Nitrogen fixation of blue-green algae and its nutritional value in fish culture | |
| Author | Wirat Jiwyam |
| Call Number | AIT Diss. no.AE-96-03 |
| Subject(s) | Fish-culture Fishes--Feeding and feeds |
| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Technical Science, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. AE-96-03 |
| Abstract | The role of biological nitrogen fixation in fish ponds, in term of natural biofertilizer and natural feed for fish, is important, but has seldom been evaluated critically. This study evaluates the role of biological nitrogen fixation by blue-green algae in those aspects. The experiments were designed to verify the indirect and direct contribution of N-fixing blue green algae in fish culture. Anabaena siamensis Antarikanonda was selected for this study. Culture in N-free BG-11 medium Anabaena siamensis exhibits a specific growth rate of 0.32/day with highest biomass of 320 ± 0.43 mg/L (dry weight). The maximum productivity was 35.7 mg/L/day (dry weight). The half-saturation constants (Ks) or substrate concentration at which specific growth rate was one-half of the maximum growth rate for NH4+ and NO3- predicted by Monod model was 0.32 mgNH4-N/L and 0.37 mgNO3-N/L, respectively. The half-saturation constant (Ks) or substrate constant at which the uptake rate was one-half of the maximum rate equal to 0.36 mgNH4-N/L. Nitrogen fixation are rate was determined in vivo by nitrogenase activity using acetylene reduction method. The highest nitrogenase activity was detected in logarithmic growth phase at 5.15 ± 1.34 μgN/h/g algae under artificial light illumination of 3000 lux. Some factors affecting nitrogenase activity were evaluate. The addition of nitrogen compounds suppressed nitrogenase activity. The effect of temperature on nitrogenase activity in this study showed that title activity occurred at 20 °C and the maximum was 23.8 ± 0.7 μgN/h/g algae at 40 °C. Rate of nitrogen fixation reached 147.9 ± 22.55 μgN/h/g algae under natural lighting of 8000 lux. The total nitrogen fixed by Anabaena siamensis was 40.89 ± 0.14 mgN/L and the maximum rate was 4.16 mg/L/day in 20 days of experimental period. Total nitrogen and protein contents of Anabaena siamensis ranged from 118.7 ± 1.78 to 325.9 ± 13.46 mg/g dW (10.94 to 32.6%) and 21.6 to 24.4% of dry weight, respectively; the higher values were in logarithmic growth phase. In lograrithmic growth phase, the total nitrogen in algal biomass contained 71.2% protein nitrogen and 28.8% non-protein nitrogen. In contrast, in stationary phase, protein nitrogen was about 27.98% and non-protein nitrogen was about 72.02%. Nitrogen release from dark incubation of culture of Anabaena showed that 93.7% of initial total nitrogen in algae was released to the medium in 20 days, giving 19.48 ± 0.64 mg/L soluble nitrogen concentration. The direct diet contribution of N-fixing blue-green algae to fish, was verified through feeding of herbivorous fish, Oreochromis niloticus, Cirrhinus mrigala, Puntius gonionotus. The ingestion rates of experimental fish were significantly differences among those species (p < 0.05). The highest ingestion rate of algal suspension was Oreochromis niloticus (2.73 mg dW/fish/h) and the lowest ingestion rate was Puntius gonionotus (0.98 mg dW/fish/h). The ingestion rate of Cirrhinus mrigala was 1.20 mg dW/fish/h. The protein digestibility of experimental fish was significantly different (p < 0.05). The highest protein digestibility was Puntiuse gonionotus (88.5%) and the lowest protein digestibility was Oreochromis niloticus (63.52%). The protein digestibility showed an inverse relationship with ingestion rate in all experimental fish. Body weight, protein and ash contents of all experimental fish increased, while moisture and crude lipid decreased after stocked in algal culture units for 20 days. It is indicated that the protein provided by Anabaena siamensis alone in this experiment was not sufficient to maintain the minimum requirement for experimental fish growth |
| Year | 1996 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. AE-96-03 |
| Type | Dissertation |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Agricultural and Food Engineering (AE) |
| Chairperson(s) | Lin, C. Kwei.; |
| Examination Committee(s) | Yakupitiyage, Amararatne;Rakshit, Sudip K;Boyd, Claude K.; |
| Scholarship Donor(s) | Royal Thai Government; |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 1996 |