medium containing 40% glucose and 1% yeast extract. Following identification of yeast using ITS gene sequencing, we focused on the process of fermentation and production of sorbitol from sucrose. The quality and quantity of sorbitol production was analyzed by thin layer chromatography, colorimetric method and Megazime kit.
The sorbitol producing yeast strain was isolated from pollen of Malva sylvestris flower, and was identified as D. hansenii. This strain produced 5.23 g l-1 sorbitol after 5 days in medium containing of 150 g l-1 sucrose.
In this study sorbitol was produced by a D. hansenii isolated from the nature. Due to high efficiency of sorbitol production from sucrose by yeast, isolation of sorbitol producing native yeasts and optimization of the production conditions can be helpful for increases in quality and quantity of sorbitol production.

Biodiversity of yeasts in extreme habitats and applications in food industry attract many of researchers. The aim of this study was evaluation of invertase activity in isolated yeasts from saline soil. In this study, kinetic activity of invertase from 27 halophilic and halotolerant yeast strains isolated from salin soil of Qom and Arak were evaluated. After collection of soil samples, the yeasts were cultured on YPD Agar containing 5% salt. Out of 27 yeast strains, 2 halophilic and 6 halotolerant strains with invertase activity were assessed for selection of best strain. Assessment of invertase activity according to the Glucose Oxidase assay showed that the enzyme productivity of G5 strain is more powerful than other isolates. The optimum enzyme activity was obtained at 65C and pH 4.5. The highest enzymatic activity was observed in the medium containing 1.7mM sodium chloride. Na+, Mg2+ and Ca2+ ions (all chlorides and 5mM concentration) have stimulation effect on enzyme's activity. The Km of enzyme for sucrose was 20 mM. Thermal stability of enzyme in 65C was one hour and decrease of activity is not observed. According to the results of this study, G5 strain has able to produce invertase in different concentrations of different salts.