Effects of two plant growth-promoting rhizobacteria containing 1-aminocyclopropane-1-carboxylate deaminase on oat growth in petroleum-contaminated soil

Abstract

Petroleum is potentially toxic to living organisms, and there are worldwide efforts to develop methods for bioremediation of petroleum-contaminated soils. Phytoremediation is an effective method to reduce the concentration of petroleum in soils, and plant growthpromoting rhizobacteria (PGPR) play an important role in the phytoremediation. Two PGPR, Pseudomonas aeruginosa SLC-2 and Serratia marcescens BC-3, were isolated from the rhizophere of Echinochloa grown in petroleumcontaminated soil. These isolates showed capacities for 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity, indole acetic acid production, siderophore synthesis, and the degradation of petroleum. The ACC deaminase activity of SLC-2 and BC-3 was 2.52 ± 0.03 lmol a-KA (mg PrÁh) -1 and 38.52 ± 0.37 lmol a-KA (mg PrÁh) -1 , respectively. On the other hand, when the concentration of L-Trp increased, the IAA synthesis of BC-3 also increased, while the synthesis of SLC-2 did not change significantly. The ability of synthesized siderophore of SLC-2 was much higher than that of BC-3. The petroleum degradations of SLC-2 and BC-3 increased 4.78 and 7.36 %, respectively. The pot experiment of oat was performed to evaluate the plant growth-promoting abilities of SLC-2 and BC-3. Compared with non-inoculated controls, the height and fresh weight of stems increased (23.64 and 42.57) % and (16.98 and 28.3) %, respectively, whereas the length and fresh weight of roots also increased (10.34 and 20.84) and (24.13 and 43.11) %, respectively, when inoculated with SLC-2 and BC-3. The results indicated that P. aeruginosa SLC-2 and S. marcescens BC-3 can serve as promising microbes for increasing plant growth in petroleum-contaminated soil to improve the phytoremediation efficiency.

Unravelling the potential of microbes isolated from rhizospheric soil of chickpea (Cicer arietinum) as plant growth promoter

“…This represents the synergistic and cumulative effect of all the strains when applied together in the agricultural production. The findings of the present study were in agreement with the study done by Pérez-Fernández and Valentine (2017), Liu et al (2015), Samaddar et al (2019) suggesting beneficial effects of consortia of PGPR is more pronounced than application of individual PGPR. Co-inoculation of microbes increases growth and yield, provides the plants with balanced nutrition and increases availability of minerals and nutrients (Manjunath et al 2011;Felici et al 2008).…”

ACC Deaminase Producing Bacteria With Multifarious Plant Growth Promoting Traits Alleviates Salinity Stress in French Bean (Phaseolus vulgaris) Plants

“…Plants being immobile means that they are confronted to various kind of stresses such as drought, flooding, salinity, heat, cold, exposure to heavy metals and nutrient deficiency, as well as phytopathogen and pests attack. The increment in synthesis of ethylene from its immediate precursor, ACC, secreted by plants as root exudates, has been found in almost all plants growing under stress conditions (Wang et al, 2013; Liu et al, 2015; Abiri et al, 2017). Ethylene is a plant hormone involved in regulation of various physiological processes of plants, but the climate change induced ethylene production in plants inflicts a significant reduction in plant growth and development and if not monitored properly could result in plant death (Iqbal et al, 2017; Dubois et al, 2018).…”

Mycorrhizal-Bacterial Amelioration of Plant Abiotic and Biotic Stress

“…Interestingly, this hydrocarbon breakdown process was carried out by rhizobacteria with good emulsification activity, in addition to the fact that these enzymatic activities were stimulated by AM in the rhizosphere. These results suggested that choosing bacteria with good production of lipolysaccharides, ACC deaminase and able to synthesize siderophores, would be an effective strategy to attack recalcitrant molecules, such as petroleum hydrocarbons (Liu et al, 2015).…”