Submerged membrane photobioreactor for the cultivation of Haslea ostrearia and the continuous extraction of extracellular marennine

Haslea ostrearia is a marine diatom known to produce and excrete the marenine blue pigment. Its controlled, continuous and intensified cultivation remains a challenge. Thus, a submerged membrane photobioreactor (MPBR) was implemented in order to simultaneously and continuously cultivate H. ostrearia and extract marennine. The MPBR was compared with a similar air-lift photobioreactor (without membrane), both working at a dilution rate equal to 0.1, 0.3 and 0.5 d^-1. Contrary to the air-lift photobioreactor, the MPBR successfully operated at high dilution rate without biomass washout. The MPBR allowed continuously recovering marennine and reaching high cell density (555 ± 25 × 10⁶ cells L^-1 at D = 0.1 d^-1), marennine concentration (36.00 ± 0.02 mg L^-1 at D = 0.1 d^-1) and marenine productivity (7.20 ± 0.01 mg L^-1 d^-1 at D = 0.5 d^-1).

Potential of Exopolysaccharide from Porphyridium marinum to Contend with Bacterial Proliferation, Biofilm Formation, and Breast Cancer

Exopolysaccharide (EPS) from marine microalgae are promising sources of a new generation of drugs. However, lot of them remain to be discovered and tested. In this study, EPS produced by Porphyridium marinum and its oligomers prepared by High Pressure Homogenizer have been tested for different biological activities, i.e., antibacterial, anti-fungal and antibiofilm activities on Candida albicans, as well as for their effects on the viability of murine breast cancer cells. Results have shown that all EPS samples present some biological activity. For antibacterial and antibiofilm activities, the native EPS exhibited a better efficiency with Minimum Inhibitory Concentration (MIC) from 62.5 µg/mL to 1000 µg/mL depending on the bacterial strain. For Candida albicans, the biofilm formation was reduced by about 90% by using only a 31.3 µg/mL concentration. Concerning breast cancer cells, lower molar masses fractions appeared to be more efficient, with a reduction of viability of up to 55%. Finally, analyses of polymers composition and viscosity measurements were conducted on all samples, in order to propose hypotheses involving the activities caused by the intrinsic properties of polymers.

New horizons in culture and valorization of red microalgae

Research on marine microalgae has been abundantly published and patented these last years leading to the production and/or the characterization of some biomolecules such as pigments, proteins, enzymes, biofuels, polyunsaturated fatty acids, enzymes and hydrocolloids. This literature focusing on metabolic pathways, structural characterization of biomolecules, taxonomy, optimization of culture conditions, biorefinery and downstream process is often optimistic considering the valorization of these biocompounds. However, the accumulation of knowledge associated with the development of processes and technologies for biomass production and its treatment has sometimes led to success in the commercial arena. In the history of the microalgae market, red marine microalgae are well positioned particularly for applications in the field of high value pigment and hydrocolloid productions. This review aims to establish the state of the art of the diversity of red marine microalgae, the advances in characterization of their metabolites and the developments of bioprocesses to produce this biomass.