Isolation and characterization of endophytic bacteria fromPlectranthus tenuiflorusmedicinal plant in Saudi Arabia desert and their antimicrobial activities

Abstract

The diversity and beneficial characteristics of endophytic microorganisms have been studied in Plectranthus tenuiflorus medicinal plant. However, information regarding naturally occurring P. tenuiflorus plant associated endophytes among different organs of host is limited. Endophytic bacteria were isolated from root, stem, and leaves of P. tenuiflorus plant. Among 28 endophytic bacterial isolates from different organs of P. tenuiflorus plant, 8 isolates were identified by partial sequencing of their 16S rRNA gene. The isolated endophytic bacteria were Bacillus sp., Bacillus megaterium, Bacillus pumilus, Bacillus licheniformis, Micrococcus luteus, Paenibacillus sp., Pseudomonas sp., and Acinetobacter calcoaceticus. The most isolates that exhibited extracellular enzymatic activity were belonged to the genus Bacillus. Furthermore, Bacillus sp. (HE613660) exhibited the stronger activities in extracellular enzymes such as amylase, esterase, lipase, protease, pectinase, xylanase, and cellulase than other strains. Considerable antimicrobial activities against a panel of human pathogenic microorganisms (Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Streptococcus agalactiae, Proteus mirabilis, and Candida albicans) were recorded using crude extracts of the collected endophytic strains.

Bioprospecting of Endophytic Bacteria from Zingiber officinale with Antibacterial Activities

“…The result of BLAST analysis along with accession number of submitted 16S rDNA sequence of purified bacteria is summarized as Table 1. The isolates ZB1 to ZB5 showed maximum identity to Bacillus sp. El-Deeb et al, (2013) reported the isolation of 28 endophytic bacterial isolates from different organs of P. tenuiflorus plant, which belonged to Bacillus sp., Bacillus megaterium, Bacillus pumilus, Bacillus licheniformis, Micrococcus luteus, Paenibacillus sp., Pseudomonas sp., and Acinetobacter calcoaceticus. De Oliveira Costa et al reported that (de Oliveira Costa et al, 2012) 23 different genera were isolated from common bean (Phaseolus vulgaris).…”

Isolation and Characterization of Endophytic Bacteria Associated with Roots of Jojoba (<i>Simmondsia chinensis</i> (Link) Schneid)

“…IN recent years, there is increasing interest regarding plant-microbe association, particularly in composition, structure and function of endophytic bacteria 1 that colonize plants without apparently causing any damage 2 . Endophytes establish a mutualistic symbiosis with their hosts because they are selectively favoured 3,4 .…”

“…Endophytes stimulate plant growth through several mechanisms such as nitrogen fixation, inorganic phosphate solubilization, siderophore production, micronutrient supply 6 , photosynthetic activity and phytostimulation 5 . Endophytic bacteria can also contribute to soil pathogen control with the production of antibiotics and secondary metabolites and induction of the plant defence system 3 , besides heavymetal biotransformation, biodegradation of organic pollutants 2 , osmotic adjustment, stomatal regulation, modification of the root morphology and metabolism 1 . Jojoba (Simmondsia chinensis) is a shrub native to northwestern Mexico and southwestern United States.…”

“…The population density of endophytes in plants from desert areas is lower (1.1  10 2 -1. 2 . This difference may be due to very different environmental conditions, even if they are desert plants 11,17 .…”

“…and KT964151 (Oceanobacillus kimchii) ( Table 2). Previously reported endophytic bacteria genus Bacillus and Pseudomonas have been isolated from plants in the arid regions 2,8 . Methylobacterium spp., a common endophyte bacterium, can form biofilms and shows resistance to stress and heavy metals 3 .…”