For the enhancement of the probiotics' survivability, a nanostructured fiber mat was developed by electrospinning. The probiotic Lactobacillus plantarum was encapsulated in the nanofibers with fructooligosaccharides (FOS) as the cell material. Fluorescence microscope image and scanning electron microscopy (SEM) showed that viable cells were successfully encapsulated in nanofibers (mean diameter = 410 +/- 150 nm), and the applied voltage had no significant influence on their viability (P > 0.05). A significantly improved viability (1.1 log) was achieved by incorporating 2.5% (w/w) of FOS as the electrospinning material (P < 0.001). Additionally, compared with free cells, the survivability of cells encapsulated in electrospun FOS/PVA/L. plantarum nanofibers was significantly enhanced under moist heat treatment (60 and 70 degrees C). This study shows that the obtained nanofiber is a feasible entrapment structure to improve the viability and thermal stability of encapsulated probiotic cells and provides an alternative approach for the development of functional food.