Microbiology Commons^™

Detection Of Beta-Lactamase Variants In Municipal Wastewater And Fresh Water, Sunil Pandey

Masters Theses

The occurrence and spread of antibiotic-resistant genes (ARGs) are pressing public health problems worldwide. A key factor contributing to the spread of ARGs is lateral gene transfer. Wastewater treatment plants (WWTPs) are measured hot spots of microbial diversity and resistance because they receive polluted wastewater from diverse sources and contain a variety of different environments with dense bacterial loads. Due to the overuse of antibiotics the genetic capacities of microbes have profited. This helps every source of resistance gene and every means of horizontal gene transmission to develop the multiple mechanism of resistance to each antibiotic used clinically, agriculturally, or …

Analysis Of The Charleston, Illinois Water Supply For The Presence Of Organic Mutagens Utilizing The Ames Salmonella/Microsome Assay, Steven Lee Washburn

Masters Theses

Water samples from the Charleston, Illinois water supply and selected agricultural run-off areas were tested for the presence of organic mutagenic chemicals. The Ames Salmonella/microsome mutagenicity assay utilizing strains TA98 and TA100 was used to analyze concentrated water samples. A special set of samples was exposed to the S9 activation system coupled with the TA98 strain to simulate the mammalian metabolic system.

No mutagens were detected in any of the samples tested. Several positive and negative control systems were included in the testing system. Negative control systems were used to determine the average spontaneous reversion rates for each strain for …

Inhibitors Affecting Bacterial Action In Reaerated Activated Sludge, Alice M. Dunn

Masters Theses

Inhibition of reaerated activated sludge was assessed using reduction of dissolved oxygen uptake by the microbial population as a criterion. Oxygen uptake is essential to biodegradation of the organic components in the activated sludge process; therefore, a decrease in dissolved oxygen uptake is an indication of reduced efficiency in wastewater treatment.

The irihibitors tested were cadmium, copper, lead, mercury, silver, 2,4-Dichlorophenoxyacetic acid (2,4-D), Terbacil and Zectran. The IIC₅₀, determined by extrapolation of plotted data, for each inhibitor in mg/l was Hg (20), Cu (50), Ag (43), Cd (115), Pb (550), and 2,4-D (430). The IIC₅₀ was determined …

The Effects Of Residual Chlorine On Selected Microflora Of Kickapoo And Cassell Creek, James A. Mcgaughey

Masters Theses

The survival of fecal coliforms, fecal streptococci, and heterotrophs after exposure to chlorine were compared in receiving waters of the Mattoon and Charleston, Illinois waste treatment facilities employing membrane filter techniques and Standard Plate Counts. Water samples were taken from receiving waters upstream from the treatment plant, from secondary effluent and chlorinated secondary effluent within the plant, and from downstream receiving waters. Stream flow contribution and plant effluent contribution required the calculation of dilution factors to determine expected numbers of the various microflora found downstream assuming no residual chlorine effect. Total chlorine concentration was measured by amperometric titration at the …

Pesticide Effects In A Simulated Soil Ecosystem, Raymond J. Samp

Masters Theses

The screening of pesticides to determine which were most inhibitory to bacteria was accomplished by testing the effects of 10 pesticides on 9 different organisms using the disk assay method. Results showed that Gram positive bacteria were more sensitive to all pesticides tested than were the Gram negative bacteria. In addition, the hormone herbicides were found to be the most inhibitory to these bacteria and 2,4-D (2,4-dichlorophenoxyacetic acid), a hormone herbicide, was chosen for subsequent in vivo studies.

A soil perfusion apparatus was used to determine the effects of 2,4-D in a typical soil ecosystem. Bacterial plate counts and nutrient …

Morphological And Physiological Effects Of 2,4-D On Gram-Negative And Gram-Positive Bacteria, John H. Rupnow

Masters Theses

Manometric, spectrophotometric, photomicrographic and quantitative biochemical techniques were employed to determine the morphological and physiological effects of 2,4-D on Gram-positive and Gram-negative bacteria.

The growth and motility of Gram-positive bacteria appeared to be more adversely affected than the growth and motility of Gram-negative species. The terminal oxidation, lysis, and chain length of both Gram-positive and Gram-negative bacteria did not appear to be affected by the concentrations used. The average cell size of both Gram-positive and Gram-negative bacteria was observed to increase after exposure to 1000 ppm 2,4-D. The normal leakage of amino acid and ultraviolet light absorbing cell constituents appeared …