Endophytic bacteria are harmless in most plant species; and known to boost the growth and development of the host plants probably by secreting growth hormones. The isolation, identification and screening of endophytic bacteria for the plant growth regulators like cytokinin are needed to get the leads for their applications in agriculture sector. We describe the isolation and identification of the bacterial endophytes from the leaves of Sambung Nyawa [Gynura procumbens (Lour.) Merr.] and their screening for cytokinin-like compounds. We isolated three endophytic bacteria from the leaves of G. procumbens collected from the forest research institute of Malaysia (FRIM). They were further identified using amplified 16S rRNA gene sequence based method of bacterial identification. The ethyl acetate extracts of the isolates-broth were analyzed using cucumber cotyledon greening bioassay (CCGB) to determine the presence of cytokinin-like compounds. Consequently, the bacterial putative endophytes were identified as Psuedomonas resinovorans, Paenibacillus polymaxa, and Acenitobacter calcoaceticus. Broth-extracts from two (Psuedomonas resinovorans and Paenibacillus polymaxa) of the three putative bacterial endophytes show the positive results in their screening for cytokinin-like compounds using CCGB. Thus, we hypothesize that the bacterial putative endophytes of G. procumbens that produce cytokinin-like compounds might have a role in the growth and development of G. procumbens.
Abbreviations: CCGB - Cucumber cotyledon greening bioassay, rDNA - Ribosomal DNA, K12, BAP - 6-Benzylaminopurine, Db1, MSA - Multiple sequence alignment. 8081.
Keywords: 16S rRNA gene; Bacteria; Cytokinin; Endophytes; Gynura procumbens; Microbial diversity; Plant growth regulators.