Liying Sui

Characterisation of high-altitude Artemia populations from the Qinghai-Tibet Plateau, PR China

The brine shrimp Artemia was discovered in a number of saline lakes on the Qinghai-Tibet Plateau, widely diverging in chemical composition. Several lakes were athalassohaline, with relatively high amounts of trace elements. Common environmental factors are their high altitude (exceeding 4500 m) and the low average annual temperatures. A number of Artemia populations in this area were analysed to assess their preference for low temperatures and an athalassohaline medium. Furthermore, their characteristics were compared with Artemia tibetiana, the species recently described for one lake in this area. All samples contained a variable mixture of parthenogenetic and bisexual individuals. A cross-breeding test of the sample from Jingyu Lake showed cross-fertility both with A. tibetiana and A. sinica. All populations showed similarities to A. tibetiana: a large cyst diameter and naupliar length, high HUFA content and a high tolerance to low temperatures, as compared to the control A. franciscana samples. These can thus be considered as recurrent characteristics of the populations from the high-altitude low-temperature environment on the Qinghai-Tibet Plateau, although further research is needed to identify their exact species status.

Effect of poly-β-hydroxybutyrate on Chinese mitten crab, Eriocheir sinensis, larvae challenged with pathogenic Vibrio anguillarum

This study investigated the protective effect of poly-β-hydroxybutyrate (PHB) on Chinese mitten crab, Eriocheir sinensis, zoea larvae challenged with pathogenic Vibrio anguillarum. PHB was delivered to the crab larvae through rotifer and Artemia bioencapsulation. Zoea 3 larvae were challenged with V. anguillarum at a final concentration of 10(5) CFU mL(-1). PHB-enriched rotifers and Artemia nauplii were added to the culture water 24 h prior to, upon and 24 h after challenge. The results confirmed that PHB could enhance the survival and growth of unexposed E. sinensis larvae. Moreover, PHB protected larvae from the pathogen as the larvae fed PHB-enriched live food showed the highest survival and development rate in all challenged groups (P < 0.05). Furthermore, larval performance was the best when PHB was delivered to the larvae 24 h before challenge (P < 0.05). In conclusion, our results indicate that PHB can be used as part of an effective strategy to protect E. sinensis larvae from V. anguillarum resulting in higher survival and better growth, especially when applied before the challenge.

High-temperature adapted Artemia franciscana (Kellogg, 1906) from Vietnam is a suitable strain for inoculation in temperate conditions of Bohai Bay Saltworks, China

The aim of this study was to investigate if the productive but high-temperature adapted Artemia franciscana (Kellogg, 1906) strain from Vietnam can be used in the biological management of the more temperate conditions of the Bohai Bay salt ponds, P.R. China. For this purpose, the effect of culture temperature (14, 25 and 33°C) and feeding level (100, 50 and 25% of optimal feeding level) on survival, length, and reproductive traits of the autochthonous parthenogenetic Artemia from Bohai Bay, China (BHB), bisexual A. franciscana originating from San Francisco Bay, CA, U.S.A. (SFB) and Vinh Chau A. franciscana from Vietnam (VCSFB), were tested. Survival rates of the three populations were not significantly affected by the feeding level at each culture temperature ( P > 0 . 05 ). At higher temperature the survival of the two bisexual populations was better than that of the parthenogenetic population. On the other hand, the length of Artemia was significantly affected by the feeding level at each culture temperature and higher feeding levels resulted in greater length ( P < 0 . 05 ). No reproduction occurred in any strain at 14°C. At 25°C, reproductive traits were significantly affected by the feeding level. The bisexual populations produced more offspring than parthenogenetic Artemia. SFB Artemia tended towards oviparity, whilst VSSFB and BHB produced more nauplii. At 33°C, all strains produced less offspring and tended to produce more nauplii than cysts. Our data provide evidence that, compared to the local parthenogenetic Artemia, the high-temperature adapted Artemia strain from Vietnam may be a more effective colonizer of the temperate Bohai Bay saltworks.

Isolation and Characterization of a New Moderately Halophilic Bacterium Strain SM. 200-5 from Solar Saltern Ponds

A new moderately halophilic bacterium strain SM. 200-5 was isolated from the solar saltern ponds with salinity 200 in Hangu Saltworks, Tianjin, China. The cells of the strain SM. 200-5 were rods and Gram-negative. They could grow in a salinity range of 30–150 and initial pH 6–11, with optimum of salinity 100 and initial pH 7. 16S rDNA alignment showed that the strain SM. 200-5 had 93–95 % similarity with those sequences of genus Salimicrobium sp.. Biochemical characterization analysis via API 20E system indicated that biochemical characters of the strain SM. 200-5 were partially different from Salimicrobium sp. ISL-25, which was its closest member in the phylogenetic tree. Therefore, the strain SM. 200-5 proposed a new species of Salimicrobium.

Characterization of halophilic C50 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 colonies were isolated from brine water in a saltern crystallizer 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 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.

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 16S rRNA gene sequences indicated that five bacteria genera Halomonas, Salinicoccus, Oceanobacillus, Gracibacillus, and Salimicrobium and one archaea genera Halorubrum were present. The genus Halomonas was predominant with eight strains distributed in a salinity range of 100–200, followed by Halorubrum 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 Salimicrobium species based on the phylogenic analysis of the 16S rRNA 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 artificially 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 significantly 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 acidification 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.

Microbiota of Salt Lakes as Food for the Brine Shrimp Artemia

The brine shrimp Artemia is often abundantly found in hypersaline environments.The larvae(‘nauplii’)hatching from its dormant embryos(‘cysts’)are a crucial live food item for the larval stages of fish and shrimp in aquaculture