Morphology, toxicity and toxin properties of cultured toxic cyanobacteria species isolated from aquaculture pond of Sarawak and Sabah

Jasmina, Majit (2012) Morphology, toxicity and toxin properties of cultured toxic cyanobacteria species isolated from aquaculture pond of Sarawak and Sabah. Masters thesis, Universiti Malaysia Sarawak.

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Abstract

(In this study, potential-toxin cyanobacteria were isolated from selected aquaculture ponds in Indigenous Fisheries Production and Research Center Sarawak and Babagon Fisheries Center Sabah. A total of 12 cyanobacterial strains from Orders Chroococcales, Oscillatoriales and Nostocales were classified morphologically based on published references. Out of this isolated strains, only six strains were successfully maintained and mass cultured, namely; Microcystis aeruginosa (MIC 1), Anabaena spp. (ANA I and ANA4), Cylindrospermopsis sp. (CYL 1), Nostoc sp. (NOS 1) and Lyngbya sp. (LYN 1). Distinct morphological features were observed during sequential developmental stages of MIC and NOS 1. For nutrient assessment, strain Anabaena spp) ANA1 and ANA4 showed the highest cell density in medium ASN3 with K2HPO4. Growth rate, μ for ANA I was maximal in medium ASN3 with NaNO3 and K2HPO4 while ANA4 was maximal in medium ASN3 with NaNO3. Strain Cylindrospermopsis sp. CYL1, achieved the highest cell density in medium ASN3 containing K2HPO4 and the maximal growth rate, g recorded in medium ASN3 with NaNO3. For the light assessment, all strains of ANA1, ANA4 and CYL 1 achieved the highest cell density under light intensity of 10 gmol photons m-2s- 1. Strain ANA1 recorded the maximal growth rate under light intensity of 20 μmol photons m-2s" . Growth rate, μ for ANA 1 and CYL 1 were maximal under light intensity of 10 gmol photons m 2s-1. For toxicity assessment, the result shows that only MIC1 extracts was toxic to brine shrimp at 24 hours in a dose dependent manner in which the LC50 recorded was below 50 μg/ml. While for mouse bioassay MIC 1 was found to be the most toxic to mouse followed by ANA 1 and NOS 1. For TLC detection, only MIC 1 and ANA I showed the same Rf value (0.97) when compared to Rf value of standard Microcystin-LR (0.97). The chromatograph peak of standard Microcystin-LR appeared at retention time of 8.18 min, while for Microcystis sp. at 8.18 and Anabaena sp. at 8.19 min, respectively. The results indicate that MC-LR toxin was found in Microcystis sp. MIC 1 and Anabaena sp. ANA 1.

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