Probiotic potential of bacterial endophytes isolated from leaves of Murraya koenigii L.

Abstract

Probiotics are live microorganisms which confer health benefits to the host when administered in adequate amounts. Endophytes, which live in plant tissues between the plant cells, can act as potential probiotic bacteria. The leaves of Murraya koenigii L. is a common cuisine and herbal ingredient used in indigenous medicine. The main objective of the current study was to assess probiotic characteristics of isolated bacterial endophytes of M. koenigii leaves. Young and mature leaves of M. koenigii were collected from sites in the wet and dry zones of Sri Lanka. The endophytes were isolated using three techniques: placing leaf segments, leaf macerations and preparation of pour plates on three different media viz., nutrient agar, Luria-Bertani (LB), and De Man, Rogosa and Sharpe agar (MRS). They were identified from morphological characteristics and preliminary biochemical tests. Probiotic characterization of the isolates was carried out by using a series of standard tests including resistance to low pH, tolerance of bile salts, antimicrobial activity (Escherichia coli and Pseudomonas aeruginosa), antibiotic resistance (Gentamycine), anti-haemolytic activity, and non-DNase activity. Ten endophytic bacteria (two bacilli, eight cocci including two Gram positive cocci, and eight Gram negative cocci and bacilli) were isolated from the young and mature leaf samples collected. While probiotic characterization tests were positive, four isolates showed antibiotic susceptibility. These results indicate the possibility that M. koenigii leaves possess bacterial endophytes with probiotic potential.