Size fractionation of bacterial functional diversity within soils Krista L. Kinneer BIOLOG ® GN and GP microtitre plates were used to compare functional diversity of large (>0.45 µm, LC) and small (<0.45 µm, SC) cells within A and B horizons of cultivated and forested Guernsey silt-loam soil without enrichment and following enrichment in dilution culture. Without enrichment, SC exhibited limited substrate utilization compared with LC. B horizon SC failed to positively utilize any carbon substrates, which suggests that they may be physiologically inactive and/or metabolically distinct from those in A horizon soils. Following enrichment, A horizon SC from highly diluted enrichment cultures produced substrate utilization patterns distinct both from all enrichments of LC and from SC obtained in less dilute enrichments. At any given inoculum dilution, A horizon SC exhibited greater substrate utilization than B horizon SC, which exhibited positive substrate utilization following enrichment. Amplified ribosomal DNA (ARDRA) analyses of SC dilution culture enrichments demonstrated distinct bacterial sub-populations from a single soil sample. iii DEDICATION This work is dedicated to my parents, Neil and Donna Kinneer. Thank you for supporting me throughout my academic career and for teaching me the value of hard work! I gratefully acknowledge my graduate committee, including Drs. Gary Bissonnette, Daniel Panaccione, and Louis McDonald for invaluable suggestions, assistance, and constructive criticism. Special thanks to Dr. Daniel Panaccione for his patient and thorough instruction during all phases of this research involving molecular techniques. I wish to thank Dr. John Sencindiver for confirming soil type at both study sites, and Dr. Joseph Morton for help with scanning and PhotoShop software programs. I am indebted to Dr. Sara Wright, USDA/ARS Beltsville, MD, for use of her microplate reader for BIOLOG ® data collection. Kelly Heldreth-Fleming deserves special recognition for her tremendous and invaluable help throughout this research project, including data entry, assistance in developing the cell extraction/size-fractionation procedure, and constant support and encouragement from the moment I arrived at WVU. Thank you so much! I also wish to thank Jim Fleming for cheerfully volunteering to help with soil sampling. I also wish to thank every graduate student in the Department of Plant Pathology and Environmental Microbiology with whom I've had the pleasure of working. I have learned more from all of you than I could in any classroom. Special thanks are extended to my family and to Daniel DeFede. Without your love, support, and patience, I could not have completed my degree. v
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