Published: June 21, 2017
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By: Ernesto Morales, Cal Poly Pomona
In this presentation, we will discuss the development of a straightforward, portable, and cost-effective approach to measuring catalase activities from biological soil crusts (BSCs), which are surface microbial communities found in arid and semi-arid environments. The study of BSCs is significant, as these communities aid in nutrient cycling and water retention and are utilized as biological indicators for climate change. To date, most BSC-related studies focus on microbial diversity, with limited emphases on the metabolic and enzymatic profiles. Among the many enzymes associated with oxidative stress is catalase, which is presumably involved in the survival of these communities under arid conditions. Typically, catalase activities from soil samples are measured using spectral or titration-based methods, which are often hampered by the abundant organic material found in BSCs and are burdened by cost and field-applicable issues. Using our volumetric displacement method, we have measured the catalase specific activities of three sets of BSCs that contain similar microbial compositions and are found along an elevation transect in the Mojave National Preserve (275 to 685 m). Our results show that the higher elevation BSCs possess ~3-fold higher activities, which suggests that the drastic change in spatial distribution of these BSCs along the elevation transect is due to metabolic rather than genetic differences. In conclusion, we plan to additionally discuss our control studies that measured the impacts of storage time, sample handling, and analytical strategies on the reproducibility of the catalase activities.