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RISS 인기검색어
- 검색키워드
- 저자 : ( Buddhi Charana Walpola ) (검색결과 45 건)
- 무료
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Walpola, Buddhi Charana,Arunakumara, K.K.I.U.,Song, Jun-Seob,Lee, Chan-Jung,Yoon, Min-Ho Korean Society of Soil Science and Fertilizer 2014 한국토양비료학회지 Vol.47 No.4
A bacterial strain with the potential ability to solubilize heavy metals was isolated from heavy metal contaminated soils collected from abandoned mines of Boryeong area in South Korea. The bacterial strain with the highest degree of metal resistance was shown to have close proximity with Shewanella xiamenensis FJ589031, according to 16S rRNA sequence analysis, and selected for investigating the mobilization of metals in soil or plant by the strain. The strain was found to be capable of solubilizing metals both in the absence and in the presence of metals (Co, Pb and Cd). Metal mobilization potential of the strain was assessed in a batch experiment and the results showed that inoculation could increase the concentrations of water soluble Co, Pb and Cd by 48, 34 and 20% respectively, compared with those of non-inoculated soils. Bacterial-assisted growth promotion and metal uptake in sunflower (Helianthus annuus) was evaluated in a pot experiment. In comparison with non-inoculated seedlings, the inoculation led to increase the growth of H. annuus by 24, 18 and 16% respectively in Co, Pb and Cd contaminated soils. Moreover, enhanced accumulation of Co, Pb and Cd in the shoot and root systems was observed in inoculated plants, where metal translocation from root to the above-ground tissues was also found to be enhanced by the strain. Plant growth promotion and metal mobilizing potential of the strain suggest that the strain could effectively be employed in enhancing phytoextraction of Co, Pb and Cd from contaminated soils.
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Evaluation of Nitrogen Mineralization in Soil Polluted by Zinc and Cadmium
Walpola, Buddhi Charana,Arunakumara, K.K.I.U.,Yoon, Min-Ho Korean Society of Soil Science and Fertilizer 2011 한국토양비료학회지 Vol.44 No.4
Soil microbial functions are considered to be effective in assessing the severity of heavy metal pollution. Therefore, this study was carried out to examine the effect of heavy metals on nitrogen mineralization by measuring the releasing pattern of inorganic nitrogen ($NH_4^+$-N and $NO_3^-$-N) in a soil treated with heavy metals. A factorial combination of two heavy metals (Zn and Cd) treated with three concentrations (50, 100 and $150{\mu}mol\;g^{-1}$ soils) was used in a laboratory incubation. Nitrogen mineralization was determined at 3, 7, 14, 21, 28, 42 and 56 days after the treatments replicated four times. Soil sample free from heavy metals was served as the control. The amount of nitrogen mineralization from heavy metal treated soils was found to be decreased at an increasing rate during the first 21 days of incubation. However, as the incubation progressed, nitrogen mineralization was found to be decreased at decreasing rates. Furthermore, during this period, nitrogen mineralization in Cd treated soils was significantly lower ($P{\leq}0.05$) than that of the control. Soils treated with Cd at the concentration of $150{\mu}mol\;g^{-1}$ showed the lowest N mineralization throughout the incubation. Nitrogen mineralization in Zn treated soils ($50{\mu}mol\;g^{-1}$) was found to be higher than the other heavy metal treated soils. On the base of present findings, nitrogen mineralization of soil could be considered as a viable assessment of the degree of heavy metal pollution.
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Buddhi Charana Walpola,Jae-Geun Noh,Chan Kyem Kim,Ki-Cheon Kyung,Won-Sik Kong,Min-Ho Yoon 한국버섯학회 2013 한국버섯학회지 Vol.11 No.2
A total of 35 phosphate solubilizing bacterial strains were isolated from waste mushroom bed of Agaricus bisporus in Buyeo-Gun, Chungnam and screened for the production of indole acetic acid (IAA). The best IAA producing strain was identified as Pantoea rodasii using 16S rRNA analysis. In addition to the IAA production, this strain could act as an efficient phosphate solubilizer (1100 μg ml-1 after 5 days of incubation) also. The selected strain was cultured under different conditions in order to assess the optimum conditions for maximum IAA production. The nutrient broth (NB) medium was recorded as the best medium, where the maximum IAA production (229 μg ml-1) was recorded at the start of stationary phase (12 hours after inoculation) of the bacteria growth. The performance of the strain was found to be maximum at the temperature of 30oC followed by 25oC. IAA production was found to be increased with increasing tryptophan concentration (from 0.1 to 0.6%), however beyond this limit, a slight reduction in IAA production was observed. The strains’ ability to produce IAA was further confirmed by extraction of crude IAA and subsequent TLC analysis. A specific spot from the extracted IAA preparation was found corresponding with the standard spot of IAA with same Rf value. The results of HPLC analysis conducted in identifying and quantifying the IAA production more precisely, are in agreement with the results of the assessment done with colorimetric method. As revealed by the results of the pot experiment, the isolated strain could significantly enhance the growth (as measured by shoot and root growth) of mung bean plants compared to that of non-inoculated plants. Therefore it can be concluded that the present strain, Pantoea rodasii has great potential to be used as bio-inoculants.
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Buddhi Charana Walpola,Mi-Jung Keum,Min-Ho Yoon 한국토양비료학회 2012 한국토양비료학회지 Vol.45 No.6
Pantoea agglomerans DSM3493 was isolated from green house soils collected from Chungchugnam-do province, Gongju-Gun area in South Korea and phosphate solubilization and organic acid production of the strain were assessed using three types of insoluble phosphate sources (Ca phosphate, Fe phosphate and Al phosphate) under three different pH conditions (7, 8 and 9). The highest Ca phosphate solubilization (651 μg mL<sup>-1</sup>) was recorded at pH 7 followed by pH 8 and 9 (428 and 424 μg mL<sup>-1</sup> respectively). The solubilization rate was found to be 80.4, 98.1 and 88.7 μg mL<sup>-1</sup> (for Fe phosphate containing medium) and 9.3, 12.1 and 29.8 μg mL<sup>-1</sup> (for the Al phosphate containing medium) respectively at pH 7, 8 and 9. Though increasing pH of the medium caused reduction in the rate of solubilization of Ca phosphate, solubilization of Fe and Al phosphates enhanced with increasing pH. By contrast, the highest amount of organic acid was produced with Ca phosphate while the lowest was recorded with the presence of Al phosphate. Among the organic acids, gluconic acid production was found to be the highest, followed by oxalic acid and citric acid regardless the source of phosphate. Results can thus be concluded that the production of organic acids appears to play a significant role in the inorganic phosphate solubilization.
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Application of Immobilization Technology in Solubilization of Rock Phosphate
Buddhi Charana Walpola,Ah Young Kim,Ju Hyeon Jeon,Min-Ho Yoon 한국토양비료학회 2014 한국토양비료학회지 Vol.47 No.4
Phosphates solubilizing bacterial strains belong to Pantoea, Burkholderia and Enterobacter were isolated and employed in assessing their solubilization ability of Ca phosphate and ER phosphate (Eppawala Rock Phosphate). Among the bacterial strains used, PSB-13 (Pantoea rodasii) showed higher Ca-phosphate solubilization (1100 μg ml<SUP>-1</SUP>) as well as rock phosphate solubilization (168 μg ml<SUP>-1</SUP>). The strain was then immobilized in agar to further assess its phosphate solubilization ability. According to the results, agar encapsulated strain solubilized 0.3%, 7.31%, 20.24%, and 20.62% more Ca-phosphate and 11.53%, 15.29%, 28.48%, 36.55% (respectively in 4 cycles) more ER- phosphate than free cells. The reuse efficiency of agar entrapped bacterial cells for Ca-phosphate and ER-phosphate solubilization was greater than that by freely suspended bacterial cells. In conclusion, immobilization could enhance the phosphate solubilization capacity of the strains and thus could be used effectively in enhancing solubilization of ER phosphate.
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Buddhi Charana Walpola,KKIU Arunakumara,Jun-Seob Song,Chan-Jung Lee,Min-Ho Yoon 한국토양비료학회 2014 한국토양비료학회지 Vol.47 No.4
A bacterial strain with the potential ability to solubilize heavy metals was isolated from heavy metal contaminated soils collected from abandoned mines of Boryeong area in South Korea. The bacterial strain with the highest degree of metal resistance was shown to have close proximity with Shewanella xiamenensis FJ589031, according to 16S rRNA sequence analysis, and selected for investigating the mobilization of metals in soil or plant by the strain. The strain was found to be capable of solubilizing metals both in the absence and in the presence of metals (Co, Pb and Cd). Metal mobilization potential of the strain was assessed in a batch experiment and the results showed that inoculation could increase the concentrations of water soluble Co, Pb and Cd by 48, 34 and 20% respectively, compared with those of non-inoculated soils. Bacterial-assisted growth promotion and metal uptake in sunflower (Helianthus annuus) was evaluated in a pot experiment. In comparison with non-inoculated seedlings, the inoculation led to increase the growth of H. annuus by 24, 18 and 16% respectively in Co, Pb and Cd contaminated soils. Moreover, enhanced accumulation of Co, Pb and Cd in the shoot and root systems was observed in inoculated plants, where metal translocation from root to the above-ground tissues was also found to be enhanced by the strain. Plant growth promotion and metal mobilizing potential of the strain suggest that the strain could effectively be employed in enhancing phytoextraction of Co, Pb and Cd from contaminated soils.
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Assessment of Plant Growth Promoting Activities of Phosphorus Solubilizing Bacteria
Buddhi Charana Walpola,June-Seob Song,Min-Ho Yoon 한국토양비료학회 2012 한국토양비료학회지 Vol.45 No.1
Plant growth promoting traits like production of indoleacetic acid (IAA), ammonia, hydrogen cyanide (HCN), siderophore, and like the enzyme activities of catalase, ACC deaminase, cellulase, chitinase and protease were assayed in vitro for twenty one phosphorus solubilizing bacteria isolated from soil isolates. Except SPP-5 and SPP-15 strains, all the other isolated strains produced IAA in various amounts of 10 to 23 ㎍ ml<SUP>-1</SUP>. All strains showed positive response for ammonia production and ACC deaminase activity implying that they are capable of growing in a N-free basal medium. Catalase activity was found to be superior in SPP-2, SPP-7, SPP-12 and SPP-17 compared to the other strains tested. HCN production was detected by 15 strains and among them SPP-9, SPP-15, SAph-11, and SAph-24 were found to be strong HCN producers. Except the isolates SPP-10, SPP-12, SPP-13 and SPP-14, all the other isolates produced more than 80% siderophore units. None of the strains showed cellulose and chitinase activity. SAph-8, SAPh-11, SAPh-24 and SPP-15 strains showed 35.84, 50.33, 56.64 and 34.78 U/ml protease activities, respectively. SPP-1, SPP-2, SPP-3, SPP-11, SPP-17, SPP-18, SAph-11 and SAph-24 strains showed positive response for all the tested plant growth promotion traits except cell wall degrading enzyme activities. According to the results, all the tested phosphorus solubilizing isolates could exhibit more than three or four plant growth promoting traits, which may promote plant growth directly or indirectly or synergistically. Therefore, these phosphorus solubilizing strains could be employed as bio-inoculants for agriculture soils.
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Evaluation of Nitrogen Mineralization in Soil Polluted by Zinc and Cadmium
Buddhi Charana Walpola,K.K.I.U. Arunakumara,윤민호 한국토양비료학회 2011 한국토양비료학회지 Vol.44 No.4
Soil microbial functions are considered to be effective in assessing the severity of heavy metal pollution. Therefore, this study was carried out to examine the effect of heavy metals on nitrogen mineralization by measuring the releasing pattern of inorganic nitrogen (NH_4^+-N and NO_3^--N) in a soil treated with heavy metals. A factorial combination of two heavy metals (Zn and Cd) treated with three concentrations (50, 100and 150 μmol g^-1 soils) was used in a laboratory incubation. Nitrogen mineralization was determined at 3, 7,14, 21, 28, 42 and 56 days after the treatments replicated four times. Soil sample free from heavy metals was served as the control. The amount of nitrogen mineralization from heavy metal treated soils was found to be decreased at an increasing rate during the first 21 days of incubation. However, as the incubation progressed,nitrogen mineralization was found to be decreased at decreasing rates. Furthermore, during this period,nitrogen mineralization in Cd treated soils was significantly lower (P≤0.05) than that of the control. Soils treated with Cd at the concentration of 150 μmol g^-1 showed the lowest N mineralization throughout the incubation. Nitrogen mineralization in Zn treated soils (50 μmol g^-1) was found to be higher than the other heavy metal treated soils. On the base of present findings, nitrogen mineralization of soil could be considered as a viable assessment of the degree of heavy metal pollution.
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