Screening Of Oleaginous Filamentous Fungi And The Optimization Of Its Fermentation Conditions

Single Cell Oil (SCO) was mainly synthesized and accumulated by fungi, yeasts, bacteria and algae under certain cultivation conditions in vivo. Triglyceride (95%) and non-esterified fatty acid, other micro component were found in it with carbon atom of 16～18 in most cases.Compositions of animal and plant oils varies with seasonal and geographical changes,in which the content of Poly-Unsarurated Fatty Acids(PUFAs) were low usually. PUFAs refer toγ-linolenic acid (GLA),α-linolenic acid (ALA),Arachidonic acid (ARA),Eicosapentaenoic acid (EPA) and Docosahexaenoic acid (DHA) etc. Many important functions, prevention and treatment of high blood pressure, heart disease, improvement of memory and sleep health were discovered.Polyunsaturated fatty acids from animal and plant fats become increasingly unable to meet growing market demand. Microorganisms were a renewable resource with short growth cycle. Making use of waste in agricultural and food industries can significantly reduce costs. Screening and identification of oil-producing strain, optimization of fermentation conditions and conditions and characterization of oil extracted have been studied in the thesis. The main researches are as follows:Single colonies of the fungus on selective medium were preserved by slant tube after Sudan black staining. Strains with large particles and deep fat shading were chosen. Spores were washed off for seed inoculation. The contents of crude oils in wet mycelia were measured by acid-heat extraction after filter.A strain, named 2-11, with high-yield was isolated from soil samples of high-latitude ranch. Content of crude oil was more than 30% after fermentation. Strain 2-11was identified as Penicillium according to colony morphology, cell morphology analysis. The highest yield of oil production by Penicillium was 64% both at home and abroad at present as reported.Fermentation medium and culture conditions were optimized by single-factor experiments and orthogonal test,The best fermentation medium (g/L):glucose 110,yeast extract 0.5,peptone 1,MgSO₄·7H₂O 0.2, K₂HPO₄ 0.03,ZnCl₂ 0.03,CaCl₂·2H₂O 0.03,MnSO₄·H₂O 0.03。Better culture conditions:initial pH 7.0,temperature prophase 28℃,anaphase 23℃,liquid volume in flask 30mL/250mL,rotation speed 180r/min,inoculation amount 3%,Fermentation period 7d.Fungal oil production content rise from 30.14% (dry mycelium) to 58.20% (dry mycelium).The fungal crude oil extraction methods were determined by comparison of Soxhlet extraction and acid-heat method. The fungi oil extraction process was studied preliminarily. The crude oil in mycelium after filter was extracted by acid-heat method.