Dissertations and Theses

Date of Award


Document Type



Earth and Atmospheric Sciences

First Advisor

Karen Block


bacteria biofilm, soil bacteria, FTIR, kaolinite, calcium montmorillonite


Soil organic carbon (SOC) accounts for 70% of the carbon on Earth. It is therefore a key player in global carbon cycling and climate change (Smith et al., 2008). Soil organic matter (SOM) is an important component of organic matter in soils (SOC), and results from biogeochemical process involving net primary producers, soil biomass and soil mineralogy (Horwath and Kuzyakov, 2018). In this study, the interplay between soil bacterial biomass and reactive clay minerals in soils was investigated. The purpose of the research was to shed light into the stabilization of SOC in a bacterial biomass-soil/clay matrix. Soils characterized as Inceptisol and Oxisols were inoculated with two biofilm forming soil bacteria; Streptomyces griseosporeus, a Gram positive bacteria and Pseudomonas syringae, a Gram negative bacteria. To better understand the effect of specific minerals, a Ca-montmorillonite (Ca-MMT) clay was also inoculated the Gram negative bacteria. The interactions within the bacteria-soil/clay matrix was analyzed using Fourier-transform infrared spectroscopy (FTIR). Through FTIR analysis we were able to confidently identify areas of bacteria biomass-mineral interactions. The spectra revealed high bacterial activity within the range of 1400 – 1800 cm-1. The results suggested production of polysaccharide nutrient storages, proteins and other compounds as well as hinted at the possibility of exfoliation and changes in adsorbed water on the clay minerals.

Included in

Soil Science Commons



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