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.

Impact of brine acidification on hatchability, survival and reproduction of Artemia parthenogenetica and Artemia franciscana in salt ponds, Bohai Bay, China

We studied the effect of pH(pH 5, 6, 7 and 8) on the hatching percentage, survival and reproduction of Artemia strains in Bohai Bay salt ponds. Strains included parthenogenetic Artemia from Bohai Bay(BHB), Artemia franciscana from San Francisco Bay, and A. franciscana artifi cially produced in salt ponds in Vietnam. The latter was included as a potential inoculum for biological management of salt ponds. The hatching percentage of cysts after 24 h and the survival rate of the tested Artemia strains were signifi cantly reduced when exposed to a culture medium at pH 5 for 18 d( P <0.05). The tolerance of Artemia to 48 h acid exposure varied with developmental stage, increasing in the following order: juvenile, nauplii, pre-adult, with maximum tolerance in adults. All strains of Artemia tested could not reproduce at pH 5. At pH levels from pH 6–8, a higher pH generally resulted in a shorter brood interval and enhanced ovoviviparity. Hence, we suggest that brine acidifi cation has a negative impact on Artemia populations in the Bohai Bay saltworks. Inoculation of Artemia with either local parthenogenetic Artemia or exotic A. franciscana should be feasible at pH 7–8.

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

Halophilic archaea comprise the maj ority 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 colonies were isolated from brine water in a saltern crystallizer pond of the Hangu Saltworks,China.16 S 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 local 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.