Characterization of halophilic C_50 carotenoid-producing archaea isolated from solar saltworks in Bohai Bay,China

Halophilic archaea comprise the majority of microorganisms found in hypersaline environments. C50 carotenoids accumulated in archaea cells are considered potential biotechnological products and possess a number of biological functions. Ten red colordes were isolated from brine water in a saltem crystaltizer pond of the Hangu Saltworks, China. 16S rRNA gene sequence analysis showed that the colonies belonged to the extremely halophilic archaea genera Halobacterium and Halorubrum. Two representative strains, Halobacterium strain SP-2 and Halorubrum strain SP-4, were selected for further study on the phenotypic characteristics and effects of salinity and pH on accumulation and composition of pigments in their cells. The archaeal strains were isolated and grown in a culture medium prepared by dissolving yeast extract （10 g/L） and acid-hydrolyzed casein （7.5 g/L） into brine water obtained from a I.ocal salt pond. Their optimum salinity and pH for growth were 250 and 7, respectively, although pigment accumulation （OD490/ mL broth） was highest at pH 8. In addition, at 150-300 salinity, increasing salinity resulted in decreasing pigment accumulation. Analysis of the UV-Vis spectrum, TLC and HLPC chromatograms showed that C50 carotenoid bacterioruberin is the major pigment in both strains.

Isolation and characterization of halophilic bacteria and archaea from salt ponds in Hangu Saltworks, Tianjin, China

A total of 26 isolates were obtained from solar salt ponds of different salinities(100, 150, 200, and 250) in Hangu Saltworks Co. Ltd., Tianjin, China. Phylogenetic analysis of 16 SrRNA gene sequences indicated that five bacteria genera H alomonas, Salinicoccus, Oceanobacillus, Gracibacillus, and Salimicrobium and one archaea genera H alorubrum were present. The genus H alomonas was predominant with eight strains distributed in a salinity range of 100–200, followed by H alorubrum with six strains in salinity 250. Based on the genus and original sampling salinity, eight bacterial and two archaeal isolates were selected for further morphological, physiological, and biochemical characterization. All of the bacterial strains were moderately halophilic with the optimal salinity for growth being either 50 or 100, while two archaeal strains were extremely halophilic with an optimal growth salinity of 200. Additionally, we put forth strain SM.200-5 as a new candidate S alimicrobium species based on the phylogenic analysis of the 16 SrRNA gene sequence and its biochemical characteristics when compared with known related species.

Genetic analysis of the br gene in halophilic archaea isolated from Xinjiang region, China

Some novel members of extremely halophilic archaea,strains AJ11,AJ12 and AJ13,were isolated from the Aularz Lake located in the Altun Mountain National Nature Reserve of Xinjiang,Uygur Autonomous Region in China.Partial DNA fragments encoding a bacteriorhodopsin(BR),as well as for 16S rRNA of isolated strains,were amplified by PCR and their DNA sequences were determined subsequently.On the basis of homology and phylogenetic analysis of the 16S rDNA,we thought that the isolated strains forming a microbiological population are the members of the genus Natrinema.The results of genetic analysis,such as GC content,transition/transversion(Ti/Tv)rate ratios and synonymous substitution rates(Ks)indicate that the br fragments,with a high level of genetic divergence,are faced with both purifying selection and bias mutation pressure.The study provides the basis for use of species and BR proteins resources.

Isolation and characterization of a novel strain of Natrinema containing a bop gene

A novel member of extremely halophilic archaea, strain AJ2, was isolated from Ayakekum Lake located in Altun Mountain National Nature Reserve of Xinjiang Uygur Autonomous Region in China. The strain A J2 requires at least 10% (w/v)NaCl and grows 10% to 30% (optimum at 20%). Phylogenetic analysis based on 16S rDNA sequence comparison revealed that strain A J2 clustered to three Natrinema species with less than 97.7% sequence similarities, suggesting A J2 is a novel member of Natrinema. A bacteriorhodopsin-encoding (bop) gene was subsequently detected in the A J2 genome using the polymerase chain reaction technique. The cloning and sequencing of a 401 base pairs fragment indicated the deduced amino acid sequence of bop from A J2 is different from that reported for bacteriorhodopsins. This is the first reported detection of a bop gene in Natrinema.

Cellular and organellar membrane-associated proteins in haloarchaea: Perspectives on the physiological significance and biotechnological applications

Halophilic archaea (haloarchaea) inhabit hypersaline environments,tolerating extreme salinity,low oxygen and nutrient availability,and in some cases,high pH (soda lakes) and irradiation (saltern ponds).Membrane-associated proteins of haloarchaea,such as surface layer (S-layer) proteins,transporters,retinal proteins,and internal organellar membrane proteins including intracellular gas vesicle proteins and those associated with polyhydroxyalkanoate (PHA) granules,contribute greatly to their environmental adaptations.This review focuses on these haloarchaeal cellular and organellar membrane-associated proteins,and provides insight into their physiological significance and biotechnological potential.

Isolation and Phylogenetic Analysis of Halophilic Archaeon AJ6

Halophilic archaeon AJ6 was isolated and purified from the Altun Mountain National Nature Reserve of the Xinjiang Uygur Autonomous Region.Strain AJ6 is a Gram-negative rod whose size is 0.2–0.6 by 1.6–4.2μm,wherein a few cells are globular.The optimum salt concentration for its growth is 20%NaCl and 0.6%Mg^(2+),and the optimum pH is 6.0–7.0.Morphological,physiological,and biochemical characteristics of strain AJ6 were observed.The 16S rRNA encoding gene(16S rDNA)sequence of strain AJ6 was amplified by PCR,and its nucleotide sequence was determined subsequently.“Clustalw”and“PHYLIP”software bags were used to analyze the 16S rDNA sequence;the homology was compared,and then the phylogenetic tree was established.The results indicate that strain AJ6 is a novel species of the genus Natrinema.The GenBank accession number of the 16S rDNA sequences of strain AJ6 is AY277584.