Buenaflor D. Jimenez1, Ruth D. Gaid2 and Cesaria R. Jimenez2
1Department of Biological Sciences
MSU-Iligan Institute of Technology, Iligan City
2MSU-Institute of Fisheries Research and Development
Naawan, Misamis Oriental
Abstract
Study on the microalgal profile of the green water in BFAR-NFRDI brackish water reservoir stocked with adult Tilapia (Oreochromis mosambique and Nile hybrid) and anti-inhibitory activity of their extracts against Vibrio harveyi was conducted weekly for one-month cycle.
Five-ten liters composite samples were collected per sampling and mixed thoroughly. From each of the composite sample, 25liters were filtered and extracted with ethyl acetate for inhibitory activity against V. harveyi. Another ten liters was filtered and preserved with buffered formalin solution for plankton composition analysis.
Four microalgae were identified from the composite samples, namely: Nitzschia, Pleurosigma, Chlorella, and Oscillatoria. Nitzschia dominated the first sampling (density, 1.54 x 106; relative abundance, 99.99) The sample also contained two other genera, Pleurosigma and Chlorella. Chlorella dominated the three subsequent samples with increasing density and relative abundance: 1.03 x 106 cells ml-L and 56.64 to 99.99%, respectively.
Preliminary screening of with disc diffusion techniques showed that only the uppermost layer or third layers of algal extracts exhibited anti-inhibitory activity against Vibrio harveyi. The minimum inhibitory concentration (MIC) of the upper layer of the extracts of the first composite sampling was 25mcg ml-L that is significantly higher (P=.0083) when compared to the MIC for the upper layer of second, third and fourth composite algal samples (12.5mcg ml-L).
Subculture of MIC tubes did not show growth after 24 hours indicating bactericidal activity, a comparative advantage to chloramphenicol, which is only bacteriostatic at 12.5mcg ml-L.
akui una maghugaw2 dire...hope someday i can work with you mga mam.d:)
ReplyDelete