Beneficial bacteria of agricultural importance

Abstract

The rhizosphere is the soil-plant root interphase and in practice consists of the soil adhering to the root besides the loose soil surrounding it. Plant growth-promoting rhizobacteria (PGPR) are potential agents for the biological control of plant pathogens. A biocontrol strain should be able to protect the host plant from pathogens and fulfill the requirement for strong colonization. Numerous compounds that are toxic to pathogens, such as HCN, phenazines, pyrrolnitrin, and pyoluteorin as well as, other enzymes, antibiotics, metabolites and phytohormones are the means by which PGPR act, just as quorum sensing and chemotaxis which are vital for rhizosphere competence and colonization. The presence of root exudates has a pronounced effect on the rhizosphere where they serve as an energy source, promoting growth and influencing the root system for the rhizobacteria. In certain instances they have products that inhibit the growth of soil-borne pathogens to the advantage of the plant root. A major source of concern is reproducibility in the field due to the complex interaction between the plant (plant species), microbe and the environment (soil fertility and moisture, day length, light intensity, length of growing season, and temperature). This review listed most of the documented PGPR genera and discussed their exploitation.

Isolation and selection of plant growth-promoting bacteria associated with sugarcane

“…Number of IAA-producing isolates associated with sugarcane after 24, 48 and 72 h of growth on 10 % TSB media, in the presence of tryptophan. ammonia by hydrolyzing urea in ammonia and carbon dioxide (Schippers et al 1990, Babalola 2010, Mbai et al 2013. Cellulase was produced by 30 % of the isolates, with enzymatic indices varying from 1.255 to 10.…”

“…Many of these mutualistic organisms can act as biofertilizers, increasing the efficiency of nutrient absorption by the plant and producing substances that promote growth. It is estimated that biofertilizers could reduce the use of common fertilizers by 50 % with no yield losses (Pereg & McMillan 2015, Suman et al 2016, in addition to increasing tolerance to abiotic and biotic stresses by promoting biological control (Babalola 2010). In general, microorganisms involved in optimizing plant growth are denominated plant 1.…”

Synergistic effect of Chryseobacterium gleum sp. SUK with ACC deaminase activity in alleviation of salt stress and plant growth promotion in Triticum aestivum L.

“…These PGPB influence the growth and development of plants by various mechanisms which includes atmospheric nitrogen fixation, phosphate solubilization, production of ACC deaminase, phytohormones, siderophore, hydrogen cyanide (HCN), antibiotics, hydrolytic enzymes and organic molecules (Babalola 2010). In addition to growth, PGPB have the ability to help the plant to tolerate abiotic stress such as soil salinity (Yang et al 2009).…”

Microbial Inoculants for Soil Quality and Plant Health

“…Production of growth hormones by microbial inoculants impact root morphogenesis such that plant root hairs and lateral roots are over produced resulting in greater uptake of plant nutrients and hence improvement of plant growth (Kumar et al 2007). Fixations of atmospheric nitrogen, solubilization of minerals such as phosphorus (P) (Babalola 2010), are also some of the direct mechanisms of influence of microbial inoculants. In indirect growth promotion, Microbial inoculants affect the status of plants by eliciting induced systemic resistance (ISR) or systemic acquired resistance (SAR), by improving disease resistance.…”