Abstract
Background: Endophytic bacteria are ubiquitous in all plant species contributing in host plant's nutrient uptake and helping the host to improve its growth. Moringa peregrina is a medicinal plant, growing in arid region of Arabia was assessed for the presence of endophytic bacterial strains. Results: PCR amplification and sequencing of 16S rRNA of bacterial endophytes revealed that the 5 endophytic bacteria, in which 2 strains were from Sphingomonas sp; 2 strains from Bacillus sp. and 1 from Methylobacterium genus. Among endophytic bacterial strains, a strain of Bacillus subtilis LK14 have shown significant prospects in phosphate solubilization (clearing zone of 56.71 mm after 5 d), ACC deaminase (448.3 ± 2.91 nM α-ketobutyrate mg -1 h -1 ) and acid phosphatase activity (8.4 ± 1.2 nM mg -1 Min -1 ). The endophytic bacteria were also assessed for their potential to produce indole-3-acetic acid (IAA). Among isolated strains, the initial spectrophotometry analysis showed significantly higher IAA production by Bacillus subtilis LK14. The diurnal production of IAA was quantified using multiple reactions monitoring method in UPLC/MS-MS. The analysis showed that LK14 produced highest (8.7 µM) IAA on 14th d of growth. Looking at LK14 potentials, it was applied to Solanum lycopersicum , where it significantly increased the shoot and root biomass and chlorophyll (a and b) contents as compared to control plants. Conclusion: The study concludes that using endophytic bacterial strains can be bio-prospective for plant growth promotion, which might an ideal strategy for improving growth of crops in marginal lands.
Highlights
The microbial flora found in plant species are known as endophytes
20 bark samples were cut into 60 pieces (0.5 cm) and surface sterilized with 2.5% sodium hypochlorite (10 min in a shaking incubator at 120 rpm) and washed with autoclaved distilled water (DW) to remove the contaminants, rhizobacteria and mycorrhizal fungi
The quantification of indole-3-acetic acid (IAA) was carried out using two external standard preparation and average response factor for the two standards. This was done by integrating the area under the peak for each Multiple Reaction Monitoring (MRM) trace which was obtained from transition of Precursor ion 175.65 to 129.8 Product ion for both the standards and the samples
Summary
Endophytic bacteria are ubiquitous in all plant species contributing in host plant's nutrient uptake and helping the host to improve its growth. Moringa peregrina which is a medicinal plant, growing in arid region of Arabia, was assessed for the presence of endophytic bacterial strains. Among the endophytic bacterial strains, a strain of Bacillus subtilis LK14 has shown significant prospects in phosphate solubilization (clearing zone of 56.71 mm after 5 d), ACC deaminase (448.3 ± 2.91 nM α-ketobutyrate mg-1 h-1) and acid phosphatase activity (8.4 ± 1.2 nM mg-1 min-1). The endophytic bacteria were assessed for their potential to produce indole-3-acetic acid (IAA). The initial spectrophotometry analysis showed significantly higher IAA production by Bacillus subtilis LK14. The analysis showed that LK14 produced the highest (8.7 μM) IAA on 14th d of growth. Conclusion: The study concludes that using endophytic bacterial strains can be bio-prospective for plant growth promotion, which might be an ideal strategy for improving growth of crops in marginal lands
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