Optimal Laboratory Cultivation Conditions of Limnospira maxima for Large-Scale Production

Abstract

Cultivating Limnospira maxima, renowned for its abundant proteins and valuable pigments, faces substantial challenges rooted in the limited understanding of its optimal growth parameters, associated high costs, and constraints in the procurement of traditional nitrogen sources, particularly NaNO₃. To overcome these challenges, we conducted a comprehensive 4 × 3 factorial design study. Factors considered included white, red, blue, and yellow light spectra, along with nitrogen sources NaNO₃ and KNO₃, as well as a nitrogen-free control, for large-scale implementation. Optimal growth, measured by Optical Density, occurred with white and yellow light combined with KNO₃ as the nitrogen source. These conditions also increased dry weight and Chl-a content. Cultures with nitrogen deprivation exhibited high values for these variables, attributed to carbon accumulation in response to nitrogen scarcity. Phycocyanin, a crucial pigment for nutrition and industry, reached its highest levels in cultures exposed to white light and supplemented with KNO₃, with an impressive content of 384.11 g kg^-1 of dry weight. These results highlight the efficacy and cost-efficiency of using a combination of white light and KNO₃ for large-scale L. maxima cultivation. This strategy offers promising opportunities to address global food security challenges and enhance the production of industrially relevant pigments.

Keywords: Arthrospira maxima; biomass production; cyanobacteria; food security; nitrogen source; phycobiliproteins.

Figure 1

Effect of light spectra and nitrogen source on optical density of Limnospira maxima cultivated under white, red, blue, and yellow light spectra, supplemented with NaNO₃, KNO₃, and a control (WN). The values presented in the figure represent the means (±standard error) of optical density. When focusing exclusively on the 27-day Limnospira maxima cell suspensions, the most favorable results were achieved under both white and yellow LEDs. In the assessment of nitrogen sources, it was observed that both KNO₃ and NaNO₃ yielded comparable performance, with no statistically significant differences between them.

Figure 2

Impact of light spectra and nitrogen source on dry weight of Limnospira maxima cultivated under white, red, blue, and yellow light spectra, supplemented with NaNO₃, KNO₃, and a control (WN). The values presented in the figure represent the means (±standard deviation) of dry weight. Dry weight trends mirror those observed for optical density (OD), underscoring the superiority of white and yellow LEDs. Remarkably, over the 27-day period, the W-WN condition demonstrated a significant.

Figure 3

Influence of light spectra and nitrogen source on chlorophyll “a” concentration in Limnospira maxima. This figure illustrates the influence of varying light spectra and nitrogen sources on chlorophyll “a” concentration in Limnospira maxima cultures. The cultures were supplemented with NaNO₃, KNO₃, or maintained as controls (WN) under white, red, blue, and yellow light spectra. When specifically considering the 27-day L. maxima cell suspension, the most favorable outcomes were observed in the W-WN condition, followed by W-KNO₃, Y-NaNO₃, Y-WN, and R-NaNO₃. Interestingly, blue LEDs and all other nitrogen sources under the red light consistently exhibited lower values throughout the study.

Figure 4

Effect of light spectra and nitrogen source on total carotenoid concentration in Limnospira maxima. This figure illustrates the influence of light spectra and nitrogen sources on the total carotenoid concentration in Limnospira maxima when grown under white, red, blue, and yellow light spectra. The cultures were supplemented with NaNO₃, KNO₃, and a control (WN). When specifically focusing on the 27-day cell suspensions, the highest carotenoid concentration was observed in the following order: W-NaNO₃, B-WN, W-KNO₃, and Y-WN.

Figure 5

Impact of light spectra and nitrogen source on phycocyanin concentration in Limnospira maxima cultivation. This figure demonstrates the influence of various light spectra and nitrogen sources on the concentration of phycocyanin in Limnospira maxima cultures. The cultures were supplemented with NaNO₃, KNO₃, or maintained as controls (WN) under white, red, blue, and yellow light spectra. At the conclusion of the 27-day cultivation period, the sequence of phycocyanin concentration was as follows: W-KNO₃, W-NaNO₃, Y-NaNO₃, R-NaNO₃, Y-KNO₃.

Figure 6

Effect of light spectra and nitrogen source on allophycocyanin concentration in Limnospira maxima. This figure examines the impact of different light spectra and nitrogen sources on the concentration of allophycocyanin in Limnospira maxima cultures. The cultures were supplemented with NaNO₃, KNO₃, or maintained as controls (WN) under white, red, blue, and yellow light spectra. Focusing exclusively on the 27-day treatments of L. maxima cell suspensions, it becomes evident that R-NaNO₃ was the most productive treatment for allophycocyanin.

Figure 7

Effect of light spectra and nitrogen source on phycoerythrin concentration in Limnospira maxima. This figure explores the influence of different light spectra and nitrogen sources on the concentration of phycoerythrin in Limnospira maxima cultures. The cultures were supplemented with NaNO₃, KNO₃, or maintained as controls (WN) under white, red, blue, and yellow light spectra. Similar to allophycocyanin, phycoerythrin exhibited higher concentrations under the red LEDs.

Figure 8

Effect of light spectra and nitrogen source on soluble protein concentration in Limnospira maxima. This figure investigates the influence of different light spectra and nitrogen sources on the concentration of soluble proteins in Limnospira maxima cultures. The cultures were supplemented with NaNO₃, KNO₃, or maintained as controls (WN) under white, red, blue, and yellow light spectra. Soluble proteins exhibited a distinct pattern when compared to the other proteins described earlier. In the case of the 27-day L. maxima cell suspension, the highest concentration was observed in the Y-WN condition.

Figure 9

Multivariate analysis of light and nitrogen source effects on various features of Limnospira maxima cultivated in different light spectra (white, red, blue, and yellow), supplemented with NaNO₃, KNO₃, and control (WN). (A) The figure depicts a five-group clustering of treatments based on their similarities. (B) The diagram illustrates the strength of each feature’s influence on L. maxima growth, as observed through the increase in optical density (OD) and dry weight (DW). All measurements were taken after 27 days of L. maxima growth. Allophy refers to allophycocyanin; Phyco represents phycoerythrin; Proteins indicates soluble proteins; Chl “a” signifies chlorophyll a.