Carotenoid Production by Halophilic Archaea Under Different Culture Conditions

Abstract

Carotenoids are pigments that may be used as colorants and antioxidants in food, pharmaceutical, and cosmetic industries. Since they also benefit human health, great efforts have been undertaken to search for natural sources of carotenoids, including microbial ones. The optimization of culture conditions to increase carotenoid yield is one of the strategies used to minimize the high cost of carotenoid production by microorganisms. Halophilic archaea are capable of producing carotenoids according to culture conditions. Their main carotenoid is bacterioruberin with 50 carbon atoms. In fact, the carotenoid has important biological functions since it acts as cell membrane reinforcement and it protects the microorganism against DNA damaging agents. Moreover, carotenoid extracts from halophilic archaea have shown high antioxidant capacity. Therefore, current review summarizes the effect of different culture conditions such as salt and carbon source concentrations in the medium, light incidence, and oxygen tension on carotenoid production by halophilic archaea and the strategies such as optimization methodology and two-stage cultivation already used to increase the carotenoid yield of these microorganisms.

Characterization of a bacterioruberin‐producing Haloarchaea isolated from the marshlands of the Odiel river in the southwest of Spain

“…It was described that an increase of 10% in salinity reduces 50% oxygen solubility . Similar results have been observed for Haloferax alexandrinus which exhibited high growth and carotenoid production under shaking conditions, reaching 2.06 mg total carotenoids g −1 DW . Halorubrum sp TBZ126 also showed higher concentrations of carotenoids upon optimized growth conditions, reaching 11.71 mg L −1 of total carotenoids …”

“…Although studies on the production of carotenoids by haloarchaea are scarce, being most research work focused on pigments isolation and characterization, the review recently published by Calegari‐Santos et al is an interesting exception, which attempts to compile the production of carotenoids by halophilic archaea under different culture conditions. Although the variety of species, conditions, evaluation approaches and units in which the carotenoid content is quantified in the different studies, makes comparison difficult, these authors conclude that in general carotenoid production by halophilic archaea is salt‐dependent and environmental conditions, such as temperature, pH, dissolved oxygen, and light incidence may also influence on the carotenoid production.…”

Lipid sugar carriers at the extremes: The phosphodolichols Archaea use in N-glycosylation

“…These include carotenoids, such as C 50 bacterioruberins and C 40 carotenes [14], retinals, such as those associated with bacteriorhodopsin and other sensory and transport rhodopsins [15], and phosphodolichols, lipids involved in protein N-glycosylation [16,17]. In the following, current knowledge on the phosphodolichols that participate in archaeal N-glycosylation is reviewed.…”

Carotenoid profile produced by Bacillus licheniformis Rt4M10 isolated from grapevines grown in high altitude and their antioxidant activity

“…Also, C50‐β‐carotene was detected but at lower concentration respect to the other C50. These results are in agreement with reportes in other bacteria and archaea (Mercadante & Egeland, ; Calegari‐Santos et al ., ). Glycosylated carotenoids, like BRu monoglc and BRu diglc, increase bacterial membrane rigidity and decrease water permeability (Falb et al ., ).…”