Astaxanthin from Haematococcus pluvialis: processes, applications, and market.

Astaxanthin is a xanthophyll carotenoid widely used in aquaculture and nutraceutical industries. Among natural sources, the microalga Haematococcus pluvialis is the non-genetically modified organism with the greatest capacity to accumulate astaxanthin. Therefore, it is important to understand emerging strategies in upstream and downstream processing of astaxanthin from this microalga. This review covers all aspects regarding the production and the market of natural astaxanthin from H. pluvialis. Astaxanthin biosynthesis, metabolic pathways, and nutritional metabolisms from the green vegetative motile to red hematocyst stage were reviewed in detail. Also, traditional and emerging techniques on biomass harvesting and astaxanthin recovery were presented and evaluated. Moreover, the global market of astaxanthin was discussed, and guidelines for sustainability increasing of the production chain of astaxanthin from H. pluvialis were highlighted, based on biorefinery models. This review can serve as a baseline on the current knowledge of H. pluvialis and encourage new researchers to enter this field of research.

Growth and nitrogen uptake by Arthrospira platensiscultured in aquaculture wastewater from Nile tilapia reared in biofloc system

This study aimed to evaluate the growth of Arthrospira (Spirulina)platensiscultivated in Zarrouk culture medium and effluent from Nile tilapia (Oreochromis niloticus) reared in biofloc system. Four treatments were used: Control (100% Zarrouk), E50 (50% Zarrouk + 50% Tilapia effluent), E75 (25% Zarrouk + 75% Tilapia effluent), and E100 (100% Tilapia effluent), and the experiment lasted 10 days. Growth parameters such as maximum cell density (MCD), doubling time (DT), and growth rate (K) were daily evaluated, as well aspH and water temperature. In addition, the concentrations of total ammonia nitrogen (TAN), nitrite-N (NO2-N), and nitrate-N (NO3-N) were analyzed in order to compare nitrogen absorption. Among treatments, E50 and E75 obtained higher maximum cell densities and presented an exponential growth rate similar to the control treatment. Regarding the concentrations of nitrogen compounds, a significant reduction was observed in all treatments, with an NO3-Nuptake of 99%, followed by 80% of TAN and 90% of NO2-N. Thus, giving the results obtained, besides being able to grow in wastewater, A. platensis can also be used in bioremediation processes, confirming the potential of this species.