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.

► Here, the thermophilic cyanobacterium belongs to Thermosynechococcus with a potential for CO2 mitigation and C-phycocyanin production.
► The significance of this thermophile is its ability to grow in an environment with 20% CO2 at 50 °C and thus has the potential for CO2 sequestration from industrial flue gases.
► The phycocyanin extracted from the biomass showed better thermo and acid–base stability than those so far reported.