Pseudomonas aeruginosa RTE4: A Tea Rhizobacterium With Potential for Plant Growth Promotion and Biosurfactant Production

Abstract

Tea is an ancient non-alcoholic beverage plantation crop cultivated in the most part of Assam, India. Being a long-term monoculture, tea plants are prone to both biotic and abiotic stresses, and requires massive amounts of chemicals as fertilizers and pesticides to achieve worthy crop productivity. The rhizosphere bacteria with the abilities to produce phytohormone, secreting hydrolytic enzyme, biofilm formation, biocontrol activity provides induced systemic resistance to plants against pathogens. Thus, plant growth promoting (PGP) rhizobacteria represents as an alternative candidate to chemical inputs for agriculture sector. Further, deciphering the secondary metabolites, including biosurfactant (BS) allow developing a better understanding of rhizobacterial strains. The acidic nature of tea rhizosphere is predominated by Bacillus followed by Pseudomonas that enhances crop biomass and yield through accelerating uptake of nutrients. In the present study, a strain Pseudomonas aeruginosa RTE4 isolated from tea rhizosphere soil collected from Rosekandy Tea Garden, Cachar, Assam was evaluated for various plant-growth promoting attributes. The strain RTE4 produces indole acetic acid (74.54 µg/ml), hydrolytic enzymes, and solubilize tri-calcium phosphate (46 µg/ml). Bio-control activity of RTE4 was recorded against two foliar fungal pathogens of tea (Corticium invisium and Fusarium solani) and a bacterial plant pathogen (Xanthomonas campestris). The strain RTE4 was positive for BS production in the preliminary screening. Detailed analytical characterization through TLC, FTIR, NMR, and LCMS techniques revealed that the strain RTE4 grown in M9 medium with glucose (2% w/v) produce dirhamnolipid BS. This BS reduced surface tension of phosphate buffer saline from 71 to 31 mN/m with a critical micelle concentration of 80 mg/L. Purified BS of RTE4 showed minimum inhibitory concentration of 5, 10, and 20 mg/ml against X. campestris, F. solani and C. invisium, respectively. Capability of RTE4 BS to be employed as a biofungicide as compared to Carbendazim-commercially available fungicide is also tested. The strain RTE4 exhibits multiple PGP attributes along with production of di-rhamnolipid BS. This gives a possibility to produce di-rhamnolipid BS from RTE4 in large scale and explore its applications in fields as a biological alternative to chemical fertilizer.

Microbial Biosurfactant: A New Frontier for Sustainable Agriculture and Pharmaceutical Industries

“…March-Mikołajczyk et al [126] reported on the Glycolipid produced by endophytic bacterial strain Bacillus pumilus 2A, which after application significantly improves the growth of bean, radish, and beetroot. Chopra et al [127] evaluated different rhizobacterial strains of tea, in which one of the strains, Pseudo- For instance, Sheng et al [122] reported that the strain Bacillus sp. J119 has biosurfactant capability, which significantly enhances the uptake of trace elements and promotes the growth potential of canola maize, sudangrass, and tomato.…”

“…March-Mikołajczyk et al [ 126 ] reported on the Glycolipid produced by endophytic bacterial strain Bacillus pumilus 2A, which after application significantly improves the growth of bean, radish, and beetroot. Chopra et al [ 127 ] evaluated different rhizobacterial strains of tea, in which one of the strains, Pseudomonas aeruginosa RTE4, produced di-rhamnolipid biosurfactant and showed multiple growth-promoting traits as well as fungicidal activity. Similarly, Alsohim et al [ 128 ] reported that the viscosin produced by Pseudomonas fluorescens S.B.W.…”

Characterization and Cytotoxicity of Pseudomonas Mediated Rhamnolipids Against Breast Cancer MDA-MB-231 Cell Line

“…All experiments were carried out in triplicates. The mean values were plotted along with standard deviation ( Hazra et al, 2010 ; Samykannu and Achary, 2017 ; Chopra et al, 2020 ).…”

Potential Application of Rhizobacteria Isolated from the Central Highland of Vietnam as an Effective Biocontrol Agent of Robusta Coffee Nematodes and as a Bio-Fertilizer

“…Biosynthesis of IAA by Pseudomonas aeruginosa has been widely reported [59][60][61][62][63][64][65][66][67][68]; however, only a few studies have reported the production of GA3 by Pseudomonas aeruginosa [67][68][69]. Although cytokinin compounds have also been reported to be produced by Pseudomonas aeruginosa, there are quite a few reports on the biosynthesis of zeatin, and kinetin by this bacterial genus [68,[70][71][72].…”