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Biodegradation of spent engine oil by bacteria isolated from the rhizosphere of legumes grown in contaminated soil  [PDF]
HY Ismail,UJJ Ijah,ML Riskuwa,II Allamin
International Journal of Environment , 2014, DOI: 10.3126/ije.v3i2.10515
Abstract: Biodegradation of spent engine oil (SEO) by bacteria isolated from the rhizosphere of Cajan cajan and Lablab purpureus was investigated. It was with a view to determining most efficient bacterial species that could degrade SEO in phytoremediation studies. Hydrocarbon degrading bacteria were isolated and identified by enrichment culture technique using oil agar supplemented with 0.1% v/v SEO. Total heterotrophic and oil utilizing bacterial count showed the occurrence of large number of bacteria predominantly in the rhizosphere soil, ranging between 54×10 8 - 144×10 8 CFU/g and 4×10 8 - 96×10 8 CFU/g respectively. Percentage of oil utilizing bacteria ranged between 0% (uncontaminated non rhizosphere soil) to 76% (contaminated rhizosphere). Turbidimetrically, five bacterial species namely Pseudomonas putrefacience CR33, Klebsiella pneumonia CR23, Pseudomonas alcaligenes LR14, Klebsiella aerogenes CR21, and Bacillus coagulans CR31 were shown to grow maximally and degraded the oil at the rate of 68%, 62%, 59%, 58%and 45% respectively. Chromatographic analysis using GC-MS showed the presence of lower molecular weight hydrocarbons in the residual oil (indicating degradation) after 21 days, whereas the undegraded oil (control) had higher molecular weight hydrocarbons after the same period. The species isolated were shown to have high ability of SEO biodegradation and therefore could be important tools in ameliorating SEO contaminated soil. DOI: http://dx.doi.org/10.3126/ije.v3i2.10515 International Journal of the Environment Vol.3(2) 2014: 63-75
The effect of rhizosphere on growth of Sphingomonas chlorophenolica ATCC 39723 during pentachlorophenol (PCP) biodegradation in batch culture and soil
Rosemeri Inês Dams,Graeme Paton,Ken Killhan
Biotemas , 2006,
Abstract: Studies on the influence of the rhizosphere on the growth of Sphingomonas chlorophenolica during Pentacholophenol (PCP) degradation in batch culture and in soil were carried out. In batch culture, a basal minimal medium with or without rhizosphere exudates extracted from winter wheat was used. In soil systems, degradation experiments were performed in the presence and absence of plants. Measurements of PCP concentrations were made using high performance liquid chromatography analysis (HPLC). Bacterial analyses of S. chlorophenolica were carried out by plating on MSM medium. The results showed that the rhizosphere exudates stimulated the growth of the cells of S. chlorophenolica at concentrations of 50 and 80mg kg dry wt soil –1 as well as stimulating the ability of S. chlorophenolica to degrade PCP at a concentration of 80mg Kg dry wt soil -1. In addition, pentachlorophenol had an adverse effect on the growth of S. chlorophenolica. The introduction of S.chlorophenolica into the loamy soil with plants showed a faster degradation when compared to the inoculated soil without plants. There was a significant increase of S. chlorophenolica in the roots in comparison to those in the soil. This study showed that the presence of the inoculum S. chlorophenolica enhanced the PCP degradation in a loamy soil and it indicates the potential for a treatment process under a appropriate environmental conditions such as there present in soil systems.
Quality control of culture media in a microbiology laboratory
Basu S,Pal A,Desai P
Indian Journal of Medical Microbiology , 2005,
Abstract: The nature of reporting of a microbiology laboratory depends upon the quality of the culture media used. Quality of media directly affects the observations and inferences drawn from the cultural characteristics of microorganisms. Checking of different parameters of media such as growth supporting characteristics, physical characteristics, gel strength and batch contamination can help to assess their quality. There are different methods to check all these parameters systematically. The meticulous performance of quality control of culture media can assure precision in reporting.
Comparison of Rhizosphere Microorganisms Between Fusarium Wilt Resistant and Susceptible Watermelon

LEI Juan-Li,SHOU Wei-Song,DONG Wen-Qi,XU Zhi-Hao,

微生物学通报 , 2008,
Abstract: In this paper, the number of rhizosphere and non-rhizosphere microbial organisms of fusarium wilt resistant and susceptible watermelon under soil culture and soilless substrate culture were was studied by traditional culture methods. The results showed that, the number of rhizoshpere microbial organisms is was significantly higher than non-rhizosphere, and the number is was changed with the stage of watermelon grow, the number is was the lowest in seedling stage and increased with the watermelon grow, and achieved highest at the flowering and fruiting stage, decreased with the watermelon ageing. The fusarium wilt resistant of watermelon is was correspondence with number of rhizosphere bacteria; the number of rhizosphere bacteria of resistant watermelon is was higher than that of susceptible watermelon in each stage under soil culture and soilless culture. The fusarium wilt resistant of watermelon is no correspondence with number of rhizosphere fungi and actinomycete. The number of non-rhizosphere microbial organisms is was changed in a small range in the whole growing stage. The non-rhizosphere bacteria have no significant change in the whole stage under soil culture and increased quickly under soilless substrate culture and decreased at the later stage. The non-rhizosphere fungi and actinomycete reached highest at the later stage under soil culture or soilless substrate culture.
Microbial Growth and Carbon Use Efficiency in the Rhizosphere and Root-Free Soil  [PDF]
Evgenia Blagodatskaya, Sergey Blagodatsky, Traute-Heidi Anderson, Yakov Kuzyakov
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0093282
Abstract: Plant-microbial interactions alter C and N balance in the rhizosphere and affect the microbial carbon use efficiency (CUE)–the fundamental characteristic of microbial metabolism. Estimation of CUE in microbial hotspots with high dynamics of activity and changes of microbial physiological state from dormancy to activity is a challenge in soil microbiology. We analyzed respiratory activity, microbial DNA content and CUE by manipulation the C and nutrients availability in the soil under Beta vulgaris. All measurements were done in root-free and rhizosphere soil under steady-state conditions and during microbial growth induced by addition of glucose. Microorganisms in the rhizosphere and root-free soil differed in their CUE dynamics due to varying time delays between respiration burst and DNA increase. Constant CUE in an exponentially-growing microbial community in rhizosphere demonstrated the balanced growth. In contrast, the CUE in the root-free soil increased more than three times at the end of exponential growth and was 1.5 times higher than in the rhizosphere. Plants alter the dynamics of microbial CUE by balancing the catabolic and anabolic processes, which were decoupled in the root-free soil. The effects of N and C availability on CUE in rhizosphere and root-free soil are discussed.
Effect of nitrogen form and pH of nutrient solution on the changes in pH and EC of spinach rhizosphere in hydroponic culture  [cached]
N. Najafi,M. Parsazadeh
Journal of Science and Technology of Greenhouse Culture , 2011,
Abstract: In this study, the effect of nitrate to ammonium ratio and pH of nutrient solution on the changes in pH and EC of rhizosphere during spinach growth period in perlite culture, under greenhouse conditions, was investigated. A split factorial experiment in a completely randomized design with four replications was conducted with three factors including nutrient solution’s pH in three levels (4.5, 6.5 and 8), nitrate to ammonium ratio of nutrient solution in five levels (100:0, 75:25, 50:50, 25:75 and 0:100) and 10 levels of time. Three seedlings of spinach plant (Spinacia oleracea L. cv. Sirius) were cultivated per pot and nourished with 15 different nutrient solutions. During the growth period and at different times, the leachate pH and EC of cultivated and uncultivated pots were measured. The results showed that the effects of time, pH and nitrate to ammonium ratio of nutrient solution on pH and EC of rhizosphere were significant (P<0.001). By increasing the nitrate to ammonium ratio of nutrient solution, the pH of rhizosphere was increased but the EC of rhizosphere was decreased. At the end of the growth period, the pH of rhizosphere in the nitrate to ammonium ratio of 100:0 was about three units higher than the nitrate to ammonium ratio of 0:100 and two pH of 4.5 and 8. While, this difference was lower at the pH of 6.5. During the spinach plant growth period, the changes in pH and EC of rhizosphere in studied treatments were different. In the nitrate to ammonium ratio of 75:25 and pH of 6.5, the pH of rhizosphere was in the optimum range for plant growth and nutrients uptake. Except in the nitrate to ammonium ratio of 100:0 and pH of 8, in the rest of the treatments, the rhizosphere pH decreased during plant growth period. The initial pH of nutrient solution had different effects on the rhizosphere pH. The average rhizosphere pH in nutrient solutions with pH of 4.5, 6.5 and 8 was 5.94, 6.5 and 7.29, respectively. The results showed that in adaptation to adverse acidic or alkaline conditions, the spinach plant changes its rhizosphere pH actively. Also, undesirable effects of pH on the spinach growth in adverse acidic or alkaline conditions can be decreased with application of proper nitrate to ammonium ratio. The rhizosphere EC was more than the leachate EC of uncultivated pots and the initial EC of nutrient solution. By decreasing the pH of nutrient solution, the rhizosphere EC of spinach was increased.
Corporate culture and participation: Independent constructs?  [cached]
A. Odendaal,G. Roodt
South African Journal of Industrial Psychology , 1998, DOI: 10.4102/sajip.v24i3.657
Abstract: The objective of this study was to determine whether participative management and corporate culture are mutually exclusive (independent) concepts. The Human Sciences Research Council (HSRC) used an organisational climate and culture questionnaire and applied it to the test sample of 2 357 personnel from a population of 23 564 people working for a paramilitary organisation. The data set of the HSRC was used for the purpose of this study. A panel of experts identified the items in the questionnaire which related to participation according to predetermined criteria and the remaining items were applicable to corporate culture. The results of the factor and item analyses indicate that participative management and corporate culture, as perceived by workers and management, were interrelated and were not independent concepts as conceptualised by the experts. Opsomming Die doel van hierdie studie is om te bepaal of deelnemende bestuur en korporatiewe kultuur onderling uitsluitende (onafhanklike) konsepte is. Die Raad vir Geesteswetenskaplike Navorsing (RGN) het 'n kultuur- en klimaatvraelys op 'n steekproef van 2 357 respondente, vanuit 'n populasie van 23 564 persone wat werksaam is in 'n para-militere instansie, toegepas. Die datastel van die RGN is vir die doel van hierdie studie gebruik. 'n Paneel deskundiges het dimensies wat op deelname betrekking het geidentifiseer aan die hand van voorafbepaalde kriteria en die oorblywende items was op kultuur van toepassing. Die resultate van die faktor- en itemontledings het bevind dat deelnemende bestuur en korporatiewe kultuur, soos bestudeer vanuit die persepsies van werknemers en bestuur, oorwegend 'n gemeenskaplike eienskap meet en nie onafhanklike konstrukte is soos wel gekonseptualiseer deur deskundiges nie.
Cadmium uptake and speciation changes in the rhizosphere of cadmium accumulator and non-accumulator oilseed rape varieties

SU Dechun,XING Jianping,JIAO Weiping,WONG Woonchung,

环境科学学报(英文版) , 2009,
Abstract: Characteristics of cadmium (Cd) uptake kinetics and distribution of Cd speciation in the rhizosphere for Cd accumulator and non-accumulator oilseed rape varieties were investigated under nutrient solution and rhizobox soil culture conditions. The results showed that the maximal influx (Vmax) for Cd2+ andKm were significantly different for the two oilseed rape varieties. The value of Vmax for Cd accumulator oilseed rape Zhucang Huazi was two-fold greater than that for oilseed rape Chuan you II-93. The exchangeable Cd concentration in the rhizosphere was significantly lower than in non-rhizospheric soils supplemented with CdSO4 for both the varieties. Carbonate-bound Cd in the rhizosphere of Cd accumulator oilseed rape was significantly higher than that in the rhizosphere of non-accumulator oilseed rape and non-rhizospheric soil. Cd accumulator oilseed rape had a higher Cd2+ affinity and more ability to uptake insoluble Cd in the soil than the non-accumulator oilseed rape.
Altitudinal Variation in Azospirillum Species Collected from the Rhizosphere and Roots of Zea mays (L.)  [PDF]
Asghari Bano
Asian Journal of Plant Sciences , 2006,
Abstract: The rhizosphere soil and roots of maize (Zea mays L.) plants were collected from plain land of Islamabad, from Durgai and from the Shringal Campus of Malakand University. Azospirillum was isolated, identified and characterized by physiological and biochemical tests using QTS (Quick Testing System) miniatured identification system from the 24 h old bacterial culture grown on Lb (liquid broth) and NFM (nitrogen free medium) suspended in saline solution. The rhizosphere and roots of maize plants collected from plain land of Islamabad at the altitude of 800 m contained Azospirillum lipoferum whereas both the roots and rhizosphere of maize plants collected from Durgai at the altitude of 3500 m and Shringal campus of Malakand University at the altitude of 4000 m contained Azospirillum brasilense.
SVARAP and aSVARAP: simple tools for quantitative analysis of nucleotide and amino acid variability and primer selection for clinical microbiology
Philippe Colson, Catherine Tamalet, Didier Raoult
BMC Microbiology , 2006, DOI: 10.1186/1471-2180-6-21
Abstract: We first tested SVARAP to improve a strategy of identification of streptococci species of the Viridans Group targeting the groESL gene. Two regions with <500 nucleotides were identified, one being significantly more discriminant than one of a similar length used in a previous study (mean number of nucleotide differences between species, 113 (range: 12–193) vs. 77 (range: 14–109); p < 10-3). Secondly, aSVARAP was tested on reverse transcriptase (RT) sequences from 129 HIV-1 clinical strains to identify natural polymorphisms and drug-selected mutations emerging under nucleoside RT inhibitor (NRTI)-selective pressure. It revealed eleven of the 18 RT mutations considered in a reference HIV-1 genotypic NRTI-resistance interpretation algorithm.SVARAP and aSVARAP are simple, versatile and helpful tools for analysis of sequence variability, and are currently being used in real practice in our clinical microbiology laboratory.Sequence variability is a major parameter when designing primers and probes for a new PCR assay, even if various other factors such as string-based alignment scores, melting temperature, primer length and GC contents are also critical [1]. Indeed, nucleotide primers are designed to specifically target a nucleotide region that must be conserved as much as possible in order to ensure their hybridization. Conversely, when nucleotide sequences are used to identify or classify strains, the amplified and then sequenced region has to be divergent enough for discrimination. Variability is also a very informative property of nucleotide and protein sequences. For instance, it may indicate if a region is targeted or not by a given selective pressure or if mutations are occurring under drug-selective pressure.The analysis of the variability of a genetic or protein region is generally impractical, exacting, and based upon non-objective criteria when performed visually from a multiple sequence alignment. Difficulties are compounded by the length of sequences and thei
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