LAUSR

Abstract Understanding adsorption of important proteins as part of a complex protein mixture onto surfaces such as soil is critical for numerous environmental applications. In this study, we investigated the adsorption of urease as part of a total bacterial protein extract from Sporosarcina pasteurii onto soil mixtures, including sand and silt, and the resulting enzymatic activity. Proteomics analysis of the proteomes revealed that larger proteins were preferentially adsorbed onto the soil surfaces regardless of the type of soil; the median molecular weight of the proteins over-represented in the supernatant and soil fractions were 29.4 kDa and 36.6 kDa, respectively. In addition, the majority of total ureases (86.2-97.2%) was present in the soil fractions of soil mixtures containing silt. Adsorbed urease exhibited enzymatic activity up to 0.2 U/mg protein in the soil fractions at a substrate concentration of 1.67 mM. Additionally, urease activity in the soil correlated with the total amount of protein adsorbed and the amounts of adsorbed urease. Although the soil-adsorbed urease retained measurable activity, an overall loss of activity was observed in all samples. Understanding the dynamics of protein adsorption onto soil surfaces can aid in improved designs for engineering applications that utilize enzymatic activities.