Discipline: Ecology Environmental and Earth Sciences
Angel Franco Arzate - California State University, Bakersfield
Co-Author(s): Antje Lauer, California State University Bakersfield; Manpreet Kaur, California State University Bakersfield
Coccidioidomycosis, more commonly known as valley fever, is a disease caused by the fungal pathogen Coccidioides spp. Coccidioides is endemic in the United States, Northern Mexico, Central America and parts of South America. In the United States, C. immitis and C. posadasii are two species of Coccidioides, with C. immitis being mostly found in the San Joaquin Valley area of California and C. posadasii being found in Arizona. These regions are characterized by dry climate, reduced precipitation, desert like conditions, and dust development which makes them favorable habitats for the arthroconidia of the pathogen. Due to the airborne nature of arthroconidia, we believe that both species of Coccidioides, immitis and posadasii, can be found in soils collected from Twentynine Palms, CA because of its proximity to both the San Joaquin Valley and Arizona. Various soil samples were taken from areas around Twentynine Palms, CA to detect the presence of the Coccidioides spp. Soil sampling locations were chosen using the USDA websoilsurvey database indicating soils with different chemical and physical parameters. DNA was extracted from around 30 soil samples collected from 5-7 cm depth using aseptic techniques. A nested PCR approach, that includes several different diagnostic primer pairs, was used to detect the presence of Coccidioides. DNA from a non-pathogenic strain of C. posadasii was isolated and used as a positive control. The fungal community diversity of the soil samples was also investigated using denaturing gradient gel electrophoresis (DGGE). All dominant DGGE bands including those found in the Coccidioides region of the DGGE gel were excised, reamplified and will be sequenced. So far, results from the DGGE show low fungal diversity in areas that support the growth of Coccidioides. DNA sequencing of nested PCR products indicate that Twentynine Palms has sites that are positive for Coccidioides posadasii, and further investigation will show if C. immitis is present as well. Environmental parameters such as soil pH, electrical conductivity and amount of organic matter was also determined. We hope that we are able to link the presence or absence of the pathogen to some of these parameters. Future investigations will include additional sampling over additional seasons, resulting in enough samples that make a meaningful statistical analysis possible. References: Kolivras, Korine N et al. 2001. Environmental variability and coccidiodomycosis (valley fever). Aerobiologia 17:31-42. Vargas- Gastélum L, Romero-Olivares AL, Escalante AE, Rocha-Olivares A, Brizuela C, Riquelme M. Impact of seasonal changes on fungal diversity of a semi-arid ecosystem revealed by 454 pyrosequencing. FEMS microbiology ecology. 2015 May 1;91(5):fiv044.Not Submitted
Funder Acknowledgement(s): United States Department of Defense (Grant# 16-RCO1-50); CSU Bakersfield Louis Stokes Alliances for Minority Participation (LSAMP) program
Faculty Advisor: Antje Lauer, email@example.com
Role: On this project, I conducted the DNA extractions from soil samples and performed nested polymerase chain reactions (PCRs) on the DNA along with agarose gel electrophoresis. I also ran DGGE gels that would give us an insight into the fungal diversity of the different soil samples.