| Author | Baiq Hana Susanti |
| Call Number | AIT Thesis no. AS-98-09 |
| Subject(s) | Microalgae
|
| Note | A thesis submitted for partial fulfilment of the requirements for the degree of
Master of Science, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Abstract | Preservation of marine microalgae is of interest for storage of culture collection as well as
a method for having living biomass available for aquaculture feeds. The development of
a simple and reliable method without an expensive programmable system would
accelerate the spread of the cryopreservation technique. The present paper repo1ts the
cryopreservation of two marine microalgae species; Tetraselmis chuii and Chaetoceros
gracilis using dimethyl sulfoxide (DMSO), glycerol and ethylene glycol as
cryoprotectants.
In the first experiment, Tetraselmis chuii grew exponentially from 24 hours to 138 hours.
The cell density peaked at 136 hours, then the population decreased until the end of the
experiment. Chaetoceros gracilis started the exponential phase from 12 hours after
incubation until 168 hours. The stationary phase staited at 172 hours, then began to
decline until the end of this experiment.
The cells from the exponential phase growth were harvested and cryopreserved. The
cryoprotectants were added gradually over period of 15 minutes, followed by an
equilibrium period of 45 minutes. The cells were frozen to -4°C in a commercial freezer
for 3 Yi hours (-4°C), then prefrozen in a deep freezer for 4 hours (-20°C). Then, the cells
were divided into 2 parts, first were stored in liquid nitrogen and second were kept in a
deep freezer for 1 month.
The best survival after freezing was evaluated by staining with erythrosin B and was 70%
for Tetraselmis chuii and 10% for Chaetoceros gracilis, using 5% DMSO and 10%
glycerol respectively.
These survival rates decreased over time in both storage systems, but in liquid nitrogen
storage, the survival rate decreased more rapidly than in deep freezer. Tetraselmis chuii
totally lost their viability in the 2"d week after storage in liquid nitrogen; but they survived
beyond the 4th week in deep freezer. Chaetoceros gracilis also lost their viability in the
211d week after storage in liquid nitrogen, and lost 100% of survival rate in the 4th week
after storage in deep freezer. It appears that cryopreservation using deep freezer as a
prefreezing equipment was only effective for short time storage and only for Tetraselmis
chuii. The steady decline in survival in liquid nitrogen over a four week period is
surprisingly and merits further research. |
| Year | 1998 |
| Type | Thesis |
| School | School of Environment, Resources, and Development |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Agricultural and Aquatic Systems(AS) |
| Chairperson(s) | Hambrey, John B. ;Steven, Willem F.; |
| Examination Committee(s) | Bart, Amrit ;Mair, Graham; |
| Scholarship Donor(s) | Asian Development Bank ; |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 1998 |