Incubation of Cyanobacteria under Dark, Anaerobic Conditions and Quantification of the Excreted Organic Acids by HPLC.

Succinate and lactate are commodity chemicals used for producing bioplastics. Recently, it was found that such organic acids are excreted from cells of the unicellular cyanobacterium sp. PCC 6803 under dark, anaerobic conditions. To conduct the dark, anaerobic incubation, cells were concentrated within a vial that was then sealed with a butyl rubber cap, following which N gas was introduced into the vial. The organic acids produced were quantified by high-performance liquid chromatography via post-labeling with bromothymol blue as a pH indicator. After separation by ion-exclusion chromatography, the organic acids were identified by comparing their retention time with that of standard solutions. These procedures allow researchers to quantify the organic acids produced by microorganisms, contributing to knowledge about the biology and biotechnology of cyanobacteria.