Determination of the bacteria present along with the tuberous root formation in yacon - Smallanthus sonchifolius

Abstract

Yacon (Smallanthus sonchifolius), a plant traditionally grown in the Northern and Central Andes, is recently cultivated in Vietnam. The edible storage roots of yacon contain a large amount of carbohydrate during the form of indigestible fructooligosaccharide (FOS), which functions as a prebiotic and gives positive effect during the treatment of obesity, diabetes, and colorectal cancer. Thus, yacon root is expected to be a good dietary supplement for patients with these diseases. There has been limited research about the impacts of microorganisms on the tuberous root formation of yacon. Therefore, this paper presents the enumeration of aerobic bacteria in the root area at the two growing stages, before and in the early stage of the tuberous root formation, of yacon by MPN (Most Probable Number) method. The obtained results show a significant change on the amount carbohydrate metabolism bacteria presence in yacon roots between the two growing stages. Besides, there are more carbohydrate metabolism bacteria (9,3 x 105 MPN/mL) in tuberous root than protein metabolism bacteria (9,3x103 MPN/mL). The isolation of aerial bacteria from yacon roots found 22 strains, which are assigned into the 10 genera including Burkholderia, Caulobacter, Myroides, Pantoea, Pseudomonas, Stenotrophomonas, Kosakonia, Rhizobium, Enterobacter, and Klebsiella based on the phylogentic analysis of the so-called 800R 16S rRNA gene sequences. The appearance of those genera in difference parts of yacon root is not the same. The presence of difference genera is also shown in the roots at the two growing stages.