Integration Bioprocess of B-Phycoerythrin and Exopolysaccharides Production From Photosynthetic Microalga Porphyridium cruentum

Hao-Chan Yin,Tian-Zhong Liu,Hui Wang,Ji-Kang Sui,Tian-Li Han

doi:10.3389/fmars.2021.836370

Abstract

Red microalgaPorphyridium cruentumhas great potential for converting CO2into high-value bioactive compounds, such as B-phycoerythrin (B-PE) and extracellular polysaccharides or exopolysaccharides (EPS). This study aimed to establish the integration bioprocess of B-PE and EPS production fromP. cruentum. First, different kinds of growth medium and CO2concentration were assessed indoor in terms of high biomass and B-PE and EPS contents. As follows,P. cruentumcells were outdoor scale-up cultured in 700 L pressurized tubular reactors for 9 days till the biomass reached 0.85 g/L and then separated from supernatantsviacentrifugation. Three different methods were adopted to extract phycobiliproteins, and the highest PE contents were extracted from cells by repeated freeze-thawing treatment along with the optimization of significant variables, and finally, 7.99 mg/L B-PE (16,500 Da) with a purity index of 0.82 was obtained. Moreover, analysis of physicochemical properties of EPS extracted fromP. cruentumshowed that the sulfate content was 14.85% and the uronic acid content was 9.36%.

Highlights

Microalgae are photoautotrophic microorganisms that use light energy, CO2, and inorganic nutrients to synthesize valuable biomass compounds
Microalga P. cruentum was cultivated in different mediums for 15 days, and the biomass, PE, and EPS contents were analyzed every 3 days
The lowest biomass production was observed at the f/2 culture medium, the maximum specific growth rate and productivity f/2 culture medium

Summary

Introduction

Microalgae are photoautotrophic microorganisms that use light energy, CO2, and inorganic nutrients to synthesize valuable biomass compounds. Porphyridium cruentum (Rhodophyta, Porphyridiophyceae, Porphyridiales, Porphyridiaceae, Prophyridium) is a spherical unicellular red alga without an organized cell wall (Arad et al, 1985; Adda et al, 1986; Vonshak, 1988; Arad and Levy-Ontman, 2010) This microalga is Integration Bioprocess Production From Microalga photoautotrophic and can capture light and CO2 into cells to convert them into abundant active molecules. PE has the advantages of high fluorescence intensity, antioxidation, scavenging free radicals, and high chroma It has a wide range of commercial value in food (Fuentes et al, 2000; Gonzalez-Ramirez et al, 2014; Bueno et al, 2020), cosmetics, and pharmaceutical industries and is used as a fluorescent marker, which is dependent on its purity (Koller et al, 1977; Ayyagari et al, 1995; Qiu et al, 2004). Many methods, such as ultrastructure, salting out, column chromatography, and aqueous two-phase system, have been developed for the recovery and purification of B-PE ( Breccia et al, 1998; Romána et al, 2002; Benavides and Rito-Palomares, 2004; Parmar et al, 2011)

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