Dietary vitamin E deficiency inhibits fat metabolism, antioxidant capacity, and immune regulation of inflammatory response in genetically improved farmed tilapia (GIFT, Oreochromis niloticus) fingerlings following Streptococcus iniae infection.

Vitamin E plays an important role in maintaining normal metabolism and physiological functions in animals. The health of fish fingerlings directly affects the rate of disease incidence in adult fish, and healthy fingerlings ultimately result in better breeding outcomes for cultured fish. To date, no previous studies have focused on the effects vitamin E deficiency on tilapia at the fingerling stage. In this study, we investigated the effects of dietary vitamin E on the growth, fat metabolism, antioxidant capacity, and inflammatory response of genetically improved farmed tilapia (GIFT, Oreochromis niloticus) fingerlings. Vitamin E at different concentrations (0, 20, 40, 80, 160, and 320 mg/kg) was added to the diet and GIFT were fed for 55 days. Then, the GIFT were intraperitoneally injected with Streptococcus iniae and tested for infection. Vitamin E deficiency decreased growth and increased the food conversion ratio of GIFT fingerlings. Vitamin E deficiency also reduced the white blood cell count, increased hematocrit and hemoglobin contents in the blood, increased serum aspartate aminotransferase and alanine aminotransferase activities, and increased liver stress (P < 0.05). Vitamin E deficiency inhibited fat metabolism, down-regulated the expression of genes encoding lipoprotein lipase and heart-type and liver-type fatty acid-binding proteins, and increased serum total protein and fat deposition. Vitamin E deficiency significantly decreased superoxide dismutase, glutathione peroxidase, and catalase activities, increased malondialdehyde content, and caused oxidative damage. Vitamin E deficiency also up-regulated the expression of genes encoding interleukin 1ß and tumor necrosis factor α in the head kidney, and stimulated a pro-inflammatory response. Overall, vitamin E deficiency inhibited growth, impaired fat metabolism, and disrupted the inflammatory response of GIFT fingerlings, whereas vitamin E supplementation in the diet reversed these negative effects. The diets with high concentrations of vitamin E (160-320 mg/kg) led to vitamin E accumulation in the fish tissues and rapid activation of the inflammatory response and antioxidant capacity in GIFT fingerlings exposed to S. iniae.

Paenibacillus solani sp. nov., isolated from potato rhizosphere soil.

A novel Gram-stain-positive, endospore-forming bacterium, designated FJAT-22460T, was isolated from a soil sample of a potato field in Xinjiang Autonomous Region, China. Cells were rods that were catalase-positive and motile by peritrichous flagella. The strain was found to grow at temperatures ranging from 10 to 40 °C (optimum 30 °C) and at pH 5.0-12.0 (optimum pH 7) with 0-5 % (w/v) NaCl (optimum 0 % NaCl). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain FJAT-22460T belonged to the genus Paenibacillus and exhibited 16S rRNA gene sequence similarities of 97.3, 97.2, 97.2 and 97.0 % with Paenibacillus glucanolyticus DSM 5162T, Paenibacillus lautus DSM 3035T, Paenibacillus lactis MB 1871T and Paenibacillus chibensis JCM 9905T, respectively. DNA-DNA relatedness of strain FJAT-22460T with Paenibacillus glucanolyticusDSM 5162T and Paenibacillus lautus DSM 3035T was 62.6 % and 33.3 %, respectively, lower than the 70 % accepted for species delineation. The menaquinone was identified as MK-7. The major fatty acids detected were anteiso-C15 : 0 (51.4 %), iso-C15 : 0 (5.3 %), C16 : 0 (12.1 %), iso-C16 : 0 (10.7 %) and anteiso-C17 : 0 (6.9 %). The DNA G+C content was determined to be 50.9 mol%. Phenotypic, chemotaxonomic and genotypic properties clearly indicated that isolate FJAT-22460T represents a novel species within the genus Paenibacillus, for which the name Paenibacillus solani sp. nov. is proposed. The type strain is FJAT-22460T (=DSM 100999T=CCTCC AB 2015207T).