Most plant-associated bacteria and fungi can produce iron chelators called siderophores in responses to low iron levels in the rhizosphere. Siderophores are low-molecular mass (400-1,000 Dalton) compounding with high association constants for complexing iron, but they can also form stable complexes with other metals, such as Al, Cd, Cu, Ga, In, Pb and Zn (Glick and Bashan 1997; Schalk et al., 2011). Although siderophores contain other functional groups, they are broadly classified into three main groups based on the chemical nature of the moieties donating the oxygen ligands for Fe (III) coordination, which are either of the catecholates (enterobactin), hydroxmate (desferrioxamines), or (α-hydroxy-) carboxylates (aerobatin). Since siderophores …show more content…
A recent study by Saravanan et al., 2007 demonstrated the Zn solublizing potential of Gluconacetobacter diazotrophicus strains under in vitro conditions with ZnO, ZnCO3 or Zn3(PO4)2 and reported the production of a gluconic acid derivatives, 5-ketogluconic acid that aid in the solubilization of Zn compounds(Rajkumar et al., 2012). Similar studies on the influence of airborne bacteria isolated from a tannery air environment on solubilizing insoluble ZnO or Zn3 (PO4)2 (Fasim et al., 2002). Experiment with rhizosphere bacteria of Cd/Zn hyperaccumulator plant, Sedum alfredii, also revealed that the inoculation of soils with CD/Zn resistant bacteria significantly increased the water soluble Zn and Cd concentrations when compared with the uninoculated controls(Rajkumar et al., 2012). In this case, enhanced heavy metal mobilization could be correlated with the increased production of organic acids such as formic acid, acetic acid, tartaric acid, succinic acid, and oxalic acid (Li et al., 2010). Inoculation with Burkholderia caribensis FeGL03 that had been isolated from Brazilian high-phosphorous iron ore has also been studued (Delvasto et al., 2009). This bacterium significantly mobilized P and Fe from crushed iron ore. Here, it was suggested that gluconic acid production together with the …show more content…
Biosurfactant are amphiphilic molecules consisting of a non polar (hydrophobic) tail and a polar/ionic (hydrophilic) head. A hydrophilic group consists of mono-, oligo- or polysaccharides, peptides or proteins and a hydrophobic fatty acids or fatty alcohols. In general the biosurfactant produced by microbes form complexes with heavy metals at the soil interface, desorbs metals from soil matrix and thus increasing metal solubility and bioavailability in the soil solution. Interestingly, there is substantial evidence suggesting that the microorganism producing surfactants increase the heavy metal mobilization in polluted soils (Juwarkar et al., 2007: Sheng et al., 2008a; Venkatesh and Vedaraman 2012). A recent study by Juwarkar et al., (2007), demonstrated the metal mobilization potential of P. aeruginosa BS2 under in vitro column experiments and reported the production of a biosurfactant, dirhamnolipid that aid in the solubilization of Cd and Pb compounds from artificially metal contaminated soil. Although the several studies of scientist reveals that significant role of microbial biosurfactant in facilitating the release of adsorbed heavy metal and in enhancing the phytoextraction potential of plants, these observations were mostly obtained from the plants grown in artificially metal contaminated soils and evidence supporting the biosurfactant
Background Information In implementing a strategic plan for Coastal Medical Center, our consulting team has conducted many analyses and formed numerous strategies in order for Coastal Medical Center to be successful. Such assessments include an internal analysis, external analysis, gap analysis, and SWOT analysis. In conducting these analyses, our consulting team was able to better understand the internal environment, external environment, where the organization currently stands in terms of performance, and the major strengths, weaknesses, opportunities and threats that oppose the Coastal Medical Center. From our inquiry, we will be able to establish a strategic plan that best fits the organization’s needs.
The word “remediate” means to solve a problem, so the word “bioremediation” refers to the use of biological organisms to solve an environmental problem. Bacteria, fungi, protists and other microorganisms in a non-polluted environment are constantly breaking down organic matter, and when the soil is polluted, some of the organisms may die, but others will still be able to break down the pollutants. Bioremediation provides organisms that can consume the pollutants with fertilizer, oxygen, and other conditions to encourage the rapid growth of these organisms. They then would be able to break down the organic pollutants at a correspondingly faster rate. There are two general ways in which bioremediation functions. One way is where specific survival conditions of a microorganism living in the soil are enhanced to increase the rate of a pollutant’s degradation. The second way is when specialized microbes are added to degrade the contaminant. This way is less common. For many types of polluted soil, bioremediation provides an excellent method of clean-up, but in some cases the pollutant is toxic even for the microbes. These pollutants include metals such as cadmium or lead, and salts such as sodium chloride. Although it may not work in all cases, bioremediation is considerably easier than other methods because it enhances the functions that the microbes already carry out in the soil. Along with being easier, it can be much less expensive because the soil does not have to be pumped out of the ground for treatment (Environmental Inquiry-Bioremediation). Serratia Marcescens is a bacterium that is commonly used for bioremediation.
Arsenic (As) is a lethal metalloid found in rocks, sediments, water, soil and air. It enters into the terrestrial and aquatic ecosystems through a combination of natural processes such as volcanism, process of weathering and biological activity, as well as a result of anthropogenic (Human made) activities. Excessive utilization of As-based pesticides, fertilizers or herbicides, wood preservatives, arsenic additives in domestic animals feeds, pharmaceutical works, electronics industries, ammunition and galvanizing factories, and coal or petroleum incineration (Simith et al., 1998:Matschullat, 2000), and indiscriminate disposal of industrial wastes and domestic (sewage) , as well as mining activities, have resulted in extensive contamination of Arsenic in soil / terrestrial ecosystems attracts worldwide attention principally because of its undesirable impact on human health(Lee et al., 2008; Duker et al., 2005; Liao et al., 2005; Liu et al., 2005; Ongley et al., 2007).
Not mentioned in the report is a technique called bioremediation, which uses microbes to clean up the hazardous waste. Some small natural organisms, such as bacteria, can eat, digest and gain energy from contaminants, converting them into small amounts of water or innocuous gases. Specific conditions must be present for bioremediation to be successful. Natural amendments can be added if ideal conditions are not present, or contaminated soil can be treated ex situ. Traditionally, it takes anywhere between a few months and several years for bioremediation to fully clean a Superfund site, depending on the size of the site and extent of contamination. Bioremediation is currently being used to clean up contaminated groundwater at the Iceland Coin Laundry Superfund Site in New Jersey (EPA, n.d.). Additionally, experiments are currently underway to determine if fungi can help remediate some of the contamination at the Newtown Creek Superfund Site in New York City (Parry, 2012). As an all-natural alternative, bioremediation is a particularly appealing clean up method. If ideal conditions for microbial growth are not present at the Portland Harbor Superfund site, bioremediation could be a good ex situ treatment
Sediment transport model plays an important part in the aquatic system as aquatic systems display slow recovery rates due to the continued presence of toxic substances. In a water column, toxic substances accumulate in the bottom sediments of aquatic systems. Depending on the chemical properties and hydraulic characteristics, sorption to biotic and abiotic suspended matter may occur, resulting in chemical settling from the water column and accumulating among bottom sediment. In addition, the effects of industrial contamination on aquatic life are a continuing concern of local, state, and federal agencies throughout the United States.
China is becoming one of the increasingly crucial environmental concerns of heavy metal contamination on agricultural land. Heavy metal contamination happens when water resources are short and wastewater is then applied to plants causing major health risks to environmental quality and food production. Many scientists have been exploring solutions of this environmental problem and some research say that mycorrhizae have made a positive outcome in fighting the heavy metals and toxins in the soil. Heggo,A. (1990) studied the mechanism of mycorrhizae and heavy metals and resulted that mycorrhizae fungi may filter excessive metals in the soil. Another study showed that mycorrhizae enhanced tolerance of plants infected with toxic soils. Scientists are still studying to find out ways how mycorrhizae fungi improve these plants and resistance from heavy metals. However, metal and toxin uptake might be also impacted from the soils condition. Mycorrhizae symbiosis are well familiar for their enhancement of phosphorus uptake. This nutritional benefit is questioned to account for the plants tolerance of heavy metals and toxins in the soil. The way that heavy metals and toxins affect the ecosystem is the life of organisms such as plants don’t grow in a healthy manner causing toxic plants where animals and humans can
In nature, the radioactive wastes and heavy metals can be present in a number of forms such as oxides, superoxides, peroxides, sulphates, nitrates, citrates, carbonates etc. Microorganisms change these forms or states of toxic substances into less toxic or non toxic states. They carry out these transformations due to their sensitivity towards presence or absence of free electrons. Under aerobic conditions, the microorganisms direct oxygen to act as electron acceptor and under anaerobic conditions the suphate group, nitrate group, phosphate group or carbonate group etc. take up the electrons (Francis 1990).
However, when the pH levels reach a certain stage, the iron can then precipitate out, coating sediments with the characteristic yellow, red or orange colourings (D.E.P. 2, 2002; U.S.G.S. ; U.S.E.P.A., 2002). The rate that A.M.D. advances is also influenced by the presence of certain bacteria (Doyle; U.S.G.S). A.M.D. that has dissolved heavy metals such as copper, lead and mercury can contaminate ground and surface water.
...imary productivity in large regions of the global open ocean. Copper (Cu), on the other hand, is a common anthropogenic contaminant to estuarine and coastal oceans that can act as a toxicant to microorganisms at elevated concentrations. The organic complexation of dissolved iron and copper by largely uncharacterized natural ligands in seawater has proven to be an integral component in the oceanic biogeochemistry of these metals, governing aspects of their solubility, supply and bioavailability in the marine environment. Recent research projects in the Buck lab have examined the distributions, sources and sinks of natural iron- and copper-binding organic ligands in seawater, biological transformations of iron and copper species, and the influence of copper-binding ligands on bioavailability and toxicity of copper in contaminated coastal and estuarine environments.
Aquaculture within the agriculture is the fastest growing food production sectors in the world. Fishes are known as the “food gold” of the present as well as future.[1] They are also known to be the richest source of high quality protein. Marine and aquatic environment are home to a vast diversity of organisms ranging from prokaryotes to higher vertebrates. Unfortunately, these environments also act as a sink for a great variety of anthropogenic pollutants, many of which are toxic. Sources for polluting water include burning of fossil fuels, industrial waste water, sewage treatment plants, agriculture and non point source runoff, etc. It is important to have an understanding of the impact and effect of these chemicals on aquatic life forms. Aquaculture is based on ecosystems and accounts for substantial contribution to Indian economy and also provides livelihood to millions of people. Fishes are highly nutritious and consumed as a delicacy food throughout world. A variety of contaminants including to toxic heavy metals (cadmium, arsenic, mercury, lead) are ubiquitously found in rivers, reservoirs and are disadvantageous for aquatic life.[2]
Soil washing is one of the most suitable ex-situ remediation techniques that have been used for the treatment of soils contaminated with heavy metals, hydrocarbons and semi-volatile organic compounds. The hazardous contaminants can be removed from soil by washing the soil with a liquid (often with a chemical additive), scrubbing the soil, and then separating the clean soils from contaminated soil and wash water. The concept of soil washing is based on the theory that contaminants are prone to bind to fine grained soils which in turn are prone to bind to coarse grained soils. Soil properties, contaminant-related parameters and process parameters are the factors that affecting soil washing. The objective of soil washing is to separate these contaminated fines (silts and clays) and wash water from the
Zinc is an essential trace element for many living organisms. While this can be said about other essential metals, zinc is unique in its physiochemical properties that give it the ability to interact with donor groups of different ligands, resulting in a broad range of stability constants and diversity of the biological functions and processes that zinc is involved in. It was discovered and recognized as a new metal in the eightieth century, While its biological essentiality was found by Raulin for the growth of Aspergillus niger In 1869 [1]. In 1933 Zinc was found essential for the growth of animals while studying its effect on rats. [2]
Bioremediation are most effective management technique for remediate this type of contaminations. Microorganism are very important to remediate the contaminated environment mainly aerobic and anaerobic organism are included in bioremediation process
Phytoremediation is a novel, efficient, environmentally friendly, low-cost technology, which uses plants and trees to clean up soil and water contaminated with heavy metals and/or organic contaminants such as solvents, crude oil, polyaromatic hydrocarbons and other toxic compounds from contaminated environments. This technology is useful for soil and water remediation.
... in 1995 showed that native plants and micro-organisms grow naturally in hostile mine environments and how they can be propagated to potentially rehabilitate TSFs and polluted soils. The programme focused on effectiveness of different types of vegetation in groundwater and soil remediation.