Lake Lanao is the second largest lake in the Philippines and is one of the 15 ancient lakes of the world. It is a home of 18 endemic cyprinid fishes and 42 endemic crab species. A hydroelectric plant installed on the Lanao Lake and Agus River system generates 70% of the electricity used by the people of Mindanao (Rosagaron, 2001). Lake Lanao is the lifeline of about 669,072 Maranaos (NSO, 2000) or the “people of the lake”. With this importance, Lake Lanao’s resources must be comprehensively explored and present status must be evaluated to provide a basis for future conservation programs. 

            Few researches about Lake Lanao in the past were focused on its status, management, fisheries (Rosagaron, 2001; Escudero, 1995) and phytoplankton (Lewis, 1978). No single published researches were done yet on the bacterial and fungal populations in Lake Lanao. While it is true that the flora and fauna of a lake ecosystem comprise the producers and consumers in the lake, respectively, but microorganisms are equally important being the decomposers that degrade dead organic bodies and make nutrients available to the producers, thus, maintaining a stable ecosystem. On the other hand, the presence of unwanted number of microorganisms as well as opportunistic and pathogenic species in the lake from exogenous sources may have contributed to the occurrence of diseases to both the aquatic organisms and indirectly affecting the community along the shorelines of Lake Lanao.

This study will look into the abundance and species composition of bacterial and fungal populations in water and surface sediments and how the physico-chemical factors affect these microorganisms in the lake. Water quality will be determined based on the presence or absence of indicator microorganisms particularly the total and fecal coliforms.  Sampling will be done in five selected sites every other month, that will be on January, March, May, July, September, and November within one year period.  Physico-chemical parameters such as pH, conductivity, Total Dissolved Solids (TDS), salinity, and temperature, and the analyses for total N, P, and K as well as Ca, Mg, Na, Mn and Zn will be obtained  (in Project 1) and will be correlated with the data on microbial populations.  

 Microbial abundance will be determined through Serial Dilution Plate Count Technique following the procedure described by Tateishi et al. (1989). The number of total and fecal coliforms will be determined using the most probable number (MPN) method and the standard Coliform Test to confirm the presence of these water contaminants. Identification of bacterial and fungal isolates will include colony and microscopic examination and the Analytical Profile Index (API) system.  This microbial study is very important in completing the information needed to fully characterize and understand the current status of Lake Lanao.