Cultivation of Arthrospira platensis in heterotrophic and mixotrophic conditions with different concentrations of whey

Wastes left over from human food production is commonly used to produce feed for animals, which is an important issue for a rational utilization of food sources globally, and a topic that attracts researcher for the establishment of best food production management. Whey as a side product from cheese production has great potentials in terms of nutritional value for both human food and animal feed production. This study aimed to investigate the possible use of whey (1, 10 and 30%, v/v) as an external carbon source for mixotrophic and heterotrophic cultivation of the cyanobacterium Arthrospira platensis. The highest specific growth rate (µ = 0.2 day-1), protein (3.76 ±0.14 mg/ g cell) and lipid (4.67 ±0.18 mg/g cell) contents were detected in heterotrophic culture while the highest chlorophyll-a (292.39 ±1.31 mg/ g cell) and total carbohydrate (1.42 ±0.07 mg/ g cell) contents were found in mixotrophic culture. In heterotrophic cultivation, it can be noted that the absorbed organic carbon source increased cell counts and triggered especially lipid production. In the mixotrophic cultivation, carbon absorbed from the culture medium or CO2 captured with chlorophyll was utilized in the production of total carbohydrate. This study provides evidence that a cyanobacterium can adapt to heterotrophic conditions without light, creating an example for an economic and ecological production model for biochemical components.