This work was conducted to study the possibility of cultivating algae for use as fish feed using vegetable and fruit canning industry wastewater treatment effluent. The results showed that Chlorella vulgaris showed successful growth in 10% initial stock solution, 20 cm water depth and for 12 days of cultivation. The algae attained a cell density of 13.72 × 10 5 cells/mL, biomass dry weight of 255 mg/L and protein content of 45.6%. Dried algae were used as a feed additive for tilapia (Oreochromis niloticus L.) cultivated in a vegetable and fruit canning industry oxidation pond. After 3 months of cultivation, fish fed 3% dried algae had a higher (P<0.05) fish survival rate and percentage weight gain than the fish fed only the commercial feed.
This research aimed to study the efficiency of free-living nitrogen fixing bacteria isolated from the samples of rice rhizosphere soil on auxin and gibberellin production. The samples of the rhizophere soil were collected from different areas. The amount of colony of isolated bacteria was counted by using plate count method. The result revealed that 183 isolated bacteria were obtained from soil samples of the organic rice fields, the amount of colony at 1.6x10 6-2.0x10 7 cfu/g and the 127 isolated bacteria were obtained from soil samples of the chemical rice fields, the amount of colony at 1.2x10 3-1.9x10 5 cfu/g. Nitrogen fixation was tested by using bromothymol blue reagent indicator method and selecting of free-living nitrogen fixing bacteria was found of 26 isolates. Auxin production test of the selected nitrogen fixing bacteria was conducted by using tryptophan as an initial sabstance and the amount of auxin was analyzed by using Salkowski coloring reagent method. The result showed that 6 isolates produced the most auxin by using tryptophan concentrations of 1,000 μg/mL and the isolate PY7-6 produced the most auxin of 23.9 mg/L, while the rest, LP8-1, CR1-2, CM12-4, PY7-5 and CM5-2, produced auxin from 7.0 to 22.3 mg/L. Gibberellin production test and gibberellin content analysis by HPLC revealed that 2 isolates: CM12-4 and LP8-1 could produced gibberellin at 13.74 and 3.94 mg/L, respectively. Classification of bacteria from sequence analysis of the 16S rRNA gene indicated that there were 4
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