ISOLATION AND CHARACTERIZATION OF BACTERIAL ENDOPHYTES ASSOCIATED WITH SAGO PALM (METROXYLON SAGU ROTTB.) IN TISSUE CULTUREK.L. LABRADOR, E.L.T. LUSTICA AND A.U. NOVERO
Endophytic bacteria are novel sources of beneficial compounds such as plant growth regulators and antibiotics. Nine bacterial isolates were obtained from sago palm tissue culture. Selected candidates were those colonies observed to have originated from the base of the explants. Eight of the isolates were Gram- negative bacilli (SEB 001, 002, 003, 004, 005, 006, 007, and 008) and one (SEB 206) was Gram-positive coccus. All eight isolates demonstrated the ability to ferment lactose and/ or sucrose, and were positive in catalase, citrate and VP tests. The isolates were negative for endospore formation, indole production, and methyl red test. Only one isolate grew in mannitol salt agar. Amplification of 16s rDNA sequences using the universal primers 16F27 and 16R1542 identified the isolates as Enterobacter ludwigii (SEBs 001, 003, and 006), Pantoea dispersa (SEBs 002 and 004), and Klebsiella variicola (SEBs 005, 007, and 008). Morphological and biochemical properties of the test isolates, as well as phylogenetic analysis, support the deduced identities. All isolates inhibited the growth of E. coli in the disc diffusion assays with SB 006 obtaining the highest mean zone of inhibition (12 mm). In the resazurin test, SEB 007 and SEB 008 showed promising antibiotic activities against E. coli, Aspergillus niger and Fusarium oxysporum. This study revealed that E. ludwigii and K. variicola isolated from sago palm possess antibiotic properties.
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