The marine flagellated Chlorophyta Tetraselmis suecica is among the most important live food species in marine aquaculture. In the present study, the effects of dietary supplementation of dried marine microalgae, Tetraselmis suecica, on growth performance; feed utilization; chemical composition; gene expression of superoxide dismutase (SOD), glutathione peroxidase (GPx) and insulin-like growth factor 2 (IGF-II) gene of Pacific white shrimp, Litopenaeus vannamei; muscle protein polymorphism; and microbial count were assessed and evaluated. Three hundred and sixty L. vannamei (postlarvae) Pls (0.124 ± 0.002 g) were randomly stocked into 40-L glass aquaria (30 shrimp/aquarium) and fed three times daily four tested diets: a basal diet (control), diet incorporated with 2.5 g kg −1 dried T. suecica (T1), 5 g kg −1 dried T. suecica (T2) and 7.5 g kg −1 dried T. suecica (T3) in triplicates, for 90 days. At the end of the trial, the survival rate (SR) of L. vannamei fed diets supplemented with different levels of T. suecica was significantly (p < .05) higher than the control diet. The highest weight gain and specific growth rate and the best feed conversion ratio were recorded on L. vannamei fed a diet supplemented with a 7.5 g/kg dried T. suecica. The highest protein, lipid and ash contents were obtained in L. vannamei fed the diet containing 7.5 g/ kg T. suecica, when compared with the remaining tested diets. The gene expression of antioxidant genes SOD and GPx was the lowest in the T3 group in comparison with the control group. Meanwhile, expression level of IGF-II was higher in the T2 group.The total heterotrophic bacterial count was significantly (p < .05) increased with the cumulative T. suecica level, while no significant (p > .05) differences were found in the total Vibrio count among treatments. Overall, the present results have shown that the diet supplemented with the highest inclusion level of dried T. suecica resulted in improved growth and nutrient utilization.

No abstract

The current study examines the effect of dietary supplementation of ethanolic extract of Arthrospira platensis NIOF17/003, which is mainly natural astaxanthins (97.50%), on the growth performance, feed utilization, bacterial abundance, and immune-related and antioxidant gene expressions of the Pacific white leg shrimp, Litopenaeus vannamei. A total of 360 healthy L. vannamei postlarvae (0.19 ± 0.003 g) were divided into four groups (0, 2, 4, and 6 g natural astaxanthins/kg diet) each in three replicates, at an initial density of 30 PLs per tank (40 L capacity). The shrimp were fed the tested diets three times a day at a rate of 10% of their total body weight for 90 days. Diets supplemented with different astaxanthin levels significantly improved shrimp growth performance and feed conversion ratio compared to the control diet. No significant differences were observed in survival rates among all experimental groups. The immune-related genes (prophenoloxidase, lysozyme, beta-glucan binding protein, transglutaminase, and crustin) mRNA levels were significantly upregulated in groups fed with different concentrations of the natural astaxanthins in a dose-dependent manner. The prophenoloxidase gene is the highest immune-upregulated gene (14.71-fold change) in response to astaxanthin supplementation. The superoxide dismutase mRNA level was significantly increased with increasing dietary astaxanthin supplementation. In addition, increasing astaxanthin supplementation levels significantly reduced the count of heterotrophic bacteria and Vibrio spp. in the culture water and shrimp intestine. Overall, the current results concluded that diet supplementation with natural astaxanthin, extracted from Arthrospira platensis, enhanced the growth performance, immune response, and antioxidant status of L. vannamei.

The aim of this work was to investigate the changes in total phenolic compounds content and free radical scavenging abilities against the stable 2,2-diphenyl-1picrylhydrazyl (DPPH assay) during soaking and germination of three cereal grains; wheat (Sids 1), corn (H310 White) and sorghum (Giza 15). Total phenolic compounds in wheat, sorghum and corn raw grains were 381.4, 288.5 and 204 mg/100g, respectively. Soaking and germination processes showed significant decrease in total phenolic compounds. Losses of total phenols during soaking for 12 hr were 15.18, 14.9 and 5.96 % of its initial values in wheat, sorghum and corn raw materials, respectively. Germination process for 48 hr led to decrement of total phenols ranged from 39.3-43.95 % of its initial values in studied raw cereal grains. The DPPH radical scavenging activity decreased during soaking and germination processes of cereal grains. MATERIALS AND METHODS Materials: Grains: Three cereal grains, including wheat (Triticum aestivum L.) Sids 1, corn (Zea maiys L.) Hybrid 310 and sorghum (Sorghum bicolor L.) Giza 15 collected from Sohag Governorate, Egypt. Chemicals: DPPH (2, 2-diphenyl-1-picrylhydrazyl), 6-hydroxy-2, 5, 7, Folin-Ciocalteau reagent, acetic acid were purchased from Sigma-Aldrich (St. Louis, MO). Methanol, ethanol, hexane, and ethyl acetate were HPLC grade. Technological processes: Soaking: Grains samples were soaked in water (1:5, w/v) at room temperature for 12 hr, water was changed every 6 hr (Abdel-Gawad, 1993). Germination: Soaked grains samples were geminated in betry dishes coating with moistened filter paper at room temperature for 12, 24, 36 and 48 hr (Youssef et al., 1987). Milling: All soaked and germinated grains were dried then conditioned by rising its moisture content up to 14 %, then left for 24 hr as tempering time. Milling was run in a Buhler experimental mill (type 212) by progressively receiving the whole flour (Sorour, M. A 1997). Analytical methods: Moisture, protein, fat and ash contents was determined according to AOAC (2000). Total carbohydrate content of grains was calculated by difference. Potassium, calcium, iron, and zanic were determind using Perkin Elmer Atomic Absorption Spectero-photometer 2380. Phosphorus content was determind by Specter-photometer according to AOAC (1980). Extraction of total antioxidants: Ten grams of dry sample were ground fine using a coffee grinder, then weighed and transferred into a test tube (25 x 150 mm). For extraction; 40 mL of methanol were added in a test tube and vortexes to mix with the sample well triplicate. The test tubes were capped and placed in a 60˚C water bath for 20 min. The tubes were vortexed twice during the incubation. Then, the solvent layer from each tube was separated by centrifugation at 2000 rpms for 15 min. The solvent supernatant was transferred to clean, previously weighed and labeled test tubes. The residue was mixed with 20 mL of the same solvent again and vortexed. The solvent supernatant was combined with the previous one. The tube with supernatant was then...

No abstract

The present study evaluated the influence of different commercial agricultural by-products as a carbon source in a bifloc-based (BFT) culture system on growth performance, whole-body proximate composition, digestive enzyme activities, gut microbial abundance, and hepatopancreas histology of Pacific whiteleg shrimp, Litopenaeus vannamei post larvae (Pls). Three groups were designed, the first group was the control group, where the shrimp was reared in clear water (without carbon source addition and water exchange rate of 100% two times a week) and fed with a commercial diet, in the second and third groups shrimp were reared in BFT systems using two different carbon sources, sugarcane bagasse (SB) and rice bran (RB) without additional feeding or water exchange. The initial stocking density was 16 Pls/liter with an average individual shrimp weight of 0.01 ± 0.002g and age (PL20). The experiment lasted 90 days. The water quality parameters were maintained at optimum levels during the experiment. The final body weight and specific growth rate of shrimp were significantly (p ≤ 0.01) higher in the control group than those reared in both SB and RB-based BFT. Meanwhile, the survival rate was significantly (p < 0.05) higher in BFT groups than in the control. The protease activity in shrimp stomach did not differ significantly. Meanwhile, protease, lipase, and amylase in the intestine showed a significant increase (p < 0.01) in BFT groups than those obtained in the control group. The total heterotrophic bacteria were significantly (p < 0.05) higher in BFT groups. Furthermore, the hepatopancreas histological status of shrimp reared in the SB-based BFT group showed an increase in the hepatopancreas tubules in the distal and B-cell zones (blister-like cells) by 16.83 and 34.89%, respectively, compared to the control. This study revealed that BFT could be used as a natural feed without artificial diets, which influenced the gut microbiota of shrimp, increased digestive enzyme activities, as well as improved the histological structure of the hepatopancreas of shrimp. However, the success of this conditions under high stocking density still needs more investigation.

Amylase producing actinobacteria were isolated and characterized from terrestrial environment. There are a limited number of reports investigating the marine environment; hence, in the present study, four marine enzymes were tested for their amylase production ability. On starch agar plates, the Streptomyces rochei strain showed a higher hydrolytic zone (24 mm) than the other isolates. Growth under optimized culture conditions using Plackett-Burman’s experimental design led to a 1.7, 9.8, 7.7, and 3.12-fold increase for the isolates S. griseorubens, S. rochei, S. parvus, and Streptomyces sp., respectively, in the specific activity measurement. When applying the Box-Behnken design on S. rochei using the most significant parameters (starch, K2HPO4, pH, and temperature), there was a 12.22-fold increase in the specific activity measurement 7.37 U/mg. The α-amylase was partially purified, and its molecular weight was determined using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. α-Amylase was particularly active at pH 6 and 65°C. The purified enzyme was most active at 65°C and pH 6, thermal stability of 70°C for 40 min, and salt concentration of 1 M with Km and Vmax of 6.58 mg/ml and 21.93 μmol/ml/min, respectively. The α-amylase was improved by adding Cu+2, Zn+2, and Fe+2 (152.21%, 207.24%, and 111.89%). Increased production of α-amylase enzyme by S. rochei KR108310 leads to production of significant industrial products.

Ten sediment samples were gathered from several geographical locations around mangrove habitat, Red Sea coast, Egypt, during summer 2019. Actinobacteria are widespread in most mangrove soil samples. The average actinomycetes counts in sediment samples were ranged from 4 to 15 CFUg-1, also physico-chemical characters for soil samples were determined. Statistical analysis was applied to assess if the geographical location and physico-chemical characters influenced the communities of actinomycetes. A total of 10 actinomycetes were isolated and characterized physiologically and biochemically. The antimicrobial activities of different actinomycetes isolates were assessed. Isolate M3 was chosen as the most promising isolate with broad antagonistic activity against Bacillus subtilis ATCC 6633, Escherichia coli ATCC 19404, Staphylococcus aureus ATCC6538, Pseudomonas aeruginosa ATCC 9027, and Candida albicans ATCC 10231 with inhibition zones ranged from 12.0 ± 0.9 to 20.0 ± 1.9 mm. Genotypic characterization of isolate M3 was made using 16S rDNA sequence analysis and identified as Streptomyces mutabilis M3 with accession number MT483919. This strain exhibited anticancer activity against breast cancer cell line (Mcf7), liver cancer cell line (HepG2) and colon cancer cell line (HCT116) and the IC50 values were 324.77, 333.71 and 354.46, respectively. Streptomyces mutabilis M3 MT483919 had high bio-flocculating activity for seawater treatment, and the recovery of the samples ranged between 71.97 and 76.05%. The crude extract of Streptomyces mutabilis MT483919 M3 was analyzed by Fourier transform infrared spectrum (FT-IR) and Gas chromatography-mass spectrometry (GC-MS).