No abstract

Chlorella ellipsoidea is a freshwater green microalga that has great prospect for the sustainable development of aquaculture industry. Microalgae require optimal lighting conditions for efficient photosynthesis. The key to costeffective algal biomass production is to optimize algae growth conditions. This study aimed to investigate the effects of various wavelengths viz. white (380-750 nm), green (510 nm), blue (475 nm), and red (650 nm) lightemitting diodes (LEDs) on the growth, pigment content (chlorophyll-a, chlorophyll-b, and β-carotene), and proximate composition of C. ellipsoidea with a photoperiod of 12 h:12 h light: dark cycle under indoor environmental conditions. C. ellipsoidea was cultured in Bold's Basal Medium for 18 days. The cell density (125.36Â10 5 cells ml À1 ), cell dry weight (58.9 AE 4.57 mg L À1 ), optical density (1.66 AE 0.08 g L À1 ), chlorophyll-a (7.31 AE 0.04 μg ml À1 ), chlorophyll-b (2.73 AE 0.13 μg ml À1 ), and β-carotene (0.39 AE 0.04 μg ml À1 ) content of C. ellipsoidea were significantly (P < 0.05) higher at 15 th -day when cultured under blue LED light exposure. Significantly lower growth and nutritional values were obtained under red LED light exposure compared to the control and other LEDs spectra. In Pearson correlation analysis, the cell density and cell dry weight values showed a strong positive correlation with the values of pigment contents of C. ellipsoidea in all the treatments. The LEDs light spectra showed significant effects on proximate composition of C. ellipsoidea. Protein and lipid contents of C. ellipsoidea were significantly higher in blue LED growth conditions compared to white, green, and red LEDs.C. ellipsoidea cells were 3À7.04 μm in size and the maximum area of the cell was 38.94 μm 2 in blue LED treatment.Results of this study demonstrated that blue LED light spectra was the most suitable condition to induce nutritionally rich biomass production of C. ellipsoidea, which can be used as a potential source of fish feed towards sustainable aquaculture.

This study aimed to isolate and identify probiotic bacteria from the gut of Barbonymus gonionotus and evaluate their effects on growth, hematological parameters, and breeding performances of the host. Five probiotic bacteria viz. Enterococcus xiangfangensis (GFB-1), Pseudomonas stutzeri (GFB-2), Bacillus subtilis (GFB-3), Citrobacter freundii (GFB-4), and P. aeruginosa (GFB-5) were isolated and identified using 16S rRNA gene sequencing. Application of a consortium of probiotic strains (1–3 × 1.35 × 109 CFU kg−1) or individual strain such as GFB-1 (1.62 × 109 CFU kg−1), GFB-2 (1.43 × 109 CFU kg−1), GFB-3 (1.06 × 109 CFU kg−1), GFB-4 (1.5 × 109 CFU kg−1) or GFB-5 (1.43 × 109 CFU kg−1feed) through feed significantly improved growth, histological and hematological parameters and reproductive performances of B. gonionotus compared to untreated control. Moreover, the application of these probiotics significantly increased gut lactic acid bacteria and activities of digestive enzymes but did not show any antibiotic resistance nor any cytotoxicity in vitro. The highest beneficial effects on treated fishes were recorded by the application of GFB-1, GFB-2, GFB-3, and a consortium of these bacteria (T2). This is the first report of the improvement of growth and health of B. gonionotus fishes by its gut bacteria.

In this study, we determined the effects of dietary chitosan on the growth, biochemical composition, gut microbiota, and hematological and histological parameters of juvenile Barbonymus gonionotus. Three test diets containing three different concentrations (1, 2, and 3 g kg-1 feed) of dietary chitosan were formulated. A basal diet without dietary chitosan was considered a control, and the fish were reared for 60 days. Comparing the effects of the dietary chitosan-containing diets with those of the control diet, we found that dietary chitosan significantly improved the muscle growth, nutrient and mineral contents, hematological parameters, lactic acid bacterium abundance, and digestive enzyme activities of B. gonionotus. Moreover, dietary chitosan significantly inhibited the growth of pathogenic bacteria in fish. Interestingly, an increase in the dietary chitosan level significantly enhanced the protein contents of the muscles and inversely significantly decreased the lipid contents compared to those with the basal diet. Quantitative study revealed that dietary chitosan significantly enhanced the length of intestinal villi, and qualitative study showed that dietary chitosan considerably reduced the fat content in the liver and improved the morphology of the kidney compared to those with the basal diet. Taken together, our results suggest that the application of dietary chitosan at a dose of 1 g kg-1 feed produced the highest benefit to treated B. gonionotus, indicating its potential for safe use in aquaculture.

This study reports the draft genome sequence of a promising fish probiotic, Bacillus subtilis strain WS1A, that possesses antimicrobial activity against Aeromonas veronii and suppressed motile Aeromonas septicemia in Labeo rohita. The de novo assembly resulted in an estimated chromosome size of 4,148,460 bp, with 4,288 open reading frames.