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Bacterial Small RNA and Nanotechnology
Published in Sunil K. Deshmukh, Mandira Kochar, Pawan Kaur, Pushplata Prasad Singh, Nanotechnology in Agriculture and Environmental Science, 2023
The soil harbours different forms of organisms: fungi, algae, nematodes, protozoa, and essentially bacteria, though the existing isolation and cultivation methods have been able to reveal just 1% of the actual bacterial population (Handelsman, 2004; Glick, 2012). These organisms interact with each other as well as influence other life forms, such as plants. The plant-microbe interaction is an age-old process where both the partners have mutually selected each other over a long evolutionary journey (Nadeem et al., 2015). These interactions may be beneficial, harmful, or neutral (Whipps et al., 2011; Beneduzi et al., 2012). The commonly found bacterial genera in the soil are Pseudomonas, Arthrobacter, Agrobacterium, Alcaligenes, Azotobacter, Klebsiella, Mycobacterium, Flavobacter, Cellulomonas, and Micrococcus (Okon and Labandera Gonzalez, 1994; Nadeem et al., 2015). The distribution of bacteria is usually uneven but the rhizosphere, i.e., the area around the plant roots is always rich due to the abundant presence of nutrients (sugars, amino-acids, organic acids) secreted by the plant roots as exudate (Lynch, 1990). In exchange of this high nutrition resource and protective habitat, the rhizobacteria influence the host plants thereby augmenting their productivity, pathogen resistance, and stress tolerance.
Plant-microbe Interaction in Attenuation of the Toxic Waste in the Ecosystem
Published in Vivek Kumar, Rhizomicrobiome Dynamics in Bioremediation, 2021
Mary Isabella Sonali, Veena Gayathri Krishnaswamy
Rhizopheric and endophytic microorganisms are found in rhizospheres and the stem, which effectively degrade anthropogenic compounds present in the contaminated soil. The most commonly and efficiently used methods are composting, bioremediation, biodegradation, and bio-transformation. Microorganisms used in the degradation are Chorella vulgaris, Corynebacterium sps., Scenedesmus platydiscus, Streptococcocus., Bacillus sps., Staphylococcus sps., etc. Biodegradation of hydrocarbons takes place in the presence of oxygen (aerobic) as well as in the absence of oxygen (anaerobic) but effective degradation takes place in the absence of oxygen (anaerobic) (Mondal and Palit 2019). Plant growth-promoting rhizobacteria are found in the rhizospheres and they help in plant growth stimulation (Saharan and Nehra 2011). They also help in phytoremediation of heavy metals (Glick 2010). Rhizobacteria can uptake the contamination from the soil, especially heavy metals involving organic acid and biosurfactant production, which help to minimize the toxicity in the root region (Wu et al. 2006). Table 7 shows different bacterial strains which could degrade different pollutants.
Bacterial-Assisted Phytoextraction Mechanism of Heavy Metals by Native Hyperaccumulator Plants from Distillery Waste–Contaminated Site for Eco-restoration
Published in Ram Chandra, R.C. Sobti, Microbes for Sustainable Development and Bioremediation, 2019
Direct plant growth promotion is based on either stipulation of the plants with favorable bacterial compounds or improving the nutrient uptake by the plant from the environment (Bashan and Holhuin 1998; Glick 2012, 2014; Kong and Glick 2017). Rhizobacteria promote plant growth and development through a variety of mechanisms, including the fixation of atmospheric nitrogen, and supply it to plants; synthesize iron chelators referred to as siderophores, which can solubilize and sequester iron from the soil and provide it to plant cells; synthesize and release different phytohormones, including auxins, cytokinins, and gibberellins, which can enhance various stages of plant growth and symbiotic N2 fixation; improve ammonia production; and have mechanisms for the solubilization of inorganic phosphate and mineralization of organic phosphate and/or other nutrients, which then become more readily available for plant growth (Glick et al. 2007; Glick 2012; Gutiérrez-Mañero et al. 2001; Kong and Glick 2017). In addition to this, PGPR enhance the tolerance capacity of the plant to a variety of environmental stresses through the production of 1-aminocyclopropane-1-carboxylate (ACC) deaminase that can modulate plant growth and development (Glick 2014).
Efficacy of rhizobacteria for degradation of profenofos and improvement in tomato growth
Published in International Journal of Phytoremediation, 2022
Muhammad Usman Ghani, Hafiz Naeem Asghar, Abdullah Niaz, Zahir Ahmad Zahir, Muhammad Farrakh Nawaz, Max M. Häggblom
The application of plant growth-promoting rhizobacteria (PGPR) is an emerging way to reduce the adverse environmental impacts of chemical fertilizers. In the rhizosphere, the use of PGPR creates a beneficial impact on crop yield and growth (Noori and Saud 2012; Glick 2012; Abed et al.2016; Adedeji et al.2020). Some PGPR may affect the growth of the plant through the production of plant hormones or by increasing the accumulation of nutrients from soil solution by various direct mechanisms including solubilization of phosphorus (P) and the fixation of atmospheric nitrogen (N) (Gyaneshwar et al.2002; Glick et al.2007). Some indirect mechanisms are also carried out by PGPR through suppressing plant pathogens by the formation of lytic enzymes, production of siderophores, or formation of antimicrobial substances (Chauhan et al.2015). Different bacterial genera are well recognized for their plant growth-promoting activities, including Enterobacter, Acinetobacter, Erwinia, Beijerinckia, Rhizobium, Arthrobacter, Serratia, Burkholderia, Klebsiella, Azotobacter, Bacillus, Azospirillum, Gluconacetobacter, Pseudomonas, and Azoarcus (Murphy et al.2003; Esitken et al.2006; Kumari et al.2018).
Bacilli as sources of agrobiotechnology: recent advances and future directions
Published in Green Chemistry Letters and Reviews, 2021
Zerihun T. Dame, Mahfuz Rahman, Tofazzal Islam
Rhizobacteria play a role as biofertilizers that enhance plant growth and development. Biofertilizers involve live microorganisms that have potential applications in stimulating plant growth and development (198). They are preferred to chemical fertilizers as they are environmentally benign, support sustainability and may also be less expensive. Examples are phosphate and potassium solubilizing and N2 fixing bacteria. Phosphorus, one of the most important nutrients needed for plant growth and development has limited availability in soluble forms. To alleviate this challenge, either soil should be supplemented with artificial fertilizer, rich in phosphate or phosphate solubilizing microorganisms (PSMs) should be introduced. Various Bacillus spp. have demonstrated phosphate solubilizing potential. Bacilli such as B. circulans, B. megaterium, B. pulvifaciens, and B. sircalmous are few examples (199). Likewise, the role of bacilli in N2 fixation has been known for a long time. The work of Wahab (200) has demonstrated the potential of Bacillus as nitrogen-fixing species. A study by Pramanik et al (201) has also demonstrated that a strain of B. pseudomycoides can be used as a Potassium-solubilizing biofertilizer.
Beneficial bacteria associated with Mimosa pudica and potential to sustain plant growth-promoting traits under heavy metals stress
Published in Bioremediation Journal, 2020
Saidu Abdullahi, Hazzeman Haris, Kamarul Zaman Zarkasi, Hamzah Ghazali Amir
Ammonia production by rhizobacteria is a source of nitrogen for plants which is one of the essential nutrients necessary for plant biomass and increases the glutamine syntheses activity (Iwata et al. 2010). In this study, all tested isolates produced substantial quantities of ammonia under metal stress conditions. The results showed that isolates 6M2 and 2M1 have higher ammonia production ability under As, Cd and Pb compared to other isolates tested. Like other PGP traits studied, there was also a decrease in the ammonia production by the isolates tested with an increase in metals concentrations. Ammonia production plays an important role in the growth and health of plants by the accumulation of nitrogen and helps in promoting root and shoot growth and biomass production (Dutta and Thakur 2017). Nitrogen-fixing soil bacteria among the plant growth-promoting rhizobacteria are well known for their ability to establish symbiotic associations with legumes and develop into nitrogenase complex that catalyzes the ATP-dependent reduction of N2 to ammonium in root nodules (Jian et al. 2019). Study have shown that co-inoculation with the PGPR and rhizobium can significantly increase the nutrient contents such as N, P, and K in plant tissues and also promote plant growth in soil contaminated with copper (Cu) (Ju et al. 2019).