Evaluation of growth and biomass production of Arthrospira (Spirulina) fusiformis in laboratory cultures using waters from the Ethiopian soda lakes Chitu and Shala

摘要

The cost of nutrient media is the major challenge for biomass production of Spirulina. Although much effort has been made to use enriched seawater for the cultivation of this microalga, little attention has been given to the potential of water of soda lakes. In this study, growth (mu, day(-1)) and biomass production (B) of Arthrospira fusiformis cultivated using waters of the soda lakes Chitu and Shala with or without supplementation were evaluated. Comparable mu and B values were achieved in both Lake Chitu water-based media (CBM) and Lake Shala water-based media (SBM), with slightly higher values in the latter. Both CBM and SBM supplemented with the standard Spirulina medium (SM) by 25 % and 50 % supported considerably higher mu and B. The pH and salinity of the cultures showed significant variations (P 0.05) among the media and had considerable effect on mu and B. The observed higher mu and B were probably associated with the reduction in pH and salinity of the supplemented media due to addition of bicarbonate-carbonates and dilution, and provision of the limiting nutrient nitrogen. The higher mu and B in SBM may have resulted from some of their aggregate chemical parameters, which were closer to those in the SM, and abundant PO4-P. This seems to suggest that Lake Shala water is more conducive to Arthrospira. We contend that 25 % and 50 % supplemented Lake Shala water can be preferably used to produce Arthrospira biomass, thereby reducing the cost of nutrients by 75 % and 50 %, respectively.