Biochemical and Molecular Mechanisms of Plant-Microbe-Metal Interactions: Relevance for Phytoremediation

Abstract

Plants and microbes coexist or compete for survival and their cohesive interactions play a vital role in adapting to metalliferous environments, and can thus be explored to improve microbe-assisted phytoremediation. Plant root exudates are useful nutrient and energy sources for soil microorganisms, with whom they establish intricate communication systems. Some beneficial bacteria and fungi, acting as plant growth promoting microorganisms (PGPMs), may alleviate metal phytotoxicity and stimulate plant growth indirectly via the induction of defense mechanisms against phytopathogens, and/or directly through the solubilization of mineral nutrients (nitrogen, phosphate, potassium, iron, etc.), production of plant growth promoting substances (e.g., phytohormones), and secretion of specific enzymes (e.g., 1-aminocyclopropane-1-carboxylate deaminase). PGPM can also change metal bioavailability in soil through various mechanisms such as acidification, precipitation, chelation, complexation, and redox reactions. This review presents the recent advances and applications made hitherto in understanding the biochemical and molecular mechanisms of plant–microbe interactions and their role in the major processes involved in phytoremediation, such as heavy metal detoxification, mobilization, immobilization, transformation, transport, and distribution.

Targered Changes in the Natural and Semi-Artificial Arid Phytocenoses in the Contact Zone with the Agrocenoses: A System Control Model-Based Approach

“…It is particularly noticeable that the presence of moderate or high intrusion influence leads to an increase in the trace elements concentration and their aggregates, which can have a negative influence on the agrophytocenosis (increasing soil toxicity to plants and microorganisms) (Totsche et al, 2018), and positively (by compensating for microelement deficiencies or stimulating growth) (Ma et al, 2016). It is important to note that such changes lead to the formation of "stress", which can both prevent the formation of agrophytocenosis, and protect agrophytocenosis from settling plants or microorganisms not peculiar to it (Drenovsky et al, 2012, Zefferman, 2015, it helps to reduce the probability of indirect competition between plants in the agrophytocenosis (Beck et al, 2010).…”

“…Incubation of seed produced at a temperature of 20-21 °C for 24-72 h. bacteria growth occurred on the agar with enzymatic beef hydrolysate. Then, we calculated the number of growing colonies and investigated morphological and cultural properties of the isolated microorganisms, identifying the dominant microorganisms (Pasternak et al, 2013;Ma et al, 2016).…”

“…Some of these species are important in nitrogen circulation and in the destruction of pollutants (Sarker et al, 2017). At the same time, the composition of bacterial communities may differ from plant to plant: some may be tied to different types of plants, others ones prefer only to certain (Ma et al, 2016).…”

Comments on bacterial and fungal interactions in medicine, agriculture and the environment

“…Certain beneficial bacteria and fungi having attributes of plant growth promoting microorganisms, PGPMs have the potential to mitigate metal phytotoxicity and stimulate plant growth: (i) indirectly via defence mechanism induction to combat phytopathogens; (ii) and/or indirectly via mineral nutrient solubilization, such as nitrogen, phosphate and potassium; (iii) formation of plant growth enhancing compounds, such as phytohormones and; (iv) specific enzyme secretion as per 1-aminocyclopropane-1-carboxylate deaminase. PGPM is capable of altering metal bioavailability in soil via diverse mechanisms, such as acidification, chelation, complexation, precipitation and redox reactions (Ma Y et al, 2016) Applications of advanced strategies can be developed to explicate the biochemical and regulatory mechanisms undergirding plant-microbial interactions (Chukwuma 2016a-c;Chukwuma, 2017), and their functionalities in the processes associated with phytoremediation, for instance, heavy metals and trace elements, detoxification, transformation, transportation and dissemination (Chukwuma, 2011;Chukwuma, 2014). Soil constitutes one of the principal habitats of fungi and bacteria, with their interactions forming an aspect of a communication network that sustains equilibrium of the microhabitats.…”

Effect of Various Culture Parameters on the Bio-surfactant Production from Bacterial Isolates

“…Biosurfactants are amphiphilic compounds which have the ability to reduce surface and interfacial tension of the surface. Biosurfactant can have several structures i.e., glycolipids, polysaccharide-lipid composite, phospholipid, mycolic acid, lipopeptide, lipoprotein, or the microbial cell surface itself [4]. Due to unique properties and a vast array of application, identification of new biosurfactant producing microbes are in great demand.…”