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Endophytic yeasts of Phragmites sp. in a copper contaminated tailings pond in Mankayan, Benguet
Dissertation Abstract:
Mining impacted landscapes are inhospitable environments for many organisms. Despite this, metallophytes have evolved various adaptive traits so as to be able to survive these environments. They also coevolved with associated microorganisms to increase their capacity to tolerate such conditions. In this study, the endophytic yeasts of Phragmites sp. found dominating the banks of the active tailings pond 5A of Lepanto Consolidated Mining Company in Mankayan, Benguet were investigated. Seven yeasts were isolated from the submerged portions of the plant which were the lower stem and roots. These endophytic yeasts were identified through molecular means and their phylogenetic placements were determined through the maximum likelihood method. Two isolates were identified as Debaryomyces hansenii YPh4 and Candida parapsilosis Yph5. All the isolates were subjected to various assays to determine their metabolic activities in vitro. Positive results in the antioxidant assays, growth promotion assays, copper tolerance assays, and growth promotion in copper stressed rice seedlings show that these yeast endophytes possess physiological characteristics that may help their host Phragmites sp. tolerate and even dominate the copper contaminated tailings pond where it is found to occur.
To my knowledge, this was the first time that yeast fungal endophytes from a metallophyte plant (Phragmites sp.) was investigated. The results of this research can definitely add to the knowledge of the diversity of fungi found in symbiosis to a metallophyte. This research may also be the first attempt at elaborating the physiological roles of endophytic yeasts toward the increase in fitness of the metallophyte host.
It is my hope that this research can contribute to the management and restoration of metal contaminated sites. Literatures often cite microorganisms as integral to ecosystem functioning. Similarly, microorganisms can also have a great role in the management of degraded landscapes. The yeast isolates in this research can be used in assisted natural phytoremediation approaches toward the management and restoration of heavy metal impacted landscapes of the Cordillera. It may result to a new microbe-assisted phytoremediation model for metal-polluted soils that uses endophytic yeastplant associations. These isolates may be used to increase plant viability and vigor for the purpose of revegetation of abandoned heavy metal impacted sites.