UTEX 3222

UTEX 3222 is a strain of the species Cyanobacterium aponinum, that was discovered off the coast of Baia di Levante, Italy.^[2] This cyanobacteria exhibits fast, high density, unicellular, planktonic growth while displaying quick settling rates in liquid.^[2] With the addition of its cyanobacterial photosynthetic function and its high carbon biomass composition, UTEX 3222 seems potentially useful for atmospheric CO₂ sequestration and optimizing bioproduction within industry.^[2]

UTEX 3222 demonstrates fast growth on solid, BG-11 freshwater medium, with a wide tolerance for growing conditions.^[2] Optimal growth rate has been achieved at a temperature of 45℃, a temperature somewhat higher than used for other cyanobacteria models.^[2] A pH of 6.5-9.8 was tolerated by UTEX 3222 with the fastest exponential growth found at pH 6.5 and highest cell density at pH 8.^[2] Moderate salinity (10g/L NaCL) produced fastest growth, yet UTEX 3222 exhibited high salt tolerance. In addition, an irradiance of 1,500 µE is tolerated but growth rates reach capacity at 500 µE.^[2] In optimal conditions, UTEX 3222 has displayed a fast doubling time of 2.35 ± 0.10 hours.^[2] As well, UTEX 3222 grows to high density (>31 g/L biomass dry weight after 12 days) in batch culture, producing larger colonies than record setting UTEX 3154.^[2]

Extracellular polysaccharides (EPS) and storage granules are common carbon storage structures within cyanobacteria.^[2] These structures appear more prominent in size and number in UTEX 3222, compared to the high-density growing cyanobacteria, UTEX 3154.^[2] These structural differences account for UTEX 3222's higher carbon content as revealed in biomass composition analysis and C/H/N elemental analysis.^[2]

In liquid cultures, UTEX 3222 aggregates into tight pellets within hours and settles quickly. The biomass of UTEX 3222 settles faster than the comparison strain, UTEX 3154, with a gravitational sinking velocity 2.16x quicker.^[2] The difference in sinking velocity is primarily due to UTEX 3222's greater cell volume rather than buoyant density.^[2] The dramatic difference in settling overnight and the speed at which UTEX 3222 forms a supernatant, cannot fully be explained by sinking velocity, indicating there are other factors involved such as cell aggregation.^[2]

Cyanobacterium aponinum UTEX 3222 was discovered in 2024 when Schubert et al. explored shallow volcanic seeps off the coast of Baia di Levante in Vulcano Island, Italy.^[2] The team was investigating illuminated marine areas with high CO₂ levels, hoping to find organisms that had evolved enhanced fitness, as adaptations would not need to focus on limitations in CO₂ availability.^[2] The closest known relative to UTEX 3222 is Cyanobacterium aponinum PCC 10605, yet the whole clade remains relatively unstudied.^[2]