Asian Journal of Applied Sciences (ISSN: 2321 – 0893) Volume 02 – Issue 05, October 2014 Asian Online Journals (www.ajouronline.com ) 636 Copper Tolerance and Copper Accumulation of Culturable Endophytic Yeasts of Phragmites Australis Cav. (Trin) ex Steud. From the Mine Tailings Pond in Mankayan, Benguet, Philippines Roland M. Hipol* 1 , Virginia C. Cuevas 2 1 Department of Biology, College of Science, University of the Philippines Baguio, Gov. Pack Road, Baguio City, Philippines. *Email: rmhipol {at} gmail.com 2 Environmental Biology Division, Institute of Biological Sciences, College of Arts and Sciences, University of the Philippines Los Baños, College, Los Baños, Laguna, Philippines. _________________________________________________________________________________ ABSTRACT— Three endophytic yeasts of Phragmites australis Cav. (Trin) ex Steud. from the tailings pond 5 of Lepanto Consolidated Mining Co. in Mankayan, Benguet, Philippines were investigated for their capacity to tolerate and accumulate copper. Two of the isolates were successfully identified through sequence homology of their ITS genes. All isolates were able to tolerate 500ppm Cu concentrations. The isolate that sequestered the most copper was D. hansenii Yph 4 at 9.38 μg/mg. The isolate that had the best bioconcentration factor was Candida parapsilosis Yph5 at 74.09%. Ascorbate peroxidase and catalase assays of yeasts grown on 50 ppm copper were done. The highest producer of APX was C. parapsilosis Yph5. On the other hand, the best catalase producer was the unidentified yeast Yph3. Keywords— Endophytic yeasts, copper tolerance, Phragmites australis, bioconcentration factor, ascorbate peroxidase, catalase _________________________________________________________________________________ 1. INTRODUCTION Remediation efforts that use physical and chemical approaches are both expensive and non-sustainable [1]. This is the reason why phytoremediation is gaining popularity as a remediation option. Phytoremediation is considered as an environmentally friendly, gentle management option for polluted soil as it uses solar-driven biological processes to manage pollutants [2], including heavy metals (HM). Phytoremediation consists of four different plant-based technologies each having a different mechanism of action for the remediation of metal-polluted soil, sediment, or water. These include: rhizofiltration, phytostabilization, phytovolatilization, and phytoextraction [3]. Phytoremediation however suffers from several limitations which include the extent of metal availability, metal uptake and phytotoxicity for the plant [4]. A promising approach to address this limitation is the optimization of the synergistic effect of plants and microorganisms [5]. This research was done to this end. Endophytic yeasts were tested in-vitro for their possible in-vivo contribution toward successful phytoremediation of Cu contaminated landscapes. All organisms when exposed to environmental stress react appropriately to allay the experienced stress. Accordingly, when organisms are exposed to increased concentrations of HM, they express adaptive responses to alleviate the effect of the stressful condition; and fungal endophytes are not an exception. Fungi in general are known to tolerate and detoxify metals by several mechanisms [6]. These include HM compartmentation, chelation and intra and extracellular complexation mechanisms [7]. Various compounds with high affinity with HM provide this function for the plant. Such compounds include metallothioneins (MT) and phytochelatins (PC). MTs are cystein-rich polypeptides while PCs consist of only three amino acids, glutamine (Glu), cystine (Cys), and glycine (Gly) and are enzymatically synthesized from glutathione (Yang, Feng, He, & Stoffella, 2005). The metal- chelate complex is then sequestered into the vacuole or into other sub-cellular compartments [8]. Another mechanism of HM tolerance is the more immediate and useful response of producing antioxidant enzymes. The toxicity of HMs to organisms is due, in part, to oxidative stress due to the production of reactive oxygen species (ROS) [9]. Ascorbate peroxidase and catalase are two enzymes that are said to be the primary line of defense in destroying free radicals [10]. In this study, the yeast isolates endophytic to Phragmites australis Cav. (Trin) ex Steud. from the tailings pond 5A of the Lepanto Consolidated Mining Co. in Mankayan, Benguet were investigated for their capacity to tolerate elevated