Accumulation And Bioactivity Of Bacteriorubrin In Three Halophilic Archaea Strains

Bacterioruberin is one of C-50 carotenoids mainly consiting in the membrane of halophilic archaea.It has various bioactivities.Halophilic archaea cell accumulate large amount bacterioruberin in salinity range of 150-250 in presence of carbon source,i.e.soluble starch,sucrose and glucose in culture medium.And bacterioruberin accumulation in the cells increases with decreasing salinity in a certain salinity range.In this thesis,the effect of different carbon and nitrogen sources and C/N ratios on bacterioruberin accumulation in three archaeal strain Halorubrum,Haloarcula and Hcloferax isolated from Hangu Saltworks,Tianjin,China were studied.The salinity of culture medium was 150.The three strains were mass cultured in optimal culture conditions in order to obtain more pigments for later analysis.The pigment extract were separated and analyzed by TLC,silica gel column chromatography,UV-VIS spectrum scanning,HPLC,LC-MS,MALDI-TOF-MS etc.And the antioxidant capacity of the pigment extract was determined.The results showed that the optimum culture condition for Halorubrum is 15 g/L yeast extract and acid hydrolyzed casein as nitrogen source,10 g/L soluble starch as carbon source.The optimum culture condition for both Haloarcula and Haloferax were 17.5 g/L yeast extract and acid hydrolyzed casein as nitrogen source,10 g/L surcose as carbon source.Pigment extract separated by gel chromatography after mass culture with optimal culture of three strains.Four major components were obtained from Halorubrum crude pigment extract,named R1-R4,respectively.Component R3 and R4 were recongized as monoanydrobacterioruberin and bacterioruberin after analysis and identification.Five major components were obtained from Haloarcula crude pigment extract,named A1-A5,respectively.These were recongized as β-carotene,lycopene,zeaxanthin,monoanydrobacterioruberin and bacterioruberin after analysis and identification.Two major components were obtained from Haloferax crude pigment extract,named F1-F2,respectively.These were recongized as β-carotene and bacterioruberin after analysis and identification.The antioxidant experiment showed that the component(R4,A5 and F2)dominated by bacterioruberin had better antioxidant activity compared with other components.DPPH radical scavenging efficiency was ranged 28.46-37.69%,reducing power was ranged 0.17-0.18,total antioxidant capacity was ranged 22.89-23.45%,ferrous chelating ability was ranged 9.96-11.24%.All of these are higher than all-transβ-carotenes’ antioxidant activity.The results of this study provide basic data for the application of carotenoids accumulated by halophilic microorganisms in food,medicine and heaith care products industry.