关键词: 南瓜, 内生菌, 抑菌活性, 薄层层析, 多酚类

Abstract: Objective: To search for endophytes capable of producing polyphenol compounds from pumpkin (Cucurbita
moschata Duch.) for the purpose of developing fully this plant resource. Methods: The endophytic bacteria present in
pumpkin flesh were isolated by tissue separation, the streak plate method and the gradient dilution method, and the plate
confrontation method was used to measure their antibacterial activity. Moreover, the antibacterial substances in the
culture broth of the isolated bacteria were identified by high performance liquid chromatography (HPLC) after thin-layer
chromatography (TLC) analysis using pumpkin extract as control. Results: Fifty-four endophytic strains were obtained. It
was found that 12 (22%) of these strains had antimicrobial activity against one or more tested microbes in bacteriostasis
experiments. Three strains (numbered as 25, 26, 29) had a broad-spectrum antimicrobial activity, and higher antibacterial
rate, (36.73 ± 0.52)%. TLC detection showed that the fermentation product of the strain No. 25 and pumpkin pulp extract
had the same spot with an Rf value of 0.57. Conclusion: The strain No. 25 can produce polyphenols or similar compounds
and therefore can provide a new strategy to produce polyphenols and alkaloids by the fermentation of endophytic bacteria.

Key words: pumpkin (Cucurbita moschata Duch.), endophyte, antibacterial activity, thin-layer chromatography, polyphenols