Growth relationships of a lipid-producing Chlorella-alga with common microalgae in laboratory co-cultures

Research paper by Yu Hong, Ke Xu, Jingjing Zhan

Indexed on: 06 Aug '14Published on: 06 Aug '14Published in: Microbiology


Co-existence growth relationships were studied in communities consisting of a lipid-producing alga Chlorella sp. HQ, another green alga and one cyanobacterium: I Scenedesmus obliquus and Microcystis aeruginosa; II Chlamydomonas reinhardtii and Anabaena flos-aquae; III Selenastrum capricornutum and Microcystis wesenbergii. The cyanobacteria and green algae except for Chlorella sp. HQ were commonly detected in Chinese reservoir and wastewater. The rate of increase of apparent cell number difference with other algae (kapp), inhibition/stimulation ratio (ISR) and the parameters of logistic model and co-existence model were determined for Chlorella. Chlorella strains were the most competitive in Combination I, and were stimulated during 75% of the cultivation time for all three combinations. Anabaena growth exceeded those of Chlorella and Chlamydomonas on the 5th cultivation day under 1 : 1 : 1 inoculum ratio. Scenedesmus colonies consisted of fewer cells, whose average length significantly shortened after the 5th cultivation day under 1 : 1 : 1 inoculum ratio. The developed co-existence model can identify the concrete growth inhibitor or stimulator among three species compared with the single method of cell number monitoring. Good correlation was found between transformed and non-transformed co-existence model through amn and bmn values. Allelopathy and nutrient competition are both possible mechanisms in the above growth relationships.