Plant-root interaction occurs in the rhizosphere, a region referred to as a biologically active zone of soil where microorganisms and plant roots interact. This study examined the impact of genetically modified (GM) maize (Bt) on functional community of rhizobacteria. Soil samples of field grown GM and non-GM maize were collected from an experimental field in Delmas, South Africa, at 30 days after sowing (DAS) and I day after harvest (DAH). Chemical analyses of soil properties in GM and Non-GM soil samples were performed. Quantitative analysis was achieved through soil dilution and plate count (colony forming units) using selective and non-selective media (tryptic soy agar, nutrient agar, Luria Bertani agar and Pseudomonas selective agar). Qualitative analysis was achieved using analytical profile index identification systems and sequence data of rhizobacterial isolates. Biolog GN2 microplate was used to compare community catabolic profile of rhizobacteria in GM and non-GM soils and denaturing gradient gel electrophoresis technique (DGGE) was used in comparing rhizobacterial community profiles in GM and non-GM soil samples. Chemical analyses of GM and non-GM soil samples collected 30 DAS and 1 DAH indicated the same elements with similar percentages. The pH of GM and non-GM soil samples range from 6.12-7.03, indicating slightly acidic to slightly alkaline soil. Total count of rhizobacteria (cfulg) in GM and non-GM maize soil samples collected 30 DAS and 1 DAH was not significantly different in the media. Similar rhizobacterial species from the rhizosphere of both GM and non- GM maize were identified using analytical profile index and sequence data. No significant difference was observed in the community catabolic profile among the rhizobacteria in GM and non-GM soil samples. Cluster analyses of DGGE bands indicated that band patterns of GM and non-GM samples 30 DAS and 1 DAH were similar to each other. These findings suggest that the GM maize was not able to alter microbial community and activity and are significant to the investigation of the impact of GM maize on rhizobacteria. / Thesis (M.Sc. (Biology) North-West University, Mafikeng Campus, 2013

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The effect of <I>L. terrestris </I>on the transport of marked bacterial inocula in the absence of percolating water was investigated using repacked soil microcosms over a 10 day period. The microcosms consisted of cylindrical cores containing loamy sand. The bacterial inoculum was applied in filter paper disks to the surface of soil cores containing <I>L. terrestris </I>and to control cores. Destructive analysis of cores was carried out 5 and 10 days after inoculation to facilitate enumeration of marked bacterial inocula at 3 depths in the soil. Significantly greater vertical transport of marked bacteria occurred in cores containing <I>L. terrestris. </I>The effect of <I>L. terrestris </I> on the dispersal of marked bacteria in the presence of percolating water was investigated using both repacked soil cores and larger intact cores over a one month period. Bacterial inocula were again applied in filter paper disks to the surface of cores and the cores subjected to simulated rainfall events at 3 day intervals. Concentrations of marked bacteria in leachate were determined and destructive harvests of cores carried out after 24 days. The results from repacked soil cores demonstrated that cores containing earthworms were associated with early breakthrough, higher percentage recovery and greater numbers of marked bacteria in the leachate than control cores without earthworms. Results from intact soil cores demonstrated that cores containing earthworms were associated with different bacterial leaching patterns, higher percentage recovery and greater numbers of bacteria in the leachate than control cores. For both repacked and intact cores, the presence of earthworms in cores led to transport of marked bacteria to greater depths in the soil. Plaster of Paris impregnation of repacked and intact cores highlighted the importance of earthworm burrowing in providing pathways for bypass water flow and hence bacterial transport through soil. Results from the use of interdisciplinary methods developed and adapted in this study identify the importance of earthworms in the fate of microbial inocula in soil and the potential for use of earthworms in biotechnology.

A Thesis submitted to The University of Arizona College of Medicine - Phoenix in partial fulfillment of the requirements for the Degree of Doctor of Medicine. / Dysphagia with aspiration (DA) is the most common presenting symptom of patients at Phoenix Children’s Hospital’s Aerodigestive Clinic (ADC). Dysphagia with aspiration is associated with respiratory and gastrointestinal symptoms, chronic oral thickener use to prevent aspiration, secondary constipation, and occasionally, enteral tube dependency. MBS is considered the gold standard in instrumental assessment of dysphagia; it is used to evaluate severity and guide thickener treatment of DA patients, monitor progress with serial studies, and for re‐evaluation after intervention when appropriate. Previous evaluation of patients with deep interarytenoid notch given laryngoplasty injection included patients with improvement in symptoms despite post‐intervention MBS scores worsening, and vice versa, challenging the use of MBS as a longitudinal tool in clinical evaluation of patients with dysphagia and aspiration. Is MBS severity score reflective of clinical symptoms in pediatric patients with dysphagia and aspiration? A clinical questionnaire of DA symptoms was developed with input from the ADC physicians. The questionnaire was administered over 3 months to patients aged 1‐3 years who had an MBS evaluation within 6 months of their initial ADC visit, standard of care for patients with DA. 17 symptoms (12 GI and 5 pulmonary) were given a numerical score 0‐4 based on parent recall of frequency. MBS was scored 1‐10 on the thickness of liquid recommended for aspiration prevention. Individual symptoms and symptom sets (total questionnaire score, GI score, pulmonary score) were compared to MBS score using linear regression model. 30 patients were surveyed with median MBS score of 6 and range from 0 to 8. 18 patients had an MBS score above 6. Median questionnaire score was 18, with a range from 4 to 53. All analysis showed no significant correlation between individual symptoms or symptom sets and MBS score; the highest R2 value for any individual symptoms was 0.05. Among ADC patients with DA, MBS severity score did not correlate with severity or specificity of symptoms, questioning the use of MBS as a tool for diagnosing severity of persistent DA or as a repetitive tool in assessing response to laryngeal cleft surgical interventions and thickener wean therapy. These findings challenge the use of repetitive MBS in the ADC patient population. Our ultimate goal is to develop a combined clinical and radiologic tool that would minimize radiation exposure and unnecessary thickener treatment while promoting best clinical outcomes.