The Isolation And Identification Study Of A Peach Gum Degrading Bacteria And Its Exo-enzyme-producing Properties

Gum exudates from peach, plum, apricot and cherry trees are called peach gum. The peachgum is of significant medical applications; however, due to its high molecular weight and highlybranched structure, the original peach gum can barely be dissolved. The traditional production ofdissolved peach gum is through acid or alkaline solutions or high temperature degradation,which in general devalues the quality of the products and leads to environmental pollution.In the study, a bacterium degrading carrageenan was isolated from deteriorated carrageenan.After fermentation with peach gum, it was found that the bacterium degraded peach gumeffectively and then its peach gum degrading activity was strengthened with higher and higherconcentration of peach gum in the medium. After determination of its morphological,physiological and chemotaxonomic characteristics, plus16S rDNA sequence identification, thisbacterium was was identified as Microbacterium sp., which was named5#. After single factorand orthogonal tests with variable factors of peach gum’s mass fraction, fermentationtemperature and initial pH, the best exo-enzyme-producing condition is12%peach gum’s massfraction and37℃, with the initial pH of4. The molecular weight of the enzyme degradingproducts were analysized with GPC, the result showed that the polysaccharides of3000KD wasincreased with the time of the fermentation, products with2100to2300Da also appeared, whichwere the galactooligosaccharides degraded from the main structure of peach gum. It indicatesthat one of the enzymes from5#can degrade the main structure of peach gum in an endo way,with the potential of producing dissolved commercial peach gum (patent applied) plusgalactooligosaccharides from peach gum as well as other polysaccharides with similar structures.