Physiological responses of carbon-sequestering microalgae to elevated carbon regimes

Abstract

In order to identify a high carbon-sequestering microalgal strain, the physiological effect of different concentrations of carbon sources on microalgae growth was investigated. Five indigenous strains (I-1, I-2, I-3, I-4 and I-5) and a reference strain (I-0: Coccolithus pelagicus 913/3) were subjected to CO 2 concentrations of 0.03-15% and NaHCO 3 of 0.05-2 g CO 2 l-1. The logistic model was applied for data fitting, as well as for estimation of the maximum growth rate (μ max) and the biomass carrying capacity (B max). Amongst the five indigenous strains, I-3 was similar to the reference strain with regards to biomass production values. The B max of I-3 significantly increased from 214 to 828 mg l-1 when CO 2 concentration was increased from 0.03 to 15% (r = 0.955, P = 0.012). Additionally, the B max of I-3 increased with increasing NaHCO 3 (r = 0.885, P = 0.046) and was recorded at 153 mg l-1 (at 0.05 g CO 2 l-1) and 774 mg l-1 at (2 g CO 2 l-1). Relative electron transport rate (rETR) and maximum quantum yield (F v /F m) were also applied to assess the impact of elevated carbon sources on the microalgal cells at the physiological level. Isolate I-3 displayed the highest rETR confirming its tolerance to higher quantities of carbon. Additionally, the decline in F v /F m with increasing carbon was similar for strains I-3 and the reference strain. Based on partial 28s ribosomal RNA gene sequencing, strain I-3 was homologous to the ribosomal genes of Chlorella sp.

A co-cultivation process of Nannochloropsis oculata and Tisochrysis lutea induces morpho-physiological and biochemical variations potentially useful for biotechnological purposes

“…This difference was considered and used to correct the values recorded from gradient-treated co-cultivated cells. In microalgae, F v /F M values of about 0.6 indicate an efficient use of light in the photosynthetic processes (White et al 2013;Sirin and Sillanpää 2015;Bhola et al 2016). F V /F M was higher in mono-cultivated than in the cocultivated cells (Fig.…”

“…The low F V /F M values is in line with the lower growth observed in co-culture and indicates a stress condition of the microorganisms; in fact, the analysis of the PSII maximum quantum yield by PAM fluorimetry allows an estimate of the photosynthetic efficiency and can be used as a parameter to evidence the physiological stress in microalgae (Cosgrove and Borowitzka 2010;Ramanna et al 2014;Dao and Beardall 2016). In microalgae, F V /F M values higher than 0.6 indicate good conditions of growth and an efficient use of light for photosynthesis, a condition met in mono-cultures (White et al 2013;Sirin and Sillanpää 2015;Bhola et al 2016). Lower F V /F M values were generally reported under nutrient deficiency or very dense cultures or light-stressed cultures (Beardall et al 2001a, b;Baldisserotto et al 2014;Benvenuti et al 2015).…”

Cultivation of hydrocarbon-tolerant microalgae in flowback wastewaters produced during hydrofracking of impermeable rocks

“…Logistic models have been widely applied in the literature to capture the growth behaviour of microalgae strains. 17,18 Model parameters were evaluated by tuning their values to obtain the best agreement between model simulations and experimental data. It should be noted that the fitted value of 𝑋 !…”

Developments in the Cryopreservation of Marine Dinoflagellates

“…In microalgae, assessment of their photosynthetic efficiency and variability in chlorophyll fluorescence can be done using Pulse Amplitude Modulation (PAM) fluorometry (Oxborough et al, 2000, Schreiber et al, 2002, Baker, 2008, Stirbet & Govindjee, 2011. Measuring photosystem II (PSII) quantum efficiency via PAM fluorometry is one of the most well used, rapid and non-invasive techniques to evaluate the physiological state of phytoplankton (Juneau et al, 2005, Lombardi & Maldonado, 2011, Bhola et al, 2016.…”