Comparisons of growth and biochemical composition between mixed culture of alga and yeast and monocultures.

The alga Isochrysis galbana 8701 and the yeast Ambrosiozyma cicatricosa were mix-cultivated in the same medium for 7 d to compare their growth performance and biochemical composition with those of the same organisms cultured under monoculture conditions. The specific growth rates of both species were significantly higher (p<0.05) in the mixed culture than in the monocultures during the corresponding experimental phases. At the end of experiment, the biomass concentration obtained in the mixed culture reached 1.32+/-0.04 g/l of dry weight, which was significantly higher (p<0.05) than those obtained in monocultures, and the alga I. galbana in the mixed culture dominated the cell numbers making up 96.64% of the cells. The biochemical profile of the mixed culture is similar to that of the I. galbana monoculture with some variations; The percentages of both the fatty acids 14:00 and 18:00 detected in the mixed culture were significantly higher (p<0.05) than those detected in the I. galbana monoculture, while the content of the fatty acid 18:2(n-6) detected in the mixed culture was significantly lower (p<0.05) than that detected in the I. galbana monoculture. This study indicates the improved growth performance in mixed culture compared with monocultures and the similarities between the biochemical compositions of the mixed culture and the I. galbana monoculture.