Silicate Bacteria Research Articles

Bioleaching of silicon in electrolytic manganese residue using single and mixed silicate bacteria.

Electrolytic manganese residue (EMR) is a type of industrial solid waste with a high silicon content. The silicon in EMR can be used as an essential nutrient for plant growth, but most of the silicon is found in silicate minerals with very low water solubility, that is, it is inactive silicon and cannot be absorbed and used by plants directly. Thus, developing a highly effective and environmentally friendly process for the activation of silicon in EMR is important both for reusing solid waste and environmental sustainability. The aim of this study was to investigate the desilication of EMR using cultures of Paenibacillus mucilaginosus (PM) and Bacillus circulans (BC). The results showed that the two types of silicate bacteria and a mixed strain of them were all able to extract silicon from EMR with a high efficiency, but the desilication performance of the mixed PM and BC was the best. Fourier transform infrared spectroscopy indicated that silicate bacteria can induce a suitable micro-environment near the EMR particles and release Si into the solution through their metabolism. X-ray diffraction analysis confirmed that layered crystal minerals, such as muscovite and diopside, were more likely to be destroyed by the bacterial action than quartz, which has a frame structure. Scanning electron microscopy-energy dispersive spectrometry proved that the silicate structures were destroyed and that Si in the residue was decreased, indicating the dissolution of silicon under the action of these microorganisms. This study suggests that bioleaching may be a promising method for the activation of silicon in EMR.

Bioleaching behaviors of silicon and metals in electrolytic manganese residue using silicate bacteria

Electrolytic manganese residue (EMR) is a kind of solid waste generated along with the production of electrolytic manganese, with a high content of quartz and metals. The former can be used as silicon fertilizer for crops after activation, while the latter may cause harm to surrounding environment due to their toxicity. The aim of this study was to investigate the effects of bacterial on the activation of silicon and fixation of heavy metals in EMR by using microbe-mineral direct contact and indirect contact methods. Mixed cultures of Bacillus mucilaginosus (BM) and Bacillus circulans (BC) were used to achieve activation of silicon in EMR, and the leaching concentration of Mn, Co and Ni and their chemical forms in the leaching residue were also investigated. The results show that the microbe-mineral direct contact method has better performance for the activation of silicon in EMR with the available silicon in the leaching solution up to 163.27 mg L−1 than the indirect contact method. The metals (Mn, Co and Ni) remaining in the residue mainly exist as the stable state after bioleaching, with lower leaching concentration after bioleaching of 20 d. And the effect of silicon bacteria on activation of silicon and the fixation mechanism of metals including the effect of silicate and silicate bacteria is confirmed, and it is verified by the identification of metabolites and the analysis of chemical reaction process. This study investigates the treatment of EMR by using mixed silicate bacteria, and reveals the mechanisms of bacteria on the activation of silicon and fixaion of heavy metals in EMR. The bioleaching method not only provides silicon source for soil but also can realize the reclamation of EMR.

Активность силикатных бактерий и Bacillus mucilaginosus в дерново-подзолистой почве в отношении деградации диатомита Инзенского месторождения

Активность силикатных бактерий и Bacillus mucilaginosus в дерново-подзолистой почве в отношении деградации диатомита Инзенского месторождения

Bioleaching of electrolytic manganese residue by silicate bacteria, and optimization of parameters during the leaching process

Electrolytic manganese residue (EMR) is a kind of industrial solid waste with high silicon content that contains harmful metal elements such as chromium (Cr), copper (Cu), lead (Pb), cadmium (Cd), nickel (Ni) and cobalt (Co). Developing a highly effective and environmentally friendly process to treat EMR is important, both for the reutilization of metal resources and for environmental sustainability. In this study, the bioleaching of available silicon from EMR using silicate bacteria is investigated, with flask experiments conducted to optimize the parameters in the bioleaching system. For metal ions, the concentrations of manganese (Mn), Co, Ni and Pb in solution were measured to determine the environmental safety effects before and after bioleaching. The results show that the bioleaching rates of available silicon in the slag were mainly affected by the temperature, pH and pulp density. Under the optimal conditions of temperature of 30 °C, pH of 7.0, pulp density of 5 percent, shake flask rotational speed of approximately 210 rpm, particle size of approximately 0.150 mm and leaching time of 16 d, the concentrations of available silicon in the bioleaching system rose to approximately 110 to 140 mg/L. The metals remaining in the residues were mainly bonded in stable fractions, with concentrations lower in the leachate after bioleaching. This study demonstrates that silicate bacteria can be used to increase the contents of available silicon from EMR, and that bioleaching technology can realize the harmless resource utilization of EMR.

Isolation and characterization of silicate-solubilizing bacteria from paddy rhizosphere (Oryza sativa L.)

Silicate is known as a beneficial element that has important role for growth and development of paddy. Paddy is the greatest accumulator of Si up to 10% of its dry weight, but this plant can’t absorb that element by itself. The uses of paddy rhizosphere bacteria as a silicate solubilizing agent should be studied furthermore. This study aims to isolate and characterize silicate bacteria from paddy rhizosphere that solubilize silicate optimally in Bunt and Rovira medium. The isolation, qualitative, quantitative test and characterization of silicate bacteria up to 39 characters, which is include of colony morphological, cell morphological and physiological-biochemical test. This study was conducted on February-June 2018 in Microbiology Laboratory and Plant Physiology Laboratory, Faculty of Mathematics and Natural Sciences, State University of Surabaya. Five isolates silicate solubilizing bacteria were found OS4, OS5, OS7, OS12 and OS13. The highest Solubilizing Index was gained by OS7 on 1,10, while the highest silicate concentration was solubilized by OS12 on 1,053 ppm in Bunt and Rovira broth.

Effects of silicate-bacteria pretreatment on desiliconization of magnesite by reverse flotation

Combined with silicate-bacteria pretreatment, the reverse flotation was utilized to achieve desiliconization of magnesite ore using dodecylamine as a collector. The reverse flotation experiments were conducted on magnesite ore with and without silicate-bacteria pretreatment. The reverse flotation experiments showed that the SiO2 grade of the concentrate decreased to 2.56% with silicate-bacteria pretreatment while the SiO2 grade of the concentrate was 4.61% without silicate-bacteria pretreatment. The concentrate was characterized using XRD and XRF, and the results indicated that the silicate-bacteria could dissolve the silicate minerals in the magnesite ore. The improved role of silicate-bacteria pretreatment on reverse flotation was investigated using microscopic view, zeta-potential, FTIR and SEM-EDX studies. The silicate minerals were dissolved as attested through microscopic view and FT-IR studies. Zeta potential indicated that the magnesite surface became hydrophilic by bio-pretreatment. SEM-EDX confirmed that there was polysaccharide secreted by the silicate bacteria attached on the magnesite surface.

Characteristics of bio-desilication and bio-flotation of Paenibacillus mucilaginosus BM-4 on aluminosilicate minerals

World reserves of bauxite include vast quantities of ore which are sub-economic due to high levels of reactive silica. It would lead to the substantial loss of caustic soda during Bayer processing. With the gradual reduction of the economic reserves of high-grade ore, people began to focus on the desiliconization treatment of the low-grade ore at reasonable cost. Biodesilication by silicate bacteria (such as Paenibacillus mucilaginosus) has been known as a potential technology for its characteristics of environmental protection, energy saving and sustainable development. In this paper, one silicate bacterial isolate with high desilication ability was screened, identified, and named as Paenibacillus mucilaginosus BM-4. The optimum cultural pH and temperature of BM-4 were also determined experimentally as 8.0 and 30°C, respectively. Under these optimum cultural conditions, silicate ores were bioleached by BM-4. It seems that the stratified structures silicate ores, such as kaolinite and chlorite, were more readily to be leached by BM-4.On the other hand, the float-abilities of BM-4 on kaolinite and bauxite were also investigated. With the experimental results shown that there existed the electrostatic adsorption process between BM-4 and kaolinite, and the Langmuir isotherm adsorption process between BM-4 and bauxite. It was observed that the float-abilities of bauxite were significantly depressed by BM-4, while the those of kaolinite were enhanced. The bioflotation test of the mixture of bauxite and kaolinite (mass ratio 5:1) through BM-4 were carried out by a modified Hallimond tube. With results shown that the Al/Si ratios of this mixed minerals were improved from 3.05 to 8.60 after bacterial conditioning due to bauxite depression. Eventually, 83.0% of Al2O3 were recovered from the mixed minerals by BM-4.

Effects of Flaveria bidentis invasion on the diversity of functional bacteria in rhizosphere soil.

Flaveria bidentis is an invasive plant found in large areas of northern China. This study conducted a separation and screening of the main functional bacteria in the soil of F. bidentis and investigated the change in the community structure. A variety of functional microbes were isolated using selective media and rep-PCR clustering, and a diversity analysis was carried out. In addition, the dominant populations of various functional bacteria were identified using 16S rRNA sequence alignment. The results showed that F. bidentis increased the contents of the major available nutrients in the soil, and the levels of azotobacteria, organic phosphorus bacteria, inorganic phosphorus bacteria, and silicate bacteria in the soil of F. bidentis were significantly higher than those of the native plant Tagetes erecta and the control. rep-PCR analysis indicated that the structure of the four functional bacterial microfloras in the soil of F. bidentis was significantly different from those of the native plant and control. The diversity analysis demonstrated that the diversity of functional microorganisms in the soil of F. bidentis was richer, the community structure was more complex, the predominant microflora comprised a greater proportion of the total population, and the ecological diversity was higher. This was further evidenced by identification of the main functional isolates from the three soil samples. Our findings indicated a mechanism of invasion by F. bidentis.

Green process using hot spring bacterium to concentrate alumina in coal fly ash

The disposal of fly ash as a by-product of incineration of coal is a more significant problem than ash produced from burning of municipal solid wastes, sugarcane bagasse, rice husks or tea dusts because of its volume. The present investigation aims at upgrading alumina in coal fly ash (CFA) through bioleaching, using Bacillus barbaricus (silicate bacterium) isolated from Taptapani hot spring, Odisha. Bioleaching has been done after washing CFA (WCFA) with water and the result obtained is compared with the results obtained by bioleaching of unwashed CFA (UCFA). The concentration of alumina in washed coal fly ash has increased to 34.72% from an initial concentration of 25.45% after 60 days. The residue also shows a reduction of silica content from an initial concentration of 62.14% to 40.71% after 60 days. All the experimental results are corroborated with chemical analysis as well as through characterization process. Thus present finding has opened an avenue for enrichment of CFA with respect to alumina which may be suitable for aluminum extraction. In addition, by-product may be used for production of silica sol.

Biomineralization and Biobeneficiation of Bauxite

Role of indigenous microbes in the formation and conversion of bauxite minerals is illustrated. Many types of microorganisms such as fungi, heterotrophic and autotrophic bacteria and yeasts inhabit bauxite ore deposits bringing about biogenesis and biomineraliztion. Organisms capable of iron oxidation and reduction and solubilising calcium carbonate and silica can be isolated from bauxite deposits and are used to bring about selective mineral beneficiation to remove iron, calcium and silica. Use of Paenibacillus polymyxa in the efficient removal of calcium from low grade bauxites is demonstrated through bioreactor technology. Similarly, for iron removal from bauxite, iron-reducing bacteria can be used. Silicate bacteria aid in selective silica solubilisation to control alumina: silica ratios. Microorganisms can also be used to bring about environmental control with respect to red mud disposal through bioremediation technology.

Microbial Variants from Iron Ore Slimes: Mineral Specificity and pH Tolerance.

This paper describes the isolation of the native bacterial strains from the iron ore mines slime pond and its extremophilic characteristics. The two microbial isolates designated as CNIOS-1 and CNIOS-2 were grown in selective silicate broth at pH 7.0 and the organisms were tested for their selective adhesion on silicate and alumina minerals. The silicate bacteria with their exopolymers are very potent to grow over aluminosilicates. It was established that CNIOS-1 grew preferentially in the presence of silicate mineral compared to CNIOS-2 which grew in the presence of alumina. The organisms were tested for growth at various pH and trials were carried to define their efficacy for eventual applications to remove gangue minerals of silica and alumina from the raw material.

Isolation and Screening of Silicate Bacteria from Various Habitats for Biological Control of Phytopathogenic Fungi

Silicate solubilizing bacteria (SSB) can play an efficient role in soil by solubilizing insoluble forms of silicates. In addition to this some SSB can also solubilize potassium and phosphates, hence increasing soil fertility and enhancing plant defense mechanisms. A total of 111 bacterial strains were isolated from various habitats of Pakistan and screened for solubilization of silicate, phosphate and potassium on respective media. Out of these, 35 bacterial isolates were capable of solubilizing either silicate, phosphate or potassium. Amongst these 7 bacterial isolates were capable of solubilizing all three minerals tested. The highest silicate (zone diameter 54 mm) and phosphate solubilization (zone diameter 55 mm) was observed for bacterial isolate NR-2 while the highest potassium solubilization was observed for NE-4b (zone diameter 11 mm). Dual culture antagonistic assays were carried out by using these bacterial isolates against four plant pathogenic fungi Magnaporthae grisae, Rhizoctonia solani, Altarnaria alternata and Macrophomina pheasolina. Mean zone of inhibition of these bacterial isolates against the four pathogenic fungi ranged between 4 mm to 39 mm. The largest zone of inhibition against all four bacterial strains was recorded for bacterial isolate NR-2 followed by NE-4b. These strains will be further investigated for their plant growth promoting activities in the future.

Effect of biological fertilization on medicinal plants

The need of increase food production in the most of developing countries becomes an ultimate goal to meet the dramatic expansion of their population. However, this is also associated many cases with a reduction of the areas of arable land which leaves no opinion for farmers but to increase the yield per unit area through the use of improved the crop varieties, irrigation and fertilization. The major problem facing the farmer is that he cannot afford the cost of these goods, particularly that of chemical fertilizers. Moreover, in countries where fertilizer production relies on imported raw materials, the costs are even higher for farmer and for the country. Besides this, chemical fertilizers production and utilization are considered as air, soil and water polluting operations. The utilization of bio-fertilizers is considered today by many scientists as a promising alternative, particularly for developing countries. Bio-fertilization is generally based on altering the rhizosphere flora, by seed or soil inoculation with certain organisms, capable of inducing beneficial effects on a compatible host. Bio-fertilizers mainly comprise nitrogen fixes, phosphate dissolvers or vesicular-arbuscular mycorrhizas and silicate bacteria. Growth characters, yield, essential oil and its constituents, fixed oil, carbohydrates, soluble sugars and nutrients contents of medicinal plants were significantly affected by adding the biological fertilizers compared with recommended chemical fertilizers.

Community analysis of plant growth promoting rhizobacteria for apple trees

Plant growth promoting rhizobacteria (PGPR) for perennial apple trees (PAT) and apple tree saplings under continuous cropping (ATS) from two places in China were isolated and analyzed, and cluster analysis of BOX-PCR data was performed. The results showed that the quantities of both total rhizobacteria and the four kinds of PGPR (nitrogen-fixing bacteria, phosphate-solubilizing bacteria, silicate bacteria and antagonistic bacteria) from PAT were higher than those of ATS at different sampling points. The largest dissimilitude of BOX-PCR patterns for the PGPR indicated the genetic evolutionary distance of bacteria isolates was closer for the same sampling point. The shared cluster groups of the same variety of PGPR from two kinds of apple rhizosphere or different sampling points were very few. The diversity index, richness index and evenness index of PGPR from PAT were higher than those of ATS at both sampling points, while the dominance index was lower. The amounts and varieties of PGPR significantly changed between the PAT and ATS from different areas, which indicated the PGPR of the same plant varied from place to place due to the different environmental conditions. These results indicate that PGPR from PAT have the advantage of species diversity compared with ATS.

Genome Sequence of Growth-Improving Paenibacillus mucilaginosus Strain KNP414

Paenibacillus mucilaginosus is a critical growth-improving silicate bacterium. Here, we report the complete genome sequence of P. mucilaginosus strain KNP414. This information will provide us with the opportunity to understand its molecular mechanisms and develop more effective utilization of the strain.

Changes in texture and retorting yield in oil shale during its bioleaching by Bacillus Mucilaginosus

Bioleaching of oil shale by Bacillus mucilaginosus was carried out in a reaction column for 13 d. The pH value of the leaching liquor decreased steadily from 7.5 to 5.5 and the free silicon dioxide concentration reached approximately 200 mg/L in it. Scanning electron microscopy(SEM) observations revealed that a mass of small particles separated from the matrix of oil shale. Energy dispersive spectrometry(EDS) analysis implied that the total content of Si,O, Al was decreased in the particle area of the matrix. These facts indicate that the silicate was removed, leading to the structural transformation of oil shale. Comparison of the shale oil yields before and after bioleaching illustrated that approximately 10% extra shale oil was obtained. This finding suggests that the demineralisation of the oil shale by silicate bacteria improves shale oil yield.

Single and Coorperative Bauxite Bioleaching by Silicate Bacteria

Silicate bacteria generally placed in the species Bacillus circulans and Bacillus mucilaginosus and Bacillus edaphics can liberated silicon from ores. Silicate bacteria from different resources have an obvious different abilities of desilicon. A single bioleaching and cooperative bioleaching(Bacillus circulans and Bacillus mucilaginosus and Bacillus edaphics) was investigated by measurements of the leaching rate of silicon from bauxite. Results shows that the leaching rate of silicon with a mixed incubation of the tested three strains in accordance with the ratio of 2: 2: 1 is much higher than that of them respective, and also obviously higher than that of other forms of mixed culture by the three strains.

Community structure of soybean plant growth-promoting rhizobacteria in the black soil region of Northeast China

为明确东北黑土区大豆根际促生菌的群落组成, 选择内蒙古自治区鄂温克族自治旗、黑龙江省海伦市、黑龙江省克山县和黑龙江省农垦红兴隆农场 4 个采样点, 分析了大豆根际自生固氮菌、解磷菌、溶磷菌和硅酸盐细菌的群落组成, 解析了促生菌种与地域之间的对应关系。 结果表明: 东北黑土区的大豆根际土壤中存在大量促生菌, 自生固氮菌达到 104 cfu·g^?1, 溶磷菌和解磷菌达到 105 cfu·g^?1, 硅酸盐细菌达到 103 cfu·g^?1; 分离得到具有自生固氮能力的菌株 5 株, 溶磷菌 6 株, 解磷菌 7 株, 硅酸盐细菌 4 株; 自生固氮菌多样性指数在 0.94~1.60 之间, 溶磷菌多样性指数在 0.83~1.52 之间, 解磷菌的多样性指数在 1.07~1.67 之间, 硅酸盐细菌多样性指数在 0.52~0.96 之间, 4 个取样点大豆根际促生菌的多样性指数均大于 2。 采用对应分析确定了不同地区的典型促生菌, 内蒙古鄂温克族自治旗的特征种为自生固氮菌 LLN8 (<i>Azotobacter beijerinckia indica</i>), 黑龙江省海伦市的特征种为溶磷菌 DHS13 (<i>Micrococcus</i>), 黑龙江省克山县的特征种为溶磷菌 DHS19 (<i>Pseudomo-nas</i>), 黑龙江省红兴隆农场的特征种为自生固氮菌 LLN1 (<i>A. chrooco-ccum</i>)和溶磷菌 DHS5 (<i>Azotobacter</i>)。同 时明确了 LLN2 (<i>A. azomonas</i>)、LLN6 (<i>Bacillus mucilaginosus</i>)、DHS9 (<i>Arthrobacter</i>)、DHSO2 (<i>Pseudomonas</i>)、DHSO14 (<i>Erwinia</i>)、DHSO17 (<i>Corynebacterium</i>)和 LSJ21 (<i>Bacillus</i>)在东北黑土区大豆根际分布较为广泛, 这些菌株为研发中国东北黑土区大豆专用型复合生物肥料提供了基础条件。

Screening of a Microbial Flocculant Producing Silicate Bacteria MT5-2 and its Flocculating Activity

A microbial flocculant (MBF) producing silicate bacteria MT5-2 was isolated from different sources of samples by silicate selected medium. Its chemical composition, optimal flocculation conditions，flocculation characteristics and primary application were studied in this paper. The results showed that the flocculant was an extracellular polysaccharide, and its flocculation activity was mainly distributed in the fermentation broth. The optimal flocculation conditions were as follows: for the 100 mL kaolin suspension, flocculant dosage was 4mL, metal cation dosage was 1% of ZnCl2 3mL, pH 7.5. The flocculation activity can reach 95% under this condition. Application results showed that flocculant MT5-2 had better flocculation activity in several common suspensions, such as kieselguhr, bentonite, soil, active carbon and starch, compared with polyacrylamide and inorganic salt.

Comparative Characteristics and Desilicon Ability of 10 Strains of Silicate Bacteria Screened from Different Bauxite Ores

Ten strains of silicate bacteria were screened from three bauxite samples in Jiangxi Province and Henan Province in China. The ten strains were determined as B. mucilaginosus according to the results of physiological and biochemical characteristics and desilicon ability. Bioleaching tests showed that the ten strains all can decompose bauxite ore and release silicon from bauxite, but had a large difference of desilicon ability among them.