Isolation and Characterization of a PEG-degrading and Mo-reducing Escherichia coli strain Amr-13 in soils from Egypt

Molybdenum is a pollutant that shows toxicity to spermatogenesis while polyethylene glycols (PEG) are used predominantly in detergents. The pollution of molybdenum and PEGs are reported worldwide. We have isolated ten molybdenum-reducing bacterial isolates from soil that can reduce molybdenum (sodium molybdate) into the colloidal molybdenum blue (Mo-blue). The screening of these isolates for PEG-degrading ability showed that one isolate was capable to utilize PEG 200, 300 and 600 for optimal conditions were pHs between 5.5 and 8.0, temperatures between 30 and 37 oC, phosphate at 5 mM, molybdate between 10 and 30 mM, and glucose as the electron donor. Biochemical analysis of the bacterium identifies it as Escherichia coli strain Amr-13. Growth was best supported by all PEGs at concentrations of between 600 and 1,000 mg/L. A complete degradation for PEG 200 and PEG 300 at 1,000 mg/L was observed on day four and five, respectively, while nearly 90% of PEG 600 was degraded on day six. The growth of this bacterium on these PEGs was modelled using the modified Gompertz model, and produced growth parameters values, which were maximum specific growth rates of 1.51, 1.45 and 1.18 d-1 and lag periods of 0.53, 0.87 and 1.02 day for PEG 200, PEG 300 and PEG 600, respectively. PEG 200 was the most preferred substrate for this bacterium, while PEG 600 was the least preferred.

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Isolation of A Molybdenum-reducing Bacillus sp. strain Zeid 15 and Modeling of its Growth on Amides

Bulletin of Environmental Science and Sustainable Management (e-ISSN 2716-5353) ◽

10.54987/bessm.v5i2.650 ◽

2021 ◽

Vol 5 (2) ◽

pp. 19-27

Author(s):

I.M. Abu Zeid ◽

M.F. Rahman ◽

Mohd Yunus Shukor

Keyword(s):

Heavy Metals ◽

Specific Growth ◽

Growth Parameters ◽

Gompertz Model ◽

Electron Donors ◽

Bacillus Sp ◽

Aquatic Life ◽

Molybdenum Blue ◽

Specific Growth Rates ◽

Modified Gompertz Model

More and more people are looking at bioremediation as a cheaper option to physhiochemical techniques for cleaning up pollution from farming, mines, and other chemical industries. Toxic effects of molybdenum on spermatogenesis harm not only humans but also livestock and aquatic life. As a result, efforts are being made to remove it from the ecosystem. A microorganism that can convert soluble molybdenum into colloidal molybdenum blue has been discovered. Phosphate concentrations were optimum between 2.5 and 5, molybdate concentrations between 15 and 20, pH between 6, and temperature between 25 and 34 degrees Celsius for the bacteria to thrive. Absorption spectrum of Mo-blue shows a peak at 865 nm and a shoulder at 700 nm, which indicates that it is in fact reduced phosphomolybdate. Copper, mercury, silver, copper, and chromium are all hazardous heavy metals that hinder the synthesis of Mo-blue. Bacillus sp. strain Zeid 15 is the most likely candidate for the bacterium's identity. As part of our screening, we look for the bacterium's capacity to employ different nitriles and amides as potential electron donors for molybdenum reduction or as substrates for growth. A microplate format was used for the screening. The bacterium was able to use the amides acrylamide and propionamide as sources of electron donor for reduction. Mo-blue production was best supported by acrylamide between 750 and 1250 mg/L, and propionamide between 750 and 1000 mg/L. In addition, these amides including acetamide could support the growth of the bacterium. The modified Gompertz model was utilized to model the growth of this bacterium on amides. The model’s growth parameters obtained were lag periods of 1.372, 1.562 and 1.639 d and maximum specific growth rates of 1.38, 0.95 and 0.734 d-1, for acrylamide, acetamide and propionamide, respectively. The capacity of this bacterium to decontaminate simultaneously amides and molybdenum is a novel characteristic that will be very beneficial in bioremediation.

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Isolation And Characterization Of A Cdna Clone Coding For α1-Antitrypsin

10.1055/s-0038-1652207 ◽

1981 ◽

Author(s):

K Kurachi ◽

K Chandra ◽

S L C Woo ◽

E W Davie

Keyword(s):

Escherichia Coli ◽

Cdna Clone ◽

Coli Strain ◽

Base Pairs ◽

Isolation And Characterization ◽

Pbr322 Dna ◽

Free Translation ◽

Alpha1 Antitrypsin ◽

Carboxyl Terminal

Poly(A)-RNA enriched for α1-antitrypsin was isolated by specific immunoprecipitation of baboon liver polysomes. Alpha1-antitrypsin consisted of greater than 90% of the cell-free translation products of this mRNA. A doublestranded cDNA was synthesized by using reverse transcriptase and made blunt-ended with nuclease S1. After tailing with dCTP and terminal transferase, the double-stranded cDNA was annealed to pBR322 DNA. The latter DNA had been cleaved previously at the single Pst I site and similarly tailed with dGTP. The resulting plasmids were used to transform Escherichia coli strain RR1. Clones that hybridized to 32P-labeled cDNA synthesized from the α1-antitrypsin-enriched mRNA were then identified. The recombinants containing baboon cDNA inserts were further screened by a solution hybridization assay with [3H]cDNA synthesized from the enriched mRNA. The cDNA inserts from the positive clones were then sequenced to identify clones containing α1-antitrypsin. One insert, designated pBaαA1, was found to code for the carboxyl-terminal region of α1-antitrypsin. It also contained a noncoding region of 76 base pairs and a poly(A) tail of 60 base pairs.

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Isolation and characterization of catabolite repression-resistant mutants of Escherichia coli

Canadian Journal of Microbiology ◽

10.1139/m77-207 ◽

1977 ◽

Vol 23 (10) ◽

pp. 1384-1393 ◽

Cited By ~ 2

Author(s):

Glen D. Armstrong ◽

Hiroshi Yamazaki

Keyword(s):

Escherichia Coli ◽

Catabolite Repression ◽

Coli Strain ◽

Wild Type ◽

Phosphotransferase System ◽

E Coli ◽

Isolation And Characterization ◽

In The Wild ◽

Resistant Mutants

A method has been developed for the isolation of Escherichia coli mutants which are resistant to catabolite repression. The method is based on the fact that a mixture of glucose and gluconate inhibits the development of chemotactic motility in the wild type, but not in the mutants. A motile E. coli strain was mutagenized and grown in glucose and gluconate. Mutants which were able to swim into a tube containing a chemotactic attractant (aspartic acid) were isolated. Most of these mutants were able to produce β-galactosidase in the presence of glucose and gluconate and were normal in their ability to degrade adenosine 3′,5′-cyclic monophosphate. Some of these mutants were defective in the glucose phosphotransferase system.

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