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1.
Singh RK Mishra RP Jaiswal HK Kumar V Pandey SP Rao SB Annapurna K 《Current microbiology》2006,52(2):117-122
Three novel endophytic rhizobial strains (RRE3, RRE5, and RRE6) were isolated from naturally growing surface sterilized rice
roots. These isolates had the ability to nodulate common bean (Phaseolus vulgaris). Polymerase chain reaction–restriction fragment length polymorphism and sequencing of 16S rDNA of these isolates revealed
that RRE3 and RRE5 are phylogenetically very close to Burkholderia cepacia complex, whereas RRE6 has affinity with Rhizobium leguminosarum bv. phaseoli. Plant infection test using gusA reporter gene tagged construct of these isolates indicated that bacterial cells can go inside and colonize the rice root
interiors. A significant increase in biomass and grain yield was also recorded in greenhouse-grown rice plants inoculated
with these isolates. 相似文献
2.
Qualitative and quantitative estimation of phenolic compounds was done through reverse phase–high performance liquid chromatography
(RP-HPLC) from different parts (leaf, stem, and root) of rice plants after inoculation with two rhizobial strains, RRE6 (Rhizobium leguminosarum bv. phaseoli) and ANU 843 (R. leguminosarum bv. trifolii) and infection by Rhizoctonia solani. On the basis of their retention time, the major phenolic acids detected in HPLC analysis were gallic, tannic, ferulic, and
cinnamic acids. Furthermore, in all Rhizobium-inoculated rice plants, synthesis of phenolic compounds was more consistently enhanced than in control (uninoculated plants),
where the maximum accumulation of phenolic compounds was observed in plants inoculated with RRE6 and infection with R. solani. Under pathogenic stress, RRE6 performed better because a relatively higher amount of phenolics was induced as compared with
plants treated with ANU 843. Phenolic acids mediate induced systemic resistance and provide bioprotection to plants during
pathogenic stresses. In addition, both rhizobial strains promote growth and productivity of rice plants in greenhouse conditions.
This report on Rhizobium-mediated defense responses and growth promotion of nonlegume (such as rice) provides a novel paradigm of symbiotic plant–microbe
interaction. 相似文献
3.
Comparative mapping of the wheat chromosome 5A Vrn-A1 region with rice and its relationship to QTL for flowering time 总被引:3,自引:0,他引:3
R. N. Sarma B. S. Gill T. Sasaki G. Galiba J. Sutka D. A. Laurie J. W. Snape 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,97(1-2):103-109
The vernalization gene Vrn-A1 on chromosome 5A is the predominant gene determining the spring/winter habit difference in bread wheat. Vrn-A1 was physically mapped using a set of deletion lines which located it to the region of chromosome 5A flanked by deletion breakpoints
0.68 and 0.78. This interval was shown to be homoeologous to a region of rice chromosome 3 that contains the flowering-time
QTL Hd-6, previously mapped in a Nipponbare×Kasalath cross, and FLTQ1, a novel QTL identified by analysis of 78 F3 families derived from a cross of ‘IR20’ב63–83’. Possible relationships between Vrn-A1 and rice QTL are discussed. Analysis of the chromosome 5A deletion lines showed evidence for a second, more proximal flowering-time
effect located between deletion breakpoints 0.56 and 0.64. The proximal part of chromosome 5A is homoeologous to rice chromosome
9, on which two QTL were detected in the ‘IR20ב63–83’ cross. The possible relationship between these effects is also discussed.
Received: 23 December 1997 / Accepted: 12 January 1998 相似文献
4.
Rice blast, caused by the fungus Magnaporthe grisea, is a globally important disease of rice that causes annual yield losses. The segregation of genes controlling the virulence
of M. grisea on rice was studied to establish the genetic basis of cultivar specificity in the interaction of rice and M. grisea. The segregation of avirulence and virulence was studied in 87 M. grisea F1 progeny isolates from a cross of two isolates, Guy11 and JS153, using resistance-gene-differential rice cultivars. The segregation
ratio indicated that avirulence and virulence in the rice cultivars Aichi–asahi and K59, respectively, are controlled by single
major genes. Genetic analyses of backcrosses and full-sib crosses in these populations were also performed. The χ2 test of goodness-of-fitness for a 1:1 ratio indicated that one dominant gene controls avirulence in Aichi-asahi and K59 in
this population. Based on the resistance reactions of rice differential lines harboring known resistance genes to the parental
isolates, two genetically independent avirulence genes, AVR–Pit and AVR–Pia, were identified. Genetic linkage analysis showed that the SSR marker m355–356 is closely linked to AVR–Pit, on the telomere of chromosome 1 at a distance of approximately 2.3 cM. The RAPD marker S487, which was converted to a sequence-characterized
amplified region (SCAR) marker, was found to be closely linked to AVR–Pia, on the chromosome 7 telomere at a distance of 3.5 cM. These molecular markers will facilitate the positional cloning of
the two AVR genes, and can be applied to molecular-marker-assisted studies of M. grisea populations. 相似文献
5.
A total of 973 isolates of endophytic fungi were recovered from 1144 tissue fragments of the six medicinal plant species belonging
to 4 families collected in the Beijing Botanical Garden. Of these isolates 778 sporulated and were identified into 21 taxa
by morphological characteristics. Among the taxa 11 belonged to Coelomycetes, 6 to Ascomycetes, and 4 to Hyphomycetes. Various
numbers of endophytic fungi (5–8 taxa) were obtained from each plant. Alternaria alternata was the dominant species in the 6 plants, and Microsphaeropsis conielloides was also dominant in Eucommia ulmoides. There were high colonization rates (47.9%–63.1%) and isolation rates (0.7–0.93) of endophytic fungi, and they were conspicuously
higher in twigs than those in leaves in the 6 plants examined. The colonization and isolation rates of endophytic fungi increased
with the twig age. The results based on the analyses of cluster and Sorenson’s similarity coefficients indicated that some
endophytic fungi showed a certain degree of host and tissue preference. 相似文献
6.
A total of 973 isolates of endophytic fungi were recovered from 1144 tissue fragments of the six me-dicinal plant species belonging to 4 families collected in the Beijing Botanical Garden. Of these isolates 778 sporulated and were identified into 21 taxa by morphological characteristics. Among the taxa 11 belonged to Coelomycetes, 6 to Ascomycetes, and 4 to Hyphomycetes. Various numbers of endophytic fungi (5―8 taxa) were obtained from each plant. Alternaria alternata was the dominant species in the 6 plants, and Microsphaeropsis conielloides was also dominant in Eucommia ulmoides. There were high colonization rates (47.9%―63.1%) and isolation rates (0.7―0.93) of endophytic fungi, and they were conspicuously higher in twigs than those in leaves in the 6 plants examined. The colonization and isolation rates of endophytic fungi increased with the twig age. The results based on the analyses of cluster and Sorenson's similarity coefficients indicated that some endophytic fungi showed a certain degree of host and tissue preference. 相似文献
7.
A. Čížek M. Dolejská R. Karpíšková D. Dědičová I. Literák 《European Journal of Wildlife Research》2007,53(1):55-60
Salmonella were isolated from black-headed gulls (Larus ridibundus) in six locations in the Czech Republic from 1984 to 2005 (Chropyně and Nymburk in 1984–1986; Nové Mlyny, Bartošovice, and
Hodonín in 1991–1994; and Nové Mlyny, Bartošovice, and Ostrava in 2005). Antimicrobial susceptibility was determined in 12
antimicrobial drugs using disk diffusion. Although 95% of Salmonella isolates (197 out of 207) were pansusceptible, the prevalences of resistance increased significantly from 1 (2%) out of 59
isolates in 1984–1986 and 3 (3%) out of 100 isolates in 1991–1994 to 6 (13%) out of 48 isolates in 2005. Furthermore, in 2005,
two isolates were nalidixic acid-resistant and one isolate was multidrug-resistant Salmonella Typhimurium DT 104. These findings suggest that the occurrence of salmonellae in black-headed gulls depends to a large extent
on the contamination where the gulls feed and possibly reflects the dissemination of these strains among farm animals and
humans. Black-headed gulls may also become infected with resistant Salmonella and thus pose a potential risk of Salmonella contamination of surface water and animal feeds, and consequently dissemination. 相似文献
8.
Two extremely thermophilic archaebacteria, strains OG-1 and SM-2, were isolated from newly discovered deep-sea hydrothermal
vent areas in the western Pacific ocean. These strains were cocci, obligately anaerobic Archaea about 0.7–2 μm in diameter.
Optimum growth conditions for OG-1 and SM-2 were at 85–90°C (range 60–100°C), pH 6 (range pH 4–8), a NaCl concentration of
3% (range 1–5%), and a nutrient concentration (tryptone plus yeast extract) of 0.2% (range 0.005–5%). Elemental sulfur stimulated
the growth rate fourfold. Ammonium slightly stimulated growth. Both tryptone and yeast extract allowed growth as sole carbon
sources; these isolates were not able to utilize or grow exclusively on sucrose, glucose, maltose, succinate, pyruvate, propionate,
acetate, or free amino acids. OG-1 showed the fastest growth rate within the genus Thermococcus. Growth was inhibited by rifampicin. The DNA G+C content was 52 mol%. Sequencing of their 16S rDNA gene fragment indicated
that these isolates belonged to the genus Thermococcus. OG-1 and SM-2 were different than the described Thermococcus species. We propose that OG-1 belongs to a new species: Thermococcus peptonophilus.
Received: 8 March 1995 / Accepted: 24 May 1995 相似文献
9.
Fantin G Giovannini PP Guerrini A Maietti S Medici A Pedrini P 《Biotechnology letters》2006,28(11):805-810
Fungi from Amazonian forest soil (Ecuador) and an Italian factory were screened for Baeyer–Villiger (BV) oxidation of bicyclo
[3.2.0]hept-2-en-6-one to 2-oxabicyclo[3.3.0]oct-6-en-3-one (Corey’s lactone). Isolates of Fusarium sp. and F. solani produced the (+)-(1R,5S)-lactone while isolates of Aspergillus terricola and A. amazonicus afforded the (−)-(1S,5R)-lactone. Highest conversions (85% yield and 70% enantiomeric excess) were obtained with A. amazonicus grown in presence of 2.7 mM titanium dioxide. 相似文献
10.
Sudathip Titapoka Suttipun Keawsompong Dietmar Haltrich Sunee Nitisinprasert 《World journal of microbiology & biotechnology》2008,24(8):1425-1433
In order to select bacterial strains effectively secreting mannanase activity for the production of prebiotic mannooligosaccharides,
a two-step screening procedure was performed. Enriched cultures from isolation medium containing copra meal were primary screened
on an isolation agar medium containing 1% locust bean gum (LBG), which resulted in 48 mannanase-producing bacterial isolates
with significant clearing zones on the mannan-containing agar. However, only nine isolates showed appreciable mannanase activities
against copra meal in their culture supernatants (0.054–0.185 U/mg of protein) as determined in a standard assay based on
the detection of reducing sugars released from this substrate. The isolates CW2-3 and ST1-1 displayed the highest activity
against LBG and copra meal, respectively. Copra mannan hydrolysates that were obtained by using crude mannanase from these
nine isolates were further used for a secondary screening towards a growth-enhancing activity on Lactobacillus reuteri and inhibitory activity against Escherichia coli as well as Salmonella Enteritidis, resulting in 0.09–2.15 log CFU/ml enhancing activity and low inhibitory activity of 0.46–1.78 log CFU/ml as
well as 0.37–1.72 log CFU/ml, respectively. The hydrolysate of CW2-3 mannanase showed the highest enhancing activity of 2.15 log
CFU/ml while isolate ST1-1 was most effective with respect to growth inhibition against E. coli E010 and S. Enteritidis S003 with 0.76 and 1.61 log CFU/ml, respectively. Based on morphological, physical, biochemical and genetics
properties, isolates CW2-3 and ST1-1 were identified as Klebsiella oxytoca and Acinetobacter sp., respectively. Crude mannanase activity from these two strains was characterized preliminarily. The pH optima of mannanase
activity from Klebsiella oxytoca CW2-3 and Acinetobacter sp. ST1-1 were 7 and 6, respectively. The enzymes were stable at 4°C over a pH range of 3–6 and 3–10, respectively. 相似文献
11.
Selenium accumulation by sequentially grown wheat and rice as influenced by gypsum application in a seleniferous soil 总被引:2,自引:0,他引:2
A field experiment was conducted for 2 years on an alkaline calcareous seleniferous soil to study the effect of different
levels of gypsum (0.2 – 3.2 t ha−1) applied to wheat only in the first year on Se accumulation by wheat (Triticum aestivum L.) – rice (Oryza sativa L.) cropping sequence. With gypsum application, grain yield of both rice and wheat crops increased by 0.4 – 0.5 t ha−1; the increase in straw yield was 0.4 – 1.1 t ha−1. Significant reduction in Se accumulation by wheat was observed with gypsum application up to 0.8 t ha−1 and its residual effect was evident on the following crops for 2 years. Reduction in Se accumulation varied from 53 to 64%
in wheat grain, 46 to 49% in wheat straw, 35 to 63% in rice grain and 36 to 51% in rice straw with an application of gypsum
at 0.8 t ha−1. A corresponding increase in S concentration was observed. In the gypsum-treated plots, the ratio of S:Se increased by 6
– 8 times in wheat and 3 – 6 times in rice. Reduction in Se accumulation by crop plants through gypsum application may help
in lowering the risk of Se over-exposure of animals and humans that depend on diet materials grown on high selenium soils.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
12.
Heavy metal content analysis of River Torsa in India did not indicate any alarming level of toxicity for human consumption
but revealed variation at the ppb level in different months. The variation in recoverable nickel and zinc resistant copiotrophic
(or eutrophic) bacterial counts was explained by the variation of the zinc content (34.0–691.3 ppb) of the river water in
different sampling months. Growth studies conducted with some purified nickel and/or zinc resistant strains revealed that
pre-exposure of the cells to ppb levels of Zn2+, comparable to the indigenous zinc ion concentration of the river, could induce the nickel or zinc resistance. A minimum
concentration of 5–10 μM Zn2+ (325–650 ppb) was found effective in inducing the Nickel resistance of the isolates. Zinc resistance of the isolates was tested
by pre-exposing the cells to 4 μM Zn2+ (260 ppb). The lag phase was reduced by 6–8 h in all the cases. Biochemical characteristics and phylogenetic analysis based
on 16S rDNA sequence indicated that some of the Torsa River isolates, having inducible nickel and zinc resistance, are members
of the genus Pseudomonas, Acinetobacter, Bacillus, Enterobacter, Serratia and Moraxella. 相似文献
13.
Abbas HK Cartwright RD Xie W Mirocha CJ Richard JL Dvorak TJ Sciumbato GL Shier WT 《Mycopathologia》1999,147(2):97-104
Twenty samples of unpolished (rough) rice collected in Arkansas and Texas during the 1995 harvesting season from fields exhibiting
Fusarium sheath rot disease or panicle blight were previously shown to include 8 samples positive for fumonisin B1(FB1) in the range 2.2–5.2 ppm, and moniliformin (MON), but no beauvericin (BEA), deoxynivalenol, its derivatives or zearalenone
were detected. Fifteen cultures of F. proliferatum were established from the 20 rough rice samples. Single spore isolates of each culture were grown on rice and tested for
the production of fumonisins (FB1, FB2, FB3, etc.), MON and BEA. All 15 isolates produced FB1, FB2, MON and BEA in culture on rice. No deoxynivalenol, its derivatives orzearalenone were detected. Seven cultures produced
FB1 at >50ppm (range 80–230 ppm), with therest producing FB1 in the range 14–43 ppm.FB2 was produced in the range 5–47 ppm, and those cultures which produced the most FB1 also produced the most FB2. Of the 15 cultures producing MON, 11 produced it at >100 ppm in the range 188–6018 ppm, with the rest producing in the range
7–64 ppm. BEA was produced in the range 109–1350 ppm. Other derivatives of fumonisins, including FA1, FA2 and partially hydrolyzed FB1, as well asseveral unknown metabolites including a compound with MW 414, were identified in culture extracts by continuous
flow fast atom bombardment with ion spraymass spectrometry (CF/FAB/MS). Further study is needed to identify the factors that
control production of FB1, MON and BEA by F.proliferatu in culture and in field samples.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
14.
E. Huq S. Harrington M. A. Hossain F. Wen S. R. McCouch T. K. Hodges 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1999,98(5):815-824
The anaerobic fermentation pathway is thought to play an important role under flooding conditions. The pyruvate decarboxylase
2 (pdc2) gene that encodes the first enzyme of this pathway has been cloned and characterized from rice. This gene has an open reading
frame that putatively encodes a 603 amino-acid-residue protein with a molecular mass of 64 kDa. pdc2 has five introns dispersed throughout the coding region, which is also true for rice pdc1. Although the length of these introns in rice pdc2 are different from those in rice pdc1, they are located in exactly the same positions based on the deduced amino-acid sequences. The temporal and spatial expression
patterns of pdc1 and pdc2 show that pdc2 is induced to a higher level during the early period (1.5–12 h) of anoxia than pdc1, which is induced more after longer time periods (24–72 h) of anoxia in both shoots and roots. The map positions of the three
pdc genes have also been determined. Rice pdc1 is located on chromosome 5 between BCD454A and RZ67, pdc2 is located on chromosome 3 between RZ329 and RZ313, and pdc3 is mapped on chromosome 7 distal to RG351.
Received: 19 May 1998 / Accepted: 29 September 1998 相似文献
15.
Subramaniam Gopalakrishnan Pagidi Humayun Bandru Keerthi Kiran Iyer Girish Kumar Kannan Meesala Sree Vidya Kanala Deepthi Om Rupela 《World journal of microbiology & biotechnology》2011,27(6):1313-1321
A total of 360 bacteria, isolated from the rhizospheres of a system of rice intensification (SRI) fields, were characterized
for the production of siderophore, fluorescence, indole acetic acid (IAA), hydrocyanic acid (HCN) and solubilization of phosphorus.
Of them, seven most promising isolates (SRI-156, -158, -178, -211, -229, -305 and -360) were screened for their antagonistic
potential against Macrophomina phaseolina (causes charcoal rot in sorghum) by dual culture assay, blotter paper assay and in greenhouse. All the seven isolates inhibited
M. phaseolina in dual culture assay, whereas six isolates solubilized phosphorous (except SRI-360), all seven produced siderophore, four
produced fluorescence (except SRI-178, -229 and -305), six produced IAA (except SRI-305) and five produced HCN (except SRI-158
and -305). In the blotter paper assay, no charcoal rot infection was observed in SRI-156-treated sorghum roots, indicating
complete inhibition of the pathogen, while the roots treated with the other isolates showed 49–76% lesser charcoal rot infection
compared to the control. In the antifungal activity test (in green house on sorghum), all the isolates increased shoot dry
mass by 15–23% and root dry mass by 15–20% (except SRI-158 and -360), over the control. In order to confirm the plant growth-promoting
(PGP) traits of the isolates, the green house experiment was repeated but, in the absence of M. phaseolina. The results further confirmed the PGP traits of the isolates as evidenced by increases in shoot and root dry mass, 22–100%
and 5–20%, respectively, over the control. The sequences of 16S rDNA gene of the isolates SRI-156, -158, -178, -211, -229,
-305 and -360 were matched with Pseudomonas
plecoglossicida, Brevibacterium antiquum, Bacillus altitudinis, Enterobacter ludwigii, E. ludwigii, Acinetobacter tandoii and P. monteilii, respectively in BLAST analysis. This study indicates that the selected bacterial isolates have the potential for PGP and
control of charcoal rot disease in sorghum. 相似文献
16.
Duckworth AW Grant WD Jones BE Meijer D Márquez MC Ventosa A 《Extremophiles : life under extreme conditions》2000,4(1):53-60
A number of novel alkaliphilic organotrophic bacteria have been isolated from several saline and alkaline East African soda
lakes. The new isolates grow at pH values between 7.0 and 11.0, with pH optima for growth between 9.0 and 10.0. Growth occurs
at total salts concentration between 0% and 20% (w/v) with optimum at 0%–7% (w/v). Phylogenetic analyses based on 16S rDNA
sequence comparison indicate that these isolates are related (>96% similarity) to members of the Halomonadaceae within the γ-3 subdivision of the Proteobacteria. These analyses indicate that existing species within the Halomonadaceae fell within three main groups, one group comprising the type species of Halomonas, Halomonas elongata, and a number of other known species including one soda lake isolate. A second group constituting most of the remaining known
species of Halomonas and related Chromohalobacter spp. includes 3 soda lake isolates with high DNA–DNA homologies. The third group included Halomonas halodenitrificans, Halomonas desiderata, Halomonas cupida, and 13 soda lake isolates. Phenotypic comparisons indicated that the majority of soda lake strains shared similar morphological,
phenotypic, and chemotaxonomic properties to known strains of Halomonas but grew under alkaline conditions. The 3 soda lake isolates with high DNA–DNA homologies were, however, significantly different
in antibiotic sensitivity pattern and in the utilization of several substrates, were unable to reduce nitrite, and showed
low DNA–DNA homologies with known halomonads in the same group. We propose that these isolates comprise a new species of the
genus Halomonas that we name Halomonas magadii sp. nov. The type strain is strain 21 MI (NCIMB 13595).
Received: July 20, 1999 / Accepted: October 29, 1999 相似文献
17.
Guohua Yang Sansi Tu Shaoqing Li Lingling Feng Jin Kong Hui Li Yangsheng Li 《Frontiers of Biology in China》2008,3(4):443-448
A population of 117 doubled haploid (DH) lines derived from the cross of Zhaiyeqing 8 (indica)× Jingxi 17 (japonica) was employed to map quantitative trait loci (QTL) underlying four physiological traits related to chlorophyll contents of
the flag leaf. There were significantly positive correlations among chlorophyll a, chlorophyll b and chlorophyll a + b content.
Chlorophyll a/b ratio was significantly negatively correlated with chlorophyll b content. These four traits were normally
distributed with transgressive segregation, suggesting that they were controlled by multiple minor genes. A total of 11 QTLs
were detected for the four traits and they lay on six chromosomes. Each of them explained 9.2%–19.6% of the phenotypic variations,
respectively. Of these, two QTLs controlling chlorophyll a content were mapped on chromosomes 2 and 5; four QTLs underlying
chlorophyll b content were mapped on chromosomes 2, 3, 5 and 9; three QTLs underlying chlorophyll a + b amount were mapped
on chromosomes 3, 5 and 9; two QTLs underlying chlorophyll a/b ratio were mapped on chromosomes 6 and 11. The intrinsic relationship
among the four traits and the practical implication in rice breeding are discussed.
__________
Translated from Journal of Wuhan University (Science Edition), 2006, 52(6): 751–756 [译自: 武汉大学学报(理学版)] 相似文献
18.
Mathurot Chaiharn Saisamorn Lumyong 《World journal of microbiology & biotechnology》2009,25(2):305-314
Plant growth-promoting rhizobacteria (PGPR) are known to influence plant growth by various direct or indirect mechanisms.
A total of 216 phosphate-solubilizing bacterial isolates were isolated from different rice rhizospheric soil in Northern Thailand.
These isolate were screened in vitro for their plant growth-promoting activities such as solubilization of inorganic phosphate,
ammonia (NH3), catalase and cell wall-degrading enzyme activity. It was found that 100% solubilized inorganic phosphate, 77.77% produced
NH3 and most of the isolates were positive for catalase. In addition, some strains also produced cell wall-degrading enzymes
such as protease (7%), chitinase (1%), cellulase (3%) and β-glucanase (3%), as evidenced by phenotypic biochemical test and quantitative assay using spectrophotometry. The isolates
could exhibit more than two or three plant growth-promoting (PGP) traits, which may promote plant growth directly or indirectly
or synergistically. Part of this study focused on the effect of NaCl, temperature, and pH on a specific the bacterial isolate
Acinetobacter CR 1.8. Strain CR 1.8 was able to grow on up to 25% NaCl, between 25 and 55°C, and at pH 5–9. Maximum solubilization of tricalcium
phosphate and aluminium phosphate was obtained at neutral pH, and 37°C. Strain CR 1.8 had protease activity but no cellulase,
β-glucanase and cellulase activities. 相似文献
19.
Enrichment-based methods targeted at uranium-tolerant populations among the culturable, aerobic, chemo-heterotrophic bacteria
from the subsurface soils of Domiasiat (India’s largest sandstone-type uranium deposits, containing an average ore grade of
0.1 % U3O8), indicated a wide occurrence of Serratia marcescens. Five representative S. marcescens isolates were characterized by a polyphasic taxonomic approach. The phylogenetic analyses of 16S rRNA gene sequences showed
their relatedness to S. marcescens ATCC 13880 (≥99.4% similarity). Biochemical characteristics and random amplified polymorphic DNA profiles revealed significant
differences among the representative isolates and the type strain as well. The minimum inhibitory concentration for uranium
U(VI) exhibited by these natural isolates was found to range from 3.5–4.0 mM. On evaluation for their uranyl adsorption properties,
it was found that all these isolates were able to remove nearly 90–92% (21–22 mg/L) and 60–70% (285–335 mg/L) of U(VI) on
being challenged with 100 μM (23.8 mg/L) and 2 mM (476 mg/L) uranyl nitrate solutions, respectively, at pH 3.5 within 10 min
of exposure. his capacity was retained by the isolates even after 24 h of incubation. Viability tests confirmed the tolerance
of these isolates to toxic concentrations of soluble uranium U(VI) at pH 3.5. This is among the first studies to report uranium-tolerant
aerobic chemoheterotrophs obtained from the pristine uranium ore-bearing site of Domiasiat. 相似文献
20.
Population ( × 107 c.f.u./g dr. soil) of the aerobic (30.5–154.1) and anaerobic (5.9–91.4) heterotrophic, aerobic (24.0–56.0) and anaerobic (2.4–4.2)
spore forming, Gram (-)ve (1.6–2.9), phosphate solubilizing (10–20), asymbiotic N2-fixing (0.5–0.9), sulfur oxidizing (1.1–2.0), nitrifying (1.0–5.8) and denitrifying (12.1–18.7) bacteria; as well as, the
actinomycetes (about 104 c.f.u./g dr. soil) and fungi (about 105 c.f.u./g dr. soil) were variable in the partially anaerobic, saline and drain out flooded rice soils during the post harvest
period of the Himalayan, brackish water flooded, island and coastal habitats of India. The aerobic heterotrophic and spore
forming bacteria were more than the anaerobic counterparts in the soils. Population (0.51–3.51 × 106 c.f.u./g dr. soil) and crystal morphotype (spherical, bipyramidal and polymorphic) of the Bacillus thuringiensis (Bt) isolates of different soils were variable. Bt index was 0.002 at Mahe but 0.006 in other soils. The Bt isolates tolerated
5–12% NaCl. The osmolytes (mg/g dr. wt.) like the amino acids (0.38–99.45) and proline (0.38–0.80); and the antioxidative
enzymes (units (U)/mg protein/min) viz. the catalase (0.17–5.59) and superoxide dismutase (0.35–74.46) were related with intrinsic
osmotic stress tolerance of the Bt but they formed spores to overcome anoxic stress. Two Bt isolates were potent tolerant
to both osmotic and anoxic stresses. 相似文献