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5176 Afr. J. Microbiol. Res. Table 2. Optimization of carbon and nitrogen sources of MSM for biosurfactant production by S. koreensis. Nitrogen source Surface tension reduction (dynes/cm) Glucose Mannitol (NH4)2SO4 31.2 29.4 KNO3 34.6 29.2 NH4NO3 21.4 24.7 NH4H2PO4 19.4 20. 2 Time (h) Figure 2. The efficiency of removal of lead Time and (h) cadmium by S. koreensis. temperature of 37°C and pH 6 were found to yield maximal levels of biosurfactant. The time required for complete emulsification of the added oils and to lower the surface tension of the production medium (MSM) was 24 to 30 h. The surface tension remained more or less the same for several days once the critical micelle concentration is attained. Using the Placket and Burman design for media optimization, it could be concluded that MgSO4 and KH2PO4 were the very critical factors that affected biosurfactant production. Thus, the enrichment and screening program on the first place and subsequently the media optimization step have been useful for obtaining more efficient organisms that could be valuable for large-scale industrial applications. Moreover, it was possible to obtain a novel strain of S. koreensis that had a high efficiency of reducing the surface tension of liquids (Table 2). Determination of lead and cadmium tolerance for S. koreensis by Kirby-Bauer method and metal removal studies In the present experiments, lead and cadmium were chosen for heavy metal removal studies due to the following reasons: (i) ease of availability of the metal salts, (ii) availability of sensitive atomic absorption spectrophotometric method for estimations (iii) huge data available on removal and recovery of these metals from solutions, (iv) large scale use of these metals in industries (viz. batteries, cable coverings, plumbing, fuel, paints, PVC plastic, pencils, pesticides, alloys for lead and Ni-Cd batteries, coating, pigments, fertilizers for cadmium) that raises environmental concerns about heavy metal pollution, (v) major toxic effects of these metals on living cells, (vi) reports on rhamnolipid (a type of biosurfactant) interactions specifically with lead and cadmium and use of the interactions to eliminate cadmium toxicity (Desai et al., 1994; Franzetti et al., 2010; Mulligan, 2005). It was found that the isolates obtained in the present studies were tolerant to high metal concentrations of 200 ppm. This resistance could be attributed to the presence of biosurfactant that could effectively complex with the metal ions in solution. The biosurfactant might confer resistance by a complexation mechanism that removes ions from solution and thus keeping the toxic metal away from the bacterial cells (Banat et al., 2010; Mulligan, 2005; Sandrin et al., 2000; Zosim et al., 1983). It was observed that more than 30% of the metal ions were removed from the media (Figure 2). It is evident from Figure 3, that there was a huge reduction in the surface tension of the medium in 24 to 30
Figure 3. The correlation of reduction in surface tension and metal removal as a result of biosurfactant productionbyS. Koreensis. h after inoculation of the culture. This reduction is seen as a spurt of increase in the difference in surface tension of sample and control that is, Δ dyne/cm. The reduction in the surface tension was due to production of biosurfactant that also reduced metal concentration of the medium. Although the metal removal efficiency appears to be low, it must be mentioned that percentage figures are often misleading, since at lower metal concentrations the observed percent removal values could be greater (Paknikar et al., 1999). Moreover, at low metal concentrations, better growth of bacteria would result in higher biomass and biosurfactant yields, and hence better metal removal efficiencies. The concentrations of heavy metals in industrial effluents are often in the range of 10 to 50 ppm. At these lower concentrations, conventional physical and chemical methods of treatment do not work efficiently; whereas, biosurfactant-based method would work efficiently. Conclusion Time (days) A novel metal resistant bacterial culture capable of high biosurfactant activity was isolated from petroleum contaminated soil through a systematic screening program. The bacterial culture produced a biosurfactant rhamnolipid that proffers resistance to metals and was also responsible for removing metals from solutions. Due to the biodegradability and low toxicity, biosurfactants may have a promising future for use in remediation of metalliferous wastes. Considering these aspects, further research on purification and detailed characterization of the material using chromatographic techniques and instrumental analysis is being pursued in the laboratory. ACKNOWLEDGEMENTS Patil et al. 5177 The authors express deep sense of gratitude to late Dr. Vasantrao Pawar (Sarchitnis, Maratha Vidyaprasarak Samaj, Nashik) and Dr. V. B. Gaikwad (Principal, KTHM College, Nashik) for providing infrastructure, laboratory facilities and constant motivation. REFERENCES Banat IM, Franzetti A, Gandolfi I, Bestetti G, Martinotti MG, Fracchia L, Smyth TJ, Marchant R (2010). Microbial biosurfactant production, applications and future potential. Appl. Microbiol. Biotechnol., 87 : 427-444. Benincasa M, Contiero J, Manresa MA, Moraes IO (2001). Rhamnolipid production by Pseudomonas aeruginosa LBI growing on soapstock as the sole carbon source. J. Food Eng., 54 : 283-288. Bodour AA, Dress KP, Mair RM (2003). Distribution of Biosurfactant- Producing in Undisturbed and Contaminated Arid Southwestern soils. Appl. Environ. Microbiol., 30 : 3280-3287. Bodour AA, Miller-Maier RM (1998). Application of a modified dropcollapse technique for surfactant quantitation and screening of biosurfactant producing microorganism. Microbiol. Methods, 32 : 273–280. Bonglo G (1998). Biosurfactants as emulsifying agents for hydrocarbons. Colloidal Surf A: Physiochem Eng. Aspects, 152 : 41- 52. Bordoloi NK, Konwar BK (2007). Microbial Surfactant-enhanced mineral oil recovery under laboratory conditions. Colloids and surfaces B : Biointerfaces, 63 : 73-82. Bosch MP, Robert M, Mercade ME, Espuni MJ, Parra JL, Guinea J (1988). Surface active compounds on microbial cultures.Tenside surfactants Deterg., 25 : 208-211. Cha DK (2000). The effect of biosurfactant on the fate and transport of non-polar organic contaminants in porous media. Environ. Eng., 20: 1-17. Das K, Mukherjee AK (2007). Comparison of lipopeptide biosurfactant production by Bacillus subtilis strain in submerged and solid state fermentation system using a cheap carbon source: Some industrial
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African Journal of Microbiology Res
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Editors Prof. Dr. Stefan Schmidt Ap
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Electronic submission of manuscript
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Fees and Charges: Authors are requi
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nces Table of Contents: Volume 6 Nu
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Table of Contents: Volume 6 Number
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Table 1. Overview of the Soil prope
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exactly. MICROBIAL BIOMASS IN ORGAN
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Table 3. Advantages and disadvantag
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analysis of polymerase chain reacti
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Enzyme assay Triplicate samples of
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Figure 2. Effect of a) incubation t
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Table 2. Plasmid profile. Emerenini
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Table 1. Properties and identity of
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more understandable by the fact tha
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fertilizers considered the most imp
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Table 3. Effect of NPK levels and s
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Table 4. Effect of NPK levels and s
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Table 5. Effect of NPK levels and f
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with mineral NPK on wheat plant. Eg
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to synthetic antibiotics. In spite
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Among these, the K. pneumonia and V
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Figure 5. Pseudomonas aeruginosa An
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pathogens of their environment (She
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cultivable indigenous fishes of Ind
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Table 1. Oxidative stress parameter
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Page 85 and 86: Bacillus colony Fig 1. Colony morph
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Page 91 and 92: Figure 1. The Kinetic of P. aerugin
Page 93 and 94: Figure 3. DNA-dosimeter determined
Page 95 and 96: Relative Fluorescence Unit Figure 4
Page 97 and 98: Conclusion The public health risk i
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Page 105 and 106: Table 1. List of decamers used in R
Page 107 and 108: Figure 2. RAPD profile of Fusarium
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Page 127 and 128: protein. DISCUSSION 70 kda 60 kda 5
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Page 135 and 136: Table 1. Primers used for PCR and s
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Figure 6. Ghrelin expression induce
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Table 1. The SNPs related to the pr
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Figure 2. The phylogenetic trees of
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a c Rex DNA Tang et al. 5235 Figure
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Table 1. Gender and division wise d
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62% were genotype D, A (14%), C (6%
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Swimming time (s) 1000 800 600 400
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Hepatic glycogen (mg/g) Hemoglobin
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Table 2. Sporulation index. Sign In
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Table 4. Conidial size of different
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Table 6. Sporulation of Alternaria
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Table 7. Reaction of different geno
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Table 2. Susceptibility of the clin
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Table 4. Aminoglycoside resistance
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Young, and the Councils on Clinical
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oleaginous microorganisms have been
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Table 2. Actual and predicted value
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Table 4. Analysis of variance (ANOV
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Huang et al. 5273 Figure 3. Respons
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the Central Universities (Grant No.
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Figure 1. Mechanism of enzymatic co
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Enzymatic activity (U/mL) Enzymatic
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prunin so far. By using the HPLC me
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Figure 7. Enzymatic conversion of n
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vaccine, HBs-Ab is negative in all
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Conferences and Advert August 2012
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