Research In Microbial Production Of Fructooligosaccharides From Inulin

Inulin is a naturally storage polysaccharide founded in various plants.Inulinase can hydrolyze inulin into fructooligosaccharides or fructose,which can be widely used in food industry.Some strains capable of producing inulinase were isolated from rhizosphere soil of Jerusalem artichoke.After further selection,a strain named FOS with higher inulinase productivity was obtained.This strain was identified as Paenibacillus sp.by the Sherlock Microbial Identification System and 16S rDNA sequence analysis.The strain was Gram-negative,non-motile and central endospore-forming straight rod.Its single colony was round,adhesive,milk white,with an irregular shape as dendritic.Through the study on fermentation time,carbon sources,nitrogen sources,initial pH,mineral ions,our research has brought about the following optimum fermentation conditions:inulin:2%,yeast:0.2%,8%NaCl:1%,7%KCl:1%,5%K2HP04:1%,0.5%MgS04:1%,pH 7.5,30℃,160rpm.Maximal inulinase activity in the culture supernatant of FOS was 26.09U·mL-1 after cultured for 48h.The transformation products were determined by TLC and HPLC methods.The main product was GF4 and its content was 5.23mg·mL-1.