Characterization of Nickel Tolerant Bacteria Isolated from Heavy Metal Polluted Glass Industry for its Potential Role in Bioremediation

Heavy metal contamination of the environment is a serious concern because of their deleterious effects on biological systems. To the best of our knowledge, this is the first investigation on isolation of heavy metal resistant bacteria from contaminated sites of glass industrial area.

The study focused on isolation and characterization of Ni²⁺ resistant bacteria from these sites and analysis of their Ni²⁺ accumulation potential. Out of 38 different bacterial isolates 3 bacteria were able to tolerate up to 24 mM Ni²⁺ concentration. These bacterial strains were identified as E. coli (AS17b), Escherichia coli (AS21) and Microbacterium sp. (AS33) by 16S rRNA (16S ribosomal RNA) sequencing and their basic local alignment search tool search analysis. Growing cell of E. coli and Microbacterium sp. revealed accumulation of 0.12, 0.08 and 0.06 µg, of Ni²⁺/mg dry weight of cells, respectively, by 72 hr. Similarly resting cell of these strains showed accumulation of 0.27, 0.11 and 0.08 µg of Ni²⁺/mg dry weight of cells by 150 min, respectively. These results reveal that strain E. coli (AS21) shows maximum accumulation efficiency for Ni²⁺ among different isolates studied under shaking as well as starving conditions. Hence, E. coli (AS21) could serve as an efficient and promising bacterium for bioremediation of nickel-contaminated sites.     

DNA Probe-Mediated Detection of Resistant Bacteria from Soils Highly Polluted by Heavy Metals

Alcaligenes eutrophus CH34 DNA fragments encoding resistance to Cd²⁺, Co²⁺, Zn²⁺ (czc), or Hg²⁺ (merA) were cloned and used as probes in colony hybridization procedures with bacteria isolated from polluted environments such as a zinc factory area (desertified because of the toxic effects of zinc contamination) and from sediments from factories of nonferrous metallurgy in Belgium and mine areas in Zaire. From the different soil samples, strains could be isolated and hybridized with the czc probe (resistance to Cd²⁺, Co²⁺, and Zn²⁺ from plasmid pMOL30). Percentages of CFU isolated on nonselective plates which hybridized with the czc and the mercury resistance probes were, respectively, 25 and 0% for the zinc desert, 15 to 20 and 10 to 20% for the two Belgian factories, and 40 and 40% for the Likasi mine area. Most of these strains also carried two large plasmids of about the same size as those of A. eutrophus CH34 and shared many phenotypic traits with this strain. These findings indicated a certain correlation between the heavy-metal content in contaminated soils and the presence of heavy-metal-resistant megaplasmid-bearing A. eutrophus strains.     

Antibiotic and Heavy Metal Resistance of Pseudomonas aeruginosa Isolated from Soils

1. 71 strains of Pseudomonas aeruginosa were isolated from soils and tested for resistance to antibiotics and heavy metals.
2. 6% were resistant both to 12/14 drugs and 9/12 heavy metals tested.     

Differential Siderophore Utilization and Iron Uptake by Soil and Rhizosphere Bacteria

The differential availabilities of the hydroxamate siderophores ferrioxamine B (FOB) and ferrichrome (FC) and the pseudobactin siderophores St3, 7NSK₂, and WCS 358 as sources of Fe for soil and rhizosphere bacteria were studied. About 20% of the total bacterial CFU from the rhizospheres of four plant species were able to use FOB as the sole Fe source in an Fe-deficient medium, while about 12, 10, 2, and > 1% were able to use FC and pseudobactins 7NSK₂, St3, and WCS 358, respectively. Of the 165 colonies isolated from plates containing pseudobactins, 64 were able to use the pseudobactin on which they were isolated as the sole Fe source in pure culture. Cross-feeding tests showed that almost all of these 64 strains were also able to use at least one of the other siderophores studied (pseudobactin, FOB, or FC). Pseudomonas putida StS2, Pseudomonas maltophilia 7NM1, and Vibrio fluvialis WS1, which were originally isolated on pseudobactins St3, 7NSK₂, and WCS 358, respectively, were selected for their ability to grow with pseudobactin St3 as the sole Fe source. They incorporated ⁵⁵Fe³⁺ mediated by pseudobactin St3 at various rates (71.5, 4, and 23 pmol/min/mg [dry weight] of cells, respectively). Similarly, P. putida St3 was shown to incorporate ⁵⁵Fe³⁺ mediated by FOB and FC. We suggest that the ability of bacteria to utilize a large variety of siderophores confers an ecological advantage.     

Utilization of Grasses for Potential Biofuel Production and Phytoremediation of Heavy Metal Contaminated Soils

This research focuses on investigating the use of common biofuel grasses to assess their potential as agents of long-term remediation of contaminated soils using lead as a model heavy metal ion. We present evidence demonstrating that switch grass and Timothy grass may be potentially useful for long-term phytoremediation of heavy metal contaminated soils and describe novel techniques to track and remove contaminants from inception to useful product. Enzymatic digestion and thermochemical approaches are being used to convert this lignocellulosic feedstock into useful product (sugars, ethanol, biocrude oil + biochar). Preliminary studies on enzymatic hydrolysis and fast pyrolysis of the Switchgrass materials that were grown in heavy metal contaminated soil and non-contaminated soils show that the presence of lead in the Switchgrass material feedstock does not adversely affect the outcomes of the conversion processes. These results indicate that the modest levels of contaminant uptake allow these grass species to serve as phytoremediation agents as well as feedstocks for biofuel production in areas degraded by industrial pollution.     

Siderophore Production and Induction of Iron-regulated Proteins by a Microorganism from Rhizosphere of Barley

This study provides new information on the Fe uptake system capable of supporting growth of the organism. Pseudomonas fluorescens isolated from the rhizosphere of barley, a gramineous plant, produced a siderophore under iron-limiting conditions. Its chemical structure was identified as pyochelin, on the basis of ¹H and ¹³C NMR data of a stable methyl ester derivative. The same iron-limiting conditions induced a new set of outer membrane proteins (75 and 55 kDa), consistent with a siderophore-mediated iron-uptake system.     

First Description of Various Bacteria Resistant to Heavy Metals and Antibiotics Isolated from Polluted Sites in Tunisia

Environmental bacteria belonging to various families were isolated from polluted water collected from ten different sites in Tunisia. Sites were chosen near industrial and urban areas known for their high degree of pollution. The aim of this study was to investigate cross-resistance between heavy metals (HM), i.e., silver, mercury and copper (Ag, Hg, and Cu), and antibiotics. In an initial screening, 80 isolates were selected on ampicillin, and 39 isolates, retained for further analysis, could grow on a Tris-buffered mineral medium with gluconate as carbon source. Isolates were identified based on their 16S rRNA gene sequence. Results showed the prevalence of antibiotic resistance genes, especially all isolates harbored the bla_TEM gene. Some of them (15.38%) harbored bla_SHV. Moreover, several were even ESBLs and MBLs-producers, which can threaten the human health. On the other hand, 92.30%, 56.41%, and 51.28% of the isolates harbored the heavy metals resistance genes silE, cusA, and merA, respectively. These genes confer resistance to silver, copper, and mercury. A cross-resistance between antibiotics and heavy metals was detected in 97.43% of our isolates.     

Siderophore Production by Microorganisms Isolated From a Podzol Soil Profile

Siderophore-producing bacteria/actinobacteria and fungi were isolated from O- (organic), E- (eluvial), B- (upper illuvial), and C- (parent material) horizons of podzol soil. Siderophores were isolated and hydroxamate type siderophores were detected and quantitated by high-performance liquid chromatography coupled to electrospray ionization mass spectrometry. The molecular identification of siderophore-producing isolates showed that there was a high diversity of fungal and bacterial/actinobacterial species throughout the soil profile. The isolated bacteria/actinobacteria showed different abilities in the production of ferrioxamines (E, B, G and D). Moreover, the isolated fungal species showed great variety in the production of ferrichromes, coprogens and fusarinines.     

Experimental Assessment of Using Soluble Humic Substances for Remediation of Heavy Metal Polluted Soils

Since heavy metals are nondegradable and strongly bonded in soils, remediation of heavy metal polluted soils by extraction is difficult and current extraction techniques require harsh chemicals such as ethylenediaminetetraacetic acid (EDTA). However, use of EDTA is environmentally problematic because of costs, persistence, toxicity and deterioration of soil structure. Therefore, the potential of soluble natural humic substances (HS) to extract heavy metals from contaminated soils is tested as an environmentally friendly substitute for EDTA. A strongly polluted, calcareous urban soil (CRC soil) and a moderately polluted agricultural soil (CUP soil) were extracted at neutral pH in batch mode by three HS solutions from beech and Norway spruce litter (Beech-HS and Spruce-HS) and processed cow slurry (Bio-HS), all containing 25 mM dissolved organic carbon (DOC). After 10 extractions with a solution to soil ratio of 5:1 (L/kg), 8% to 39% of the total Cd, Cu, Ni and Pb soil contents, lowest for Ni and highest for Cu/Pb, were extracted. Natural and processed HS samples had comparable capacities to extract the heavy metals. A comparison of 100 mM DOC of Bio-HS and EDTA as extractants for Cu from the CRC soil showed extraction of 67% by EDTA and 41% by Bio-HS, indicating somewhat higher efficiency of EDTA than of HS. Sequential extraction of the CRC soil after Bio-HS and EDTA extraction showed removal of exchangeable, carbonate- and metal oxide-bound Cu but also of some residual Cu. It is therefore concluded that HS appears to be an attractive and promising alternative to EDTA as remediation agent for heavy metal polluted soils provided cheap HS of good quality is easily available.     

植物修复——治理土壤重金属污染的新途径

介绍了重金属污染土壤的植物修复的概念、原理与研究动态以及重金属超积累植物的特性 ,及其在治理污染土壤中的潜力 ,为土壤重金属污染的整治及其生态的修复提出新途径。     

Hemolytic Activity and Siderophore Production in Different Aeromonas Species Isolated from Fish

The hemolytic activity and siderophore production of several strains of motile aeromonads were determined. The hemolytic activity of Aeromonas caviae and Aeromonas eucrenophila was enhanced after trypsinization of the samples. The enhancement of hemolysis was observed in strains that carried an aerolysin-like gene, detected by a PCR procedure. Siderophore production was demonstrated in all but one strain of Aeromonas jandaei. No apparent relationship was observed between the presence of plasmid DNA and hemolysis or siderophore production.     

Free-Living Heterotrophic Nitrogen-Fixing Bacteria Isolated from Fuel-Contaminated Antarctic Soils

Five bacterial isolates enriched from fuel-contaminated Antarctic soils fixed nitrogen in the dark heterotrophically and nonsymbiotically. Two isolates utilized jet fuel vapors and volatile hydrocarbons for growth but not in N-deficient medium. Bacteria such as these may contribute to in situ biodegradation of hydrocarbons in Antarctic soils.     

Chelate-Enhanced Phytoremediation of Soils Polluted with Heavy Metals

In general, hyperaccumulators are low biomass, slow-growing plants. High biomass non-hyperaccumulator plants by themselves are not a valid alternative for phytoextraction as they also have many limitations, such as small root uptake and little root-to-shoot translocation. In this context, chemically-induced phytoextraction (based on the fact that the application of certain chemicals, mostly chelating agents, to the soil significantly enhances metal accumulation by plants) has been proposed as an alternative for the cleaning up of metal polluted soils. But chelate-induced phytoextraction increases the risk of adverse environmental effects due to metal mobilization during extended periods of time. In order to minimize the phytotoxicity and environmental problems associated with the use of chelating agents, nowadays, research is being carried out on the gradual application of small doses of the chelating agent during the growth period. However, EDTA utilization in the future will most likely be limited to ex situconditions where control of the leachates can be achieved. There are other mobilizing agents which are much less harmful to the environment such as citric acid, NTA, and particularly EDDS. Research should also be aimed towards more innovative agronomic practices. Environmentally safe methods of chelate-induced phytoextraction must be developed before steps towards further development and commercialization of this remediation technology are taken. Most importantly, more applied projects in this field are needed to clarify the real potential and risks of this technology.     

Production of Plant Growth Regulators by Rhizosphere Phosphate-solubilizing Bacteria

Culture supernatant fluids of 50 phosphate-dissolving bacteria isolated from rhizospheres of crop plants were examined for IAA, gibberellins and cytokinins. These bacteria possessed phytase activity and 27 could dissolve rock phosphate. Twenty bacteria synthesized all 3 types of plant hormones, 43 produced IAA, 29 formed gibberellins and 45 cultures produced cytokinin-like substances. Of the 50 bacteria tested 28 decomposed IAA. Plant growth inhibitors were detected in cultures of some isolates. The ecological significance of these rhizosphere bacteria and their mode of action when used as inoculants is considered.     

Production and utilization of aminoacids by various species of Rhizosphere Bacteria

Было выделено с поверхности корней и из почвы ризос?еры пшеницы и иденти?ицировано 11 видов микроорганизмов, растущих в минеральной среде с глюкозой и выделяющих в среду различные аминокислоты. Наиболее часто в ?ильтратах находились аспрагин, серин, аспарагиновая кислота, α-аланин и метионин (валин). В подобранных ?ильтратах, качественно различных по содержанию аминокислот, большая часть исследуемых микроорганизмов использовала эти амниокислоты для своего роста. Авторы полагают, что микроорганизмы споверхности корней и ризос?еры, растущие только в минеральной средес глюкозой и выделяюощие аминокислоты, могут иметь определенное значение в экологии микробных сообществ ризос?еры.     

Production of Antimicrobial Substances by Bacteria Isolated from Fermented Table Olives

Summary The production of antimicrobial substances was studied among 195 bacterial isolates from retail table olives. A total 86 isolates tested positive, and they clustered in 10 groups according to their inhibitory spectra. Many isolates (38.37%) produced strong inhibition against all bacteria tested (Listeria innocua, Lactococcus lactis, Bacillus cereus, B. megaterium, Staphylococcus aureus, Micrococcus luteus, Enterococcus faecalis, and Escherichia coli). The selected bacterial isolates were Gram-positive bacteria with rod morphology (62.67%), short rods (26.65%) or cocci (10.67%). Isolates producing antimicrobial substances may be useful as starters to enhance control of table olive fermentation and improve the safety of retail table olives.     

锌厂Pb污染农田小麦根际与非根际土壤酶活性特征研究

土壤酶是一种生物催化剂 ,它们参与土壤系统中诸多重要代谢过程 ,即土壤发生与发育、土壤肥力的形成、土壤净化等。土壤酶活性反映了土壤中进行的各种生物化学过程的强度和方向。研究表明 ,耕作土壤酶活性与土壤肥力、作物营养利用效率显著相关[1～ 4 ,10 ] 。土壤酶活性易受环境中物理、化学和生物的影响 ,环境污染条件下土壤酶活性变化很大 ,因此 ,土壤酶活性在一定程度上可以反映出环境状况。某些污染物的存在能抑制土壤酶活性 ,例如脲酶与磷酸酶活性对某些重金属很敏感[5] 。这使得土壤酶学研究在环境科学研究中的应用成为可能 ,但国内…     

The Chemophytostabilisation Process of Heavy Metal Polluted Soil

Industrial areas are characterised by soil degradation processes that are related primarily to the deposition of heavy metals. Areas contaminated with metals are a serious source of risk due to secondary pollutant emissions and metal leaching and migration in the soil profile and into the groundwater. Consequently, the optimal solution for these areas is to apply methods of remediation that create conditions for the restoration of plant cover and ensure the protection of groundwater against pollution. Remediation activities that are applied to large-scale areas contaminated with heavy metals should mainly focus on decreasing the degree of metal mobility in the soil profile and metal bioavailability to levels that are not phytotoxic. Chemophytostabilisation is a process in which soil amendments and plants are used to immobilise metals. The main objective of this research was to investigate the effects of different doses of organic amendments (after aerobic sewage sludge digestion in the food industry) and inorganic amendments (lime, superphosphate, and potassium phosphate) on changes in the metals fractions in soils contaminated with Cd, Pb and Zn during phytostabilisation. In this study, the contaminated soil was amended with sewage sludge and inorganic amendments and seeded with grass (tall fescue) to increase the degree of immobilisation of the studied metals. The contaminated soil was collected from the area surrounding a zinc smelter in the Silesia region of Poland (pH 5.5, Cd 12 mg kg^-1, Pb 1100 mg kg^-1, Zn 700 mg kg^-1). A plant growth experiment was conducted in a growth chamber for 5 months. Before and after plant growth, soil subsamples were subjected to chemical and physical analyses. To determine the fractions of the elements, a sequential extraction method was used according to Zeien and Brümmer. Research confirmed that the most important impacts on the Zn, Cd and Pb fractions included the combined application of sewage sludge from the food industry and the addition of lime and potassium phosphate. Certain doses of inorganic additives decreased the easily exchangeable fraction from 50% to 1%. The addition of sewage sludge caused a decrease in fraction I for Cd and Pb. In combination with the use of inorganic additives, a mobile fraction was not detected and an easily mobilisable fraction was reduced by half. For certain combinations of metals, the concentrations were detected up to a few percent. The application of sewage sludge resulted in a slight decrease in a mobile (water soluble and easily exchangeable metals) fraction of Zn, but when inorganic additives were applied, this fraction was not detected. The highest degree of immobilisation of the tested heavy metals relative to the control was achieved when using both sewage sludge and inorganic additives at an experimentally determined dose. The sequential extraction results confirmed this result. In addition, the results proved that the use of the phytostabilisation process on contaminated soils should be supported.     

Novel Hyper Antimony-Oxidizing Bacteria Isolated from Contaminated Mine Soils in China

Antimony (Sb)-oxidizing bacteria play an important role in environmental Sb bioremediation because of their ability to convert the more toxic Sb(III) to the less toxic Sb(V). So far, the information about the Sb(III)-oxidizing bacteria species is still limited. In this study, three highly Sb(III)-resistant bacterial strains were isolated from contaminated mine soils after aerobic enrichment culturing with Sb(III) (1 mM). The morphological, biochemical, and 16S rRNA gene sequencing analysis suggested that the three novel bacterial isolates fell within Cupriavidus, Moraxella, and Bacillus, respectively. Among the strains, Moraxella sp. S2 isolated from soils with the highest Sb content exhibited the highest minimum inhibitory concentration for Sb(III) but the lowest Sb(III) oxidation efficiency, which could not completely oxidize 50 μM Sb(III) in 15 days. Cupriavidus sp. S1 was able to oxidize 50 μM Sb(III) completely in 12 days, but could not oxidize 100 μM Sb(III) even with extended time of incubation, while Bacillus sp. S3 with the lowest resistance to Sb(III) could aerobically oxidize 100 µM Sb(III) within 2 days, showing high Sb(III) oxidation efficiency. Our research demonstrated that indigenous microorganisms associated with Sb mine soils were capable of Sb oxidation, and the novel bacteria isolated could represent good candidates for Sb remediation in heavily polluted sites.     

Biotechnological Potential of Some Cold-Adapted Bacteria Isolated from North-Western Himalaya

Microbiology - In the present study, cold-adapted bacteria were isolated from soil, water and glacial ice samples collected from various geographical locations within the north-western Himalayan...