Studies on the factors modulating indole-3-acetic acid production in endophytic bacterial isolates fromPiper nigrumand molecular analysis ofipdcgene

Abstract

Aims: The study mainly aimed quantitative analysis of IAA produced by endophytic bacteria under various conditions including the presence of extract from Piper nigrum. Analysis of genetic basis of IAA production was also conducted by studying the presence and diversity of the ipdc gene among the selected isolates. Materials and methods: Five endophytic bacteria isolated previously from P. nigrum were used for the study. The effect of temperature, pH, agitation, tryptophan concentration and plant extract on modulating IAA production of selected isolates was analysed by colorimetric method. Comparative and quantitative analysis of IAA production by colorimetric isolates under optimal culture condition was analysed by HPTLC method. Presence of ipdc gene and thereby biosynthetic basis of IAA production among the selected isolates were studied by PCR-based amplification and subsequent insilico analysis of sequence obtained. Conclusions: Among the selected bacterial isolates from P. nigrum, isolate PnB 8 (Klebsiella pneumoniae) was found to have the maximum yield of IAA under various conditions optimized and was confirmed by colorimetric, HPLC and HPTLC analysis. Very interestingly, the study showed stimulating effect of phytochemicals from P. nigrum on IAA production by endophytic bacteria isolated from same plant. Significance and Impact of the Study: This study is unique because of the selection of endophytes from same source for comparative and quantitative analysis of IAA production under various conditions. Study on stimulatory effect of phytochemicals on bacterial IAA production as explained in the study is a novel approach. Studies on molecular basis of IAA production which was confirmed by sequence analysis of ipdc gene make the study scientifically attractive. Even though microbial production of IAA is well known, current report on detailed optimization, effect of plant extract and molecular confirmation of IAA biosynthesis is comparatively novel in its approach.

Characterization of plant growth promoting traits of bacterial isolates from the rhizosphere of barley ( Hordeum vulgare L.) and tomato ( Solanum lycopersicon L.) grown under Fe sufficiency and deficiency

“…The IAA production was measured by modifying the method reported by Jasim et al (2014). The selected strains were grown in 10 mL Nutrient Broth suplemented with 0.1% (w/v) L-Trp at 28 C for 48 h under shaking.…”

Studies on Plant Growth Promoting Properties of Fruit-Associated Bacteria from Elettaria cardamomum and Molecular Analysis of ACC Deaminase Gene

“…For IAA production screening, the isolates were grown for 10 days at 28°C in nutrient broth supplemented with 0.2 % (v/v) of L-tryptophan. After incubation, IAA production in the cell-free supernatant was assayed by Salkowski's method as per the methods described previously by Jasim et al [22]. The bacterial isolates were screened for phosphate-solubilizing property using the procedure described by Jimtha et al [21].…”

Effect of endophytic Bacillus sp. from selected medicinal plants on growth promotion and diosgenin production in Trigonella foenum-graecum

“…All the isolates were grown in triplicates and were incubated for 10 days at room temperature with continuous shaking. After incubation, the cultures were centrifuged at 10,000 rpm for 10 min at 4°C and the culture supernatant were aseptically transferred and stored in sterile tubes for further experiments (Jasim et al 2014). …”

“…The culture supernatant of the selected bacterial isolates were initially subjected to quantitative estimation of IAA using the method described by Jasim et al (2014). For this, 1 mL of the cell free supernatant from each sample and control was treated with 2 mL Salkowski's reagent (0.5 M FeCl 2 and 35 % Perchloric acid) and incubated in dark for 20 min.…”