1. The Graduate School, University of Santo Tomas , Manila 1015 , the Philippines
2. Laboratory of Pure and Applied Microbiology, Research Center for the Natural and Applied Sciences, University of Santo Tomas , Manila 1015 , the Philippines
3. Aquaculture Department, Southeast Asian Fisheries Development Center, Binangonan Freshwater Station , Binangonan, Rizal 1940 , the Philippines
4. Graduate School of Integrated Sciences for Life, Hiroshima University , 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530 , Japan
5. Department of Biological Sciences, College of Science, University of Santo Tomas , Manila 1015 , the Philippines