Evaluation of test media for routine monitoring of Escherichia coli in nonpotable waters

Article Abstract:

Lauryl tryptose agar (LTA) with 4-methylumbelliferyl-beta-D-glucuronide (MUG) or 5-bromo-3-indolyl-beta-D-glucuronide (X-Gluc) are the best test media for the enumeration of Escherichia coli in nonpotable waters. The efficiency of m-TEC, m-TEC with MUG, LTA with MUG, LTA with X-Gluc and EC medium with MUG in enumerating E. coli was compared with three reference media. The ability of the media to identify E. coli in surface waters and differentiate between related microorganisms was also determined. The study shows that the recovery rate of E. coli is significantly affected by the test media.

Analysis, Microbiological assay

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Starved cells of the fatty acid auxotroph Escherichia coli AK7 develop abnormal sensitivity to media with low osmolarity

Article Abstract:

The unsaturated fatty acid auxotroph Escherichia coli AK7 supplied with linolenic acid, normal during logarithmic growth indicated a rapid reduction in CFU during starvation due to osmotic downshift when transferred to standard agar plates unsupplemented with an osmolyte such as 300 mos M sucrose or salt (NaCl or KCl). An energy source added to the starvation medium indicated that the starved cells recouped their osmoresistance. The osmolarities of the liquid media and the agar plates were evaluated by measurement of the vapor pressure of the samples with a Wescor microosmometer.

Evaluation, Chromogen

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Highly efficient expression of fish growth hormone by Escherichia coli cells

Article Abstract:

Introduction of a polymerase chain reaction product that encodes the fish pregrowth hormone (pre-GH) into an Escherichia coli expression vector producing high levels of recombinant GH (rGH). The rGH stimulates fish growth when injected into 16 week-old fish and the growth continues for 4 weeks after the treatment is stopped. The rGH is immunoreactive to antibodies of GH, which triggers growth by stimulating metabolism of proteins, lipids, carbohydrates and minerals.

Growth, Fishes, Somatotropin

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