Characterization of a Rhizobium larrymoorei FJ Exhibiting High Level Cr(VI) Reduction Potential

2011 ◽  
Vol 356-360 ◽  
pp. 1009-1014 ◽  
Author(s):  
Jun Hui Zhang
Keyword(s):  
High Efficiency ◽  
Anaerobic Respiration ◽  
Waste Recycling ◽  
Soluble Form ◽  
Rrna Gene ◽  
Resting Cells ◽  
Surface Binding ◽  
Batch Cultures ◽  
High Level

The investigation was conducted to evaluate mechanism of Cr(VI) resistance and reduction by a bacterial strain named FJ under different conditions. This strain, identified as a member of Rhizobium larrymoorei by analysis of its 16S rRNA gene sequence was previously isolated from a paddy soil contaminated by e-waste recycling. Good Cr(VI) reduction ability catalyzed by growing cells of R. larrymoorei FJ was observed in batch cultures conducted at different initial Cr(VI) concentrations. Up to 83.23% reduction was shown in LB medium supplemented with 2.50 mM Cr(VI). Cr(VI) was transformed to some soluble form of Cr(III) due to anaerobic respiration. Biosorption was also observed in the process of bioreduction. But only loosely cell-surface binding Cr(VI) was detected in cells grown in medium supplied with different concentrations of Cr(VI). Present of yeast or citrate could enhance Cr(VI) reduction of resting cells. However, Cr(VI) reduction by resting cells was only observed at Cr(VI) concentration lower than 0.25 mM. R. larrymoorei FJ exhibited a high efficiency of Cr(VI) reduction at temperatures from 28°C to 37°C and pH values from 6.0 to 7.0.

scholarly journals Isolation, Identification, and Molecular Characterization of Strains of Photorhabdus luminescens from Infected Humans in Australia

1999 ◽  
Vol 37 (11) ◽  
pp. 3647-3653 ◽  
Author(s):  
Margaret M. Peel ◽  
David A. Alfredson ◽  
John G. Gerrard ◽  
Jennifer M. Davis ◽  
Jennifer M. Robson ◽  
...  
Keyword(s):  
The United States ◽  
Skin Lesions ◽  
Pcr Analysis ◽  
Rrna Gene ◽  
Unique Type ◽  
Clinical Strains ◽  
Source Of Infection ◽  
Spider Bite ◽  
High Level

We describe the isolation of Photorhabdus(Xenorhabdus) luminescens from four Australian patients: two with multiple skin lesions, one with bacteremia only, and one with disseminated infection. One of the patients had multiple skin lesions following the bite of a spider, while the lesions in the other patient were possibly associated with a spider bite. The source of infection for the remaining two patients is unknown. As a member of the family Enterobacteriaceae, P. luminescens is unusual in that it fails to reduce nitrate and ferments only glucose and mannose. It gives negative reactions for lysine decarboxylase, arginine dihydrolase, and ornithine decarboxylase (Moeller). The species is motile, utilizes citrate, hydrolyzes urea, and usually produces a unique type of annular hemolysis on sheep blood agar plates incubated at 25°C. A weak bioluminescence is the defining characteristic. P. luminescens is an insect pathogen and is symbiotically associated with entomopathogenic nematodes. Its isolation from human clinical specimens has been reported previously from the United States. Restriction fragment length polymorphism-PCR analysis of the 16S rRNA gene demonstrated a high level of similarity among the Australian clinical strains and significant differences between the Australian clinical strains and the U.S. clinical strains. However, numerical analyses of the data suggest that the two groups of clinical strains are more similar to each other than they are to the symbiotic strains found in nematodes. This is the first report of the isolation of P. luminescens from infected humans in Australia and the second report of the isolation of this species from infected humans worldwide.

scholarly journals High-Level Production of the Low-Calorie Sugar Sorbitol by Lactobacillus plantarum through Metabolic Engineering

2007 ◽  
Vol 73 (6) ◽  
pp. 1864-1872 ◽  
Author(s):  
Victor Ladero ◽  
Ana Ramos ◽  
Anne Wiersma ◽  
Philippe Goffin ◽  
André Schanck ◽  
...  
Keyword(s):  
Lactate Dehydrogenase ◽  
Lactobacillus Plantarum ◽  
Mutant Strain ◽  
High Efficiency ◽  
High Specific Activity ◽  
Ph Control ◽  
Glycolytic Flux ◽  
Resting Cells ◽  
Low Calorie ◽  
High Level

ABSTRACT Sorbitol is a low-calorie sugar alcohol that is largely used as an ingredient in the food industry, based on its sweetness and its high solubility. Here, we investigated the capacity of Lactobacillus plantarum, a lactic acid bacterium found in many fermented food products and in the gastrointestinal tract of mammals, to produce sorbitol from fructose-6-phosphate by reverting the sorbitol catabolic pathway in a mutant strain deficient for both l- and d-lactate dehydrogenase activities. The two sorbitol-6-phosphate dehydrogenase (Stl6PDH) genes (srlD1 and srlD2) identified in the genome sequence were constitutively expressed at a high level in this mutant strain. Both Stl6PDH enzymes were shown to be active, and high specific activity could be detected in the overexpressing strains. Using resting cells under pH control with glucose as a substrate, both Stl6PDHs were capable of rerouting the glycolytic flux from fructose-6-phosphate toward sorbitol production with a remarkably high efficiency (61 to 65% glucose conversion), which is close to the maximal theoretical value of 67%. Mannitol production was also detected, albeit at a lower level than the control strain (9 to 13% glucose conversion), indicating competition for fructose-6-phosphate rerouting by natively expressed mannitol-1-phosphate dehydrogenase. By analogy, low levels of this enzyme were detected in both the wild-type and the lactate dehydrogenase-deficient strain backgrounds. After optimization, 25% of sugar conversion into sorbitol was achieved with cells grown under pH control. The role of intracellular NADH pools in the determination of the maximal sorbitol production is discussed.

scholarly journals Psychroserpens mesophilus sp. nov., a mesophilic marine bacterium belonging to the family Flavobacteriaceae isolated from a young biofilm

2006 ◽  
Vol 56 (5) ◽  
pp. 1055-1058 ◽  
Author(s):  
Kae Kyoung Kwon ◽  
Soon Jae Lee ◽  
Jae Hyun Park ◽  
Tae-Young Ahn ◽  
Hong Kum Lee
Keyword(s):  
Marine Bacterium ◽  
Methyl Esters ◽  
Rrna Gene ◽  
Respiratory Quinone ◽  
The Family ◽  
Major Respiratory Quinone ◽  
Dominant Fatty Acid ◽  
High Level ◽  
Taxonomic Characterization

A number of marine bacteria isolated from young biofilms were characterized as belonging to the family Flavobacteriaceae. The taxonomic characterization of strain KOPRI 13649T, which was isolated from an acrylic surface at the seashore at Gangneung, Korea, is reported here. The nearly complete 16S rRNA gene sequence of strain KOPRI 13649T was determined and was found to have a high level of similarity with that of Psychroserpens burtonensis (95.0–95.6 %). In addition, phylogenetic analysis and comparison with closely related strains confirmed that the strain represented a novel member of the genus Psychroserpens. The major respiratory quinone of strain KOPRI 13649T was MK-6 and the DNA G+C content was 29.8 mol%. The dominant fatty acid methyl esters were i-15 : 0, a-15 : 0, i-16 : 0, i-15 : 1ω10, 16 : 1ω7 and 15 : 0. Growth was observed at 10–34 °C (optimum 30 °C), at pH 6–9 (optimum 6.5–8.0) and with 0.5–4 % NaCl (optimum 1 %). On the basis of the polyphasic taxonomic evidence presented, strain KOPRI 13649T (=KCCM 42261T=JCM 13413T) should be classified as the type strain of a novel species in the genus Psychroserpens, for which the name Psychroserpens mesophilus sp. nov. is proposed.

scholarly journals Heterologous Expression and Characterization of a High-Efficiency Chitosanase From Bacillus mojavensis SY1 Suitable for Production of Chitosan Oligosaccharides

2021 ◽  
Vol 12 ◽  
Author(s):  
Jianrong Wang ◽  
Xiaoming Li ◽  
Hao Chen ◽  
Bilian Lin ◽  
Liangzhong Zhao
Keyword(s):  
Recombinant Strain ◽  
High Efficiency ◽  
Batch Cultivation ◽  
Maximum Activity ◽  
Gene Encoding ◽  
Enzymatic Production ◽  
Bacillus Mojavensis ◽  
Chitosan Oligosaccharides ◽  
High Level

Chitosanase plays an important role in enzymatic production of chitosan oligosaccharides (COSs). The present study describes the gene cloning and high-level expression of a high-efficiency chitosanase from Bacillus mojavensis SY1 (CsnBm). The gene encoding CsnBm was obtained by homologous cloning, ligated to pPICZαA, and transformed into Pichia pastoris X33. A recombinant strain designated X33-C3 with the highest activity was isolated from 120 recombinant colonies. The maximum activity and total protein concentration of recombinant strain X33-C3 were 6,052 U/ml and 3.75 g/l, respectively, which were obtained in fed-batch cultivation in a 50-l bioreactor. The optimal temperature and pH of purified CsnBm were 55°C and 5.5, respectively. Meanwhile, CsnBm was stable from pH 4.0 to 9.0 and 40 to 55°C. The purified CsnBm exhibited high activity toward colloidal chitosan with degrees of deacetylation from 85 to 95%. Furthermore, CsnBm exhibited high efficiency to hydrolyze different concentration of colloidal chitosan to produce COSs. The result of this study not only identifies a high-efficiency chitosanase for preparation of COSs, but also casts some insight into the high-level production of chitosanase in heterologous systems.

Research and Characterization of an Absorber Layer Material — Cu(In,Ga)Se2 Sputtered on Polyimide Substrate in Material Engineering

2012 ◽  
Vol 583 ◽  
pp. 370-373
Author(s):  
Yong Ping Zhao ◽  
Cong Chun Zhang ◽  
Gui Fu Ding ◽  
Yong Liang Wang
Keyword(s):  
High Efficiency ◽  
Rf Magnetron Sputtering ◽  
Absorber Layer ◽  
Layer Material ◽  
Material Engineering ◽  
High Efficiency Solar Cells ◽  
Lower Temperature ◽  
High Level

Cu(In,Ga)Se2 is a very important type of absorber layer material for high efficiency solar cells in material engineering. Cu(In,Ga)Se2 thin films were prepared on polyimide (PI) substrates coated with Mo by RF magnetron sputtering in one-stage at temperature below 450 °C. Samples with high level crystallization were deposited on polyimide coated with Mo by optimizing process parameters. Lower electric resistivity, better quality of CIGS absorber layer was fabricated in lower temperature by sputtering.

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