Population growth and increase in food requirement is the global problem. It is inevitable to introduce new practices that help to increase agricultural productivity. Use of plant growth promoting rhizobacteria (PGPR) has shown potentials to be a promising technique in the practice of sustainable agriculture. A group of natural soil microbial flora acquire dwelling in the rhizosphere and on the surface of the plant roots which impose beneficial effect on the overall well-being of the plant are categorized as PGPR. Researchers are actively involved in understanding plant growth promoting mechanics employed by PGPR. Broadly, these are divided into direct and indirect mechanics. Any mechanism that directly enhances plant growth either by providing nutrients or by producing growth regulators are portrayed as direct mechanics. Whereas, any mechanisms that protects plant from acquiring infections (biotic stress) or helps plant to grow healthily under environmental stresses (abiotic stress) are considere...

Portraying mechanics of plant growth promoting rhizobacteria (PGPR): A review

Plant roots communicate with microbes in a sophisticated manner through chemical communication within the rhizosphere, thereby leading to biofilm formation of beneficial microbes and, in the case of plant growth-promoting rhizomicrobes / -bacteria (PGPR), resulting in priming of defense or induced resistance in the plant host. The knowledge of plant-plant and plant-microbe interactions have been greatly extended over recent years; however, the chemical communication leading to priming is far from being well understood. Furthermore, linkage between below- and above-ground plant physiological processes adds to the complexity. In metabolomics studies, the main aim is to profile and annotate all exo- and endo-metabolites in a biological system that drive and participate in physiological processes. Recent advances in this field has enabled researchers to analyze hundreds of compounds in one sample over a short time period. Here, from a metabolomics viewpoint, we review the interactions within the rhizosphere and subsequent above-ground ‘signalomics’, and emphasize the contributions that mass spectrometric-based metabolomic approaches can bring to the study of plant-beneficial – and priming events.

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The Chemistry of Plant-Microbe Interactions in the Rhizosphere and the Potential for Metabolomics to Reveal Signaling Related to Defense Priming and Induced Systemic Resistance.

Role of allelochemicals in plant growth promoting rhizobacteria for biocontrol of phytopathogens

1-アミノシクロプロパン-1-カルボン酸処理が,種々の発育段階のカキ果実のエチレン生成に及ぼす影響

Study of endophytic bacteria within plant seeds is very essential and meaningful on account of their heritability and versatility. This study investigated Bacillus bacterial communities within the seeds of four commercial tomato varieties, by 16S rRNA gene PCR-RFLP (restriction fragment length polymorphism). Phylogenetic analysis of 16S rRNA gene sequences indicated that the 22 representative isolates belonged to five species of genus Bacillus and the bacterial compositions showed remarkable differences among tomato varieties. Isolates exhibited multiple plant growth promoting (PGP) traits: 37 % of indole-3-acetic acid production; 37 % of phosphate solubilization; 24 % of siderophores production; 85 % of potential nitrogen fixation and 6 % of 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity. Isolate HYT-12-1 was shown to have highest ACC deaminase activity (112.02 nmol α-ketobutyrate mg⁻¹ protein h⁻¹) among the five ACC deamiase producing strains. 16S rRNA gene sequencing indicated that the isolate HYT-12-1 shared the highest sequence similarity (100 %) with B. subtilis. PGP experiments under gnotobiotic and greenhouse conditions revealed the ability of strain HYT-12-1 to enhance the growth of tomato seedlings. This is the first study to describe endophytic Bacillus communities within tomato seeds, and the results suggest that B. subtilis strain HYT-12-1 would have a great potential for industrial application as biofertilizer in the future.

Bacterial community compositions of tomato ( Lycopersicum esculentum Mill.) seeds and plant growth promoting activity of ACC deaminase producing Bacillus subtilis (HYT-12-1) on tomato seedlings

A novel Enterobacter cancerogenus MSA2 is a plant growth promoting gamma-proteobacterium that was isolated from the rhizosphere of Jatropha cucas a potentially important biofuel feed stock plant. Based on phenotypic, physiological, biochemical and phylogenetic studies, strain MSA2 could be classified as a member of E. cancerogenus. However, comparisons of characteristics with other known species of the genus Enterobacter suggested that strain MSA2 could be a novel PGPB strain. In vitro studies were carried for the plant growth promoting attribute of this culture. It tested positive for ACC (1-aminocyclopropane-1-carboxylic acid) deaminase production, phytase, phosphate solubilization, IAA (Indole acetic acid) production, siderophore, and ammonia production. The isolate was then used as a inoculant for the vegetative study of Jatropha curcas plant. Enterobacter cancerogenus MSA2 supplemented with 1% carboxymethylcellulose showed overall plant growth promotion effect resulting in enhanced root length (124.14%), fresh root mass (81%), fresh shoot mass (120.02%), dry root mass (124%), dry shoot mass (105.54%), number of leaf (30.72%), chlorophyll content (50.41%), and biomass (87.20%) over control under the days of experimental observation. This study was designed for 120 days and was in triplicate and the data was collected at every 30 days.

Stimulation of the growth of Jatropha curcas by the plant growth promoting bacterium Enterobacter cancerogenus MSA2

Reckoning a fungal metabolite, Pyranonigrin A as a potential Main protease (Mpro) inhibitor of novel SARS-CoV-2 virus identified using docking and molecular dynamics simulation

It is believed that inoculation with rhizobacteria containing plant growth promoting (PGP) characteristics consequently promote root and shoot growth. Further evaluation of these bacteria exhibiting multiple PGP traits on soil–plant system is needed to uncover their efficacy as effective PGP rhizobacteria (PGPR) or PGP bacteria (PGPB) depending upon their nature. The genera within the family Enterobacteriaceae that feature members described as PGPB are Citrobacter, Enterobacter, Erwinia, Klebsiella, Kluyvera, Pantoea and Serratia, although some of these genera also contain species reported to be plant pathogens. Genus Enterobacter is a Gram-negative, straight rod which is motile with peritrichous flagella and is facultatively anaerobic. Enterobacter spp. are known to have a wide range of PGP characteristics involving in nitrogen fixation, soil phosphorus solubilisation, production of antibiotics, having ability to secrete siderophore produce, chitinase, ACC deaminase, hydrolytic enzymes besides exopolysaccharides and in the enhancement of soil porosity. Numerous Enterobacter strains express these activities which promote plant growth and suppress soilborne plant pathogens. These PGP abilities of Enterobacter can make them a potential candidate suitable for plant growth and development. Due to their multifarious role in crop growth, a number of these strains have been developed commercially as plant growth promoters and biocontrol agents.

Enterobacter : Role in Plant Growth Promotion

https://www.scielo.br/pdf/bjm/v43n2/28.pdf

Evaluation and biochemical characterization of a distinctive pyoverdin from a pseudomonas isolated from chickpea rhizosphere

In recent years, heavy metal pollution has become one of the most serious environmental problems. The pollution of environment with toxic heavy metals is spreading throughout the world along with industrial progress. Presence of heavy metals even in traces is toxic and detrimental to all living organisms. Moreover it cannot be degraded in to simpler harmless compounds like other pollutants including, diverse range of organics, poly aromatic hydrocarbons (PAHs), organochlorines, dyes etc. The south Gujarat area is “Toxic Hotspot” in this state. In the presence study we have isolated and characterized six heavy metal resistant bacteria from industrial effluents from Amala Khadi, Ankleshwar (Gujarat). Initially total of 40 isolates were screened on Nutrient Agar plates containing different heavy metals Cr 6+ , Cu 2+ , Cd 2+ , Ni 2+ at concentration 50 ppm in their salt form. Isolates were selected based on high level of heavy metal resistance and it’s morphological and biochemical characterization was done. Identification based on 16S rRNA gene sequencing identified Comamonas testosteroni (JX028142), Bacillus sp. (JX028143), Aeromonas hdrophila (JX028144), Exibacterium profundum (JX028145), Bacillus cereus (JX028146) and Exiguobacterium sp. (JX028147). Isolates showed high degree of resistance to heavy metals under investigation, ranging from 25-300 ppm. These isolates can further be used for bioremediation of heavy metals form industrial effluent.

Baldev Patel

Papers

Stimulation of the growth of Jatropha curcas by the plant growth promoting bacterium Enterobacter cancerogenus MSA2

Reckoning a fungal metabolite, Pyranonigrin A as a potential Main protease (Mpro) inhibitor of novel SARS-CoV-2 virus identified using docking and molecular dynamics simulation

Enterobacter : Role in Plant Growth Promotion

Evaluation and biochemical characterization of a distinctive pyoverdin from a pseudomonas isolated from chickpea rhizosphere

Isolation, characterization and molecular identification of heavy metal resistant bacteria from industrial effluents, Amala-khadi- Ankleshwar, Gujarat