1996 Fiscal Year Final Research Report Summary
Studies on the control of environmental bacterial flora for mass production of food microalgae
| Project/Area Number |
06660243
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
General fisheries
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| Research Institution | Nagasaki University |
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Principal Investigator |
HIRAYAMA Kazutsugu Nagasaki Univ., Faculty of Fisheries, Professor, 水産学部, 教授 (80039718)
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| Co-Investigator(Kenkyū-buntansha) |
HAGIWARA Atsushi Nagasaki Univ., Faculty of Fisheries, Associate Professor, 水産学部, 助教授 (50208419)
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| Project Period (FY) |
1994 – 1995
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| Keywords | Coexistence bacteria / Diatom Chaetoceros gracilis / Nannochloropsis oculata / Growth promoting factor / Biocontrol / Larval culture / Food organisms |
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| Research Abstract |
1) Growth promoting effects of bacterial coexistence on marine diatom Chaetoceros gracilis
When each of 12 bacterial strains isolated from diatom mass culture tanks, was added into the axnic culture of the diatom, Chaetoceras gracilis, only one strain, Fravobacterium sp.greatly promoted the diatom growth. In practical mass cultures of three marine microalgae (C.gracilis, Isochrysis galbana and Pavlova Iutheri) using 5 l flasks in indoor culture system, this bacterial strain was inoculated together with the microalgae at the inoculation. The maximum cell density of macroalgae was significantly higher than that in the control culture, and the stationary growth phase lasted longer than that of control.
2) Growth-suppressing effect of the contaminated substances in one lot of NaCl special grade reagent on the population growth of so-called marine Chlorella and the elimination of the effect by the coexistence of bacterial strain.
I cultured so-called marine Chlorella Nannochloropsis oculata in ASP6 medium prepared by some lots of NaCl special grade reagents, and then found one lot which did not support the algal growth. This contaminated substances were made clear as the organic substnces having less than 500 molecular weight. If the alga was cultured together with the bacterial strain Fravobacterium sp., it grew steadily as well as in ASP6 prepared by another lot Nacl. This fact tells us that this bacterial strains has the special ability for adsorption or absorption of these contaminated substances.
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