Abstract: An internally-illuminated photobioreactor was designed to maximize the astaxanthin production by Haematococcus pluvialis. Four optimization steps were conducted: 1. light wavelength 2. light intensity 3. astaxanthin formation and 4. astaxanthin extraction methods. Efficient biomass production of H. pluvialis of 4.58 ± 0.15 × 105 cells/ml and dry biomass of 520 ± 12.5 mg/L was accomplished under red LED light (660 nm) with 70 μmol m-2 s-1. Besides, the biomass production can be optimized to 5.31 ± 0.15 × 105 cells/ml and dry biomass of 680 ± 10.5 mg/L under 140 μmol m-2 s-1 in the light intensity of 70-210 μmol m-2 s-1. Furthermore, the astaxanthin accumulation was significant with 7 days encystment under 140 μmol m-2 s-1 blue LED lights. For extraction method, using hydrochloric acid could obtain the highest astaxanthin yield of 3.85 ± 0.05% (% to dry weight). Further studies were proposed whatever such photobioreactor can be applied to different microalgal strains.Abstract: An internally-illuminated photobioreactor was designed to maximize the astaxanthin production by Haematococcus pluvialis. Four optimization steps were conducted: 1. light wavelength 2. light intensity 3. astaxanthin formation and 4. astaxanthin extraction methods. Efficient biomass production of H. pluvialis of 4.58 ± 0.15 × 105 cells/ml and dry bi...Show More
Abstract: Escherichia coli O157:H7 has been considered an emerging foodborne pathogen causing severe diarrheal disease globally especially among children under the age of five years in Sub-Saharan Africa. This study was aimed at conducting a comparative study on the rate of isolation of Escherichia coli O157:H7 from diarrhoeic and non- diarrhoeic children in selected communities in Cross River State, Nigeria. Stool samples were collected from children under the age of five yrs and the pathogen isolated and identified using standard microbiological and biochemical procedures. Serological analysis to detect E. coli 0157:H7 serotype was carried out using Enzyme-linked immunosorbent assay (ELISA) and anti-rabbit H7 latex serum agglutination techniques. Out of 367 diarrhoeic children sampled, 70 (19.07%) were positive for E. coli 0157:H7 and the prevalence differed significantly (p<0.05) with the control. The prevalence of E. coli 0157:H7 between diarrhoeal (19.07%) and non-diarrhoeal (1.39%) cases also differed significantly (p<0.05) among the sampling areas. Diarrhoeric children below the age of one year had significantly highest prevalence of 26.83% at p<0.05 though no significant relationship between the sex of the children and the rate of infection with the organism was observed. Children diarrhoaeic stool therefore serves as a major vehicle in the domestic transmission of Escherichia coli O157:H7. Improved personal hygiene and environmental sanitation among parents and care givers can reduce the spread of diarrheal disease caused by this pathogen amongst children under the age of five years.Abstract: Escherichia coli O157:H7 has been considered an emerging foodborne pathogen causing severe diarrheal disease globally especially among children under the age of five years in Sub-Saharan Africa. This study was aimed at conducting a comparative study on the rate of isolation of Escherichia coli O157:H7 from diarrhoeic and non- diarrhoeic children in...Show More
