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Simultaneous control of turbidity and dilution rate through adjustment of medium composition in semi‐continuous Chlamydomonas cultures

2006; Wiley; Volume: 94; Issue: 4 Linguagem: Inglês

10.1002/bit.20884

1097-0290

Isamu Maeda, Yoshiaki Seto, Shunsaku Ueda, Yukoh Cheng, Junko Hari, Masaya Kawase, Hitoshi Miyasaka, Kiyohito Yagi,

Marine Bivalve and Aquaculture Studies

Abstract For production of starch in algal cultures, a growth rate limited by a nutrient is an important factor. Under phototrophic conditions, turbidity must be also paid attention, as the shading effect may affect its productivity. Semi‐continuous cultivation methods, which enable control of turbidity and dilution rate ( D ) at the same time, have been developed for evaluation of those factors on starch production in Chlamydomonas sp. A specific feature of the methods is in a process of alternately feeding medium adjusted at two different nitrogen (N) concentrations. In the turbidostat‐based method, a turbidostat culture was operated repeating three steps of determining D within a preset interval, alternating media by comparing the D with a preset value, and adjusting D in the next interval by feeding the selected medium. In the chemostat‐based method, turbidity of a chemostat culture was controlled by repeating two steps of alternating media by comparing transmitted photon flux intensity ( I ) with a preset value and adjusting I by feeding the selected medium. D controlled by the turbidostat‐based method reached quickly a preset value as low as 0.010/h, and then it was dispersed around but above the preset value. On the other hand, mean N concentrations of fed media formed a plateau. In the chemostat‐based method, I was well controlled to a preset value while the mean N concentrations were a bit fluctuated. Starch concentration varied from 0.052 to 0.41 g/L with turbidity and D defined by these methods. © 2006 Wiley Periodicals, Inc.