Microalgae are being evaluated for the production of bioenergy (hydrogen and biodiesel), and as potential source of high value compounds such as polyunsatured fatty acids (PUFA), pigments, and bioactive substances. The basic advantages of microalgae over conventional crops are that they do not compete for agricultural land use, do not pollute, the production per hectare is higher, they can use nutrients contained in wastewater (N, P), and flue gas as a source of CO2. Among several biotechnological approaches, photobiological hydrogen production carried out with the model microalga Chlamydomonas reinhardtii has been intensively investigated in the recent years in our laboratories. It was found that sulfur-deprived C. reinhardtii CC124 cultures grown in laboratory photobioreactors (PBRs) equipped with an improved mixing system, the light conversion efficiency can reach 1.6% of PAR (photosynthetically active radiation), and up to 3.2 % of PAR which is remarkably high, with the D1 protein mutant L159I-N230Y which is considered one of the highest worldwide H2 producers. Recently, a strain of Chlorella able to growth both under heterotrophic and autotrophic conditions is being investigated in our institute for hydrogen production. The strain is able to produce hydrogen both under light and dark conditions making it promising for outdoor operations. With this strain, it is possible to circumvent the problems of the sulfur-starvation procedure, which strongly limits the photobiological hydrogen production. However, the use of solar light is mandatory to make the process sustainable and scalable to an industrial level outdoors. A number of PBR designs have been devised and constructed for both production of energy and biomass. Several microalgal species have been selected in the laboratory for their lipid content. Among the marine strains, Nannochloropsis has showed to respond to nutrient stress (N and/or P deficiency) which promote lipid accumulation, with no significant decrease in productivity. This microalga can accumulate very high amount of lipids (up to 70% of the dry biomass) of which over 50% are triglycerides (TAG), the most suitable raw material for biodiesel production. The high amount of TAG after the starving process, makes Nannochloropsis one of the best candidates for large scale oil rich-biomass. Extraction and purification of phycocyanin from the cyanobacterium Arthrospira platensis (Spirulina) is another very promising marketable bio product. In 2018 the global phycocyanin market was valued about 112 million US$, and it is foreseen to reach a value of about 230 million US$ by 2028. PC is largely used in food industry, being one of the very few natural, safe blue colorant available. PC is used as natural cosmetic dye, fluorescent probe and in biomedical research. However, currently the widespread use of PC has been hindered by the high cost of large-scale extraction and, especially, purification, which remains problematic and expensive. The cost of PC as food colorant is relatively low, about US$ 0.35 per gram, because low purity is requested, but for cosmetic use it increases to about US$ 135, and for therapeutic and biomedicine applications, where a higher purity is required, PC cost can reach as much as US$ 4,500 per gram. Recently a simple and rapid method to purify phycocyanin from A. platensis based on membrane chromatography (MC) is being patented by us.
Biohydrogen and bioproducts from microalgae
2019
Abstract
Microalgae are being evaluated for the production of bioenergy (hydrogen and biodiesel), and as potential source of high value compounds such as polyunsatured fatty acids (PUFA), pigments, and bioactive substances. The basic advantages of microalgae over conventional crops are that they do not compete for agricultural land use, do not pollute, the production per hectare is higher, they can use nutrients contained in wastewater (N, P), and flue gas as a source of CO2. Among several biotechnological approaches, photobiological hydrogen production carried out with the model microalga Chlamydomonas reinhardtii has been intensively investigated in the recent years in our laboratories. It was found that sulfur-deprived C. reinhardtii CC124 cultures grown in laboratory photobioreactors (PBRs) equipped with an improved mixing system, the light conversion efficiency can reach 1.6% of PAR (photosynthetically active radiation), and up to 3.2 % of PAR which is remarkably high, with the D1 protein mutant L159I-N230Y which is considered one of the highest worldwide H2 producers. Recently, a strain of Chlorella able to growth both under heterotrophic and autotrophic conditions is being investigated in our institute for hydrogen production. The strain is able to produce hydrogen both under light and dark conditions making it promising for outdoor operations. With this strain, it is possible to circumvent the problems of the sulfur-starvation procedure, which strongly limits the photobiological hydrogen production. However, the use of solar light is mandatory to make the process sustainable and scalable to an industrial level outdoors. A number of PBR designs have been devised and constructed for both production of energy and biomass. Several microalgal species have been selected in the laboratory for their lipid content. Among the marine strains, Nannochloropsis has showed to respond to nutrient stress (N and/or P deficiency) which promote lipid accumulation, with no significant decrease in productivity. This microalga can accumulate very high amount of lipids (up to 70% of the dry biomass) of which over 50% are triglycerides (TAG), the most suitable raw material for biodiesel production. The high amount of TAG after the starving process, makes Nannochloropsis one of the best candidates for large scale oil rich-biomass. Extraction and purification of phycocyanin from the cyanobacterium Arthrospira platensis (Spirulina) is another very promising marketable bio product. In 2018 the global phycocyanin market was valued about 112 million US$, and it is foreseen to reach a value of about 230 million US$ by 2028. PC is largely used in food industry, being one of the very few natural, safe blue colorant available. PC is used as natural cosmetic dye, fluorescent probe and in biomedical research. However, currently the widespread use of PC has been hindered by the high cost of large-scale extraction and, especially, purification, which remains problematic and expensive. The cost of PC as food colorant is relatively low, about US$ 0.35 per gram, because low purity is requested, but for cosmetic use it increases to about US$ 135, and for therapeutic and biomedicine applications, where a higher purity is required, PC cost can reach as much as US$ 4,500 per gram. Recently a simple and rapid method to purify phycocyanin from A. platensis based on membrane chromatography (MC) is being patented by us.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
