Biosorption and Bioaccumulation Abilities of Actinomycetes/Streptomycetes Isolated from Metal Contaminated Sites

Abstract

Heavy metal pollution is of great concern. Due to expansion of industrial activities, a large amount of metal is released into the environment, disturbing its fragile balance. Conventional methods of remediation of heavy metal-polluted soil and water are expensive and inefficient. Therefore, new techniques are needed to provide environmentally friendly and highly selective remediation. Streptomycetes, with their unique growth characteristics, ability to form spores and mycelia, and relatively rapid colonization of substrates, act as suitable agents for bioremediation of metals and organic compounds in polluted soil and water. A variety of mechanisms could be involved in reduction of metals in the environment, e.g., sorption to exopolymers, precipitation, biosorption and bioaccumulation. Studies performed on biosorption and bioaccumulation potential of streptomycetes could be used as a basis for further development in this field. Streptomycetes are of interest because of their ability to survive in environments contaminated by metals through the production of a wide range of metal ion chelators, such as siderophores, which provide protection from the negative effects of heavy metals or specific uptake for specialized metabolic processes. Many strains also have the equally important characteristic of resistance to high concentrations of heavy metals.Separations 2018, 5, 54 2 of 14 materials, pesticides, phosphate fertilizers, printing pigments, textiles, sewage, irrigation, smelting, steel and electroplating industries, dyes, and wood preservation. While anthropogenic sources increasingly give rise to permanent pollution, natural sources are usually a seasonal phenomenon influenced by weather, which generally does not generate pollution [4].Many heavy metals are capable of entering the food chain, where they cause serious damage. The toxicity of each metal and their potential harmful effects depends on the amount, route of admission, and duration of exposure [5]. A major source of heavy metals in the soil is mining activities and subsequent ore processing. During these processes, metals are mobilized by biological or chemical leaching, and pass to the soil and nearby water sources. As a result of leaching, heavy metals migrate to the lower soil layers and cause destruction and alteration of the ecosystem, including accumulation of pollutants and a loss of biodiversity. The subsequent recovery could take several decades [6]. Techniques for Heavy Metals RemovalRemoval of pollutants in the form of heavy metals has become an urgent requirement in recent decades. Technologies routinely used for heavy metal removal from the environment include chemical precipitation, reverse osmosis, ion-exchange, ultrafiltration, and electro-dialysis. They are, unfortunately, often inefficient and extremely expensive. Moreover, they can generate toxic compounds, which are seen as unfavorable and uneconomical [7]. There is, therefore, an acute need for the development of cheap, highly efficient and selective alternatives that can allevia...

The Aromatic Plant Clary Sage Shaped Bacterial Communities in the Roots and in the Trace Element-Contaminated Soil More Than Mycorrhizal Inoculation – A Two-Year Monitoring Field Trial

“…to Firmicutes, Proteobacteria, and Actinobacteria phyla, are among the most widely spread and frequently listed bacterial genera in TE-contaminated soils, and at the same time display a high TE tolerance (Pires et al, 2017;Chellaiah, 2018;Chen et al, 2018;Cui et al, 2018). Nonetheless, Sphingomonas, member of the Proteobacteria (Xie et al, 2010;Chen et al, 2014;Jaafar, 2019), as well as Pseudarthrobacter (Chen et al, 2014;Fekih et al, 2018;Park et al, 2019), Nocardioides (Bagade et al, 2016;Cui et al, 2018), and Streptomyces (Álvarez et al, 2013;Cui et al, 2018;Durand et al, 2018;Lasudee et al, 2018;Timková et al, 2018;Álvarez-López et al, 2020), belonging to the Actinobacteria, were also highlighted for displaying TE-tolerance and even studied for potential remediation applications. Indeed, these bacterial genera are known to accumulate Cd, Ni, Cr or Pb from TE-contaminated soils and to induce changes in the oxidation state of the TE (Pires et al, 2017;Chellaiah, 2018;Timková et al, 2018).…”

Screening and identification of Lactic acid bacteria from Ya’an pickle water to effectively remove Pb2+

“…In addition, cell wall peptidoglycans and/or surface extracellular polymers with cell wall dissociation could also form effective biosorption matrices to adsorb metal ions (Vijayaraghavan and Yun 2008). Gram-positive microorganisms had a large adsorption capacity because they have a thick peptidoglycan layer and contain a large number of adsorption sites (Timková et al 2018). François et al (2012) also confirmed that the biosorption of mercury by Bacillus sp.…”

Processing of Metals and Metalloids by Actinobacteria: Cell Resistance Mechanisms and Synthesis of Metal(loid)-Based Nanostructures

“…The scarce aqueous solubility and bioavailability of Fe and its importance for several biological functions led microorganisms to evolve specific mechanisms of Fe-uptake and Fe-trapping, mostly represented by siderophore biosynthesis [ 51 , 52 ]. Siderophores are low-molecular-weight (200–2000 Da) and diffusible molecules featuring a high affinity and selectivity for the insoluble ferric (Fe 3+ ) as compared to ferrous (Fe 2+ ) cations, which guarantees a low level of competition with other bivalent yet essential metal cations(e.g., Zn 2+ , Cu 2+ , Ni 2+ , and Mn 2+ ) [ 53 ].…”

“…Siderophores are low-molecular-weight (200–2000 Da) and diffusible molecules featuring a high affinity and selectivity for the insoluble ferric (Fe 3+ ) as compared to ferrous (Fe 2+ ) cations, which guarantees a low level of competition with other bivalent yet essential metal cations(e.g., Zn 2+ , Cu 2+ , Ni 2+ , and Mn 2+ ) [ 53 ]. Thus, siderophores’ biosynthesis and secretion usually depend on Fe 3+ environmental concentration [ 52 , 53 , 54 ], as they act as Fe-chelators, creating extracellular iron-siderophore complexes from which Fe 3+ is taken up by bacterial cells through redox processes [ 53 , 55 ]. After the first study reporting the production of the siderophores arthrobactin and mycobactin by Arthrobacter terregens and Mycobacterium johnei in the 1950s [ 53 ], actinobacterial members have been described to be able to synthesize siderophores, which, depending on their chemical structure, are indicated as phenolates, catecholates, carboxylates, hydroxamates, or mixed types [ 56 , 57 , 58 ] ( Table 1 ).…”