Characterization of a novel thermophilic cyanobacterial strain from Taian hot springs in Taiwan for high CO2 mitigation and C-phycocyanin extraction

The photosynthetic thermophiles have advantage in sequestering CO₂ emitted from the energy sector due to their adaptation to high temperatures, growth at high concentrations of CO₂, and economically important metabolites. The characterization of such a microorganism, a cyanobacterium from Taian hot springs in Taiwan is described here. This thermophilic cyanobacterium is rod-shaped with a size of 1.2–2.5 μm × 6.0–9.0 μm. A comparison of the 16S RNA and cpcBA-IGS sequences revealed that it is closely related to Thermosynechococcus elongatus BP-1 and so named as Thermosynechococcus elongatus TA-1. This cyanobacterium has better growth at 10% and 20% CO₂, at 50 °C with 6000 lx light intensity, at a starting pH of 7–9 and in a medium with 20 mM NaCl. The preferred nitrogen source is NaNO₃ of which the minimal requirement is 10 mM. The purified phycocyanin (C-PC) from TA-1 is still kept native and active at a wide range of temperatures (4–60 °C) with a 65.65% activity even at 60 °C, as well as pH values from 4 to 9 and thus exhibiting a good thermal and acid–base stability. This thermophilic cyanobacterium could make integration of CO₂ mitigation from industrial flue gas and production of economically important product, like C-PC, more feasible.