Isolation and Characterization of Endophytic Bacteria from Piper longum

Abstract

Endophytes are non-pathogenic microorganisms that reside within internal tissues of plant, without causing any apparent symptoms of infection. In an attempt to identify endophytes from Piper longum, the Indian long pepper, a combination of conventional and molecular approaches was used. Using culture-dependent approach, six different bacterial isolates were obtained from various surface-sterilized parts (roots, nodes, internodes, petioles, leaves and spikes) of the plant. In general, roots harboured maximum concentration of endophytic bacterial isolates, while leaves contained the minimum levels. These endophytes were analyzed on the basis of colony morphology and biochemical characteristics. Based on the results obtained after BLAST search of 16S rDNA sequence in NCBI database, the endophytes isolated from Piper longum showed highest similarity to Endophytic bacteria 135L-3, Enterobacter sp. SQ6-43, Bacillus casamancensis strain TN3, Alishewanella sp. JS-30, Bacterium B28 and Enterobacter ludwigii strain g45. Most of the identified bacteria belong to the phylum Proteobacteria and Firmicutes, whose members have been reported to act as growth-promoting bacteria in other plant species. Some of these endophytes tested positive for the ability to produce indole-3-acetic acid and hydrogen cyanide, suggesting their potential roles in plant growth promotion and biological control against pathogens, respectively.