Selected nondigestible carbohydrates and prebiotics support the growth of probiotic fish bacteria mono-cultures in vitro

To search for nondigestible but fermentable (NDF) carbohydrates and prebiotics with a potency to promote the growth of selected bacteria in vitro. The growth of three reference bacteria strains Bacillus subtilis LMG 7135(T), Carnobacterium piscicola LMG 9839, Lactobacillus plantarum LMG 9211 and one candidate probiotic bacteria Lactobacillus delbrueckii subsp. lactis was investigated over a minimum period of 48 h in the presence of beta-glucan, xylo-oligosaccharide, arabinoxylo-oligosaccharide, inulin, oligofructose and glucose. Besides the capability to grow on inulin and oligofructose containing media, a distinct high growth in beta-glucan based substrates and a low growth in (arabino)xylooligosaccharide containing media were evident for most bacteria tested. With the exception of B. subtilis and L. plantarum, other bacteria grew equally well or even better on different substrates than on glucose. The fermentation of studied carbohydrates by these micro-organisms was dominated by the production of acetic acid as the main short chain fatty acid. Selected bacteria are able to ferment and grow on NDF and prebiotic carbohydrates but in a substrate dependent manner. This study delivers a first screening of which NDF or prebiotic carbohydrates are the most promising for aquaculture feed supplementations

Annulation of phenols with methylbutenol over MOFs: The role of catalyst structure and acid strength in producing 2,2-dimethylbenzopyran derivatives

The catalytic behavior of metal-organic frameworks of different structures (Fe(BTC), MIL-100(Fe), MIL-100(Cr) and Cu-3(BTC)(2)) was investigated in annulation reaction between 2-methyl-3-buten-2-ol and phenols differing in size (phenol, 2-naphthol). MIL-100(Fe) possessing intermediate Lewis acidity, perfect crystalline structure, and the highest S-BET surface area showed the highest activity (TOF = 0.7 and 1.4h(-1) for phenol and 2-naphthol, respectively) and selectivities to target benzopyran (45% and 65% at 16% of phenol and 2-naphthol conversion, respectively). The increasing strength of Lewis acid centers for MIL-100(Cr) was found to result in the dramatically decreased activity of the catalyst, while negligible conversion of phenols was found over Fe(BTC), characterized by a less ordered framework.M.O. and J.C. acknowledge the Czech Science Foundation for the support (14-07101S) and RNDr. Libor Brabec, CSc. for SEM images.Shamzhy, MV.; Opanasenko, MV.; García Gómez, H.; Cejka, J. (2015). Annulation of phenols with methylbutenol over MOFs: The role of catalyst structure and acid strength in producing 2,2-dimethylbenzopyran derivatives. Microporous and Mesoporous Materials. 202:297-302. doi:10.1016/j.micromeso.2014.10.003S29730220

Food habits and trophic resource partitioning among three mormyrid fishes from man-made Lake Ayame, Ivory Coast

Feeding habits and trophic relationships among three mormyrid species  (Petrocephalus bovei, Marcusenius ussheri and Marcusenius furcidens) were assessed in the man-made Lake Ayame in Ivory Coast. The index of preponderance combining the occurrence and weight percentages of the identified prey items  showed that these three mormyrid species mainly feed on invertebrates, especially aquatic insects. Petrocephalus bovei mainly feeds on chaoborid larvae, whereas both Marcusenius species preferentially feed on chironomid larvae. This segregation of food items associated with the relative  abundance of chironomid larvae may reduce interspecific competition between these three fish species, and may therefore allow their  coexistence. Horn’s food overlap index revealed highly significant similarities in the trophic spectrum between both   Marcusenius species, and for the dry as well as the rainy season.Key words: Mormyridae, feeding, competition, man-made lake, Ivory Coast, West Africa

Influence des facteurs environnementaux sur la répartition spatiale des crevettes dans un petit bassin ouest africain – rivière Boubo- Côte d'Ivoire

Environnemental Control of Shrimps Communities Structure along a Small West African Basin- Boubo River- Ivory Coast. The relationship between shrimps species and environmental variables were studied in Boubo River, a costal river in Ivory Coast. The river is submitted to the impact of human activities (dam construction and oils factory). This survey achieved for the first time in the Boubo River permitted to put in evidence nine freshwater shrimps species [Atya africana (Bouvier 1904), Caridina africana (Kingsley, 1882), Caridina nilotica (P. Roux 1833), Desmocaris trispinosa (Aurivillius 1898), Macrobrachium vollenhovenii (Herklots 1851), Macrobrachium macrobrachion (Herklots 1851), Macrobrachium felicinum (Holthuis 1949), Macrobrachium dux (Lenz 1910) and Macrobrachium sollaudii (De Man 1912)] belonging to two families (Atyidae and Palaemonidae) and four genera (Atya, Caridina, Desmocaris and Macrobrachium) were captured. Significant correlation between habitat characteristics and presence or absence of shrimps species suggest that rocky, leaves and death-woods substrates, canopy closure, width, depth and transparency were the main environmental variables influencing shrimps distribution

An improved method for artificial infection of the European eel, <i>Anguilla anguilla</i>, with <i>Anguillicola crassus</i> (Nematoda, Dracunculoidea)

A standardized method was developed for artificially infecting the European eel with Anguillicola crassus, a parasitical swim bladder nematode. For this purpose, an intermediate host, Paracyclops fimbriatus, and a paratenic host, Cyprinus carpio, were used. Parasite prevalence in the artificially infected eels was very high, although there was a large variation in the number of worms per eel. Compared to other methods of artificial infection described in the literature, this method appears to be more efficient ad reliable; there were also more infectious larvae that were recovered and the mortality rate of eels under treatment was lower

The effect of supplemental ascorbic acid in enriched live food for <i>Clarias gariepinus</i> larvae at startfeeding

The effect of three dietary ascorbic acid (AA) concentrations, each applied via two feed types, on production characteristics and physiological condition of African catfish (Clarius gariepinus) larvae has been assessed in two 10-day culture trials. Three treatments received only Artemia nauplii enriched with an experimental emulsion containing 0, 10 or 20% ascorbyl palmitate (AP) and yielding 530, 1200 and 1600 µg AA g-1 DW Artemia , respectively; the other three treatments were fed the same Artemia diets which were partially substituted by an artificial diet containing no vitamin C (ratio 20:80). No differences in survival could be observed: however, from day 6 onwards the 20%-AP group showed significantly better growth compared to the 0%- and 10%- treatments. For the cofeeding series, the same positive, but not significant, influence of vitamin C on dry weight was found. Moreover, the animals receiving the highest vitamin C supplementation displayed a considerably lower stress sensitivity than those of the 0%- and the 10%-AP groups, for both the 100%-and the 20%- Artemia series. These differences had occurred by day 2, which might be indicative of the importance of AA in early development. A second trial, which was a repetition of the first one, revealed the same tendencies; however, growth differences were smaller, probably due to the higher incorporation levels of AA obtained in the live diet (530, 1700 and 2300 µg AA g -1 DW) and in the catfish larvae. Growth results of both experiments were supported with data from the ultrastructural evaluation of the hepatocytes: i.e. a more organized cell compartmentation and better-structured cell organelles in the 20%-AP group of the Artemia series compared to the control are indicative of a more active metabolism. The slow growth in the cofeeding series was documented by the poor condition of the hepatocytes.In a third experiment it was verified that the growth effect of the 20%-AP boosted Artemia diet was the result of the extra AA incorporation and not of the concomitant palmitic acid (PA), which was set free after hydrolysis of AP in the Artemia nauplii, and which could possibly be used as a supplemental energy source. The three treatments were fed Artemia nauplii enriched with 0% AP, 12% PA and 20% AP, respectively. Growth and stress resistance of the latter group were significantly higher compared to the control and the PA-supplemented fish. To our knowledge this is the first evidence for the positive role of high dietary vitamin C levels (more than 1500 µg AA g-1 DW) on larval development of an aquaculture species, and more specifically of C. gariepinus