Biological Synthesis of Ginsenoside Rd Using Paenibacillus horti sp. nov. Isolated from Vegetable Garden

A Gram-stain positive, aerobic, motile, rod-shaped, and ginsenoside Rd producing novel bacterial strain, designated as MAH-16^T, was isolated from soil sample of a vegetable garden and was characterized by using a polyphasic approach. The colonies were beige color, smooth, circular, and 0.3-0.7 mm in diameter when grown on tryptone soya agar for 3 days. Strain MAH-16^T can grow at 20-40 °C temperature, at pH 5.0-7.0 and at 0-1% NaCl. Cell growth occurs on nutrient agar, R2A agar, tryptone soya agar, and Luria-Bertani agar but not on MacConkey agar. The strain was positive for both catalase and oxidase test. The novel strain rapidly synthesized ginsenoside Rd from major ginsenoside Rb1. According to the 16S rRNA gene sequence comparisons, the isolate was identified as a member of the genus Paenibacillus and was most closely related to Paenibacillus barengoltzii SAFN-016^T (97.1%), Paenibacillus faecis 656.84^T (96.7%), and Paenibacillus konsidensis LBY^T (96.2%). In DNA-DNA hybridization tests, the DNA relatedness between strain MAH-16^T and its closest phylogenetic neighbor was below 45.0%. The genomic DNA G + C content of isolated strain was determined to be 52.0 mol% and the predominant isoprenoid quinine was menaquinone-7 (MK-7). The major fatty acids were identified as anteiso-C_15:0. The genetic characteristics in combination with chemotaxonomic and physiological data demonstrated that strain MAH-16^T represented a novel species within the genus Paenibacillus, for which the name Paenibacillus horti sp. nov. is proposed, with MAH-16^T as the type strain (=KACC 19299^T = CGMCC1.16487^T).