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Study on the effect of magnetic field treatment of newly isolated Paenibacillus sp.

Botanical StudiesAn International Journal201556:2

DOI: 10.1186/s40529-015-0083-9

Received: 5 April 2014

Accepted: 13 January 2015

Published: 30 January 2015

Abstract

Background

Symbiotic nitrogen fixation in plants occurs in roots with the help of some bacteria which help in soil nitrogen fertility management. Isolation of significant environment friendly bacteria for nitrogen fixation is very important to enhance yield in plants.

Results

In this study effect of different magnetic field intensity and treatment time was studied on the morphology, physiology and nitrogen fixing capacity of newly isolated Paenibaccilus sp. from brown soil. The bacterium was identified by 16S rDNA sequence having highest similarity (99%) with Paenibacillus sp as revealed by BLAST. Different magnetic intensities such as 100mT, 300mT and 500mT were applied with processing time of 0, 5, 10, 20 and 30 minutes. Of all these treatment 300mT with processing time of 10 minutes was found to be most suitable treatment. Results revealed that magnetic treatment improve the growth rate with shorter generation time leading to increased enzyme activities (catalase, peroxidase and superoxide dismutase) and nitrogen fixing efficiencies. High magnetic field intensity (500mT) caused ruptured cell morphology and decreased enzyme activities which lead to less nitrogen fixation.

Conclusion

It is concluded that appropriate magnetic field intensity and treatment time play a vital role in the growth of soil bacteria which increases the nitrogen fixing ability which affects the yield of plant. These results were very helpful in future breading programs to enhance the yield of soybean.

Keywords

Magnetic treatment Paenibaccilus sp Catalase Peroxidase Superoxide dismutase

Background

Paenibacillus genus of bacteria was first included in Bacillus genus and then reclassified to a separate genus in 1993 (Ash et al. [1993]). These bacteria found in variety of environments like soil, water, forage, rhizosphere, insect larvae, vegetable matter and in clinical samples (McSpadden Gardener [2004], (Montes et al. [2004]; Ouyang et al. [2008]; Lal & Tabacchioni [2009])). These bacteria are of prime importance in agriculture for nitrogen fixation and industrial importance due to production of antibiotics and enzymes (Mavingui & Heulin [1994]; Von der Weid et al. [2003]). These bacteria produce plant growth hormones, suppress phytopathogens and solubilize organic phosphate (Mavingui & Heulin [1994]; Lebuhn et al. [1997]; Pires & Seldin [1997]).

Nitrogen is very essential nutrient for the growth of plants. So, these bacteria fix nitrogen from the air and provide this nitrogen to plants in the form of ammonium ions or other nitrogenous compounds essential for growth. From this symbiotic association, plant provides some organic compounds synthesized from photosynthesis (Sawada et al. [2003]). These bacteria not only fix the nitrogen but also enrich the soil fertility, increase plant production, and improve the quality, degrade organic pollutants and production of vitamin B series compounds (Sierra et al. [1999]; Agus et al. [2000]). The nitrogen deficiency was recovered by these rhizobia (Fisher & Long [1992]). In this process, plant produced some reactive oxygen species including the hydrogen peroxide and hydroxyl radicals and superoxide anion by defence reaction (Lamb & Dixon [1997]; Santos et al. [2001]). So it was necessary to study the rhizobia catalase, peroxidase and superoxide dismutase active changes.

A lot of research showed that the magnetic treatments have certain stimulative effect on crop production and development and, it also affect the genetic quality of seeds ((Zhu et al. [1996]; Liu et al. [1996]; Yan et al. [1997]; He et al. [1999]; Mao et al. [2002]); Jia et al. [2002]; (Liu et al. [2003])). Enzyme as protein with catalytic activity has an important role in the life process, and as a catalyst it was increasingly being attention (Cheng et al. [2007]). Magnetic field on the influence of the enzyme activity has been reported (He et al. [1998]; Li et al. [2007]; Hua et al. [2008]), and this area now attracts more and more people’s attention, but most of these studies focused on animals, plants and very little research on bacteria. So this study was aimed to check the effect of magnetic field on soybean rhizobia isolated from brown soil and their enzyme activities (peroxidase, catalase and superoxide dismutase) under the influence various intensity of magnetic treatment.

Methods

Materials

The Brown soil samples were collected from Shenyang Agriculture University, Shenyang Liaoning P.R. China. The samples were kept in sterile plastic bags and transferred aseptically to the lab.

Isolation of Paenibacillus

The Paenibacillus sp. were isolated using standard procedures, and were purified by repeatedly streaking the bacteria on yeast extract-mannitol agar (YMA) medium (Vincent [1970]) and stored at 4°C.

Molecular identification of Paenibacillus

Genomic DNA of the newly isolated bacterial strain was extracted by method as described by Ausubel et al. ([1994]). The DNA was amplified using universal primers 27 F:5′ -GAGAGTTTGATCCTGGCTCAG-3′ and 1492R:5′ -GGYTACCTTGTTACGACTT-3′. PCR reactions were performed in 50 l volume containing 1 μL template DNA, 4 μL MgCl2 (25 mmol/L), 5 μL 10× PCR buffer (Mg2+free), 4 μL dNTP(10 mmol/L), 1 μL of each primer (10 μmol/L), 0.5 μL of TaqDNA polymerase (5u/μL) and 33.5 μL ddH2O. PCR amplification conditions as follows: Initial denaturation at 94°C for 5 min followed by 30 cycles of denaturation at 94°C for 30 s, annealing at 55°C for 30 s and extension 72°C for 1 min, final extension at 72°C for 10 min. Amplification products were separated by 1 · 0% agarose gel electrophoresis and visualized under UV light after staining with ethidium bromide. The amplified 16S rRNA gene was sequenced using ABI 3730xl DNA Analyzer (Applied Biosystems, USA). The sequences were identified based on similarity using the Basic Local Alignment Search Tool (BLAST) program National Centre for Biotechnology Information (NCBI) online standard (http://www.ncbi.nlm.nih.gov/).

Magnetic treatment of soil

The soil was treated by magnetic field in 100 mT, 300 mT and 500 mT for 5 min, 10 min, 20 min and 30 min respectively. Soybean was planted in the treated soil samples using phosphate and potash fertilizers (75 mg kg−1P2O5;75 mg kg−1 K2O). After harvestation the plants and soil was used to determine the soybean nodulation and nitrogen fixation capacities.

Magnetic treatment of Paenibacillus sp.

The Paenibacillus sp. was inoculated in 100 mL of YMA medium, incubated at 28°C for 36 h with agitation speed 200 rpm. The cell growth was measured by taking OD at 520 nm. After the cell growth, 25 mL of Paenibacillus sp. cell suspension was taken in a test tube and treated it with different magnetic fields like 100, 300 and 500 mT with different time period such as 0, 5, 10, 20 and 30 min. Each experiment was conducted in triplicates and Paenibacillus sp. without magnetic treatment was taken as control.

Enzyme assay

The Paenibacillus sp. broth was centrifuge at 5000 × g, 4°C for 10 min. After centrifugation the supernatant was discarded and the pellet was suspended in 50 mmol L−1 phosphate buffer (pH 7.0) and then subjected to sonication. The homogenate solution was centrifuged for 10 min at 10000 × g, 4°C. After centrifugation, the supernatant was used for determination of peroxidase (POD), superoxidase dismutase (SOD) and catalase (CAT) activities. Catalase activity was assay of hydrogen peroxide based on the formation of its stable complex with ammonium molkbdate and the OD was measured at 405 nm (Fang et al. [2004]). One unit of catalase activity was defined as the decomposition of 1 μ mol of hydrogen peroxide per minute under standard assay conditions. Peroxidase activity was determined by hydrogen peroxide-dependent oxidation of guaiacol. Samples were mixed with guaiacol solution (20 mmol/L guaiacol in 0.1 mol/L phosphate buffer (pH 6.8) and 0.03% (v/w) hydrogen peroxide) (Bergmeger et al. [1983]). Increase in absorbance at 470 nm was recorded using UV-visible spectrophotometer. One unit of POD activity was defined as the change in absorbance of 0.01 per minute at room temperature. Total SOD activity was assayed by the inhibition of the photochemical reduction of pyrogallol (PAPG) by following the photo reduction of nitroblue tetrazolium (Cai et al. [2006]). One unit of SOD activity was defined as amount of enzyme producing a 50% suppression of PAPG reduction. All the Enzyme specific activity is expressed as U/ml.

Total nitrogen determination

Total plant nitrogen (N) concentration was analysed with Kjeldahl determination and colorimetric method as described by Baethgen and Alley (Baethgen & Alley [1989]). Nitrogen fixed was calculated as the total plant nitrogen content at harvest, minus the total nitrogen content at the start of the treatments.

Statistical analysis

The data obtained after experimentation was statistically evaluated using ANOVA at significance level of p < 0.05 by using computer based programme SPSS.

Results and discussion

Molecular identification of Paenibacillus sp.

The newly isolated bacterial strain was identified by molecular techniques using 16S rDNA sequencing. Product of 1442 bp was obtained after PCR amplification (Figure 1). The sequencing result was compared by BLAST for homology analysis. The isolated strain had 99% similarity with Paenibacillus sp. 9-2AIA (FN397529.1), Paenibacillus sp. Gi-691 (EU497639.1), Paenibacillus chibensis strain ZYb3 (FJ432004.1), 98% similarity with Paenibacillus sp. C-2 (KF479638.1), Paenibacillus sp. CC-YHH111 (JN806383.1), Paenibacillus sp. BM-7 (AY635866.1), 97% similarity with Paenibacillus sp. E18 (FJ899682.1), Paenibacillus sp. D27 (KF479657.1), Paenibacillus favisporus isolate MKI10 (EF173324.1) and 96% similarity with Paenibacillus rhizosphaerae strain CECAP16 (AY751755.1) and Paenibacillus sp. SSG-1 (KF750627.1) as shown in phylogenetic tree (Figure 2).
https://static-content.springer.com/image/art%3A10.1186%2Fs40529-015-0083-9/MediaObjects/40529_2015_Article_83_Fig1_HTML.jpg
Figure 1

Amplified product of 16S rDNA from newly isolated bacterial species.

https://static-content.springer.com/image/art%3A10.1186%2Fs40529-015-0083-9/MediaObjects/40529_2015_Article_83_Fig2_HTML.jpg
Figure 2

Neighbor-joining phylogenetic analysis of 16S rDNA sequences (1442 bp) of newly isolated Paenibacillus sp. compared with the sequence of standard strains. The bar represents a 0.002% of nucleotide variance.

Effect of magnetic field treated soil soybean nodular and nitrogen fixation

The soybean was planted in the brown soil treated with magnetic field, and the plants were harvested to measure the nodular situation and nitrogen content. The soybean was planted in the absence of nitrogen fertilizer and the difference in nitrogen content before and after treatment was used to compare the treatment effects. Thus we can use plant nitrogen to respond to the difference in the amount of nitrogen-fixing performance. Results shown in the Table 1 described that the soybean plant root dry weight, effective number of Paenibacillus sp. and total nitrogen content which treated by 100 mT, 300 mT magnetic field in plant were significantly higher as compared to control (CK). Results of this study was in agreement with Jing et al. (Jing et al. [1992]) who reported that appropriate intensity of magnetic field increased 4–5 time nitrogen fixing efficiency of the Bradyrhizobium japonicum 005. High treatment (500 mT) of magnetic field resulted decreased number of effective rhizobia thus leading to decreased total nitrogen content. This low nitrogen content leads to less growth because nitrogen is the main nutrition factor that influences the growth in plants (Marschner [1995]; Barker & Bryson [2007]). Nitrate is inorganic nitrogen which is dominant in agricultural soils and present in three or more times higher than natural soils (Hagedorn et al. [2001]; Owen & Jones [2001]).
Table 1

Effect of magnetic field treated soil on soybean nodular and nitrogen content

Treatment

Bacterial dry weight

Effective number of root nodule

Total nitrogen

Magnetic field (mT)

Time (min)

Weight (g dry wt pl−1)

Percentage change (%)

Amount (No./plant)

Percentage change (%)

Content (mg/g)

Percentage change (%)

Control (CK)

0.06h

-

7 ± 1.23

-

3.23 ± 0.12

-

100

5

0.20c

233

24 ± 3.47

243

3.46 ± 0.13

7.12

10

0.19d

217

18 ± 1.76

157.

3.51 ± 0.12

8.67

20

0.17e

183

17 ± 1.84

143

3.35 ± 0.11

3.72

30

0.15f

150

16 ± 1.34

129

3.25 ± 0.12

0.62

300

5

0.27a

350

37 ± 1.63

429

4.33 ± 0.17

34.06

10

0.26b

333

28 ± 2.95

300

4.55 ± 0.15

40.87

20

0.15f

150

24 ± 2.58

243

3.58 ± 0.13

10.84

30

0.09g

50

13 ± 1.72

86

3.51 ± 0.16

8.67

500

5

0.04j

−33

7 ± 1.25

0

3.34 ± 0.13

3.41

10

0.06h

0

7 ± 1.13

0

3.25 ± 0.12

0.62

20

0.05i

−17

6 ± 1.13

−14

3.17 ± 0.11

−1.86

30

0.05i

−17

7 ± 1.12

0

3.14 ± 0.13

−2.79

The different letters show significant difference (P < 0.05).

Effect of magnetic treatment on generation time of Paenibacillus sp.

In order to check the effect of magnetic field on Paenibacillus sp. morphology and physiology, all the effects were studied before and after treatment using various magnetic intensities and treatment time. After the magnetic field treatment, Paenibacillus sp. I and Paenibacillus sp. II quantity and generation time were changed. On magnetic treatment, the number of Paenibacillus sp. was increased as compared to control (CK). This effect was changed with respect to magnetic intensity and time duration. Results (Table 2) showed that magnetic intensity of 300 mT had strong effect on the population of Paenibacillus sp. The growth of Paenibacillus sp. was influenced by magnetic intensity and magnetic treatment time. By increasing the treatment time, number of Paenibacillus sp. was increased and further increase in treatment time resulted decline in Paenibacillus sp. growth. Of all the treatment time, 10 minutes of magnetic treatment gave better yield. The generation time of 100 mT, 300 mT magnetic field intensity treatments were shortened as compared to control (CK) while 500 mT magnetic field intensity treatments has no significant effect on the generation time as compared to control. These results indicated that magnetic field treatment significantly enhance the Paenibacillus sp. population in shorter time. Cheng and Yi (Cheng & Yi [2009]) reported that magnetic field intensity of 300 mT had a significant positive effect on the generation time of slow-growing rhizobium (USDA110) and fast-growing rhizobium (USDA191).
Table 2

The magnetic treatment of soybean purification number and generation of rhizobium time influence

Treatment

Paenibacillussp. I

Paenibacillussp. II

Magnetic field (mT)

Time (min)

Number

Generation ofPaenibacillussp. (h)

Number

Generation ofPaenibacillussp. (h)

CK

42

10.0

40

3.9

100

5

65

8.6

75

3.0

10

101

8.2

68

3.1

20

79

8.4

62

3.3

30

55

8.6

64

3.5

300

5

85

8.0

122

3.1

10

127

8.0

83

2.8

20

95

8.1

77

3.1

30

66

8.1

81

3.1

500

5

94

9.6

115

3.8

10

102

9.6

84

3.9

20

86

9.8

82

3.9

30

42

9.7

78

4.0

Effect of magnetic treatment on morphology of the Paenibacillus sp.

The effect of magnetic field on morphology of Paenibacillus sp. was also studied as shown in the Figures 3 and 4. Results showed that morphology of Paenibacillus sp. was affected by magnetic treatment. Only 10 minutes of magnetic treatment time with intensity of 300 mT and 500 mT was studied. In 300 mT treatment the cell becomes thin and longer while in case of 500 mT treatment the cell membrane was ruptured and the cytoplasmic sap was released leading to the death of the Paenibacillus sp. These results revealed that suitable processing time with specific intensity can promote the growth of the Paenibacillus sp. but high and long time magnetic processing inhibited the growth thus leading to the death of Paenibacillus sp. Our findings were similar as reported by Fadel et al. (Fadel et al. [2003]). Various reports suggested that exposure of microorganisms to magnetic field caused changes in morphology and growth (Mohamed et al. [1997]; Gaafar et al. [2006]).
https://static-content.springer.com/image/art%3A10.1186%2Fs40529-015-0083-9/MediaObjects/40529_2015_Article_83_Fig3_HTML.jpg
Figure 3

Effects of magnetic fields on the morphology of Paenibacillus sp.

https://static-content.springer.com/image/art%3A10.1186%2Fs40529-015-0083-9/MediaObjects/40529_2015_Article_83_Fig4_HTML.jpg
Figure 4

Effect of magnetic fields on the morphology of Paenibacillus sp.II.

Effect of magnetic field treatment on enzyme activity of Paenibacillus sp.

The influence of magnetic field was also checked on the catalase, peroxidase and superoxide dismutase activity of Paenibacillus sp. I and II. The catalases activity of Paenibacillus sp. I and II were enhanced by 300 mT intensity as shown in Figure 5. Paenibacillus sp. I showed more catalase activity as compared to Paenibacillus sp. II. The effective intensity and magnetic treatment time for Paenibacillus sp. I and II were 300 mT intensity for 10 and 20 minutes respectively. Both 100 mT and 300 mT increased the catalase activity while 500 mT decreased catalase activity as compared to control. The highest growth rate of Paenibacillus sp. I and II was 77% and 95% respectively. These results suggested that magnetic treatment time and intensity had strong influence on metabolic activity of Paenibacillus sp.
https://static-content.springer.com/image/art%3A10.1186%2Fs40529-015-0083-9/MediaObjects/40529_2015_Article_83_Fig5_HTML.jpg
Figure 5

Effect of magnetic fields on CAT activity of Paenibacillus sp.I (upper) and Paenibacillus sp.II (lower). Error bars indicate SD among triplicates. Stars represent significance level at P > 0.05.

Figure 6 showed the influence of different magnetic field on peroxidase activity of Paenibacillus sp. The 100 and 300 mT magnetic field treatment have growth trend to the peroxidase activity of Paenibacillus sp. The highest growth rate of Paenibacillus sp. I and II was 68% and 203% in 10 min and 30 min magnetic treatment respectively. Both Paenibacillus sp. showed maximum peroxidase activity at 10 min of treatment time with intensity of 300 mT. This activity behavior is almost similar to that of catalase activity.
https://static-content.springer.com/image/art%3A10.1186%2Fs40529-015-0083-9/MediaObjects/40529_2015_Article_83_Fig6_HTML.jpg
Figure 6

Effect of magnetic field on Peroxidase activity of Paenibacillus sp.I (upper) and Paenibacillus sp.II (lower). Error bars indicate SD among triplicates. Stars represent significance level at P > 0.05.

Figure 7 depicted the effect of different magnetic field on superoxide dismutase activity from Paenibacillus sp. Superoxide dismutase activity was found maximum at 20 min of magnetic treatment with intensity of 300 mT. This enzyme activity also showed the same trend as the previous ones (catalase and peroxidase activity) but here increased treatment time resulted increased superoxide dismutase activity. In all the three enzyme activities (catalase, peroxidase and superoxide dismutase) magnetic field intensity of 500 mT inhibited the enzyme activity because this magnetic intensity ruptured the cell shape which leads to decline in enzyme activities. The growth rate at 300 mT magnetic treatment was 340% and 153% for Paenibacillus sp. I and II respectively. So this study was in good agreement with Liu et al. (Liu et al. [1996]) who reported that appropriate magnetic field intensity enhanced the activities of hydrogen peroxidases, invertases, amylases and phosphatases in the three tested soils. Another study also revealed that magnetic field enhances the catalase and superoxide dismutase activity isolated from the roots of soybean (Celik et al. [2009]).
https://static-content.springer.com/image/art%3A10.1186%2Fs40529-015-0083-9/MediaObjects/40529_2015_Article_83_Fig7_HTML.jpg
Figure 7

Effect of magnetic fields on Superoxide dismutase activity (SOD) of Paenibacillus sp.I (upper) and Paenibacillus sp.II (lower). Error bars indicate SD among triplicates. Stars represent significance level at P > 0.05.

Conclusion

In conclusion the magnetic treatment significantly enhances the bacterial population with shorter generation time. This increased population of Paenibacillus sp. would increase the nitrogen fixing efficiency thus leading to greater yield. The enzyme activities were also increased under the influence of magnetic treatment. Increased magnetic field intensity and longer magnetic processing time resulted ruptured bacterial cell which leads to cell death, thus reduction in nitrogen fixation efficiency. To achieve the better yield, appropriate magnetic field intensity and magnetic processing time is very important for this whole process.

Declarations

Acknowledgment

This study was supported by the National Natural Science Foundation of China (Grant No. 40771111) and the Shenyang agricultural university youth fund (Grant No. 20070136).

Authors’ Affiliations

(1)
Key Laboratory of Preservation of Northeast Cultivated Land, Ministry of Agriculture, National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer, College of Land and Enviroment, Shenyang Agricultural University
(2)
Liaoning Academy of Environmental Sciences
(3)
Bioscience and Biotechnology College, Shenyang Agricultural University

References

  1. Agus JE, Steven DG, Brian ND: Isolation and characterization of 2,3-dichloro-Ipropanol-edgrading. Appl Environ Microbiol 2000,66(7):2882–2887. 10.1128/AEM.66.7.2882-2887.2000View ArticleGoogle Scholar
  2. Ash C, Priest FG, Collins MD: Molecular identification of rRNA group 3 Bacilli (Ash, Farrow, Wallbanks and Collins) using a PCR probe test. Proposal for the creation of a new genus Paenibacillus . Antonie Van Leeuwenhoek 1993, 64: 253–260. 10.1007/BF00873085View ArticlePubMedGoogle Scholar
  3. Ausubel M, Brent R, Kingston RE, Moore DD, Smit JA, Seidman JC, Struhl KS: Current protocols in molecular biology, section 2.4. John Wiley and Sons, New York; 1994.Google Scholar
  4. Baethgen WE, Alley MM: A manual colorimetric procedure for measuring ammonium nitrogen in soil and plant. Commun Soil Sci Plant Anal 1989,20(9&10):961–969. 10.1080/00103628909368129View ArticleGoogle Scholar
  5. Barker AV, Bryson GM: Nitrogen. In Handbook of Plant nutrition. Edited by: Barker AV, Pilbeam DJ. CRC Press, Boca Raton; 2007:21–50.Google Scholar
  6. Bergmeger H, Bergmeyer J, Grabl M: Methods of enzymatic Analysis. 3rd edition. Verlag Chemie Press, Weinheim; 1983.Google Scholar
  7. Cai Y, Lai Z, Shen J: Detection of superoxide dismutase activities in different organsim Phyllanthus emblica L. Chin J Trop Crops 2006,27(4):29–33.Google Scholar
  8. Celik Ö, Büyükuslu N, Atak C, Rzakoulieva A: Effects of magnetic field on activity of superoxide dismutase and catalase in Glycine max (L.) Merr. Roots. Pol J Environ Stud 2009,18(2):175–182.Google Scholar
  9. Cheng X, Yi Y: Effect of Magnetic Treatment on Amount and Generation Time of Slow-Growing Rhizobium (USDA110) and Fast-growing Rhizobium (USDA191). Southwest Chin J Agri Sci 2009,22(5):1400–1403.Google Scholar
  10. Cheng X, Yi Y, Du A: Effects of Magnetic treatment on the Azotobacter contents in brown Earth. Chin J Soil Sci 2007,38(5):1025–1027.Google Scholar
  11. Fadel MA, Wael SM, Mostafa RM: Effect of 50 Hz, 0.2 mT magnetic fields on RBC properties and heart functions of albino rats. Bioelectromagnetics 2003, 24: 535–545. 10.1002/bem.10134View ArticleGoogle Scholar
  12. Fang F, Li Y, Du GC: Themo-alkali stable catalase Themoascus aurantiacus and its potential use in textile bleaching process. Chin J Biotechnol 2004,20(3):423–428.Google Scholar
  13. Fisher RF, Long SR: Rhizobium-plant signal exchange. Nature 1992,357(6380):655–660. 10.1038/357655a0View ArticlePubMedGoogle Scholar
  14. Gaafar EA, Hanafy MS, Tohamy EY, Ibrahim MH: Stimulation and control of E. coli by using an extremely low frequency magnetic field. Rom J Biophys 2006,16(4):283–296.Google Scholar
  15. Hagedorn F, Bucher JB, Schleppi P: Contrasting dynamics of dissolved inorganic and organic nitrogen in soil and surface waters of forested catchments with Gleysols. Geoderma 2001, 100: 173–192. 10.1016/S0016-7061(00)00085-9View ArticleGoogle Scholar
  16. He H, Zhu Y, Zhong K: Effect of magnetic field on celhlase activity and conformation. J Jishou Univ 1998,19(1):42–46.Google Scholar
  17. He H, Zhu Y, Fan Q: The Effect of Magnetic Field on Escherichia Coli and Glutamic Acid Decarbolxylase. J Jishou Univ 1999,20(3):26–29.Google Scholar
  18. Hua H, Shen Y, Wu W: Effects of magnetic field on seed quality, POD and SOD of Pinus massoniana. J Nanjing For Univ 2008,32(3):39–42.Google Scholar
  19. Jia Y, Ma Y, Wang Z: The enzymatic activity of tomato seeds with magnetic field treatment. Biotechnology 2002,10(2):14–17.Google Scholar
  20. Jing Y, Zhang B, Wang Y, Lin X: Effect of magnetic field on symbiotic nitrogen fixation of soybean nodules. Acta Botanica Sinica 1992,34(5):364–368.Google Scholar
  21. Lal S, Tabacchioni S: Ecology and biotechnological potential of Paenibacillus polymyxa: a minireview. Indian J Microbiol 2009, 49: 2–10. 10.1007/s12088-009-0008-yPubMed CentralView ArticlePubMedGoogle Scholar
  22. Lamb C, Dixon RA: The oxidative burst in plant disease resistance. Annu Rev Plant Physiol Plant Mol Biol 1997, 48: 251–275. 10.1146/annurev.arplant.48.1.251View ArticlePubMedGoogle Scholar
  23. Lebuhn M, Heulin T, Hartmann A: Production of auxin and other indolic and phenolic compounds by Paenibacillus polymyxa strains isolated from different proximity to plant roots. FEMS Micr Eco 1997, 22: 325–334. 10.1111/j.1574-6941.1997.tb00384.xView ArticleGoogle Scholar
  24. Li J, Jiao Y, Yi Y: Effects of magnetic field on catalase and peroxidase activities in brown earth. J Shenyang Agric Univ 2007,38(1):70–74.Google Scholar
  25. Liu XY, Yi YL, Xia LH: Effect of magnetic field on enzyme activities in main soils of Northeast China. Pedosphere 1996,6(4):341–348.Google Scholar
  26. Liu YH, Xu LH, Tang X: The Effect of Magnetic Field Treatment on Artificially Aging Pepper Seeds. J Shandong Inst Build Mat 2003,17(3):286–288.Google Scholar
  27. Mao N, Huang Y, Zhang Z: Study on Biological Effect of Magnetic Resonance and Magnetized Water on Agricus bisporus Strain 176. J Fujian Teachers Univ (Nat Sci) 2002,18(3):61–65.Google Scholar
  28. Marschner H: Mineral Nutrition of Higher Plants. Academic Press Limited, San Diego, London; 1995.Google Scholar
  29. Mavingui P, Heulin T: In vitro chitinase antifungal activity of a soil, rhizosphere and rhizoplane populations of Bacillus polymyxa . Soil Biol Biochem 1994, 26: 801–803. 10.1016/0038-0717(94)90277-1View ArticleGoogle Scholar
  30. McSpadden Gardener BB: Ecology of Bacillus and Paenibacillus spp. in Agricultural Systems. Phytopathology 2004, 94: 1252–1258. 10.1094/PHYTO.2004.94.11.1252View ArticlePubMedGoogle Scholar
  31. Mohamed AA, Ali FM, Gaafar EA, Magda HR (1997) Effects of magnetic field on the biophysical, biochemical properties and biological activity of Salmonella typhi., Master thesis submitted for Biophysics department, Faculty of science, Cairo University, Egypt.
  32. Montes MJ, Mercade E, Bozal N, Guinea J: Paenibacillus antarcticus sp. nov., a novel psychrotolerant organism from the Antarctic environment. Int J Syst Evol Microbiol 2004, 54: 1521–1526. 10.1099/ijs.0.63078-0View ArticlePubMedGoogle Scholar
  33. Ouyang J, Pei Z, Lutwick L, Dalal S, Yang L, Cassai N, Sandhu K, Hanna B, Wieczorek RL, Bluth M, Pincus MR: Case report: Paenibacillus thiaminolyticus : a new cause of human infection, inducing bacteremia in a patient on hemodialysis. Ann Clin Lab Sci 2008, 38: 393–400.PubMed CentralPubMedGoogle Scholar
  34. Owen AG, Jones DL: Competition for amino acids between wheat roots and rhizosphere microorganisms and the role of amino acids in plant N acquisition. Soil Biol Biochem 2001, 33: 651–657. 10.1016/S0038-0717(00)00209-1View ArticleGoogle Scholar
  35. Pires MN, Seldin L: Evaluation of Biology system for identification of strains of Paenibacillus azotofixans . Ant Van Leeu 1997, 71: 195–200. 10.1023/A:1000128314946View ArticleGoogle Scholar
  36. Santos R, Herouart D, Sigaud S, Touati D, Puppo A: Oxidative burst in alfalfa-Sinorhisobium meltloti symbiotic interaction. Mol Plant Micobe Interact 2001,14(1):86–89. 10.1094/MPMI.2001.14.1.86View ArticleGoogle Scholar
  37. Sawada H, Kuykendall LD, Young JM: Changing concepts in the systematics of bacterial nitrogen-fixing legume symbionts. J Gen Appl Microbiol 2003,49(3):155–79. 10.2323/jgam.49.155View ArticlePubMedGoogle Scholar
  38. Sierra S, Rodelas B, Martinez-Toledo MV, Pozo C, González-López J: Production of B-group vitamins by two Rhizobium stains in chemically defined media. J Appl Microbiol 1999, 86: 851–858. 10.1046/j.1365-2672.1999.00765.xView ArticleGoogle Scholar
  39. Vincent JM: A Manual for the Practical Study of Root-Nodule Bacteria. Blackwell Scientific, Oxford; 1970.Google Scholar
  40. Von der Weid I, Alviano DS, Santos ALS, Soares RMA, Alviano CS, Seldin L: Antimicrobial activity of Paenibacillus peoriae against a broad spectrum of phytopathogenic bacteria and fungi. J Appl Microbiol 2003, 95: 1143–1151. 10.1046/j.1365-2672.2003.02097.xView ArticlePubMedGoogle Scholar
  41. Yan L, Zhu Y, He S, Cao Z: Effect of static magnetic field on activity of immobilized a-amylase. Chinese Sci Bull 1997,42(2):127–130. 10.1007/BF03182784View ArticleGoogle Scholar
  42. Zhu Y, Zhong K, He S: Efect of Magnetic Field on Activity of Immobilized LDH. J Hunan Univ 1996,23(5):57–61.Google Scholar

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This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited.