Biodiversity, enzymatic and antimicrobial activities of bacterial endophytes in selected local medicinal plants

Abstract

Endophytic bacteria existing in healthy medicinal plants of Ocimumbasilicum, Cymbopogoncitratus, MorindacitrifoliaandTriticumaestivumwere isolated to evaluate their diversity, enzyme production and antimicrobial potentials of their bioactive compounds. The molecular characterization of their 16S rRNA gene indicated 41 isolates to have 98-100% similarity with the respective organisms of 14 genera and 32 species. The dominant genera are Pseudomonas and Bacillus. Antimicrobial activities of the ethylacetateextracts of their metabolites revealed 20 isolates (48%) that inhibit at least two of the nine pathogens tested with inhibition zone from 7.3 to 15.0 ±0.5 mm. Isolates-Bacillus mycoides OBR-1, Acinetobacterbaumannii LGL-1, SphingomonasyabuuchiaeTAR-1 inhibited at least five pathogens and they are considered to be the most active with zone of inhibition from 7.7 to 15.0 ±0.5 mm. In addition, eight isolates were found to produce all the four enzymes-cellulase, xylanase, amylase and pectinase with B. cereus and B.weihenstenphenensis to be the most active producers of the enzymes. Also, C. citratuswas found to have been mostly colonized by Bacilli species with high potentials to produce cellulase, amylase, pectinase and xylanase enzymes. Thus, this study revealed bacterial endophytes with ability of producing antimicrobial substances of pharmacological importance.

Key words: Bioactive compounds; 16S rRNA gene; endophytes