Photoautotrophic cultivation of oleaginous microalgae and co-pelletization with filamentous fungi for cost-effective harvesting process and improved lipid yield

Oleaginous microalga Scenedesmus obliquus SIT06 was selected as potential biodiesel feedstocks due to its high lipid content and suitable fatty acid composition for production of biodiesel with high oxidative stability and high cetane number. The important factors for cultivating microalgae in photoautotrophic mode were optimized through response surface methodology (RSM). The highest microalgal biomass obtained was 1.99?±?0.12 g L^?1 with a high lipid content of 40.86?±?0.32%. To simplify harvesting process of microalgal cells, pellet-forming filamentous fungi were inoculated into the late log-phase of microalgae culture. Among the fungi tested, Cunninghamella echinulata TPU 4652 most effectively harvested the microalgal cells with the highest flocculation efficiency of 92.7%. Moreover, the biomass and lipids of microalgae-fungi pellets were as high as 4.45?±?0.06 and 1.21?±?0.08 g L^?1, respectively. The extracted lipids were mainly composed of C16:0, C18:0, and C18:1, and their estimated fuel properties meet with the international standards indicating their potential use as biodiesel feedstocks. This study has shown the strategies not only to simplify the harvesting process but also to increase the lipid yield and tailor the lipid composition.     

Pharmacokinetics of ivermectin in cats receiving a single subcutaneous dose

Ivermectin is effective against ecto- and endoparasites. It is included in a plan of the Filariasis Division, Thailand for filariasis control and prevention by interrupting transmission of Brugia malayi-microfilariae from cat reservoirs to humans via mosquitoes. The pharmacokinetics of ivermectin in eight healthy cats receiving a single subcutaneous dose of 0.2mg/kg was investigated. Jugular blood samples were collected periodically for up to 30days after dosing. The serum ivermectin concentrations were measured by high performance liquid chromatography with fluorescence detection. The pharmacokinetic parameters (mean+/-S.D.) derived from one-compartment model analysis were as follows: T(max) 1.22+/-0.49day, C(max) 16.75+/-4.04ng/mL, k(ab) 2.62+/-1.86day(-1), t(1/2)(ab) 0.27+/-0.25day, k(el) 0.27+/-0.14day(-1), t(1/2)(el) 2.53+/-2.24day, V(d)/F 9.81+/-5.41L/kg, Cl/F 2.21+/-0.69L/kg/day and AUC(0-->infinity) 98.31+/-30.52ngday/mL. In conclusion, the pharmacokinetics of ivermectin in cats receiving a single dose of 0.2mg/kg by subcutaneous injection revealed a rapid absorption, high distribution, slow elimination and high possibility for the elimination of B. malayi-microfilariae from currently endemic regions.     

Water quality control using Spirulina platensis in shrimp culture tanks

A cyanobacterium (Spirulina platensis) was co-cultured with black tiger shrimp (Penaeus monodon) for water quality control. We evaluated the effects of: (1) three S. platensis trial conditions on inorganic nitrogen concentrations at one shrimp density (S. platensis trial conditions included: absent, nonharvested and semicontinuous harvesting) and (2) two shrimp densities on inorganic nitrogen concentrations, with and without S. platensis. Semicontinuous harvesting of S. platensis at one shrimp density resulted in significantly reduced (P<0.05) inorganic nitrogen concentrations (NH₄, NO₂ and NO₃). With S. platensis absent, ammonium and nitrite concentrations ranged from 0.5 to 0.6 mg l⁻¹, while nitrate concentrations ranged from 16 to 18 mg l⁻¹ by day 44. With nonharvested S. platensis, considerable variability occurred with nitrogen concentrations. Semicontinuous harvest of S. platensis reduced nitrate to 4 mg l⁻¹, while ammonium and nitrite ranged from 0.0 to 0.15 mg l⁻¹, respectively. The factorial evaluation of shrimp density versus presence and absence of S. platensis resulted in greatly reduced nitrogenous compounds with S. platensis present regardless of shrimp density, and only moderately increased nitrogen with greater shrimp density. Without S. platensis, all nitrogen compounds were substantially elevated and shrimp survived was significantly reduced at high shrimp density.