S. Hirata et al., EFFECT OF TEMPERATURE ON CHANGE IN CELL D IAMETER OF CHLORELLA SP. UK-001 IN PHOTOAUTOTROPHIC CULTURE, Kagaku kogaku ronbunshu, 23(2), 1997, pp. 200-207
Chlorella sp. UK 001 cells were cultivated under a photoautotrophic co
ndition, utilizing carbon dioxide and light as carbon and energy sourc
es, respectively. In batch cultures of the cells for 96 h at incident
light intensity (I-0) of 21.8 W m(-2), when the culture temperature (T
) was kept at 40 degrees C, mean diameter of the cells (<(d)(c) over b
ar>) increased from 2.3 mu m (standard deviation (SD) = 0.36 mu m) to
11 mu m (SD = 1.9 mu m), while at T = 20, 30, 35 and 45 degrees C, the
Values of a hardly changed. Under the conditions examined, the apprec
iable enlargement of the cells occurred at T = 40 degrees C and at I-0
= 16 to 46 W m(-2), and was not accompanied by a substantial increase
in the number of cells. From the data on cell viability, oxygen gener
ation rate under light conditions and oxygen consumption rate under da
rk conditions, the enlarged cells in the culture at 40 degrees C were
found to have sufficient activities as living cells. Sedimentation exp
eriments were carried out by standing the cells which were cultivated
at 30 and 40 degrees C. The interfacial sedimentation rate of the cell
s ((d) over bar(c) = 11 mu m, SD = 1.9 mu m) obtained from the culture
at 40 degrees C was about twelve times higher than that of cells ((d)
over bar(c) = 2.3 mu m, SD = 0.38 mu m) at 30 degrees C.