This study aimed to evaluate the effects of four potential microbial strains, consisting of Candida parapsilosis, Pseudoalteromonas flavipulchra, Lactobacillus sakei, and Bacillus natto, on the ...suppression of Vibrio and the increase of population growth and enzyme activity in the copepod Tigriopus japonicus. Five treatments were set up, including four experimental groups and a control, each with four replicates. For each strain a concentration 108CFU/mL−1 was applied. The results demonstrated that the use of L. sakei and B. natto, besides suppression of Vibrio, could increase the population growth and enzyme activity in copepods. The longevity of B. natto was recorded as the best in long-term inoculation in a way that after 8 days of copepod starvation, the count of B. natto after a significant decrease first, increased again. The findings showed that B. natto appears to be a promising bacterial strain for the copepod T. japonicus in the suppression of Vibrio and also in increasing the population growth, enzyme activity, and long-term inoculation potential.
•Bacillus natto is an impressive strain that can stick in Copepods' digestive tract for long term, even if used for once.•Tigriopus japonicus base on its response in this study can be a potential live food for larviculture with enrichment possibility.•The use of C. parapsilosis, P. flavipulchra, L. sakei, and B. natto besides suppression of Vibrio showed a proper effect on population growth and enzyme activity.
Abstract Species are fundamental units of nature that need proper identification in order to assess and conserve biodiversity. Artemia is a model crustacean for population analysis and comparison in ...regionally endemic sexual species and parthenogenetic lineages distributed in hypersaline lakes, lagoons, and solar saltworks scattered in arid and semi-arid areas worldwide. The taxonomy of two American Artemia species has been controversial: Artemia monicaVerrill, 1869, adapted to the carbonate-rich conditions of Mono Lake (CA, USA), and Artemia franciscanaKellogg, 1906, a species broadly distributed in the Americas. The former species has been studied little, despite being listed as threatened in the IUCN Red List. In contrast, the latter has been studied extensively, is broadly distributed in the Americas, and has become established as a non-native invasive species in Europe, Asia, Africa, and Australia. Given the need to conserve A. monica, the intraspecific diversity of invasive A. franciscana, and the local species in areas invaded by this species, we reconsider their biodiversity and taxonomic status currently threatened by synonymization. In conclusion, A. monica and A. franciscana should be treated as two separate species that are isolated both ecologically and reproductively.
The notion that phenotypic traits emerging from environmental experiences are heritable remains under debate. However, the recent report of nonmendelian transgenerational epigenetic inheritance, ...i.e., the inheritance of traits not determined by the DNA sequence, might make such a phenomenon plausible. In our study, by carrying out common garden experiments, we could provide clear evidences that, on exposure to nonlethal heat shocks, a parental population of parthenogenetic (all female) Artemia (originating from one single female) experiences an increase in levels of Hsp70 production, tolerance toward lethal heat stress, and resistance against pathogenic Vibrio campbellii. Interestingly, these acquired phenotypic traits were transmitted to three successive generations, none of which were exposed to the parental stressor. This transgenerational inheritance of the acquired traits was associated with altered levels of global DNA methylation and acetylated histones H3 and H4 in the heat‐shocked group compared to the control group, where both the parental and successive generations were reared at standard temperature. These results indicated that epigenetic mechanisms, such as global DNA methylation and histones H3 and H4 acetylation, have particular dynamics that are crucial in the heritability of the acquired adaptive phenotypic traits across generations.—Norouzitallab, P., Baruah, K., Vandegehuchte, M., Van Stappen, G., Catania, F., Vanden Bussche, J., Vanhaecke, L., Sorgeloos, P., Bossier, P. Environmental heat stress induces epigenetic transgenerational inheritance of robustness in parthenogenetic Artemia model. FASEB J. 28, 3552–3563 (2014). www.fasebj.org
Axenic rotifers (
Brachionus plicatilis sensu strictu, clone 10) were obtained by treating amictic eggs with glutaraldehyde. Depending of the batch of rotifers, total disinfection could be obtained ...by exposure to 50–100 ppm from 1 to 2 h at 28 °C. The hatched axenic neonates were used to test the effect of microbial communities (MCs) which were isolated from either normal-performing or crashed rotifer cultures. These MCs were either used directly or were first regrown on Marine Agar. MCs were introduced to gnotobiotic
Brachionus cultures in combination with three different food types, i.e.
Chlorella, wild-type yeast and the
mnn9 yeast mutant, which is deficient in cell wall-bound mannoprotein. In the absence of MCs or when heat-killed MCs were added,
Chlorella was always the best food, while lower growth rates were observed with wild-type yeast and the
mnn9 mutant as food. In the presence of live MCs and when rotifers were fed with
Chlorella, the added MCs had no effect on rotifer performance. When yeasts were used as major food, all the tested MCs were able to increase the rotifer growth rate. The experiments with heat-killed MCs yielded no increase in rotifer growth rate, suggesting that the observed enhancement in rotifer growth rate was truly a probiotic effect rather than a nutritional effect. The results of this study demonstrate that gnotobiotic rotifer cultures obtained from axenic amictic eggs can be used as a test system for studying microbial-attributed as well as nutritional functions in the aquatic food chain. In addition, since the MCs originating from the crashed rotifer cultures did not decrease the growth rate in the tested rotifer cultures, it is likely that the observed crashes were not due to the presence of a standing deleterious MC.
The use of beneficial microbes, i.e., probiotics, to reduce pathogens and promote the performance of the target species is an important management strategy in mariculture. This study aimed to ...investigate the potential of four microbes, Debaryomyces hansenii, Ruegeria mobilis, Lactobacillus plantarum, and Bacillus subtilis, to suppress Vibrio and increase survival, population growth and digestive enzyme activity (protease, lipase, and amylase) in the harpacticoid copepod, Tigriopus japonicus. Copepod, T. japonicus stock culture with an initial mean density of 50 individual/mL (25 adult male and 25 adult female) was distributed into five treatments (i.e., four experimental and a control, each with four replicates; repeated twice) using 20 beakers (100 mL capacity each). The copepods were fed a mixture of the dinoflagellate Alexandrium tamarense and the diatom Phyaeodactylum tricornutum (3 × 104 cells/mL−1). Each microbe's concentration was adjusted at 108 CFU/mL−1 and applied to the culture condition. D. hansenii, L. plantarum, and B. subtilis all improved the copepods' survival and population growth, likely by including a higher lipase activity (P < 0.05). In contrast, using R. mobilis did not improve the copepod's culture performance compared to control. B. subtilis was the most effective in decreasing the copepod's external and internal Vibrio loading. The probiotic concentrations in the copepod decreased within days during starvation, suggesting that routine re-application of the probiotics would be needed to sustain the microbial populations and the benefits they provide. Our results demonstrated that D. hansenii and B. subtilis are promising probiotics for mass copepod culture as live food for mariculture purposes.
•B. subtilis was the most effective for suppressing Vibrio in Tigriopus japonicus.•D. hansenii improved population growth and increased the survival of T. japonicus.•The probiotic concentrations in T. japonicus declined over time during starvation.•Routine re-applications of the probiotics would be needed to sustain the microbial populations in T. japonicus.
1. A wide range of species that are cultivated in commercial mariculture are planktonic during at least part of their life cycle; for example, the larval stages of shellfish (shrimp and molluscs) and ...the live feeds (rotifers, brine shrimp, copepods) used in the larviculture of marine fish and shellfish. Over the last decades various techniques have been developed to deliver nutrients to these zooplanktonic organisms either through artificial diets or by manipulating the composition of the live prey fed to the carnivorous stages. This paper reviews the methodology that has allowed aquaculturists to gain knowledge of nutritional requirements and may offer interesting opportunities for ecologists to verify the importance of key nutrients in the natural food chain of marine as well as freshwater ecosystems.
2. Live micro‐algae can be replaced partially or completely in the diet of filter‐feeders such as rotifers, Artemia, shrimp larvae and bivalves, by various types of preserved algae, micro‐encapsulated diets and yeast‐based diets, whereas lipid emulsions and liposomes may be utilized to supplement specific lipid‐and water‐soluble nutrients, respectively. Microbound and micro‐encapsulated diets have been designed to supplement live feed in the culture of micro‐predators such as fish and shrimp larvae.
3. Live prey organisms, in particular rotifers and Artemia, can be ‘bio‐encapsulated’ with a variety of enrichment diets to manipulate their content in certain nutrients, including ω3 highly unsaturated fatty acids (FA) and the vitamins C, A and E. Nevertheless, the enrichment techniques are not applicable for all nutrients and prey organisms. Phospholipid composition is difficult to manipulate through the diet of live feed and the enrichment of the essential FA docosahexaenoic acid (DHA) is hampered in most Artemia species due to the catabolism of this FA following enrichment.
Rotifer growth performance and microbial community changes associated with rotifer cultures were monitored while different feed types (
Nannochloropsis oculata
paste and the commercial yeast based ...feed CS-3000), different regimes (daily changes, changes per batch and no changes) and mixtures of three probionts (
Phenylobacterium
sp.;
Gluconobacter
sp. and
Paracoccus denitrificans
) were provided. It was shown that the dominant bacterial species in the cultures receiving either
N. oculata
or CS-3000 were different. However, in cultures receiving both feeds (either switching between feeds on a daily basis or on a batch basis), a high similarity in microbial community fingerprint was found. The presence of probionts was detected by the end of four batch culture cycles in spite of strong shifts of the bacterial community. By group discriminant analysis, it was found that
Phenylobacterium
sp. and
Paracoccus
sp. contributed positively to the CS-3000-fed group, while
Gluconobacter
sp. contributed positively to the
N. oculata
-fed group, although they did not appear as very dominant species.
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）, Artemiafranciscana 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. franeiscana should be feasible at pH 7-8.
Few efforts have dealt with the genetic make up of the
Brachionus plicatilis rotifers which are often used as live feed in the larviculture of many marine fish. Recent results have demonstrated that ...the
B. plicatilis species is actually a species complex. In this study a number of molecular markers (Restriction Fragment Length Polymorphism (RFLP) analysis of mitochondrial COI gene, Single-Stranded Conformation Polymorphism (SSCP) analysis and Denaturing Gradient Gel Electrophoresis (DGGE) of mitochondrial 16S rRNA gene as well as microsatellite genotyping of nuclear loci) have been developed and applied to identify genetically rotifer strains used in European hatcheries. All methods have proven highly efficient for the reliable diagnosis of the genetic variability within hatchery strains at bulk or individual level. Results point towards an absence of the typical
B. plicatilis and
Brachionus rotundiformis species and a predominance of the
Brachionus sp. Cayman biotype (
Brachionus SM morphological type). All the other biotypes/species were either rarely found or were coexistent with
B. sp. Cayman. These biotypes were
B. plicatilis sensu stricto,
B. sp. Nevada and
B. sp. Austria, all belonging to the
Brachionus L group. Minimal genetic variability was detected within strains. The above results have important implications for rotifer cultures, with respect to the different temperature and salinity optima of each biotype/species. Caution is needed regarding the common practice used by hatcheries around the world of exchanging samples based solely on morphological criteria.
