Anticandidal Potential of Endophytic Bacteria Isolated from Dryopteris uniformis (Makino)

Candida infection currently presents a major problem. The natural products from endophytic bacteria are thought to have a strong potential for treatment. The present study aimed to isolate endophytic bacteria from Dryopteris uniformis, its identification, and investigation of their anticandidal activity and confirm it. The isolated endophytic bacteria from D. uniformis were identified by using 16S rRNA gene sequencing. The anticandidal assay of endophytic bacteria was performed by using the patch method. Endophytic bacteria were successively fractionated by using different polarity solvents. The anticandidal activity of each solvent fraction was evaluated by using the disc diffusion method and was confirmed by scanning electron microscopy. Fifty-one endophytic bacteria were isolated from the lead and stem/root of D. uniformis and screened for anticandidal activity against five Candida species, Candida saitoana (KACC 41238), C. albicans (KACC 30062), C. albicans (KACC 30003), C. glabrata (KBNO6P00368) and C. glochares (KACC 30061). Among these, six endophytic bacteria exhibited strong anticandidal activity with an inhibition zone diameter between 9.29 and 47.67 mm against four Candida species; these bacteria were identified as Burkholderia sp. UR 1-07 (DUS14), Staphylococcus sp. WW60 (DUS56), Bacillus sp. cryopeg (DUS59), Paenibacillus sp. rif200865 (DUL128), Staphylococcus warneri (DUS130), and Bacillus psychrodurans (DUS131) using 16S rRNA gene sequencing. The minimum inhibitory concentration (MIC) of the butanol fraction of the selected endophytic bacteria, Burkholderia sp., was 250 µg/mL and the minimum fungicidal concentration (MFC) was 500 µg/mL. Scanning electron microscopy result indicated that, MIC of promising endophytic bacteria Burkholderia sp. destroyed the target Candida cells. This study demonstrated anticandidal potential of endophytic bacteria derived from D. uniformis.